/*
  * Microsoft Advanced Streaming Format demuxer
  * Copyright (c) 2014 Alexandra Hájková
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "libavutil/attributes.h"
 #include "libavutil/avassert.h"
 #include "libavutil/avstring.h"
 #include "libavutil/bswap.h"
 #include "libavutil/common.h"
 #include "libavutil/dict.h"
 #include "libavutil/internal.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/time_internal.h"
 
 #include "avformat.h"
 #include "avio_internal.h"
 #include "avlanguage.h"
 #include "id3v2.h"
 #include "internal.h"
 #include "riff.h"
 #include "asf.h"
 #include "asfcrypt.h"
 
 #define ASF_BOOL                              0x2
 #define ASF_WORD                              0x5
 #define ASF_GUID                              0x6
 #define ASF_DWORD                             0x3
 #define ASF_QWORD                             0x4
 #define ASF_UNICODE                           0x0
 #define ASF_FLAG_BROADCAST                    0x1
 #define ASF_BYTE_ARRAY                        0x1
 #define ASF_TYPE_AUDIO                        0x2
 #define ASF_TYPE_VIDEO                        0x1
 #define ASF_STREAM_NUM                        0x7F
 #define ASF_MAX_STREAMS                       128
 #define BMP_HEADER_SIZE                       40
 #define ASF_NUM_OF_PAYLOADS                   0x3F
 #define ASF_ERROR_CORRECTION_LENGTH_TYPE      0x60
 #define ASF_PACKET_ERROR_CORRECTION_DATA_SIZE 0x2
 
 typedef struct GUIDParseTable {
     const char *name;
     ff_asf_guid guid;
     int (*read_object)(AVFormatContext *, const struct GUIDParseTable *);
     int is_subobject;
 } GUIDParseTable;
 
 typedef struct ASFPacket {
     AVPacket avpkt;
     int64_t dts;
     uint32_t frame_num; // ASF payloads with the same number are parts of the same frame
     int flags;
     int data_size;
     int duration;
     int size_left;
     uint8_t stream_index;
 } ASFPacket;
 
 typedef struct ASFStream {
     uint8_t stream_index; // from packet header
     int index;  // stream index in AVFormatContext, set in asf_read_stream_properties
     int type;
     int indexed; // added index entries from the Simple Index Object or not
     int8_t span;   // for deinterleaving
     uint16_t virtual_pkt_len;
     uint16_t virtual_chunk_len;
     int16_t lang_idx;
     ASFPacket pkt;
 } ASFStream;
 
 typedef struct ASFStreamData{
     char langs[32];
     AVDictionary *asf_met; // for storing per-stream metadata
     AVRational aspect_ratio;
 } ASFStreamData;
 
 typedef struct ASFContext {
     int data_reached;
     int is_simple_index; // is simple index present or not 1/0
     int is_header;
 
     uint64_t preroll;
     uint64_t nb_packets; // ASF packets
     uint32_t packet_size;
     int64_t send_time;
     int duration;
 
     uint32_t b_flags;    // flags with broadcast flag
     uint32_t prop_flags; // file properties object flags
 
     uint64_t data_size; // data object size
     uint64_t unknown_size; // size of the unknown object
 
     int64_t offset; // offset of the current object
 
     int64_t data_offset;
     int64_t first_packet_offset; // packet offset
     int64_t unknown_offset;   // for top level header objects or subobjects without specified behavior
 
     // ASF file must not contain more than 128 streams according to the specification
     ASFStream *asf_st[ASF_MAX_STREAMS];
     ASFStreamData asf_sd[ASF_MAX_STREAMS];
     int nb_streams;
 
     int stream_index; // from packet header, for the subpayload case
 
     // packet parameteres
     uint64_t sub_header_offset; // offset of subplayload header
     int64_t sub_dts;
     uint8_t dts_delta; // for subpayloads
     uint32_t packet_size_internal; // packet size stored inside ASFPacket, can be 0
     int64_t packet_offset; // offset of the current packet inside Data Object
     uint32_t pad_len; // padding after payload
     uint32_t rep_data_len;
 
     // packet state
     uint64_t sub_left;  // subpayloads left or not

     unsigned int nb_sub; // number of subpayloads read so far from the current ASF packet

     uint16_t mult_sub_len; // total length of subpayloads array inside multiple payload
     uint64_t nb_mult_left; // multiple payloads left
     int return_subpayload;
     enum {
         PARSE_PACKET_HEADER,
         READ_SINGLE,
         READ_MULTI,
         READ_MULTI_SUB
     } state;
 } ASFContext;
 
 static int detect_unknown_subobject(AVFormatContext *s, int64_t offset, int64_t size);
 static const GUIDParseTable *find_guid(ff_asf_guid guid);
 
 static int asf_probe(AVProbeData *pd)
 {
     /* check file header */
     if (!ff_guidcmp(pd->buf, &ff_asf_header))
         return AVPROBE_SCORE_MAX/2;
     else
         return 0;
 }
 
 static void swap_guid(ff_asf_guid guid)
 {
     FFSWAP(unsigned char, guid[0], guid[3]);
     FFSWAP(unsigned char, guid[1], guid[2]);
     FFSWAP(unsigned char, guid[4], guid[5]);
     FFSWAP(unsigned char, guid[6], guid[7]);
 }
 
 static void align_position(AVIOContext *pb,  int64_t offset, uint64_t size)
 {

     if (size < INT64_MAX - offset && avio_tell(pb) != offset + size)

         avio_seek(pb, offset + size, SEEK_SET);
 }
 
 static int asf_read_unknown(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint64_t size   = avio_rl64(pb);
     int ret;
 

     if (size > INT64_MAX)
         return AVERROR_INVALIDDATA;
 

     if (asf->is_header)
         asf->unknown_size = size;
     asf->is_header = 0;
     if (!g->is_subobject) {
         if (!(ret = strcmp(g->name, "Header Extension")))
             avio_skip(pb, 22); // skip reserved fields and Data Size
         if ((ret = detect_unknown_subobject(s, asf->unknown_offset,
                                             asf->unknown_size)) < 0)
             return ret;

     } else {
         if (size < 24) {
             av_log(s, AV_LOG_ERROR, "Too small size %"PRIu64" (< 24).\n", size);
             return AVERROR_INVALIDDATA;
         }

         avio_skip(pb, size - 24);

     }

 
     return 0;
 }
 
 static int get_asf_string(AVIOContext *pb, int maxlen, char *buf, int buflen)
 {
     char *q = buf;
     int ret = 0;
     if (buflen <= 0)
         return AVERROR(EINVAL);
     while (ret + 1 < maxlen) {
         uint8_t tmp;
         uint32_t ch;
         GET_UTF16(ch, (ret += 2) <= maxlen ? avio_rl16(pb) : 0, break;);
         PUT_UTF8(ch, tmp, if (q - buf < buflen - 1) *q++ = tmp;)
     }
     *q = 0;
 
     return ret;
 }
 
 static int asf_read_marker(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint64_t size   = avio_rl64(pb);
     int i, nb_markers, ret;
     size_t len;
     char name[1024];
 
     avio_skip(pb, 8);
     avio_skip(pb, 8); // skip reserved GUID
     nb_markers = avio_rl32(pb);
     avio_skip(pb, 2); // skip reserved field
     len = avio_rl16(pb);
     for (i = 0; i < len; i++)
         avio_skip(pb, 1);
 
     for (i = 0; i < nb_markers; i++) {
         int64_t pts;
 
         avio_skip(pb, 8);
         pts = avio_rl64(pb);
         pts -= asf->preroll * 10000;
         avio_skip(pb, 2); // entry length
         avio_skip(pb, 4); // send time
         avio_skip(pb, 4); // flags
         len = avio_rl32(pb);
 
         if ((ret = avio_get_str16le(pb, len, name,
                                     sizeof(name))) < len)
             avio_skip(pb, len - ret);
         avpriv_new_chapter(s, i, (AVRational) { 1, 10000000 }, pts,
                            AV_NOPTS_VALUE, name);
     }
     align_position(pb, asf->offset, size);
 
     return 0;
 }
 
 static int asf_read_metadata(AVFormatContext *s, const char *title, uint16_t len,
                              unsigned char *ch, uint16_t buflen)
 {
     AVIOContext *pb = s->pb;
 
     avio_get_str16le(pb, len, ch, buflen);

     if (ch[0]) {
         if (av_dict_set(&s->metadata, title, ch, 0) < 0)
             av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
     }

 
     return 0;
 }
 

 static int asf_read_value(AVFormatContext *s, const uint8_t *name,

                           uint16_t val_len, int type, AVDictionary **met)
 {
     int ret;
     uint8_t *value;
     uint16_t buflen = 2 * val_len + 1;
     AVIOContext *pb = s->pb;
 
     value = av_malloc(buflen);
     if (!value)
         return AVERROR(ENOMEM);
     if (type == ASF_UNICODE) {
         // get_asf_string reads UTF-16 and converts it to UTF-8 which needs longer buffer
         if ((ret = get_asf_string(pb, val_len, value, buflen)) < 0)
             goto failed;
         if (av_dict_set(met, name, value, 0) < 0)
             av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
     } else {
         char buf[256];

         if (val_len > sizeof(buf)) {
             ret = AVERROR_INVALIDDATA;
             goto failed;
         }

         if ((ret = avio_read(pb, value, val_len)) < 0)
             goto failed;
         if (ret < 2 * val_len)
             value[ret] = '\0';
         else
             value[2 * val_len - 1] = '\0';
         snprintf(buf, sizeof(buf), "%s", value);
         if (av_dict_set(met, name, buf, 0) < 0)
             av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
     }
     av_freep(&value);
 
     return 0;
 
 failed:
     av_freep(&value);
     return ret;
 }

 static int asf_read_generic_value(AVIOContext *pb, int type, uint64_t *value)

 {
 
     switch (type) {
     case ASF_BOOL:

         *value = avio_rl16(pb);

         break;
     case ASF_DWORD:

         *value = avio_rl32(pb);

         break;
     case ASF_QWORD:

         *value = avio_rl64(pb);

         break;
     case ASF_WORD:

         *value = avio_rl16(pb);

         break;
     default:
         return AVERROR_INVALIDDATA;
     }

 
     return 0;
 }
 
 static int asf_set_metadata(AVFormatContext *s, const uint8_t *name,

                             int type, AVDictionary **met)

 {
     AVIOContext *pb = s->pb;
     uint64_t value;
     char buf[32];
     int ret;
 
     ret = asf_read_generic_value(pb, type, &value);
     if (ret < 0)
         return ret;
 

     snprintf(buf, sizeof(buf), "%"PRIu64, value);
     if (av_dict_set(met, name, buf, 0) < 0)
         av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
 
     return 0;
 }
 
 /* MSDN claims that this should be "compatible with the ID3 frame, APIC",
  * but in reality this is only loosely similar */
 static int asf_read_picture(AVFormatContext *s, int len)
 {
     ASFContext *asf       = s->priv_data;
     AVPacket pkt          = { 0 };
     const CodecMime *mime = ff_id3v2_mime_tags;
     enum  AVCodecID id    = AV_CODEC_ID_NONE;
     char mimetype[64];
     uint8_t  *desc = NULL;
     AVStream   *st = NULL;
     int ret, type, picsize, desc_len;
     ASFStream *asf_st;
 
     /* type + picsize + mime + desc */
     if (len < 1 + 4 + 2 + 2) {
         av_log(s, AV_LOG_ERROR, "Invalid attached picture size: %d.\n", len);
         return AVERROR_INVALIDDATA;
     }
 
     /* picture type */
     type = avio_r8(s->pb);
     len--;
     if (type >= FF_ARRAY_ELEMS(ff_id3v2_picture_types) || type < 0) {
         av_log(s, AV_LOG_WARNING, "Unknown attached picture type: %d.\n", type);
         type = 0;
     }
 
     /* picture data size */
     picsize = avio_rl32(s->pb);
     len    -= 4;
 
     /* picture MIME type */
     len -= avio_get_str16le(s->pb, len, mimetype, sizeof(mimetype));
     while (mime->id != AV_CODEC_ID_NONE) {
         if (!strncmp(mime->str, mimetype, sizeof(mimetype))) {
             id = mime->id;
             break;
         }
         mime++;
     }
     if (id == AV_CODEC_ID_NONE) {
         av_log(s, AV_LOG_ERROR, "Unknown attached picture mimetype: %s.\n",
                mimetype);
         return 0;
     }
 
     if (picsize >= len) {
         av_log(s, AV_LOG_ERROR, "Invalid attached picture data size: %d >= %d.\n",
                picsize, len);
         return AVERROR_INVALIDDATA;
     }
 
     /* picture description */
     desc_len = (len - picsize) * 2 + 1;
     desc     = av_malloc(desc_len);
     if (!desc)
         return AVERROR(ENOMEM);
     len -= avio_get_str16le(s->pb, len - picsize, desc, desc_len);
 
     ret = av_get_packet(s->pb, &pkt, picsize);
     if (ret < 0)
         goto fail;
 
     st  = avformat_new_stream(s, NULL);
     if (!st) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }
     asf->asf_st[asf->nb_streams] = av_mallocz(sizeof(*asf_st));
     asf_st = asf->asf_st[asf->nb_streams];

     if (!asf_st) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }

 
     st->disposition              |= AV_DISPOSITION_ATTACHED_PIC;
     st->codec->codec_type         = asf_st->type = AVMEDIA_TYPE_VIDEO;
     st->codec->codec_id           = id;
     st->attached_pic              = pkt;
     st->attached_pic.stream_index = asf_st->index = st->index;
     st->attached_pic.flags       |= AV_PKT_FLAG_KEY;
 
     asf->nb_streams++;
 
     if (*desc) {
         if (av_dict_set(&st->metadata, "title", desc, AV_DICT_DONT_STRDUP_VAL) < 0)
             av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
     } else
         av_freep(&desc);
 
     if (av_dict_set(&st->metadata, "comment", ff_id3v2_picture_types[type], 0) < 0)
         av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
 
     return 0;
 
 fail:
     av_freep(&desc);

     av_packet_unref(&pkt);

     return ret;
 }
 
 static void get_id3_tag(AVFormatContext *s, int len)
 {
     ID3v2ExtraMeta *id3v2_extra_meta = NULL;
 
     ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta, len);
     if (id3v2_extra_meta)
         ff_id3v2_parse_apic(s, &id3v2_extra_meta);
     ff_id3v2_free_extra_meta(&id3v2_extra_meta);
 }
 

 static int process_metadata(AVFormatContext *s, const uint8_t *name, uint16_t name_len,

                             uint16_t val_len, uint16_t type, AVDictionary **met)
 {
     int ret;
     ff_asf_guid guid;
 
     if (val_len) {
         switch (type) {
         case ASF_UNICODE:

             asf_read_value(s, name, val_len, type, met);

             break;
         case ASF_BYTE_ARRAY:
             if (!strcmp(name, "WM/Picture")) // handle cover art
                 asf_read_picture(s, val_len);
             else if (!strcmp(name, "ID3")) // handle ID3 tag
                 get_id3_tag(s, val_len);
             else

                 asf_read_value(s, name, val_len, type, met);

             break;
         case ASF_GUID:
             ff_get_guid(s->pb, &guid);
             break;
         default:

             if ((ret = asf_set_metadata(s, name, type, met)) < 0)

                 return ret;
             break;
         }
     }
 
     return 0;
 }
 
 static int asf_read_ext_content(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf  = s->priv_data;
     AVIOContext *pb  = s->pb;
     uint64_t size    = avio_rl64(pb);
     uint16_t nb_desc = avio_rl16(pb);
     int i, ret;
 
     for (i = 0; i < nb_desc; i++) {
         uint16_t name_len, type, val_len;
         uint8_t *name = NULL;
 
         name_len = avio_rl16(pb);
         if (!name_len)
             return AVERROR_INVALIDDATA;
         name = av_malloc(name_len);
         if (!name)
             return AVERROR(ENOMEM);
         avio_get_str16le(pb, name_len, name,
                          name_len);
         type    = avio_rl16(pb);

         // BOOL values are 16 bits long in the Metadata Object
         // but 32 bits long in the Extended Content Description Object
         if (type == ASF_BOOL)
             type = ASF_DWORD;

         val_len = avio_rl16(pb);
 

         ret = process_metadata(s, name, name_len, val_len, type, &s->metadata);
         av_freep(&name);
         if (ret < 0)

             return ret;
     }
 
     align_position(pb, asf->offset, size);
     return 0;
 }
 
 static AVStream *find_stream(AVFormatContext *s, uint16_t st_num)
 {
     AVStream *st = NULL;
     ASFContext *asf = s->priv_data;
     int i;
 
     for (i = 0; i < asf->nb_streams; i++) {
         if (asf->asf_st[i]->stream_index == st_num) {
             st = s->streams[asf->asf_st[i]->index];
             break;
         }
     }
 
     return st;
 }
 

 static int asf_store_aspect_ratio(AVFormatContext *s, uint8_t st_num, uint8_t *name, int type)

 {
     ASFContext *asf   = s->priv_data;
     AVIOContext *pb   = s->pb;

     uint64_t value = 0;
     int ret;

     ret = asf_read_generic_value(pb, type, &value);
     if (ret < 0)
         return ret;

 
     if (st_num < ASF_MAX_STREAMS) {
         if (!strcmp(name, "AspectRatioX"))
             asf->asf_sd[st_num].aspect_ratio.num = value;
         else
             asf->asf_sd[st_num].aspect_ratio.den = value;
     }

     return 0;

 }
 
 static int asf_read_metadata_obj(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf   = s->priv_data;
     AVIOContext *pb   = s->pb;
     uint64_t size     = avio_rl64(pb);
     uint16_t nb_recs  = avio_rl16(pb); // number of records in the Description Records list
     int i, ret;
 
     for (i = 0; i < nb_recs; i++) {
         uint16_t name_len, buflen, type, val_len, st_num;
         uint8_t *name = NULL;
 
         avio_skip(pb, 2); // skip reserved field
         st_num   = avio_rl16(pb);
         name_len = avio_rl16(pb);
         buflen   = 2 * name_len + 1;
         if (!name_len)
             break;
         type     = avio_rl16(pb);
         val_len  = avio_rl32(pb);

         name     = av_malloc(buflen);

         if (!name)
             return AVERROR(ENOMEM);
         avio_get_str16le(pb, name_len, name,
                          buflen);
         if (!strcmp(name, "AspectRatioX") || !strcmp(name, "AspectRatioY")) {

             ret = asf_store_aspect_ratio(s, st_num, name, type);

             if (ret < 0) {
                 av_freep(&name);
                 break;
             }

         } else {
             if (st_num < ASF_MAX_STREAMS) {
                 if ((ret = process_metadata(s, name, name_len, val_len, type,

                                             &asf->asf_sd[st_num].asf_met)) < 0) {
                     av_freep(&name);

                     break;

                 }
             }

         }

         av_freep(&name);

     }
 
     align_position(pb, asf->offset, size);
     return 0;
 }
 
 static int asf_read_content_desc(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     int i;
     static const char *const titles[] =
     { "Title", "Author", "Copyright", "Description", "Rate" };
     uint16_t len[5], buflen[5] = { 0 };
     uint8_t *ch;
     uint64_t size = avio_rl64(pb);
 
     for (i = 0; i < 5; i++) {
         len[i]  = avio_rl16(pb);
         // utf8 string should be <= 2 * utf16 string, extra byte for the terminator
         buflen[i]  = 2 * len[i] + 1;
     }
 
     for (i = 0; i < 5; i++) {
         ch = av_malloc(buflen[i]);
         if (!ch)
             return(AVERROR(ENOMEM));
         asf_read_metadata(s, titles[i], len[i], ch, buflen[i]);
         av_freep(&ch);
     }
     align_position(pb, asf->offset, size);
 
     return 0;
 }
 
 static int asf_read_properties(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;

     time_t creation_time;

 
     avio_rl64(pb); // read object size
     avio_skip(pb, 16); // skip File ID
     avio_skip(pb, 8);  // skip File size
     creation_time = avio_rl64(pb);
     if (!(asf->b_flags & ASF_FLAG_BROADCAST)) {
         struct tm tmbuf;
         struct tm *tm;
         char buf[64];
 
         // creation date is in 100 ns units from 1 Jan 1601, conversion to s
         creation_time /= 10000000;
         // there are 11644473600 seconds between 1 Jan 1601 and 1 Jan 1970
         creation_time -= 11644473600;
         tm = gmtime_r(&creation_time, &tmbuf);
         if (tm) {
             if (!strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
                 buf[0] = '\0';
         } else
             buf[0] = '\0';
         if (buf[0]) {
             if (av_dict_set(&s->metadata, "creation_time", buf, 0) < 0)
                 av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
         }
     }
     asf->nb_packets  = avio_rl64(pb);
     asf->duration    = avio_rl64(pb) / 10000; // stream duration
     avio_skip(pb, 8); // skip send duration
     asf->preroll     = avio_rl64(pb);
     asf->duration   -= asf->preroll;
     asf->b_flags     = avio_rl32(pb);
     avio_skip(pb, 4); // skip minimal packet size
     asf->packet_size  = avio_rl32(pb);
     avio_skip(pb, 4); // skip max_bitrate
 
     return 0;
 }
 
 static int parse_video_info(AVIOContext *pb, AVStream *st)
 {
     uint16_t size;
     unsigned int tag;
 
     st->codec->width  = avio_rl32(pb);
     st->codec->height = avio_rl32(pb);
     avio_skip(pb, 1); // skip reserved flags
     size = avio_rl16(pb); // size of the Format Data
     tag  = ff_get_bmp_header(pb, st, NULL);
     st->codec->codec_tag = tag;
     st->codec->codec_id  = ff_codec_get_id(ff_codec_bmp_tags, tag);
 
     if (size > BMP_HEADER_SIZE) {
         int ret;
         st->codec->extradata_size  = size - BMP_HEADER_SIZE;
         if (!(st->codec->extradata = av_malloc(st->codec->extradata_size +

                                                AV_INPUT_BUFFER_PADDING_SIZE))) {

             st->codec->extradata_size = 0;
             return AVERROR(ENOMEM);
         }
         memset(st->codec->extradata + st->codec->extradata_size , 0,

                AV_INPUT_BUFFER_PADDING_SIZE);

         if ((ret = avio_read(pb, st->codec->extradata,
                              st->codec->extradata_size)) < 0)
             return ret;
     }
     return 0;
 }
 
 static int asf_read_stream_properties(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint64_t size;
     uint32_t err_data_len, ts_data_len; // type specific data length
     uint16_t flags;
     ff_asf_guid stream_type;
     enum AVMediaType type;
     int i, ret;
     uint8_t stream_index;
     AVStream *st;
     ASFStream *asf_st;
 
     // ASF file must not contain more than 128 streams according to the specification
     if (asf->nb_streams >= ASF_MAX_STREAMS)
         return AVERROR_INVALIDDATA;
 
     size = avio_rl64(pb);
     ff_get_guid(pb, &stream_type);
     if (!ff_guidcmp(&stream_type, &ff_asf_audio_stream))
         type = AVMEDIA_TYPE_AUDIO;
     else if (!ff_guidcmp(&stream_type, &ff_asf_video_stream))
         type = AVMEDIA_TYPE_VIDEO;
     else if (!ff_guidcmp(&stream_type, &ff_asf_jfif_media))
         type = AVMEDIA_TYPE_VIDEO;
     else if (!ff_guidcmp(&stream_type, &ff_asf_command_stream))
         type = AVMEDIA_TYPE_DATA;
     else if (!ff_guidcmp(&stream_type,
                          &ff_asf_ext_stream_embed_stream_header))
         type = AVMEDIA_TYPE_UNKNOWN;
     else
         return AVERROR_INVALIDDATA;
 
     ff_get_guid(pb, &stream_type); // error correction type
     avio_skip(pb, 8); // skip the time offset
     ts_data_len      = avio_rl32(pb);
     err_data_len     = avio_rl32(pb);
     flags            = avio_rl16(pb); // bit 15 - Encrypted Content
 
     stream_index = flags & ASF_STREAM_NUM;
     for (i = 0; i < asf->nb_streams; i++)
         if (stream_index == asf->asf_st[i]->stream_index) {
             av_log(s, AV_LOG_WARNING,
                    "Duplicate stream found, this stream will be ignored.\n");
             align_position(pb, asf->offset, size);
             return 0;
         }
 
     st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
     avpriv_set_pts_info(st, 32, 1, 1000); // pts should be dword, in milliseconds
     st->codec->codec_type = type;
     asf->asf_st[asf->nb_streams] = av_mallocz(sizeof(*asf_st));
     if (!asf->asf_st[asf->nb_streams])
         return AVERROR(ENOMEM);
     asf_st                       = asf->asf_st[asf->nb_streams];

     asf->nb_streams++;

     asf_st->stream_index         = stream_index;
     asf_st->index                = st->index;
     asf_st->indexed              = 0;
     st->id                       = flags & ASF_STREAM_NUM;
     av_init_packet(&asf_st->pkt.avpkt);
     asf_st->pkt.data_size        = 0;
     avio_skip(pb, 4); // skip reserved field
 
     switch (type) {
     case AVMEDIA_TYPE_AUDIO:
         asf_st->type = AVMEDIA_TYPE_AUDIO;

         if ((ret = ff_get_wav_header(s, pb, st->codec, ts_data_len, 0)) < 0)

             return ret;
         break;
     case AVMEDIA_TYPE_VIDEO:
         asf_st->type = AVMEDIA_TYPE_VIDEO;
         if ((ret = parse_video_info(pb, st)) < 0)
             return ret;
         break;
     default:
         avio_skip(pb, ts_data_len);
         break;
     }
 
     if (err_data_len) {
         if (type == AVMEDIA_TYPE_AUDIO) {
             uint8_t span = avio_r8(pb);
             if (span > 1) {
                 asf_st->span              = span;
                 asf_st->virtual_pkt_len   = avio_rl16(pb);
                 asf_st->virtual_chunk_len = avio_rl16(pb);

                 if (!asf_st->virtual_chunk_len || !asf_st->virtual_pkt_len)
                     return AVERROR_INVALIDDATA;

                 avio_skip(pb, err_data_len - 5);
             } else
                 avio_skip(pb, err_data_len - 1);
         } else
             avio_skip(pb, err_data_len);
     }
 
     align_position(pb, asf->offset, size);
 
     return 0;
 }
 
 static void set_language(AVFormatContext *s, const char *rfc1766, AVDictionary **met)
 {
     // language abbr should contain at least 2 chars
     if (rfc1766 && strlen(rfc1766) > 1) {
         const char primary_tag[3] = { rfc1766[0], rfc1766[1], '\0' }; // ignore country code if any
         const char *iso6392       = av_convert_lang_to(primary_tag,
                                                        AV_LANG_ISO639_2_BIBL);
         if (iso6392)
             if (av_dict_set(met, "language", iso6392, 0) < 0)
                 av_log(s, AV_LOG_WARNING, "av_dict_set failed.\n");
     }
 }
 
 static int asf_read_ext_stream_properties(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     AVStream *st    = NULL;
     ff_asf_guid guid;
     uint16_t nb_st_name, nb_pay_exts, st_num, lang_idx;
     int i, ret;
     uint32_t bitrate;
     uint64_t start_time, end_time, time_per_frame;
     uint64_t size = avio_rl64(pb);
 
     start_time = avio_rl64(pb);
     end_time   = avio_rl64(pb);
     bitrate    = avio_rl32(pb);
     avio_skip(pb, 28); // skip some unused values
     st_num     = avio_rl16(pb);
     st_num    &= ASF_STREAM_NUM;
     lang_idx   = avio_rl16(pb); // Stream Language ID Index
     for (i = 0; i < asf->nb_streams; i++) {
         if (st_num == asf->asf_st[i]->stream_index) {
             st                       = s->streams[asf->asf_st[i]->index];
             asf->asf_st[i]->lang_idx = lang_idx;
             break;
         }
     }
     time_per_frame = avio_rl64(pb); // average time per frame
     if (st) {
         st->start_time           = start_time;
         st->duration             = end_time - start_time;
         st->codec->bit_rate      = bitrate;
         st->avg_frame_rate.num   = 10000000;
         st->avg_frame_rate.den   = time_per_frame;
     }
     nb_st_name = avio_rl16(pb);
     nb_pay_exts   = avio_rl16(pb);
     for (i = 0; i < nb_st_name; i++) {
         uint16_t len;
 
         avio_rl16(pb); // Language ID Index
         len = avio_rl16(pb);
         avio_skip(pb, len);
     }
 
     for (i = 0; i < nb_pay_exts; i++) {
         uint32_t len;
         avio_skip(pb, 16); // Extension System ID
         avio_skip(pb, 2);  // Extension Data Size
         len = avio_rl32(pb);
         avio_skip(pb, len);
     }
 
     if ((ret = ff_get_guid(pb, &guid)) < 0) {
         align_position(pb, asf->offset, size);
 
         return 0;
     }
 
     g = find_guid(guid);
     if (g && !(strcmp(g->name, "Stream Properties"))) {
         if ((ret = g->read_object(s, g)) < 0)
             return ret;
     }
 
     align_position(pb, asf->offset, size);
     return 0;
 }
 
 static int asf_read_language_list(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf   = s->priv_data;
     AVIOContext *pb   = s->pb;
     int i, ret;
     uint64_t size     = avio_rl64(pb);
     uint16_t nb_langs = avio_rl16(pb);
 
     if (nb_langs < ASF_MAX_STREAMS) {
         for (i = 0; i < nb_langs; i++) {
             size_t len;
             len = avio_r8(pb);
             if (!len)
                 len = 6;
             if ((ret = get_asf_string(pb, len, asf->asf_sd[i].langs,
                                       sizeof(asf->asf_sd[i].langs))) < 0) {
                 return ret;
             }
         }
     }
 
     align_position(pb, asf->offset, size);
     return 0;
 }
 
 // returns data object offset when reading this object for the first time
 static int asf_read_data(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint64_t size   = asf->data_size = avio_rl64(pb);
     int i;
 

     if (!asf->data_reached) {

         asf->data_reached       = 1;
         asf->data_offset        = asf->offset;
     }
 
     for (i = 0; i < asf->nb_streams; i++) {
         if (!(asf->b_flags & ASF_FLAG_BROADCAST))
             s->streams[i]->duration = asf->duration;
     }
     asf->nb_mult_left           = 0;
     asf->sub_left               = 0;
     asf->state                  = PARSE_PACKET_HEADER;
     asf->return_subpayload      = 0;
     asf->packet_size_internal   = 0;
     avio_skip(pb, 16); // skip File ID
     size = avio_rl64(pb); // Total Data Packets
     if (size != asf->nb_packets)
         av_log(s, AV_LOG_WARNING,
                "Number of Packets from File Properties Object is not equal to Total"
                "Datapackets value! num of packets %"PRIu64" total num %"PRIu64".\n",
                size, asf->nb_packets);
     avio_skip(pb, 2); // skip reserved field
     asf->first_packet_offset = avio_tell(pb);

     if (pb->seekable && !(asf->b_flags & ASF_FLAG_BROADCAST))

         align_position(pb, asf->offset, asf->data_size);

 
     return 0;
 }
 
 static int asf_read_simple_index(AVFormatContext *s, const GUIDParseTable *g)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     AVStream *st    = NULL;
     uint64_t interval; // index entry time interval in 100 ns units, usually it's 1s
     uint32_t pkt_num, nb_entries;
     int32_t prev_pkt_num = -1;

     int i, ret;

     uint64_t size = avio_rl64(pb);
 
     // simple index objects should be ordered by stream number, this loop tries to find
     // the first not indexed video stream
     for (i = 0; i < asf->nb_streams; i++) {
         if ((asf->asf_st[i]->type == AVMEDIA_TYPE_VIDEO) && !asf->asf_st[i]->indexed) {
             asf->asf_st[i]->indexed = 1;
             st = s->streams[asf->asf_st[i]->index];
             break;
         }
     }
     if (!st) {
         avio_skip(pb, size - 24); // if there's no video stream, skip index object
         return 0;
     }
     avio_skip(pb, 16); // skip File ID
     interval = avio_rl64(pb);
     avio_skip(pb, 4);
     nb_entries = avio_rl32(pb);
     for (i = 0; i < nb_entries; i++) {
         pkt_num = avio_rl32(pb);

         ret = avio_skip(pb, 2);
         if (ret < 0) {
             av_log(s, AV_LOG_ERROR, "Skipping failed in asf_read_simple_index.\n");
             return ret;
         }

         if (prev_pkt_num != pkt_num) {
             av_add_index_entry(st, asf->first_packet_offset + asf->packet_size *
                                pkt_num, av_rescale(interval, i, 10000),
                                asf->packet_size, 0, AVINDEX_KEYFRAME);
             prev_pkt_num = pkt_num;
         }
     }
     asf->is_simple_index = 1;
     align_position(pb, asf->offset, size);
 
     return 0;
 }
 
 static const GUIDParseTable gdef[] = {
     { "Data",                         { 0x75, 0xB2, 0x26, 0x36, 0x66, 0x8E, 0x11, 0xCF, 0xA6, 0xD9, 0x00, 0xAA, 0x00, 0x62, 0xCE, 0x6C }, asf_read_data, 1 },
     { "Simple Index",                 { 0x33, 0x00, 0x08, 0x90, 0xE5, 0xB1, 0x11, 0xCF, 0x89, 0xF4, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xCB }, asf_read_simple_index, 1 },
     { "Content Description",          { 0x75, 0xB2, 0x26, 0x33, 0x66 ,0x8E, 0x11, 0xCF, 0xA6, 0xD9, 0x00, 0xAA, 0x00, 0x62, 0xCE, 0x6C }, asf_read_content_desc, 1 },
     { "Extended Content Description", { 0xD2, 0xD0, 0xA4, 0x40, 0xE3, 0x07, 0x11, 0xD2, 0x97, 0xF0, 0x00, 0xA0, 0xC9, 0x5e, 0xA8, 0x50 }, asf_read_ext_content, 1 },
     { "Stream Bitrate Properties",    { 0x7B, 0xF8, 0x75, 0xCE, 0x46, 0x8D, 0x11, 0xD1, 0x8D, 0x82, 0x00, 0x60, 0x97, 0xC9, 0xA2, 0xB2 }, asf_read_unknown, 1 },
     { "File Properties",              { 0x8C, 0xAB, 0xDC, 0xA1, 0xA9, 0x47, 0x11, 0xCF, 0x8E, 0xE4, 0x00, 0xC0, 0x0C, 0x20, 0x53, 0x65 }, asf_read_properties, 1 },
     { "Header Extension",             { 0x5F, 0xBF, 0x03, 0xB5, 0xA9, 0x2E, 0x11, 0xCF, 0x8E, 0xE3, 0x00, 0xC0, 0x0C, 0x20, 0x53, 0x65 }, asf_read_unknown, 0 },
     { "Stream Properties",            { 0xB7, 0xDC, 0x07, 0x91, 0xA9, 0xB7, 0x11, 0xCF, 0x8E, 0xE6, 0x00, 0xC0, 0x0C, 0x20, 0x53, 0x65 }, asf_read_stream_properties, 1 },
     { "Codec List",                   { 0x86, 0xD1, 0x52, 0x40, 0x31, 0x1D, 0x11, 0xD0, 0xA3, 0xA4, 0x00, 0xA0, 0xC9, 0x03, 0x48, 0xF6 }, asf_read_unknown, 1 },
     { "Marker",                       { 0xF4, 0x87, 0xCD, 0x01, 0xA9, 0x51, 0x11, 0xCF, 0x8E, 0xE6, 0x00, 0xC0, 0x0C, 0x20, 0x53, 0x65 }, asf_read_marker, 1 },
     { "Script Command",               { 0x1E, 0xFB, 0x1A, 0x30, 0x0B, 0x62, 0x11, 0xD0, 0xA3, 0x9B, 0x00, 0xA0, 0xC9, 0x03, 0x48, 0xF6 }, asf_read_unknown, 1 },
     { "Language List",                { 0x7C, 0x43, 0x46, 0xa9, 0xef, 0xe0, 0x4B, 0xFC, 0xB2, 0x29, 0x39, 0x3e, 0xde, 0x41, 0x5c, 0x85 }, asf_read_language_list, 1},
     { "Padding",                      { 0x18, 0x06, 0xD4, 0x74, 0xCA, 0xDF, 0x45, 0x09, 0xA4, 0xBA, 0x9A, 0xAB, 0xCB, 0x96, 0xAA, 0xE8 }, asf_read_unknown, 1 },
     { "DRMv1 Header",                 { 0x22, 0x11, 0xB3, 0xFB, 0xBD, 0x23, 0x11, 0xD2, 0xB4, 0xB7, 0x00, 0xA0, 0xC9, 0x55, 0xFC, 0x6E }, asf_read_unknown, 1 },
     { "DRMv2 Header",                 { 0x29, 0x8A, 0xE6, 0x14, 0x26, 0x22, 0x4C, 0x17, 0xB9, 0x35, 0xDA, 0xE0, 0x7E, 0xE9, 0x28, 0x9c }, asf_read_unknown, 1 },
     { "Index",                        { 0xD6, 0xE2, 0x29, 0xD3, 0x35, 0xDA, 0x11, 0xD1, 0x90, 0x34, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xBE }, asf_read_unknown, 1 },
     { "Media Object Index",           { 0xFE, 0xB1, 0x03, 0xF8, 0x12, 0xAD, 0x4C, 0x64, 0x84, 0x0F, 0x2A, 0x1D, 0x2F, 0x7A, 0xD4, 0x8C }, asf_read_unknown, 1 },
     { "Timecode Index",               { 0x3C, 0xB7, 0x3F, 0xD0, 0x0C, 0x4A, 0x48, 0x03, 0x95, 0x3D, 0xED, 0xF7, 0xB6, 0x22, 0x8F, 0x0C }, asf_read_unknown, 0 },
     { "Bitrate_Mutual_Exclusion",     { 0xD6, 0xE2, 0x29, 0xDC, 0x35, 0xDA, 0x11, 0xD1, 0x90, 0x34, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xBE }, asf_read_unknown, 1 },
     { "Error Correction",             { 0x75, 0xB2, 0x26, 0x35, 0x66, 0x8E, 0x11, 0xCF, 0xA6, 0xD9, 0x00, 0xAA, 0x00, 0x62, 0xCE, 0x6C }, asf_read_unknown, 1 },
     { "Content Branding",             { 0x22, 0x11, 0xB3, 0xFA, 0xBD, 0x23, 0x11, 0xD2, 0xB4, 0xB7, 0x00, 0xA0, 0xC9, 0x55, 0xFC, 0x6E }, asf_read_unknown, 1 },
     { "Content Encryption",           { 0x22, 0x11, 0xB3, 0xFB, 0xBD, 0x23, 0x11, 0xD2, 0xB4, 0xB7, 0x00, 0xA0, 0xC9, 0x55, 0xFC, 0x6E }, asf_read_unknown, 1 },
     { "Extended Content Encryption",  { 0x29, 0x8A, 0xE6, 0x14, 0x26, 0x22, 0x4C, 0x17, 0xB9, 0x35, 0xDA, 0xE0, 0x7E, 0xE9, 0x28, 0x9C }, asf_read_unknown, 1 },
     { "Digital Signature",            { 0x22, 0x11, 0xB3, 0xFC, 0xBD, 0x23, 0x11, 0xD2, 0xB4, 0xB7, 0x00, 0xA0, 0xC9, 0x55, 0xFC, 0x6E }, asf_read_unknown, 1 },
     { "Extended Stream Properties",   { 0x14, 0xE6, 0xA5, 0xCB, 0xC6, 0x72, 0x43, 0x32, 0x83, 0x99, 0xA9, 0x69, 0x52, 0x06, 0x5B, 0x5A }, asf_read_ext_stream_properties, 1 },
     { "Advanced Mutual Exclusion",    { 0xA0, 0x86, 0x49, 0xCF, 0x47, 0x75, 0x46, 0x70, 0x8A, 0x16, 0x6E, 0x35, 0x35, 0x75, 0x66, 0xCD }, asf_read_unknown, 1 },
     { "Group Mutual Exclusion",       { 0xD1, 0x46, 0x5A, 0x40, 0x5A, 0x79, 0x43, 0x38, 0xB7, 0x1B, 0xE3, 0x6B, 0x8F, 0xD6, 0xC2, 0x49 }, asf_read_unknown, 1},
     { "Stream Prioritization",        { 0xD4, 0xFE, 0xD1, 0x5B, 0x88, 0xD3, 0x45, 0x4F, 0x81, 0xF0, 0xED, 0x5C, 0x45, 0x99, 0x9E, 0x24 }, asf_read_unknown, 1 },
     { "Bandwidth Sharing Object",     { 0xA6, 0x96, 0x09, 0xE6, 0x51, 0x7B, 0x11, 0xD2, 0xB6, 0xAF, 0x00, 0xC0, 0x4F, 0xD9, 0x08, 0xE9 }, asf_read_unknown, 1 },
     { "Metadata",                     { 0xC5, 0xF8, 0xCB, 0xEA, 0x5B, 0xAF, 0x48, 0x77, 0x84, 0x67, 0xAA, 0x8C, 0x44, 0xFA, 0x4C, 0xCA }, asf_read_metadata_obj, 1 },
     { "Metadata Library",             { 0x44, 0x23, 0x1C, 0x94, 0x94, 0x98, 0x49, 0xD1, 0xA1, 0x41, 0x1D, 0x13, 0x4E, 0x45, 0x70, 0x54 }, asf_read_metadata_obj, 1 },
     { "Audio Spread",                 { 0xBF, 0xC3, 0xCD, 0x50, 0x61, 0x8F, 0x11, 0xCF, 0x8B, 0xB2, 0x00, 0xAA, 0x00, 0xB4, 0xE2, 0x20 }, asf_read_unknown, 1 },
     { "Index Parameters",             { 0xD6, 0xE2, 0x29, 0xDF, 0x35, 0xDA, 0x11, 0xD1, 0x90, 0x34, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xBE }, asf_read_unknown, 1 },
     { "Content Encryption System Windows Media DRM Network Devices",
                                       { 0x7A, 0x07, 0x9B, 0xB6, 0xDA, 0XA4, 0x4e, 0x12, 0xA5, 0xCA, 0x91, 0xD3, 0x8D, 0xC1, 0x1A, 0x8D }, asf_read_unknown, 1 },
     { "Mutex Language",               { 0xD6, 0xE2, 0x2A, 0x00, 0x25, 0xDA, 0x11, 0xD1, 0x90, 0x34, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xBE }, asf_read_unknown, 1 },
     { "Mutex Bitrate",                { 0xD6, 0xE2, 0x2A, 0x01, 0x25, 0xDA, 0x11, 0xD1, 0x90, 0x34, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xBE }, asf_read_unknown, 1 },
     { "Mutex Unknown",                { 0xD6, 0xE2, 0x2A, 0x02, 0x25, 0xDA, 0x11, 0xD1, 0x90, 0x34, 0x00, 0xA0, 0xC9, 0x03, 0x49, 0xBE }, asf_read_unknown, 1 },

     { "Bandwidth Sharing Exclusive",  { 0xAF, 0x60, 0x60, 0xAA, 0x51, 0x97, 0x11, 0xD2, 0xB6, 0xAF, 0x00, 0xC0, 0x4F, 0xD9, 0x08, 0xE9 }, asf_read_unknown, 1 },
     { "Bandwidth Sharing Partial",    { 0xAF, 0x60, 0x60, 0xAB, 0x51, 0x97, 0x11, 0xD2, 0xB6, 0xAF, 0x00, 0xC0, 0x4F, 0xD9, 0x08, 0xE9 }, asf_read_unknown, 1 },

     { "Payload Extension System Timecode", { 0x39, 0x95, 0x95, 0xEC, 0x86, 0x67, 0x4E, 0x2D, 0x8F, 0xDB, 0x98, 0x81, 0x4C, 0xE7, 0x6C, 0x1E }, asf_read_unknown, 1 },
     { "Payload Extension System File Name", { 0xE1, 0x65, 0xEC, 0x0E, 0x19, 0xED, 0x45, 0xD7, 0xB4, 0xA7, 0x25, 0xCB, 0xD1, 0xE2, 0x8E, 0x9B }, asf_read_unknown, 1 },
     { "Payload Extension System Content Type", { 0xD5, 0x90, 0xDC, 0x20, 0x07, 0xBC, 0x43, 0x6C, 0x9C, 0xF7, 0xF3, 0xBB, 0xFB, 0xF1, 0xA4, 0xDC }, asf_read_unknown, 1 },
     { "Payload Extension System Pixel Aspect Ratio", { 0x1, 0x1E, 0xE5, 0x54, 0xF9, 0xEA, 0x4B, 0xC8, 0x82, 0x1A, 0x37, 0x6B, 0x74, 0xE4, 0xC4, 0xB8 }, asf_read_unknown, 1 },
     { "Payload Extension System Sample Duration", { 0xC6, 0xBD, 0x94, 0x50, 0x86, 0x7F, 0x49, 0x07, 0x83, 0xA3, 0xC7, 0x79, 0x21, 0xB7, 0x33, 0xAD }, asf_read_unknown, 1 },
     { "Payload Extension System Encryption Sample ID", { 0x66, 0x98, 0xB8, 0x4E, 0x0A, 0xFA, 0x43, 0x30, 0xAE, 0xB2, 0x1C, 0x0A, 0x98, 0xD7, 0xA4, 0x4D }, asf_read_unknown, 1 },
     { "Payload Extension System Degradable JPEG", { 0x00, 0xE1, 0xAF, 0x06, 0x7B, 0xEC, 0x11, 0xD1, 0xA5, 0x82, 0x00, 0xC0, 0x4F, 0xC2, 0x9C, 0xFB }, asf_read_unknown, 1 },
 };
 
 #define READ_LEN(flag, name, len)            \
     do {                                     \
         if ((flag) == name ## IS_BYTE)       \
             len = avio_r8(pb);               \
         else if ((flag) == name ## IS_WORD)  \
             len = avio_rl16(pb);             \
         else if ((flag) == name ## IS_DWORD) \
             len = avio_rl32(pb);             \
         else                                 \
             len = 0;                         \
     } while(0)
 
 static int asf_read_subpayload(AVFormatContext *s, AVPacket *pkt, int is_header)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint8_t sub_len;
     int ret, i;
 
     if (is_header) {
         asf->dts_delta = avio_r8(pb);
         if (asf->nb_mult_left) {
             asf->mult_sub_len = avio_rl16(pb); // total
         }
         asf->sub_header_offset = avio_tell(pb);
         asf->nb_sub = 0;
         asf->sub_left = 1;
     }
     sub_len = avio_r8(pb);
     if ((ret = av_get_packet(pb, pkt, sub_len)) < 0) // each subpayload is entire frame
         return ret;
     for (i = 0; i < asf->nb_streams; i++) {
         if (asf->stream_index == asf->asf_st[i]->stream_index) {
             pkt->stream_index  = asf->asf_st[i]->index;
             break;
         }
     }
     asf->return_subpayload = 1;
     if (!sub_len)
         asf->return_subpayload = 0;
 
     if (sub_len)
         asf->nb_sub++;
     pkt->dts = asf->sub_dts + (asf->nb_sub - 1) * asf->dts_delta - asf->preroll;
     if (asf->nb_mult_left && (avio_tell(pb) >=
                               (asf->sub_header_offset + asf->mult_sub_len))) {
         asf->sub_left = 0;
         asf->nb_mult_left--;
     }
     if (avio_tell(pb) >= asf->packet_offset + asf->packet_size - asf->pad_len) {
         asf->sub_left = 0;
         if (!asf->nb_mult_left) {
             avio_skip(pb, asf->pad_len);
             if (avio_tell(pb) != asf->packet_offset + asf->packet_size) {
                 if (!asf->packet_size)
                     return AVERROR_INVALIDDATA;
                 av_log(s, AV_LOG_WARNING,
                        "Position %"PRId64" wrong, should be %"PRId64"\n",
                        avio_tell(pb), asf->packet_offset + asf->packet_size);
                 avio_seek(pb, asf->packet_offset + asf->packet_size, SEEK_SET);
             }
         }
     }
 
     return 0;
 }
 
 static void reset_packet(ASFPacket *asf_pkt)
 {
     asf_pkt->size_left = 0;
     asf_pkt->data_size = 0;
     asf_pkt->duration  = 0;
     asf_pkt->flags     = 0;
     asf_pkt->dts       = 0;
     asf_pkt->duration  = 0;

     av_packet_unref(&asf_pkt->avpkt);

     av_init_packet(&asf_pkt->avpkt);
 }
 

 static int asf_read_replicated_data(AVFormatContext *s, ASFPacket *asf_pkt)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;

     int ret, data_size;

 
     if (!asf_pkt->data_size) {

         data_size = avio_rl32(pb); // read media object size
         if (data_size <= 0)

             return AVERROR_INVALIDDATA;

         if ((ret = av_new_packet(&asf_pkt->avpkt, data_size)) < 0)

             return ret;

         asf_pkt->data_size = asf_pkt->size_left = data_size;

     } else
         avio_skip(pb, 4); // reading of media object size is already done
     asf_pkt->dts = avio_rl32(pb); // read presentation time
     if (asf->rep_data_len && (asf->rep_data_len >= 8))
         avio_skip(pb, asf->rep_data_len - 8); // skip replicated data
 
     return 0;
 }
 

 static int asf_read_multiple_payload(AVFormatContext *s, AVPacket *pkt,
                                  ASFPacket *asf_pkt)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint16_t pay_len;
     unsigned char *p;
     int ret;
     int skip = 0;
 

     // if replicated length is 1, subpayloads are present

     if (asf->rep_data_len == 1) {
         asf->sub_left = 1;
         asf->state = READ_MULTI_SUB;
         pkt->flags = asf_pkt->flags;
         if ((ret = asf_read_subpayload(s, pkt, 1)) < 0)
             return ret;
     } else {

         if (asf->rep_data_len)
             if ((ret = asf_read_replicated_data(s, asf_pkt)) < 0)
                 return ret;

         pay_len = avio_rl16(pb); // payload length should be WORD
         if (pay_len > asf->packet_size) {
             av_log(s, AV_LOG_ERROR,
                    "Error: invalid data packet size, pay_len %"PRIu16", "
                    "asf->packet_size %"PRIu32", offset %"PRId64".\n",
                    pay_len, asf->packet_size, avio_tell(pb));
             return AVERROR_INVALIDDATA;
         }
         p = asf_pkt->avpkt.data + asf_pkt->data_size - asf_pkt->size_left;
         if (pay_len > asf_pkt->size_left) {
             av_log(s, AV_LOG_ERROR,
                    "Error: invalid buffer size, pay_len %d, data size left %d.\n",
             pay_len, asf_pkt->size_left);
             skip = pay_len - asf_pkt->size_left;
             pay_len = asf_pkt->size_left;
         }

         if (asf_pkt->size_left <= 0)
             return AVERROR_INVALIDDATA;

         if ((ret = avio_read(pb, p, pay_len)) < 0)
             return ret;
         if (s->key && s->keylen == 20)
             ff_asfcrypt_dec(s->key, p, ret);
         avio_skip(pb, skip);
         asf_pkt->size_left -= pay_len;
         asf->nb_mult_left--;
     }
 
     return 0;
 }
 

 static int asf_read_single_payload(AVFormatContext *s, ASFPacket *asf_pkt)

 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     int64_t  offset;
     uint64_t size;
     unsigned char *p;

     int ret, data_size;

 
     if (!asf_pkt->data_size) {

         data_size = avio_rl32(pb); // read media object size
         if (data_size <= 0)

             return AVERROR_EOF;

         if ((ret = av_new_packet(&asf_pkt->avpkt, data_size)) < 0)

             return ret;

         asf_pkt->data_size = asf_pkt->size_left = data_size;

     } else
         avio_skip(pb, 4); // skip media object size
     asf_pkt->dts = avio_rl32(pb); // read presentation time

     if (asf->rep_data_len >= 8)

         avio_skip(pb, asf->rep_data_len - 8); // skip replicated data
     offset = avio_tell(pb);
 
     // size of the payload - size of the packet without header and padding
     if (asf->packet_size_internal)
         size = asf->packet_size_internal - offset + asf->packet_offset - asf->pad_len;
     else
         size = asf->packet_size - offset + asf->packet_offset - asf->pad_len;
     if (size > asf->packet_size) {
         av_log(s, AV_LOG_ERROR,
                "Error: invalid data packet size, offset %"PRId64".\n",
                avio_tell(pb));
         return AVERROR_INVALIDDATA;
     }
     p = asf_pkt->avpkt.data + asf_pkt->data_size - asf_pkt->size_left;

     if (size > asf_pkt->size_left || asf_pkt->size_left <= 0)

         return AVERROR_INVALIDDATA;
     if (asf_pkt->size_left > size)
         asf_pkt->size_left -= size;
     else
         asf_pkt->size_left = 0;
     if ((ret = avio_read(pb, p, size)) < 0)
         return ret;
     if (s->key && s->keylen == 20)
             ff_asfcrypt_dec(s->key, p, ret);
     if (asf->packet_size_internal)
         avio_skip(pb, asf->packet_size - asf->packet_size_internal);
     avio_skip(pb, asf->pad_len); // skip padding
 
     return 0;
 }
 
 static int asf_read_payload(AVFormatContext *s, AVPacket *pkt)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     int ret, i;
     ASFPacket *asf_pkt = NULL;
 
     if (!asf->sub_left) {
         uint32_t off_len, media_len;
         uint8_t stream_num;
 
         stream_num = avio_r8(pb);
         asf->stream_index = stream_num & ASF_STREAM_NUM;
         for (i = 0; i < asf->nb_streams; i++) {
             if (asf->stream_index == asf->asf_st[i]->stream_index) {
                 asf_pkt               = &asf->asf_st[i]->pkt;
                 asf_pkt->stream_index = asf->asf_st[i]->index;
                 break;
             }
         }

         if (!asf_pkt) {
             if (asf->packet_offset + asf->packet_size <= asf->data_offset + asf->data_size) {

                 if (!asf->packet_size) {
                     av_log(s, AV_LOG_ERROR, "Invalid packet size 0.\n");
                     return AVERROR_INVALIDDATA;
                 }

                 avio_seek(pb, asf->packet_offset + asf->packet_size, SEEK_SET);
                 av_log(s, AV_LOG_WARNING, "Skipping the stream with the invalid stream index %d.\n",
                        asf->stream_index);
                 return AVERROR(EAGAIN);
             } else
                 return AVERROR_INVALIDDATA;
         }
 

         if (stream_num >> 7)
             asf_pkt->flags |= AV_PKT_FLAG_KEY;
         READ_LEN(asf->prop_flags & ASF_PL_MASK_MEDIA_OBJECT_NUMBER_LENGTH_FIELD_SIZE,
                  ASF_PL_FLAG_MEDIA_OBJECT_NUMBER_LENGTH_FIELD_, media_len);
         READ_LEN(asf->prop_flags & ASF_PL_MASK_OFFSET_INTO_MEDIA_OBJECT_LENGTH_FIELD_SIZE,
                  ASF_PL_FLAG_OFFSET_INTO_MEDIA_OBJECT_LENGTH_FIELD_, off_len);
         READ_LEN(asf->prop_flags & ASF_PL_MASK_REPLICATED_DATA_LENGTH_FIELD_SIZE,
                  ASF_PL_FLAG_REPLICATED_DATA_LENGTH_FIELD_, asf->rep_data_len);
         if (asf_pkt->size_left && (asf_pkt->frame_num != media_len)) {
             av_log(s, AV_LOG_WARNING, "Unfinished frame will be ignored\n");
             reset_packet(asf_pkt);
         }
         asf_pkt->frame_num = media_len;
         asf->sub_dts = off_len;
         if (asf->nb_mult_left) {
             if ((ret = asf_read_multiple_payload(s, pkt, asf_pkt)) < 0)
                 return ret;
         } else if (asf->rep_data_len == 1) {
             asf->sub_left = 1;
             asf->state    = READ_SINGLE;
             pkt->flags    = asf_pkt->flags;
             if ((ret = asf_read_subpayload(s, pkt, 1)) < 0)
                 return ret;
         } else {

             if ((ret = asf_read_single_payload(s, asf_pkt)) < 0)

                 return ret;
         }
     } else {
         for (i = 0; i <= asf->nb_streams; i++) {
             if (asf->stream_index == asf->asf_st[i]->stream_index) {
                 asf_pkt = &asf->asf_st[i]->pkt;
                 break;
             }
         }
         if (!asf_pkt)
             return AVERROR_INVALIDDATA;
         pkt->flags         = asf_pkt->flags;
         pkt->dts           = asf_pkt->dts;
         pkt->stream_index  = asf->asf_st[i]->index;
         if ((ret = asf_read_subpayload(s, pkt, 0)) < 0) // read subpayload without its header
             return ret;
     }
 
     return 0;
 }
 
 static int asf_read_packet_header(AVFormatContext *s)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     uint64_t size;
     uint32_t av_unused seq;
     unsigned char error_flags, len_flags, pay_flags;
 
     asf->packet_offset = avio_tell(pb);
     error_flags = avio_r8(pb); // read Error Correction Flags

     if (error_flags & ASF_PACKET_FLAG_ERROR_CORRECTION_PRESENT) {

         if (!(error_flags & ASF_ERROR_CORRECTION_LENGTH_TYPE)) {
             size = error_flags & ASF_PACKET_ERROR_CORRECTION_DATA_SIZE;
             avio_skip(pb, size);
         }

         len_flags       = avio_r8(pb);
     } else
         len_flags = error_flags;

     asf->prop_flags = avio_r8(pb);
     READ_LEN(len_flags & ASF_PPI_MASK_PACKET_LENGTH_FIELD_SIZE,
              ASF_PPI_FLAG_PACKET_LENGTH_FIELD_, asf->packet_size_internal);
     READ_LEN(len_flags & ASF_PPI_MASK_SEQUENCE_FIELD_SIZE,
              ASF_PPI_FLAG_SEQUENCE_FIELD_, seq);
     READ_LEN(len_flags & ASF_PPI_MASK_PADDING_LENGTH_FIELD_SIZE,
              ASF_PPI_FLAG_PADDING_LENGTH_FIELD_, asf->pad_len );
     asf->send_time = avio_rl32(pb); // send time
     avio_skip(pb, 2); // skip duration
     if (len_flags & ASF_PPI_FLAG_MULTIPLE_PAYLOADS_PRESENT) { // Multiple Payloads present
         pay_flags = avio_r8(pb);
         asf->nb_mult_left = (pay_flags & ASF_NUM_OF_PAYLOADS);
     }
 
     return 0;
 }
 
 static int asf_deinterleave(AVFormatContext *s, ASFPacket *asf_pkt, int st_num)
 {
     ASFContext *asf    = s->priv_data;
     ASFStream *asf_st  = asf->asf_st[st_num];
     unsigned char *p   = asf_pkt->avpkt.data;
     uint16_t pkt_len   = asf->asf_st[st_num]->virtual_pkt_len;
     uint16_t chunk_len = asf->asf_st[st_num]->virtual_chunk_len;
     int nchunks        = pkt_len / chunk_len;
     AVPacket pkt;
     int pos = 0, j, l, ret;
 
 
     if ((ret = av_new_packet(&pkt, asf_pkt->data_size)) < 0)
         return ret;
 
     while (asf_pkt->data_size >= asf_st->span * pkt_len + pos) {
         if (pos >= asf_pkt->data_size) {
             break;
         }
         for (l = 0; l < pkt_len; l++) {
             if (pos >= asf_pkt->data_size) {
                 break;
             }
             for (j = 0; j < asf_st->span; j++) {
                 if ((pos + chunk_len) >= asf_pkt->data_size)
                     break;
                 memcpy(pkt.data + pos,
                        p + (j * nchunks + l) * chunk_len,
                        chunk_len);
                 pos += chunk_len;
             }
         }
         p += asf_st->span * pkt_len;
         if (p > asf_pkt->avpkt.data + asf_pkt->data_size)
             break;
     }

     av_packet_unref(&asf_pkt->avpkt);

     asf_pkt->avpkt = pkt;
 
     return 0;
 }
 
 static int asf_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     int ret, i;
 
     if ((avio_tell(pb) >= asf->data_offset + asf->data_size) &&
         !(asf->b_flags & ASF_FLAG_BROADCAST))
         return AVERROR_EOF;
     while (!pb->eof_reached) {
         if (asf->state == PARSE_PACKET_HEADER) {
             asf_read_packet_header(s);

             if (pb->eof_reached)
                 break;

             if (!asf->nb_mult_left)
                 asf->state = READ_SINGLE;
             else
                 asf->state = READ_MULTI;
         }

         ret = asf_read_payload(s, pkt);
         if (ret == AVERROR(EAGAIN)) {
             asf->state = PARSE_PACKET_HEADER;
             continue;
         }
         else if (ret < 0)

             return ret;

         switch (asf->state) {
         case READ_SINGLE:
             if (!asf->sub_left)
                 asf->state = PARSE_PACKET_HEADER;
             break;
         case READ_MULTI_SUB:
             if (!asf->sub_left && !asf->nb_mult_left) {
                 asf->state = PARSE_PACKET_HEADER;

                 if (!asf->return_subpayload &&
                     (avio_tell(pb) <= asf->packet_offset +
                      asf->packet_size - asf->pad_len))

                     avio_skip(pb, asf->pad_len); // skip padding
                 if (asf->packet_offset + asf->packet_size > avio_tell(pb))
                     avio_seek(pb, asf->packet_offset + asf->packet_size, SEEK_SET);
             } else if (!asf->sub_left)
                 asf->state = READ_MULTI;
             break;
         case READ_MULTI:
             if (!asf->nb_mult_left) {
                 asf->state = PARSE_PACKET_HEADER;

                 if (!asf->return_subpayload &&
                     (avio_tell(pb) <= asf->packet_offset +
                      asf->packet_size - asf->pad_len))

                     avio_skip(pb, asf->pad_len); // skip padding
                 if (asf->packet_offset + asf->packet_size > avio_tell(pb))
                     avio_seek(pb, asf->packet_offset + asf->packet_size, SEEK_SET);
             }
             break;
         }
         if (asf->return_subpayload) {
             asf->return_subpayload = 0;
             return 0;
         }
         for (i = 0; i < s->nb_streams; i++) {
             ASFPacket *asf_pkt = &asf->asf_st[i]->pkt;
             if (asf_pkt && !asf_pkt->size_left && asf_pkt->data_size) {
                 if (asf->asf_st[i]->span > 1 &&
                     asf->asf_st[i]->type == AVMEDIA_TYPE_AUDIO)
                     if ((ret = asf_deinterleave(s, asf_pkt, i)) < 0)
                         return ret;
                 av_packet_move_ref(pkt, &asf_pkt->avpkt);
                 pkt->stream_index  = asf->asf_st[i]->index;
                 pkt->flags         = asf_pkt->flags;
                 pkt->dts           = asf_pkt->dts - asf->preroll;
                 asf_pkt->data_size = 0;
                 asf_pkt->frame_num = 0;
                 return 0;
             }
         }
     }
 
     if (pb->eof_reached)
         return AVERROR_EOF;
 
     return 0;
 }
 
 static int asf_read_close(AVFormatContext *s)
 {
     ASFContext *asf = s->priv_data;
     int i;
 

     for (i = 0; i < ASF_MAX_STREAMS; i++) {

         av_dict_free(&asf->asf_sd[i].asf_met);

         if (i < asf->nb_streams) {

             av_packet_unref(&asf->asf_st[i]->pkt.avpkt);

             av_freep(&asf->asf_st[i]);
         }

     }
 

     asf->nb_streams = 0;

     return 0;
 }
 
 static void reset_packet_state(AVFormatContext *s)
 {
     ASFContext *asf        = s->priv_data;
     int i;
 
     asf->state             = PARSE_PACKET_HEADER;
     asf->offset            = 0;
     asf->return_subpayload = 0;
     asf->sub_left          = 0;
     asf->sub_header_offset = 0;
     asf->packet_offset     = asf->first_packet_offset;
     asf->pad_len           = 0;
     asf->rep_data_len      = 0;
     asf->dts_delta         = 0;
     asf->mult_sub_len      = 0;
     asf->nb_mult_left      = 0;
     asf->nb_sub            = 0;
     asf->prop_flags        = 0;
     asf->sub_dts           = 0;
     for (i = 0; i < asf->nb_streams; i++) {
         ASFPacket *pkt = &asf->asf_st[i]->pkt;
         pkt->size_left = 0;
         pkt->data_size = 0;
         pkt->duration  = 0;
         pkt->flags     = 0;
         pkt->dts       = 0;
         pkt->duration  = 0;

         av_packet_unref(&pkt->avpkt);

         av_init_packet(&pkt->avpkt);
     }
 }
 
 /*
  * Find a timestamp for the requested position within the payload
  * where the pos (position) is the offset inside the Data Object.
  * When position is not on the packet boundary, asf_read_timestamp tries
  * to find the closest packet offset after this position. If this packet
  * is a key frame, this packet timestamp is read and an index entry is created
  * for the packet. If this packet belongs to the requested stream,
  * asf_read_timestamp upgrades pos to the packet beginning offset and
  * returns this packet's dts. So returned dts is the dts of the first key frame with
  * matching stream number after given position.
  */
 static int64_t asf_read_timestamp(AVFormatContext *s, int stream_index,
                                   int64_t *pos, int64_t pos_limit)
 {
     ASFContext *asf = s->priv_data;
     int64_t pkt_pos = *pos, pkt_offset, dts = AV_NOPTS_VALUE, data_end;
     AVPacket pkt;
     int n;
 
     data_end = asf->data_offset + asf->data_size;
 
     n = (pkt_pos - asf->first_packet_offset + asf->packet_size - 1) /
         asf->packet_size;
     n = av_clip(n, 0, ((data_end - asf->first_packet_offset) / asf->packet_size - 1));
     pkt_pos = asf->first_packet_offset +  n * asf->packet_size;
 
     avio_seek(s->pb, pkt_pos, SEEK_SET);
     pkt_offset = pkt_pos;
 
     reset_packet_state(s);
     while (avio_tell(s->pb) < data_end) {
 
         int i, ret, st_found;
 
         av_init_packet(&pkt);
         pkt_offset = avio_tell(s->pb);
         if ((ret = asf_read_packet(s, &pkt)) < 0) {
             dts = AV_NOPTS_VALUE;
             return ret;
         }
         // ASFPacket may contain fragments of packets belonging to different streams,
         // pkt_offset is the offset of the first fragment within it.
         if ((pkt_offset >= (pkt_pos + asf->packet_size)))
             pkt_pos += asf->packet_size;
         for (i = 0; i < asf->nb_streams; i++) {
             ASFStream *st = asf->asf_st[i];
 
             st_found = 0;
             if (pkt.flags & AV_PKT_FLAG_KEY) {
                 dts = pkt.dts;
                 if (dts) {
                     av_add_index_entry(s->streams[pkt.stream_index], pkt_pos,
                                        dts, pkt.size, 0, AVINDEX_KEYFRAME);
                     if (stream_index == st->index) {
                         st_found = 1;
                         break;
                     }
                 }
             }
         }
         if (st_found)
             break;

         av_packet_unref(&pkt);

     }
     *pos = pkt_pos;
 

     av_packet_unref(&pkt);

     return dts;
 }
 
 static int asf_read_seek(AVFormatContext *s, int stream_index,
                          int64_t timestamp, int flags)
 {
     ASFContext *asf = s->priv_data;
     int idx, ret;
 
     if (s->streams[stream_index]->nb_index_entries && asf->is_simple_index) {
         idx = av_index_search_timestamp(s->streams[stream_index], timestamp, flags);
         if (idx < 0 || idx >= s->streams[stream_index]->nb_index_entries)
             return AVERROR_INVALIDDATA;
         avio_seek(s->pb, s->streams[stream_index]->index_entries[idx].pos, SEEK_SET);
     } else {
         if ((ret = ff_seek_frame_binary(s, stream_index, timestamp, flags)) < 0)
             return ret;
     }
 

     reset_packet_state(s);
 

     return 0;
 }
 
 static const GUIDParseTable *find_guid(ff_asf_guid guid)
 {
     int j, ret;
     const GUIDParseTable *g;
 
     swap_guid(guid);
     g = gdef;
     for (j = 0; j < FF_ARRAY_ELEMS(gdef); j++) {
         if (!(ret = memcmp(guid, g->guid, sizeof(g->guid))))
             return g;
         g++;
     }
 
     return NULL;
 }
 
 static int detect_unknown_subobject(AVFormatContext *s, int64_t offset, int64_t size)
 {
     ASFContext *asf = s->priv_data;
     AVIOContext *pb = s->pb;
     const GUIDParseTable *g = NULL;
     ff_asf_guid guid;
     int ret;
 
     while (avio_tell(pb) <= offset + size) {

         if (avio_tell(pb) == asf->offset)
             break;

         asf->offset = avio_tell(pb);
         if ((ret = ff_get_guid(pb, &guid)) < 0)
             return ret;
         g = find_guid(guid);
         if (g) {
             if ((ret = g->read_object(s, g)) < 0)
                 return ret;
         } else {
             GUIDParseTable g2;
 
             g2.name         = "Unknown";
             g2.is_subobject = 1;
             asf_read_unknown(s, &g2);
         }
     }
 
     return 0;
 }
 
 static int asf_read_header(AVFormatContext *s)
 {
     ASFContext *asf         = s->priv_data;
     AVIOContext *pb         = s->pb;
     const GUIDParseTable *g = NULL;
     ff_asf_guid guid;
     int i, ret;
     uint64_t size;
 
     asf->preroll         = 0;
     asf->is_simple_index = 0;
     ff_get_guid(pb, &guid);
     if (ff_guidcmp(&guid, &ff_asf_header))
         return AVERROR_INVALIDDATA;
     avio_skip(pb, 8); // skip header object size
     avio_skip(pb, 6); // skip number of header objects and 2 reserved bytes
     asf->data_reached = 0;
 
     /* 1  is here instead of pb->eof_reached because (when not streaming), Data are skipped
      * for the first time,
      * Index object is processed and got eof and then seeking back to the Data is performed.
      */
     while (1) {
         // for the cases when object size is invalid

         if (avio_tell(pb) == asf->offset)

             break;
         asf->offset = avio_tell(pb);
         if ((ret = ff_get_guid(pb, &guid)) < 0) {

             if (ret == AVERROR_EOF && asf->data_reached)

                 break;

             else

                 goto failed;

         }
         g = find_guid(guid);
         if (g) {
             asf->unknown_offset = asf->offset;
             asf->is_header = 1;
             if ((ret = g->read_object(s, g)) < 0)

                 goto failed;

         } else {
             size = avio_rl64(pb);
             align_position(pb, asf->offset, size);
         }

         if (asf->data_reached && (!pb->seekable || (asf->b_flags & ASF_FLAG_BROADCAST)))

             break;
     }
 

     if (!asf->data_reached) {
         av_log(s, AV_LOG_ERROR, "Data Object was not found.\n");

         ret = AVERROR_INVALIDDATA;
         goto failed;

     }
     if (pb->seekable)
         avio_seek(pb, asf->first_packet_offset, SEEK_SET);
 

     for (i = 0; i < asf->nb_streams; i++) {
         const char *rfc1766 = asf->asf_sd[asf->asf_st[i]->lang_idx].langs;
         AVStream *st        = s->streams[asf->asf_st[i]->index];
         set_language(s, rfc1766, &st->metadata);
     }
 
     for (i = 0; i < ASF_MAX_STREAMS; i++) {
         AVStream *st = NULL;
 
         st = find_stream(s, i);
         if (st) {
             av_dict_copy(&st->metadata, asf->asf_sd[i].asf_met, AV_DICT_IGNORE_SUFFIX);
             if (asf->asf_sd[i].aspect_ratio.num > 0 && asf->asf_sd[i].aspect_ratio.den > 0) {
                 st->sample_aspect_ratio.num = asf->asf_sd[i].aspect_ratio.num;
                 st->sample_aspect_ratio.den = asf->asf_sd[i].aspect_ratio.den;
             }
         }
     }
 
     return 0;

 
 failed:
     asf_read_close(s);
     return ret;

 }
 
 AVInputFormat ff_asf_o_demuxer = {
     .name           = "asf_o",
     .long_name      = NULL_IF_CONFIG_SMALL("ASF (Advanced / Active Streaming Format)"),
     .priv_data_size = sizeof(ASFContext),
     .read_probe     = asf_probe,
     .read_header    = asf_read_header,
     .read_packet    = asf_read_packet,
     .read_close     = asf_read_close,
     .read_timestamp = asf_read_timestamp,
     .read_seek      = asf_read_seek,
     .flags          = AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH,
 };