/*

  * FLV muxer

  * Copyright (c) 2003 The FFmpeg Project

  *

  * 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/intreadwrite.h"

 #include "libavutil/dict.h"

 #include "libavutil/intfloat.h"

 #include "libavutil/avassert.h"

 #include "libavutil/mathematics.h"

 #include "avio_internal.h"
 #include "avio.h"

 #include "avc.h"

 #include "avformat.h"

 #include "flv.h"

 #include "internal.h"

 #include "metadata.h"

 #include "libavutil/opt.h"
 #include "libavcodec/put_bits.h"
 #include "libavcodec/aacenctab.h"

 static const AVCodecTag flv_video_codec_ids[] = {

     { AV_CODEC_ID_FLV1,     FLV_CODECID_H263 },

     { AV_CODEC_ID_H263,     FLV_CODECID_REALH263 },
     { AV_CODEC_ID_MPEG4,    FLV_CODECID_MPEG4 },

     { AV_CODEC_ID_FLASHSV,  FLV_CODECID_SCREEN },
     { AV_CODEC_ID_FLASHSV2, FLV_CODECID_SCREEN2 },
     { AV_CODEC_ID_VP6F,     FLV_CODECID_VP6 },

     { AV_CODEC_ID_VP6,      FLV_CODECID_VP6 },

     { AV_CODEC_ID_VP6A,     FLV_CODECID_VP6A },

     { AV_CODEC_ID_H264,     FLV_CODECID_H264 },
     { AV_CODEC_ID_NONE,     0 }

 };
 

 static const AVCodecTag flv_audio_codec_ids[] = {

     { AV_CODEC_ID_MP3,        FLV_CODECID_MP3        >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_PCM_U8,     FLV_CODECID_PCM        >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_PCM_S16BE,  FLV_CODECID_PCM        >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_PCM_S16LE,  FLV_CODECID_PCM_LE     >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_ADPCM_SWF,  FLV_CODECID_ADPCM      >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_AAC,        FLV_CODECID_AAC        >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_NELLYMOSER, FLV_CODECID_NELLYMOSER >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_PCM_MULAW,  FLV_CODECID_PCM_MULAW  >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_PCM_ALAW,   FLV_CODECID_PCM_ALAW   >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_SPEEX,      FLV_CODECID_SPEEX      >> FLV_AUDIO_CODECID_OFFSET },
     { AV_CODEC_ID_NONE,       0 }

 };
 

 typedef enum {
     FLV_AAC_SEQ_HEADER_DETECT = (1 << 0),

     FLV_NO_SEQUENCE_END = (1 << 1),

     FLV_ADD_KEYFRAME_INDEX = (1 << 2),

     FLV_NO_METADATA = (1 << 3),

     FLV_NO_DURATION_FILESIZE = (1 << 4),

 } FLVFlags;
 

 typedef struct FLVFileposition {
     int64_t keyframe_position;
     double keyframe_timestamp;
     struct FLVFileposition *next;
 } FLVFileposition;
 

 typedef struct FLVContext {

     AVClass *av_class;

     int     reserved;

     int64_t duration_offset;
     int64_t filesize_offset;

     int64_t duration;

     int64_t delay;      ///< first dts delay (needed for AVC & Speex)

     int64_t datastart_offset;
     int64_t datasize_offset;
     int64_t datasize;
     int64_t videosize_offset;
     int64_t videosize;
     int64_t audiosize_offset;
     int64_t audiosize;
 
     int64_t metadata_size_pos;
     int64_t metadata_totalsize_pos;
     int64_t metadata_totalsize;
     int64_t keyframe_index_size;
 
     int64_t lasttimestamp_offset;
     double lasttimestamp;
     int64_t lastkeyframetimestamp_offset;
     double lastkeyframetimestamp;
     int64_t lastkeyframelocation_offset;
     int64_t lastkeyframelocation;
 
     int acurframeindex;
     int64_t keyframes_info_offset;
 
     int64_t filepositions_count;
     FLVFileposition *filepositions;
     FLVFileposition *head_filepositions;
 

     AVCodecParameters *audio_par;
     AVCodecParameters *video_par;

     double framerate;

     AVCodecParameters *data_par;

 
     int flags;

 } FLVContext;
 

 typedef struct FLVStreamContext {
     int64_t last_ts;    ///< last timestamp for each stream
 } FLVStreamContext;
 

 static int get_audio_flags(AVFormatContext *s, AVCodecParameters *par)

 {

     int flags = (par->bits_per_coded_sample == 16) ? FLV_SAMPLESSIZE_16BIT

                                                    : FLV_SAMPLESSIZE_8BIT;

     if (par->codec_id == AV_CODEC_ID_AAC) // specs force these parameters

         return FLV_CODECID_AAC | FLV_SAMPLERATE_44100HZ |
                FLV_SAMPLESSIZE_16BIT | FLV_STEREO;

     else if (par->codec_id == AV_CODEC_ID_SPEEX) {
         if (par->sample_rate != 16000) {

             av_log(s, AV_LOG_ERROR,

                    "FLV only supports wideband (16kHz) Speex audio\n");

             return AVERROR(EINVAL);

         }

         if (par->channels != 1) {

             av_log(s, AV_LOG_ERROR, "FLV only supports mono Speex audio\n");

             return AVERROR(EINVAL);

         }
         return FLV_CODECID_SPEEX | FLV_SAMPLERATE_11025HZ | FLV_SAMPLESSIZE_16BIT;
     } else {

         switch (par->sample_rate) {

         case 48000:
             // 48khz mp3 is stored with 44k1 samplerate identifer
             if (par->codec_id == AV_CODEC_ID_MP3) {
                 flags |= FLV_SAMPLERATE_44100HZ;
                 break;
             } else {
                 goto error;
             }

         case 44100:

             flags |= FLV_SAMPLERATE_44100HZ;

             break;

         case 22050:

             flags |= FLV_SAMPLERATE_22050HZ;

             break;

         case 11025:

             flags |= FLV_SAMPLERATE_11025HZ;

             break;

         case 16000: // nellymoser only
         case  8000: // nellymoser only
         case  5512: // not MP3

             if (par->codec_id != AV_CODEC_ID_MP3) {

                 flags |= FLV_SAMPLERATE_SPECIAL;
                 break;

             }

         default:

 error:

             av_log(s, AV_LOG_ERROR,

                    "FLV does not support sample rate %d, "

                    "choose from (44100, 22050, 11025)\n", par->sample_rate);

             return AVERROR(EINVAL);

         }

     }

     if (par->channels > 1)

         flags |= FLV_STEREO;

     switch (par->codec_id) {

     case AV_CODEC_ID_MP3:

         flags |= FLV_CODECID_MP3    | FLV_SAMPLESSIZE_16BIT;

         break;

     case AV_CODEC_ID_PCM_U8:

         flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_8BIT;

         break;

     case AV_CODEC_ID_PCM_S16BE:

         flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_16BIT;

         break;

     case AV_CODEC_ID_PCM_S16LE:

         flags |= FLV_CODECID_PCM_LE | FLV_SAMPLESSIZE_16BIT;

         break;

     case AV_CODEC_ID_ADPCM_SWF:

         flags |= FLV_CODECID_ADPCM  | FLV_SAMPLESSIZE_16BIT;

         break;

     case AV_CODEC_ID_NELLYMOSER:

         if (par->sample_rate == 8000)

             flags |= FLV_CODECID_NELLYMOSER_8KHZ_MONO  | FLV_SAMPLESSIZE_16BIT;

         else if (par->sample_rate == 16000)

             flags |= FLV_CODECID_NELLYMOSER_16KHZ_MONO | FLV_SAMPLESSIZE_16BIT;

         else
             flags |= FLV_CODECID_NELLYMOSER            | FLV_SAMPLESSIZE_16BIT;

         break;

     case AV_CODEC_ID_PCM_MULAW:

         flags = FLV_CODECID_PCM_MULAW | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT;
         break;

     case AV_CODEC_ID_PCM_ALAW:

         flags = FLV_CODECID_PCM_ALAW  | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT;

         break;

     case 0:

         flags |= par->codec_tag << 4;

         break;
     default:

         av_log(s, AV_LOG_ERROR, "Audio codec '%s' not compatible with FLV\n",

                avcodec_get_name(par->codec_id));

         return AVERROR(EINVAL);

     }

     return flags;
 }
 

 static void put_amf_string(AVIOContext *pb, const char *str)

 {
     size_t len = strlen(str);

     avio_wb16(pb, len);
     avio_write(pb, str, len);

 }
 

 static void put_avc_eos_tag(AVIOContext *pb, unsigned ts)
 {

     avio_w8(pb, FLV_TAG_TYPE_VIDEO);

     avio_wb24(pb, 5);               /* Tag Data Size */
     avio_wb24(pb, ts);              /* lower 24 bits of timestamp in ms */
     avio_w8(pb, (ts >> 24) & 0x7F); /* MSB of ts in ms */
     avio_wb24(pb, 0);               /* StreamId = 0 */
     avio_w8(pb, 23);                /* ub[4] FrameType = 1, ub[4] CodecId = 7 */
     avio_w8(pb, 2);                 /* AVC end of sequence */
     avio_wb24(pb, 0);               /* Always 0 for AVC EOS. */
     avio_wb32(pb, 16);              /* Size of FLV tag */

 }
 

 static void put_amf_double(AVIOContext *pb, double d)

 {

     avio_w8(pb, AMF_DATA_TYPE_NUMBER);

     avio_wb64(pb, av_double2int(d));

 }
 

 static void put_amf_byte(AVIOContext *pb, unsigned char abyte)
 {
     avio_w8(pb, abyte);
 }
 
 static void put_amf_dword_array(AVIOContext *pb, uint32_t dw)
 {
     avio_w8(pb, AMF_DATA_TYPE_ARRAY);
     avio_wb32(pb, dw);
 }
 

 static void put_amf_bool(AVIOContext *pb, int b)
 {

     avio_w8(pb, AMF_DATA_TYPE_BOOL);
     avio_w8(pb, !!b);

 }
 

 static void write_metadata(AVFormatContext *s, unsigned int ts)

 {

     AVIOContext *pb = s->pb;

     FLVContext *flv = s->priv_data;

     int write_duration_filesize = !(flv->flags & FLV_NO_DURATION_FILESIZE);

     int metadata_count = 0;

     int64_t metadata_count_pos;

     AVDictionaryEntry *tag = NULL;

     /* write meta_tag */

     avio_w8(pb, FLV_TAG_TYPE_META);            // tag type META
     flv->metadata_size_pos = avio_tell(pb);

     avio_wb24(pb, 0);           // size of data part (sum of all parts below)

     avio_wb24(pb, ts);          // timestamp

     avio_wb32(pb, 0);           // reserved

 
     /* now data of data_size size */
 
     /* first event name as a string */

     avio_w8(pb, AMF_DATA_TYPE_STRING);

     put_amf_string(pb, "onMetaData"); // 12 bytes
 
     /* mixed array (hash) with size and string/type/data tuples */

     avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);

     metadata_count_pos = avio_tell(pb);

     metadata_count = 4 * !!flv->video_par +
                      5 * !!flv->audio_par +

                      1 * !!flv->data_par;

     if (write_duration_filesize) {

         metadata_count += 2; // +2 for duration and file size
     }

     avio_wb32(pb, metadata_count);

     if (write_duration_filesize) {

         put_amf_string(pb, "duration");
         flv->duration_offset = avio_tell(pb);
         // fill in the guessed duration, it'll be corrected later if incorrect
         put_amf_double(pb, s->duration / AV_TIME_BASE);
     }

     if (flv->video_par) {

         put_amf_string(pb, "width");

         put_amf_double(pb, flv->video_par->width);

 
         put_amf_string(pb, "height");

         put_amf_double(pb, flv->video_par->height);

 
         put_amf_string(pb, "videodatarate");

         put_amf_double(pb, flv->video_par->bit_rate / 1024.0);

         if (flv->framerate != 0.0) {

             put_amf_string(pb, "framerate");

             put_amf_double(pb, flv->framerate);

             metadata_count++;

         }

 
         put_amf_string(pb, "videocodecid");

         put_amf_double(pb, flv->video_par->codec_tag);

     }
 

     if (flv->audio_par) {

         put_amf_string(pb, "audiodatarate");

         put_amf_double(pb, flv->audio_par->bit_rate / 1024.0);

         put_amf_string(pb, "audiosamplerate");

         put_amf_double(pb, flv->audio_par->sample_rate);

 
         put_amf_string(pb, "audiosamplesize");

         put_amf_double(pb, flv->audio_par->codec_id == AV_CODEC_ID_PCM_U8 ? 8 : 16);

 
         put_amf_string(pb, "stereo");

         put_amf_bool(pb, flv->audio_par->channels == 2);

 
         put_amf_string(pb, "audiocodecid");

         put_amf_double(pb, flv->audio_par->codec_tag);

     }
 

     if (flv->data_par) {

         put_amf_string(pb, "datastream");
         put_amf_double(pb, 0.0);
     }
 

     ff_standardize_creation_time(s);

     while ((tag = av_dict_get(s->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {

         if(   !strcmp(tag->key, "width")
             ||!strcmp(tag->key, "height")
             ||!strcmp(tag->key, "videodatarate")
             ||!strcmp(tag->key, "framerate")
             ||!strcmp(tag->key, "videocodecid")
             ||!strcmp(tag->key, "audiodatarate")
             ||!strcmp(tag->key, "audiosamplerate")
             ||!strcmp(tag->key, "audiosamplesize")
             ||!strcmp(tag->key, "stereo")
             ||!strcmp(tag->key, "audiocodecid")
             ||!strcmp(tag->key, "duration")
             ||!strcmp(tag->key, "onMetaData")

             ||!strcmp(tag->key, "datasize")
             ||!strcmp(tag->key, "lasttimestamp")
             ||!strcmp(tag->key, "totalframes")
             ||!strcmp(tag->key, "hasAudio")
             ||!strcmp(tag->key, "hasVideo")
             ||!strcmp(tag->key, "hasCuePoints")
             ||!strcmp(tag->key, "hasMetadata")
             ||!strcmp(tag->key, "hasKeyframes")

         ){

             av_log(s, AV_LOG_DEBUG, "Ignoring metadata for %s\n", tag->key);

             continue;
         }

         put_amf_string(pb, tag->key);

         avio_w8(pb, AMF_DATA_TYPE_STRING);

         put_amf_string(pb, tag->value);

         metadata_count++;

     }
 

     if (write_duration_filesize) {

         put_amf_string(pb, "filesize");
         flv->filesize_offset = avio_tell(pb);
         put_amf_double(pb, 0); // delayed write
     }

     if (flv->flags & FLV_ADD_KEYFRAME_INDEX) {
         flv->acurframeindex = 0;
         flv->keyframe_index_size = 0;
 
         put_amf_string(pb, "hasVideo");
         put_amf_bool(pb, !!flv->video_par);
         metadata_count++;
 
         put_amf_string(pb, "hasKeyframes");
         put_amf_bool(pb, 1);
         metadata_count++;
 
         put_amf_string(pb, "hasAudio");
         put_amf_bool(pb, !!flv->audio_par);
         metadata_count++;
 
         put_amf_string(pb, "hasMetadata");
         put_amf_bool(pb, 1);
         metadata_count++;
 
         put_amf_string(pb, "canSeekToEnd");
         put_amf_bool(pb, 1);
         metadata_count++;
 
         put_amf_string(pb, "datasize");
         flv->datasize_offset = avio_tell(pb);
         flv->datasize = 0;
         put_amf_double(pb, flv->datasize);
         metadata_count++;
 
         put_amf_string(pb, "videosize");
         flv->videosize_offset = avio_tell(pb);
         flv->videosize = 0;
         put_amf_double(pb, flv->videosize);
         metadata_count++;
 
         put_amf_string(pb, "audiosize");
         flv->audiosize_offset = avio_tell(pb);
         flv->audiosize = 0;
         put_amf_double(pb, flv->audiosize);
         metadata_count++;
 
         put_amf_string(pb, "lasttimestamp");
         flv->lasttimestamp_offset = avio_tell(pb);
         flv->lasttimestamp = 0;
         put_amf_double(pb, 0);
         metadata_count++;
 
         put_amf_string(pb, "lastkeyframetimestamp");
         flv->lastkeyframetimestamp_offset = avio_tell(pb);
         flv->lastkeyframetimestamp = 0;
         put_amf_double(pb, 0);
         metadata_count++;
 
         put_amf_string(pb, "lastkeyframelocation");
         flv->lastkeyframelocation_offset = avio_tell(pb);
         flv->lastkeyframelocation = 0;
         put_amf_double(pb, 0);
         metadata_count++;
 
         put_amf_string(pb, "keyframes");
         put_amf_byte(pb, AMF_DATA_TYPE_OBJECT);
         metadata_count++;
 
         flv->keyframes_info_offset = avio_tell(pb);
     }
 

     put_amf_string(pb, "");

     avio_w8(pb, AMF_END_OF_OBJECT);

 
     /* write total size of tag */

     flv->metadata_totalsize = avio_tell(pb) - flv->metadata_size_pos - 10;

 
     avio_seek(pb, metadata_count_pos, SEEK_SET);
     avio_wb32(pb, metadata_count);
 

     avio_seek(pb, flv->metadata_size_pos, SEEK_SET);
     avio_wb24(pb, flv->metadata_totalsize);
     avio_skip(pb, flv->metadata_totalsize + 10 - 3);
     flv->metadata_totalsize_pos = avio_tell(pb);
     avio_wb32(pb, flv->metadata_totalsize + 11);

 }
 

 static int unsupported_codec(AVFormatContext *s,
                              const char* type, int codec_id)
 {
     const AVCodecDescriptor *desc = avcodec_descriptor_get(codec_id);
     av_log(s, AV_LOG_ERROR,
            "%s codec %s not compatible with flv\n",
             type,
             desc ? desc->name : "unknown");
     return AVERROR(ENOSYS);
 }
 

 static void flv_write_codec_header(AVFormatContext* s, AVCodecParameters* par) {
     int64_t data_size;
     AVIOContext *pb = s->pb;
     FLVContext *flv = s->priv_data;
 
     if (par->codec_id == AV_CODEC_ID_AAC || par->codec_id == AV_CODEC_ID_H264
             || par->codec_id == AV_CODEC_ID_MPEG4) {
         int64_t pos;
         avio_w8(pb,
                 par->codec_type == AVMEDIA_TYPE_VIDEO ?
                         FLV_TAG_TYPE_VIDEO : FLV_TAG_TYPE_AUDIO);
         avio_wb24(pb, 0); // size patched later
         avio_wb24(pb, 0); // ts
         avio_w8(pb, 0);   // ts ext
         avio_wb24(pb, 0); // streamid
         pos = avio_tell(pb);
         if (par->codec_id == AV_CODEC_ID_AAC) {
             avio_w8(pb, get_audio_flags(s, par));
             avio_w8(pb, 0); // AAC sequence header
 

             if (!par->extradata_size && (flv->flags & FLV_AAC_SEQ_HEADER_DETECT)) {

                 PutBitContext pbc;
                 int samplerate_index;
                 int channels = flv->audio_par->channels
                         - (flv->audio_par->channels == 8 ? 1 : 0);
                 uint8_t data[2];
 
                 for (samplerate_index = 0; samplerate_index < 16;
                         samplerate_index++)
                     if (flv->audio_par->sample_rate
                             == mpeg4audio_sample_rates[samplerate_index])
                         break;
 
                 init_put_bits(&pbc, data, sizeof(data));
                 put_bits(&pbc, 5, flv->audio_par->profile + 1); //profile
                 put_bits(&pbc, 4, samplerate_index); //sample rate index
                 put_bits(&pbc, 4, channels);
                 put_bits(&pbc, 1, 0); //frame length - 1024 samples
                 put_bits(&pbc, 1, 0); //does not depend on core coder
                 put_bits(&pbc, 1, 0); //is not extension
                 flush_put_bits(&pbc);
 
                 avio_w8(pb, data[0]);
                 avio_w8(pb, data[1]);
 
                 av_log(s, AV_LOG_WARNING, "AAC sequence header: %02x %02x.\n",
                         data[0], data[1]);
             }
             avio_write(pb, par->extradata, par->extradata_size);
         } else {
             avio_w8(pb, par->codec_tag | FLV_FRAME_KEY); // flags
             avio_w8(pb, 0); // AVC sequence header
             avio_wb24(pb, 0); // composition time
             ff_isom_write_avcc(pb, par->extradata, par->extradata_size);
         }
         data_size = avio_tell(pb) - pos;
         avio_seek(pb, -data_size - 10, SEEK_CUR);
         avio_wb24(pb, data_size);
         avio_skip(pb, data_size + 10 - 3);
         avio_wb32(pb, data_size + 11); // previous tag size
     }
 }
 

 static int flv_append_keyframe_info(AVFormatContext *s, FLVContext *flv, double ts, int64_t pos)
 {
     FLVFileposition *position = av_malloc(sizeof(FLVFileposition));
 
     if (!position) {
         av_log(s, AV_LOG_WARNING, "no mem for add keyframe index!\n");
         return AVERROR(ENOMEM);
     }
 
     position->keyframe_timestamp = ts;
     position->keyframe_position = pos;
 
     if (!flv->filepositions_count) {
         flv->filepositions = position;
         flv->head_filepositions = flv->filepositions;
         position->next = NULL;
     } else {
         flv->filepositions->next = position;
         position->next = NULL;
         flv->filepositions = flv->filepositions->next;
     }
 
     flv->filepositions_count++;
 
     return 0;
 }
 
 static int shift_data(AVFormatContext *s)
 {
     int ret = 0;
     int n = 0;
     int64_t metadata_size = 0;
     FLVContext *flv = s->priv_data;
     int64_t pos, pos_end = avio_tell(s->pb);
     uint8_t *buf, *read_buf[2];
     int read_buf_id = 0;
     int read_size[2];
     AVIOContext *read_pb;
 
     metadata_size = flv->filepositions_count * 9 * 2 + 10; /* filepositions and times value */
     metadata_size += 2 + 13; /* filepositions String */
     metadata_size += 2 + 5; /* times String */
     metadata_size += 3; /* Object end */
 
     flv->keyframe_index_size = metadata_size;
 
     if (metadata_size < 0)
         return metadata_size;
 
     buf = av_malloc_array(metadata_size, 2);
     if (!buf) {
         return AVERROR(ENOMEM);
     }
     read_buf[0] = buf;
     read_buf[1] = buf + metadata_size;
 
     avio_seek(s->pb, flv->metadata_size_pos, SEEK_SET);
     avio_wb24(s->pb, flv->metadata_totalsize + metadata_size);
 
     avio_seek(s->pb, flv->metadata_totalsize_pos, SEEK_SET);
     avio_wb32(s->pb, flv->metadata_totalsize + 11 + metadata_size);
     avio_seek(s->pb, pos_end, SEEK_SET);
 
     /* Shift the data: the AVIO context of the output can only be used for
      * writing, so we re-open the same output, but for reading. It also avoids
      * a read/seek/write/seek back and forth. */
     avio_flush(s->pb);
     ret = s->io_open(s, &read_pb, s->filename, AVIO_FLAG_READ, NULL);
     if (ret < 0) {
         av_log(s, AV_LOG_ERROR, "Unable to re-open %s output file for "
                "the second pass (add_keyframe_index)\n", s->filename);
         goto end;
     }
 
     /* mark the end of the shift to up to the last data we wrote, and get ready
      * for writing */
     pos_end = avio_tell(s->pb);
     avio_seek(s->pb, flv->keyframes_info_offset + metadata_size, SEEK_SET);
 
     /* start reading at where the keyframe index information will be placed */
     avio_seek(read_pb, flv->keyframes_info_offset, SEEK_SET);
     pos = avio_tell(read_pb);
 

 #define READ_BLOCK do {                                                             \

     read_size[read_buf_id] = avio_read(read_pb, read_buf[read_buf_id], metadata_size);  \

     read_buf_id ^= 1;                                                               \
 } while (0)

     /* shift data by chunk of at most keyframe *filepositions* and *times* size */
     READ_BLOCK;
     do {
         READ_BLOCK;

         n = read_size[read_buf_id];
         if (n < 0)
             break;
         avio_write(s->pb, read_buf[read_buf_id], n);
         pos += n;
     } while (pos <= pos_end);
 
     ff_format_io_close(s, &read_pb);
 
 end:
     av_free(buf);
     return ret;
 }
 
 

 static int flv_write_header(AVFormatContext *s)
 {
     int i;
     AVIOContext *pb = s->pb;
     FLVContext *flv = s->priv_data;
 
     for (i = 0; i < s->nb_streams; i++) {

         AVCodecParameters *par = s->streams[i]->codecpar;

         FLVStreamContext *sc;

         switch (par->codec_type) {

         case AVMEDIA_TYPE_VIDEO:
             if (s->streams[i]->avg_frame_rate.den &&
                 s->streams[i]->avg_frame_rate.num) {
                 flv->framerate = av_q2d(s->streams[i]->avg_frame_rate);
             }

             if (flv->video_par) {

                 av_log(s, AV_LOG_ERROR,
                        "at most one video stream is supported in flv\n");
                 return AVERROR(EINVAL);
             }

             flv->video_par = par;
             if (!ff_codec_get_tag(flv_video_codec_ids, par->codec_id))
                 return unsupported_codec(s, "Video", par->codec_id);

             if (par->codec_id == AV_CODEC_ID_MPEG4 ||
                 par->codec_id == AV_CODEC_ID_H263) {

                 int error = s->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL;
                 av_log(s, error ? AV_LOG_ERROR : AV_LOG_WARNING,

                        "Codec %s is not supported in the official FLV specification,\n", avcodec_get_name(par->codec_id));

 
                 if (error) {
                     av_log(s, AV_LOG_ERROR,
                            "use vstrict=-1 / -strict -1 to use it anyway.\n");
                     return AVERROR(EINVAL);
                 }

             } else if (par->codec_id == AV_CODEC_ID_VP6) {

                 av_log(s, AV_LOG_WARNING,
                        "Muxing VP6 in flv will produce flipped video on playback.\n");

             }
             break;
         case AVMEDIA_TYPE_AUDIO:

             if (flv->audio_par) {

                 av_log(s, AV_LOG_ERROR,
                        "at most one audio stream is supported in flv\n");
                 return AVERROR(EINVAL);
             }

             flv->audio_par = par;
             if (get_audio_flags(s, par) < 0)
                 return unsupported_codec(s, "Audio", par->codec_id);

             if (par->codec_id == AV_CODEC_ID_PCM_S16BE)

                 av_log(s, AV_LOG_WARNING,
                        "16-bit big-endian audio in flv is valid but most likely unplayable (hardware dependent); use s16le\n");

             break;
         case AVMEDIA_TYPE_DATA:

             if (par->codec_id != AV_CODEC_ID_TEXT && par->codec_id != AV_CODEC_ID_NONE)

                 return unsupported_codec(s, "Data", par->codec_id);
             flv->data_par = par;

             break;

         case AVMEDIA_TYPE_SUBTITLE:

             if (par->codec_id != AV_CODEC_ID_TEXT) {

                 av_log(s, AV_LOG_ERROR, "Subtitle codec '%s' for stream %d is not compatible with FLV\n",

                        avcodec_get_name(par->codec_id), i);

                 return AVERROR_INVALIDDATA;
             }

             flv->data_par = par;

             break;

         default:

             av_log(s, AV_LOG_ERROR, "Codec type '%s' for stream %d is not compatible with FLV\n",

                    av_get_media_type_string(par->codec_type), i);

             return AVERROR(EINVAL);

         }
         avpriv_set_pts_info(s->streams[i], 32, 1, 1000); /* 32 bit pts in ms */
 
         sc = av_mallocz(sizeof(FLVStreamContext));
         if (!sc)
             return AVERROR(ENOMEM);
         s->streams[i]->priv_data = sc;
         sc->last_ts = -1;
     }
 
     flv->delay = AV_NOPTS_VALUE;
 
     avio_write(pb, "FLV", 3);
     avio_w8(pb, 1);

     avio_w8(pb, FLV_HEADER_FLAG_HASAUDIO * !!flv->audio_par +
                 FLV_HEADER_FLAG_HASVIDEO * !!flv->video_par);

     avio_wb32(pb, 9);
     avio_wb32(pb, 0);
 
     for (i = 0; i < s->nb_streams; i++)

         if (s->streams[i]->codecpar->codec_tag == 5) {

             avio_w8(pb, 8);     // message type
             avio_wb24(pb, 0);   // include flags
             avio_wb24(pb, 0);   // time stamp
             avio_wb32(pb, 0);   // reserved
             avio_wb32(pb, 11);  // size
             flv->reserved = 5;
         }
 

     if (flv->flags & FLV_NO_METADATA) {
         pb->seekable = 0;
     } else {
         write_metadata(s, 0);
     }

     for (i = 0; i < s->nb_streams; i++) {

         flv_write_codec_header(s, s->streams[i]->codecpar);

     }
 

     flv->datastart_offset = avio_tell(pb);

     return 0;
 }
 
 static int flv_write_trailer(AVFormatContext *s)
 {

     int64_t file_size;

     AVIOContext *pb = s->pb;

     FLVContext *flv = s->priv_data;

     int build_keyframes_idx = flv->flags & FLV_ADD_KEYFRAME_INDEX;
     int i, res;
     int64_t cur_pos = avio_tell(s->pb);
 
     if (build_keyframes_idx) {
         FLVFileposition *newflv_posinfo, *p;
 
         avio_seek(pb, flv->videosize_offset, SEEK_SET);
         put_amf_double(pb, flv->videosize);
 
         avio_seek(pb, flv->audiosize_offset, SEEK_SET);
         put_amf_double(pb, flv->audiosize);
 
         avio_seek(pb, flv->lasttimestamp_offset, SEEK_SET);
         put_amf_double(pb, flv->lasttimestamp);
 
         avio_seek(pb, flv->lastkeyframetimestamp_offset, SEEK_SET);
         put_amf_double(pb, flv->lastkeyframetimestamp);

         avio_seek(pb, flv->lastkeyframelocation_offset, SEEK_SET);
         put_amf_double(pb, flv->lastkeyframelocation + flv->keyframe_index_size);
         avio_seek(pb, cur_pos, SEEK_SET);
 
         res = shift_data(s);
         if (res < 0) {
              goto end;
         }
         avio_seek(pb, flv->keyframes_info_offset, SEEK_SET);
         put_amf_string(pb, "filepositions");
         put_amf_dword_array(pb, flv->filepositions_count);
         for (newflv_posinfo = flv->head_filepositions; newflv_posinfo; newflv_posinfo = newflv_posinfo->next) {
             put_amf_double(pb, newflv_posinfo->keyframe_position + flv->keyframe_index_size);
         }
 
         put_amf_string(pb, "times");
         put_amf_dword_array(pb, flv->filepositions_count);
         for (newflv_posinfo = flv->head_filepositions; newflv_posinfo; newflv_posinfo = newflv_posinfo->next) {
             put_amf_double(pb, newflv_posinfo->keyframe_timestamp);
         }
 
         newflv_posinfo = flv->head_filepositions;
         while (newflv_posinfo) {
             p = newflv_posinfo->next;
             if (p) {
                 newflv_posinfo->next = p->next;
                 av_free(p);
                 p = NULL;
             } else {
                 av_free(newflv_posinfo);
                 newflv_posinfo = NULL;
             }
         }
 
         put_amf_string(pb, "");
         avio_w8(pb, AMF_END_OF_OBJECT);
 
         avio_seek(pb, cur_pos + flv->keyframe_index_size, SEEK_SET);
     }
 
 end:

     if (flv->flags & FLV_NO_SEQUENCE_END) {
         av_log(s, AV_LOG_DEBUG, "FLV no sequence end mode open\n");
     } else {
         /* Add EOS tag */
         for (i = 0; i < s->nb_streams; i++) {
             AVCodecParameters *par = s->streams[i]->codecpar;
             FLVStreamContext *sc = s->streams[i]->priv_data;
             if (par->codec_type == AVMEDIA_TYPE_VIDEO &&
                     (par->codec_id == AV_CODEC_ID_H264 || par->codec_id == AV_CODEC_ID_MPEG4))
                 put_avc_eos_tag(pb, sc->last_ts);
         }

     }

     file_size = avio_tell(pb);

     if (build_keyframes_idx) {
         flv->datasize = file_size - flv->datastart_offset;
         avio_seek(pb, flv->datasize_offset, SEEK_SET);
         put_amf_double(pb, flv->datasize);
     }

     if (!(flv->flags & FLV_NO_METADATA)) {
         if (!(flv->flags & FLV_NO_DURATION_FILESIZE)) {
             /* update information */
             if (avio_seek(pb, flv->duration_offset, SEEK_SET) < 0) {
                 av_log(s, AV_LOG_WARNING, "Failed to update header with correct duration.\n");
             } else {
                 put_amf_double(pb, flv->duration / (double)1000);
             }
             if (avio_seek(pb, flv->filesize_offset, SEEK_SET) < 0) {
                 av_log(s, AV_LOG_WARNING, "Failed to update header with correct filesize.\n");
             } else {
                 put_amf_double(pb, file_size);
             }

         }
     }

     return 0;
 }
 

 static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)

 {

     AVIOContext *pb      = s->pb;

     AVCodecParameters *par = s->streams[pkt->stream_index]->codecpar;

     FLVContext *flv      = s->priv_data;

     FLVStreamContext *sc = s->streams[pkt->stream_index]->priv_data;

     unsigned ts;

     int size = pkt->size;
     uint8_t *data = NULL;

     int flags = -1, flags_size, ret;

     int64_t cur_offset = avio_tell(pb);

     if (par->codec_id == AV_CODEC_ID_VP6F || par->codec_id == AV_CODEC_ID_VP6A ||

         par->codec_id == AV_CODEC_ID_VP6  || par->codec_id == AV_CODEC_ID_AAC)

         flags_size = 2;

     else if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id == AV_CODEC_ID_MPEG4)

         flags_size = 5;

     else

         flags_size = 1;

     if (par->codec_id == AV_CODEC_ID_AAC || par->codec_id == AV_CODEC_ID_H264
             || par->codec_id == AV_CODEC_ID_MPEG4) {
         int side_size = 0;
         uint8_t *side = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, &side_size);
         if (side && side_size > 0 && (side_size != par->extradata_size || memcmp(side, par->extradata, side_size))) {
             av_free(par->extradata);
             par->extradata = av_mallocz(side_size + AV_INPUT_BUFFER_PADDING_SIZE);

             if (!par->extradata) {
                 par->extradata_size = 0;
                 return AVERROR(ENOMEM);
             }

             memcpy(par->extradata, side, side_size);
             par->extradata_size = side_size;
             flv_write_codec_header(s, par);
         }
     }
 

     if (flv->delay == AV_NOPTS_VALUE)
         flv->delay = -pkt->dts;
 
     if (pkt->dts < -flv->delay) {
         av_log(s, AV_LOG_WARNING,
                "Packets are not in the proper order with respect to DTS\n");
         return AVERROR(EINVAL);
     }
 

     ts = pkt->dts;

 
     if (s->event_flags & AVSTREAM_EVENT_FLAG_METADATA_UPDATED) {
         write_metadata(s, ts);
         s->event_flags &= ~AVSTREAM_EVENT_FLAG_METADATA_UPDATED;
     }
 

     avio_write_marker(pb, av_rescale(ts, AV_TIME_BASE, 1000),
                       pkt->flags & AV_PKT_FLAG_KEY && (flv->video_par ? par->codec_type == AVMEDIA_TYPE_VIDEO : 1) ? AVIO_DATA_MARKER_SYNC_POINT : AVIO_DATA_MARKER_BOUNDARY_POINT);
 

     switch (par->codec_type) {

     case AVMEDIA_TYPE_VIDEO:

         avio_w8(pb, FLV_TAG_TYPE_VIDEO);

         flags = ff_codec_get_tag(flv_video_codec_ids, par->codec_id);

         flags |= pkt->flags & AV_PKT_FLAG_KEY ? FLV_FRAME_KEY : FLV_FRAME_INTER;

         break;
     case AVMEDIA_TYPE_AUDIO:

         flags = get_audio_flags(s, par);

         av_assert0(size);

         avio_w8(pb, FLV_TAG_TYPE_AUDIO);

         break;

     case AVMEDIA_TYPE_SUBTITLE:

     case AVMEDIA_TYPE_DATA:

         avio_w8(pb, FLV_TAG_TYPE_META);

         break;
     default:
         return AVERROR(EINVAL);

     }

     if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id == AV_CODEC_ID_MPEG4) {

         /* check if extradata looks like mp4 formatted */

         if (par->extradata_size > 0 && *(uint8_t*)par->extradata != 1)

             if ((ret = ff_avc_parse_nal_units_buf(pkt->data, &data, &size)) < 0)
                 return ret;

     } else if (par->codec_id == AV_CODEC_ID_AAC && pkt->size > 2 &&

                (AV_RB16(pkt->data) & 0xfff0) == 0xfff0) {

         if (!s->streams[pkt->stream_index]->nb_frames) {

         av_log(s, AV_LOG_ERROR, "Malformed AAC bitstream detected: "

                "use the audio bitstream filter 'aac_adtstoasc' to fix it "

                "('-bsf:a aac_adtstoasc' option with ffmpeg)\n");

         return AVERROR_INVALIDDATA;

         }
         av_log(s, AV_LOG_WARNING, "aac bitstream error\n");

     }

     /* check Speex packet duration */

     if (par->codec_id == AV_CODEC_ID_SPEEX && ts - sc->last_ts > 160)

         av_log(s, AV_LOG_WARNING, "Warning: Speex stream has more than "
                                   "8 frames per packet. Adobe Flash "
                                   "Player cannot handle this!\n");
 

     if (sc->last_ts < ts)
         sc->last_ts = ts;

     if (size + flags_size >= 1<<24) {
         av_log(s, AV_LOG_ERROR, "Too large packet with size %u >= %u\n",
                size + flags_size, 1<<24);
         return AVERROR(EINVAL);
     }
 

     avio_wb24(pb, size + flags_size);

     avio_wb24(pb, ts & 0xFFFFFF);

     avio_w8(pb, (ts >> 24) & 0x7F); // timestamps are 32 bits _signed_
     avio_wb24(pb, flv->reserved);

     if (par->codec_type == AVMEDIA_TYPE_DATA ||
         par->codec_type == AVMEDIA_TYPE_SUBTITLE ) {

         int data_size;

         int64_t metadata_size_pos = avio_tell(pb);

         if (par->codec_id == AV_CODEC_ID_TEXT) {

             // legacy FFmpeg magic?
             avio_w8(pb, AMF_DATA_TYPE_STRING);
             put_amf_string(pb, "onTextData");
             avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);
             avio_wb32(pb, 2);
             put_amf_string(pb, "type");
             avio_w8(pb, AMF_DATA_TYPE_STRING);
             put_amf_string(pb, "Text");
             put_amf_string(pb, "text");
             avio_w8(pb, AMF_DATA_TYPE_STRING);
             put_amf_string(pb, pkt->data);
             put_amf_string(pb, "");
             avio_w8(pb, AMF_END_OF_OBJECT);
         } else {
             // just pass the metadata through
             avio_write(pb, data ? data : pkt->data, size);
         }

         /* write total size of tag */
         data_size = avio_tell(pb) - metadata_size_pos;
         avio_seek(pb, metadata_size_pos - 10, SEEK_SET);
         avio_wb24(pb, data_size);
         avio_seek(pb, data_size + 10 - 3, SEEK_CUR);
         avio_wb32(pb, data_size + 11);
     } else {

         av_assert1(flags>=0);

         avio_w8(pb,flags);

         if (par->codec_id == AV_CODEC_ID_VP6)

             avio_w8(pb,0);

         if (par->codec_id == AV_CODEC_ID_VP6F || par->codec_id == AV_CODEC_ID_VP6A) {
             if (par->extradata_size)
                 avio_w8(pb, par->extradata[0]);

             else

                 avio_w8(pb, ((FFALIGN(par->width,  16) - par->width) << 4) |
                              (FFALIGN(par->height, 16) - par->height));
         } else if (par->codec_id == AV_CODEC_ID_AAC)

             avio_w8(pb, 1); // AAC raw

         else if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id == AV_CODEC_ID_MPEG4) {

             avio_w8(pb, 1); // AVC NALU
             avio_wb24(pb, pkt->pts - pkt->dts);
         }

         avio_write(pb, data ? data : pkt->data, size);

         avio_wb32(pb, size + flags_size + 11); // previous tag size
         flv->duration = FFMAX(flv->duration,
                               pkt->pts + flv->delay + pkt->duration);

     }

     if (flv->flags & FLV_ADD_KEYFRAME_INDEX) {
         switch (par->codec_type) {
             case AVMEDIA_TYPE_VIDEO:
                 flv->videosize += (avio_tell(pb) - cur_offset);
                 flv->lasttimestamp = flv->acurframeindex / flv->framerate;
                 if (pkt->flags & AV_PKT_FLAG_KEY) {
                     double ts = flv->acurframeindex / flv->framerate;
                     int64_t pos = cur_offset;
 
                     flv->lastkeyframetimestamp = flv->acurframeindex / flv->framerate;
                     flv->lastkeyframelocation = pos;
                     flv_append_keyframe_info(s, flv, ts, pos);
                 }
                 flv->acurframeindex++;
                 break;
 
             case AVMEDIA_TYPE_AUDIO:
                 flv->audiosize += (avio_tell(pb) - cur_offset);
                 break;
 
             default:
                 av_log(s, AV_LOG_WARNING, "par->codec_type is type = [%d]\n", par->codec_type);
                 break;
         }
     }
 

     av_free(data);
 

     return pb->error;

 }
 

 static const AVOption options[] = {
     { "flvflags", "FLV muxer flags", offsetof(FLVContext, flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },

     { "aac_seq_header_detect", "Put AAC sequence header based on stream data", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_AAC_SEQ_HEADER_DETECT}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },

     { "no_sequence_end", "disable sequence end for FLV", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_NO_SEQUENCE_END}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },

     { "no_metadata", "disable metadata for FLV", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_NO_METADATA}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },

     { "no_duration_filesize", "disable duration and filesize zero value metadata for FLV", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_NO_DURATION_FILESIZE}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },

     { "add_keyframe_index", "Add keyframe index metadata", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_ADD_KEYFRAME_INDEX}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },

     { NULL },
 };
 
 static const AVClass flv_muxer_class = {
     .class_name = "flv muxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 AVOutputFormat ff_flv_muxer = {

     .name           = "flv",

     .long_name      = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"),

     .mime_type      = "video/x-flv",
     .extensions     = "flv",
     .priv_data_size = sizeof(FLVContext),

     .audio_codec    = CONFIG_LIBMP3LAME ? AV_CODEC_ID_MP3 : AV_CODEC_ID_ADPCM_SWF,
     .video_codec    = AV_CODEC_ID_FLV1,

     .write_header   = flv_write_header,
     .write_packet   = flv_write_packet,
     .write_trailer  = flv_write_trailer,

     .codec_tag      = (const AVCodecTag* const []) {
                           flv_video_codec_ids, flv_audio_codec_ids, 0
                       },

     .flags          = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS |
                       AVFMT_TS_NONSTRICT,

     .priv_class     = &flv_muxer_class,

 };