/*
  * QDesign Music 2 (QDM2) payload for RTP
  * Copyright (c) 2010 Ronald S. Bultje
  *
  * 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
  */
 
 /**
  * @file
  * @brief RTP support for the QDM2 payload (todo: wiki)
  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
  */
 
 #include <string.h>

 #include "libavutil/avassert.h"

 #include "libavutil/intreadwrite.h"
 #include "libavcodec/avcodec.h"

 #include "internal.h"

 #include "rtp.h"
 #include "rtpdec.h"

 #include "rtpdec_formats.h"

 
 struct PayloadContext {
     /** values read from the config header, used as packet headers */
     //@{
     int block_type;            ///< superblock type, value 2 .. 8
     int block_size;            ///< from extradata, used as pkt length
     int subpkts_per_block;     ///< max. nr. of subpackets to add per output buffer
     //@}
 
     /** Temporary storage for superblock restoring, per packet ID (0x80 total) */
     //@{
     uint16_t len[0x80];        ///< how much the temporary buffer is filled
     uint8_t  buf[0x80][0x800]; ///< the temporary storage buffer
 
     unsigned int cache;        ///< number of data packets that we have cached right now
     unsigned int n_pkts;       ///< number of RTP packets received since last packet output / config
     uint32_t timestamp;        ///< timestamp of next-to-be-returned packet
     //@}
 };
 
 /**

  * Parse configuration (basically the codec-specific extradata) from
  * an RTP config subpacket (starts with 0xff).

  *
  * Layout of the config subpacket (in bytes):
  * 1: 0xFF          <- config ID
  * then an array {
  *     1: size      <- of the current item
  *     1: item type <- 0 .. 4
  *     size-2: data <- data depends on the item type
  * }
  *
  * Item 0 implies the end of the config subpacket, and has no data.
  * Item 1 implies a stream configuration without extradata.
  * Item 2 max. nr. of subpackets per superblock
  * Item 3 superblock type for the stream
  * Item 4 implies a stream configuration with extradata (size >= 0x1c).
  *
  * @return <0 on error, otherwise the number of bytes parsed from the
  *         input buffer.
  */
 static int qdm2_parse_config(PayloadContext *qdm, AVStream *st,
                              const uint8_t *buf, const uint8_t *end)
 {
     const uint8_t *p = buf;
 
     while (end - p >= 2) {
         unsigned int item_len = p[0], config_item = p[1];
 
         if (item_len < 2 || end - p < item_len || config_item > 4)
             return AVERROR_INVALIDDATA;
 
         switch (config_item) {
             case 0: /* end of config block */
                 return p - buf + item_len;
             case 1: /* stream without extradata */
                 /* FIXME: set default qdm->block_size */
                 break;
             case 2: /**< subpackets per block */
                 if (item_len < 3)
                     return AVERROR_INVALIDDATA;
                 qdm->subpkts_per_block = p[2];
                 break;
             case 3: /* superblock type */
                 if (item_len < 4)
                     return AVERROR_INVALIDDATA;
                 qdm->block_type = AV_RB16(p + 2);
                 break;
             case 4: /* stream with extradata */
                 if (item_len < 30)
                     return AVERROR_INVALIDDATA;
                 av_freep(&st->codec->extradata);

                 if (ff_alloc_extradata(st->codec, 26 + item_len)) {

                     return AVERROR(ENOMEM);
                 }
                 AV_WB32(st->codec->extradata, 12);
                 memcpy(st->codec->extradata + 4, "frma", 4);
                 memcpy(st->codec->extradata + 8, "QDM2", 4);
                 AV_WB32(st->codec->extradata + 12, 6 + item_len);
                 memcpy(st->codec->extradata + 16, "QDCA", 4);
                 memcpy(st->codec->extradata + 20, p + 2, item_len - 2);
                 AV_WB32(st->codec->extradata + 18 + item_len, 8);
                 AV_WB32(st->codec->extradata + 22 + item_len, 0);
 
                 qdm->block_size = AV_RB32(p + 26);
                 break;
         }
 
         p += item_len;
     }
 
     return AVERROR(EAGAIN); /* not enough data */
 }
 
 /**

  * Parse a single subpacket. We store this subpacket in an intermediate

  * buffer (position depends on the ID (byte[0]). When called, at least
  * 4 bytes are available for reading (see qdm2_parse_packet()).
  *
  * Layout of a single subpacket (RTP packets commonly contain multiple
  * such subpackets) - length in bytes:
  * 1:    ordering ID        <- 0 .. 0x7F
  * 1:    subpacket type     <- 0 .. 0x7F; value & 0x80 means subpacket length = 2 bytes, else 1 byte
  * 1/2:  subpacket length   <- length of the data following the flags/length fields
  * if (subpacket type & 0x7F) == 0x7F
  *   1:  subpacket type, higher bits
  * size: subpacket data
  *
  * The subpackets come in randomly, and should be encapsulated into 1
  * or more superblocks (containing qdm->subpkts_per_block subpackets
  * each) per RTP packet, in order of ascending "ordering ID", see
  * qdm2_restore_block().
  *
  * @return <0 on error, otherwise the number of bytes parsed from the
  *         input buffer.
  */
 static int qdm2_parse_subpacket(PayloadContext *qdm, AVStream *st,
                                 const uint8_t *buf, const uint8_t *end)
 {
     const uint8_t *p = buf;
     unsigned int id, len, type, to_copy;
 
     /* parse header so we know the size of the header/data */
     id       = *p++;
     type     = *p++;
     if (type & 0x80) {
         len   = AV_RB16(p);
         p    += 2;
         type &= 0x7F;
     } else
         len = *p++;
 
     if (end - p < len + (type == 0x7F) || id >= 0x80)
         return AVERROR_INVALIDDATA;
     if (type == 0x7F)
         type |= *p++ << 8;
 
     /* copy data into a temporary buffer */
     to_copy = FFMIN(len + (p - &buf[1]), 0x800 - qdm->len[id]);
     memcpy(&qdm->buf[id][qdm->len[id]], buf + 1, to_copy);
     qdm->len[id] += to_copy;
 
     return p + len - buf;
 }
 
 /**

  * Add a superblock header around a set of subpackets.

  *
  * @return <0 on error, else 0.
  */
 static int qdm2_restore_block(PayloadContext *qdm, AVStream *st, AVPacket *pkt)
 {
     int to_copy, n, res, include_csum;
     uint8_t *p, *csum_pos = NULL;
 
     /* create packet to hold subpkts into a superblock */
     assert(qdm->cache > 0);
     for (n = 0; n < 0x80; n++)
         if (qdm->len[n] > 0)
             break;

     av_assert0(n < 0x80);

 
     if ((res = av_new_packet(pkt, qdm->block_size)) < 0)
         return res;
     memset(pkt->data, 0, pkt->size);
     pkt->stream_index  = st->index;
     p                  = pkt->data;
 
     /* superblock header */
     if (qdm->len[n] > 0xff) {
         *p++ = qdm->block_type | 0x80;
         AV_WB16(p, qdm->len[n]);
         p   += 2;
     } else {
         *p++ = qdm->block_type;
         *p++ = qdm->len[n];
     }
     if ((include_csum = (qdm->block_type == 2 || qdm->block_type == 4))) {
         csum_pos = p;
         p       += 2;
     }
 
     /* subpacket data */
     to_copy = FFMIN(qdm->len[n], pkt->size - (p - pkt->data));
     memcpy(p, qdm->buf[n], to_copy);
     qdm->len[n] = 0;
 
     /* checksum header */
     if (include_csum) {
         unsigned int total = 0;
         uint8_t *q;
 
         for (q = pkt->data; q < &pkt->data[qdm->block_size]; q++)
             total += *q;
         AV_WB16(csum_pos, (uint16_t) total);
     }
 
     return 0;
 }
 
 /** return 0 on packet, no more left, 1 on packet, -1 on partial packet... */
 static int qdm2_parse_packet(AVFormatContext *s, PayloadContext *qdm,
                              AVStream *st, AVPacket *pkt,
                              uint32_t *timestamp,

                              const uint8_t *buf, int len, uint16_t seq,
                              int flags)

 {
     int res = AVERROR_INVALIDDATA, n;
     const uint8_t *end = buf + len, *p = buf;
 
     if (len > 0) {
         if (len < 2)
             return AVERROR_INVALIDDATA;
 
         /* configuration block */
         if (*p == 0xff) {
             if (qdm->n_pkts > 0) {
                 av_log(s, AV_LOG_WARNING,
                        "Out of sequence config - dropping queue\n");
                 qdm->n_pkts = 0;
                 memset(qdm->len, 0, sizeof(qdm->len));
             }
 
             if ((res = qdm2_parse_config(qdm, st, ++p, end)) < 0)
                 return res;
             p += res;
 

             /* We set codec_id to AV_CODEC_ID_NONE initially to

              * delay decoder initialization since extradata is
              * carried within the RTP stream, not SDP. Here,

              * by setting codec_id to AV_CODEC_ID_QDM2, we are signalling

              * to the decoder that it is OK to initialize. */

             st->codec->codec_id = AV_CODEC_ID_QDM2;

         }

         if (st->codec->codec_id == AV_CODEC_ID_NONE)

             return AVERROR(EAGAIN);

 
         /* subpackets */
         while (end - p >= 4) {
             if ((res = qdm2_parse_subpacket(qdm, st, p, end)) < 0)
                 return res;
             p += res;
         }
 
         qdm->timestamp = *timestamp;
         if (++qdm->n_pkts < qdm->subpkts_per_block)
             return AVERROR(EAGAIN);
         qdm->cache = 0;
         for (n = 0; n < 0x80; n++)
             if (qdm->len[n] > 0)
                 qdm->cache++;
     }
 
     /* output the subpackets into freshly created superblock structures */
     if (!qdm->cache || (res = qdm2_restore_block(qdm, st, pkt)) < 0)
         return res;
     if (--qdm->cache == 0)
         qdm->n_pkts = 0;
 
     *timestamp = qdm->timestamp;
     qdm->timestamp = RTP_NOTS_VALUE;
 
     return (qdm->cache > 0) ? 1 : 0;
 }
 
 static PayloadContext *qdm2_extradata_new(void)
 {
     return av_mallocz(sizeof(PayloadContext));
 }
 
 static void qdm2_extradata_free(PayloadContext *qdm)
 {
     av_free(qdm);
 }
 
 RTPDynamicProtocolHandler ff_qdm2_dynamic_handler = {

     .enc_name         = "X-QDM",
     .codec_type       = AVMEDIA_TYPE_AUDIO,

     .codec_id         = AV_CODEC_ID_NONE,

     .alloc            = qdm2_extradata_new,
     .free             = qdm2_extradata_free,

     .parse_packet     = qdm2_parse_packet,

 };