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  1. /*
  2.  * RTP Depacketization of QCELP/PureVoice, RFC 2658
  3.  * Copyright (c) 2010 Martin Storsjo
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "rtpdec_formats.h"
  23.  
  24. static const uint8_t frame_sizes[] = {
  25.     1, 4, 8, 17, 35
  26. };
  27.  
  28. typedef struct InterleavePacket {
  29.     int pos;
  30.     int size;
  31.     /* The largest frame is 35 bytes, only 10 frames are allowed per
  32.      * packet, and we return the first one immediately, so allocate
  33.      * space for 9 frames */
  34.     uint8_t data[35*9];
  35. } InterleavePacket;
  36.  
  37. struct PayloadContext {
  38.     int interleave_size;
  39.     int interleave_index;
  40.     InterleavePacket group[6];
  41.     int group_finished;
  42.  
  43.     /* The maximum packet size, 10 frames of 35 bytes each, and one
  44.      * packet header byte. */
  45.     uint8_t  next_data[1 + 35*10];
  46.     int      next_size;
  47.     uint32_t next_timestamp;
  48. };
  49.  
  50. static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
  51.                                AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  52.                                const uint8_t *buf, int len);
  53.  
  54. static int store_packet(AVFormatContext *ctx, PayloadContext *data,
  55.                         AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  56.                         const uint8_t *buf, int len)
  57. {
  58.     int interleave_size, interleave_index;
  59.     int frame_size, ret;
  60.     InterleavePacket* ip;
  61.  
  62.     if (len < 2)
  63.         return AVERROR_INVALIDDATA;
  64.  
  65.     interleave_size  = buf[0] >> 3 & 7;
  66.     interleave_index = buf[0]      & 7;
  67.  
  68.     if (interleave_size > 5) {
  69.         av_log(ctx, AV_LOG_ERROR, "Invalid interleave size %d\n",
  70.                                    interleave_size);
  71.         return AVERROR_INVALIDDATA;
  72.     }
  73.     if (interleave_index > interleave_size) {
  74.         av_log(ctx, AV_LOG_ERROR, "Invalid interleave index %d/%d\n",
  75.                                    interleave_index, interleave_size);
  76.         return AVERROR_INVALIDDATA;
  77.     }
  78.     if (interleave_size != data->interleave_size) {
  79.         int i;
  80.         /* First packet, or changed interleave size */
  81.         data->interleave_size = interleave_size;
  82.         data->interleave_index = 0;
  83.         for (i = 0; i < 6; i++)
  84.             data->group[i].size = 0;
  85.     }
  86.  
  87.     if (interleave_index < data->interleave_index) {
  88.         /* Wrapped around - missed the last packet of the previous group. */
  89.         if (data->group_finished) {
  90.             /* No more data in the packets in this interleaving group, just
  91.              * start processing the next one */
  92.             data->interleave_index = 0;
  93.         } else {
  94.             /* Stash away the current packet, emit everything we have of the
  95.              * previous group. */
  96.             for (; data->interleave_index <= interleave_size;
  97.                  data->interleave_index++)
  98.                 data->group[data->interleave_index].size = 0;
  99.  
  100.             if (len > sizeof(data->next_data))
  101.                 return AVERROR_INVALIDDATA;
  102.             memcpy(data->next_data, buf, len);
  103.             data->next_size = len;
  104.             data->next_timestamp = *timestamp;
  105.             *timestamp = RTP_NOTS_VALUE;
  106.  
  107.             data->interleave_index = 0;
  108.             return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
  109.         }
  110.     }
  111.     if (interleave_index > data->interleave_index) {
  112.         /* We missed a packet */
  113.         for (; data->interleave_index < interleave_index;
  114.              data->interleave_index++)
  115.             data->group[data->interleave_index].size = 0;
  116.     }
  117.     data->interleave_index = interleave_index;
  118.  
  119.     if (buf[1] >= FF_ARRAY_ELEMS(frame_sizes))
  120.         return AVERROR_INVALIDDATA;
  121.     frame_size = frame_sizes[buf[1]];
  122.     if (1 + frame_size > len)
  123.         return AVERROR_INVALIDDATA;
  124.  
  125.     if (len - 1 - frame_size > sizeof(data->group[0].data))
  126.         return AVERROR_INVALIDDATA;
  127.  
  128.     if ((ret = av_new_packet(pkt, frame_size)) < 0)
  129.         return ret;
  130.     memcpy(pkt->data, &buf[1], frame_size);
  131.     pkt->stream_index = st->index;
  132.  
  133.     ip = &data->group[data->interleave_index];
  134.     ip->size = len - 1 - frame_size;
  135.     ip->pos = 0;
  136.     memcpy(ip->data, &buf[1 + frame_size], ip->size);
  137.     /* Each packet must contain the same number of frames according to the
  138.      * RFC. If there's no data left in this packet, there shouldn't be any
  139.      * in any of the other frames in the interleaving group either. */
  140.     data->group_finished = ip->size == 0;
  141.  
  142.     if (interleave_index == interleave_size) {
  143.         data->interleave_index = 0;
  144.         return !data->group_finished;
  145.     } else {
  146.         data->interleave_index++;
  147.         return 0;
  148.     }
  149. }
  150.  
  151. static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
  152.                                AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  153.                                const uint8_t *buf, int len)
  154. {
  155.     InterleavePacket* ip = &data->group[data->interleave_index];
  156.     int frame_size, ret;
  157.  
  158.     if (data->group_finished && data->interleave_index == 0) {
  159.         *timestamp = data->next_timestamp;
  160.         ret = store_packet(ctx, data, st, pkt, timestamp, data->next_data,
  161.                            data->next_size);
  162.         data->next_size = 0;
  163.         return ret;
  164.     }
  165.  
  166.     if (ip->size == 0) {
  167.         /* No stored data for this interleave block, output an empty packet */
  168.         if ((ret = av_new_packet(pkt, 1)) < 0)
  169.             return ret;
  170.         pkt->data[0] = 0; // Blank - could also be 14, Erasure
  171.     } else {
  172.         if (ip->pos >= ip->size)
  173.             return AVERROR_INVALIDDATA;
  174.         if (ip->data[ip->pos] >= FF_ARRAY_ELEMS(frame_sizes))
  175.             return AVERROR_INVALIDDATA;
  176.         frame_size = frame_sizes[ip->data[ip->pos]];
  177.         if (ip->pos + frame_size > ip->size)
  178.             return AVERROR_INVALIDDATA;
  179.  
  180.         if ((ret = av_new_packet(pkt, frame_size)) < 0)
  181.             return ret;
  182.         memcpy(pkt->data, &ip->data[ip->pos], frame_size);
  183.  
  184.         ip->pos += frame_size;
  185.         data->group_finished = ip->pos >= ip->size;
  186.     }
  187.     pkt->stream_index = st->index;
  188.  
  189.     if (data->interleave_index == data->interleave_size) {
  190.         data->interleave_index = 0;
  191.         if (!data->group_finished)
  192.             return 1;
  193.         else
  194.             return data->next_size > 0;
  195.     } else {
  196.         data->interleave_index++;
  197.         return 1;
  198.     }
  199. }
  200.  
  201. static int qcelp_parse_packet(AVFormatContext *ctx, PayloadContext *data,
  202.                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  203.                               const uint8_t *buf, int len, uint16_t seq,
  204.                               int flags)
  205. {
  206.     if (buf)
  207.         return store_packet(ctx, data, st, pkt, timestamp, buf, len);
  208.     else
  209.         return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
  210. }
  211.  
  212. RTPDynamicProtocolHandler ff_qcelp_dynamic_handler = {
  213.     .enc_name           = "x-Purevoice",
  214.     .codec_type         = AVMEDIA_TYPE_AUDIO,
  215.     .codec_id           = AV_CODEC_ID_QCELP,
  216.     .priv_data_size     = sizeof(PayloadContext),
  217.     .static_payload_id  = 12,
  218.     .parse_packet       = qcelp_parse_packet,
  219. };
  220.