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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 {
  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 PayloadContext *qcelp_new_context(void)
  51. {
  52.     return av_mallocz(sizeof(PayloadContext));
  53. }
  54.  
  55. static void qcelp_free_context(PayloadContext *data)
  56. {
  57.     av_free(data);
  58. }
  59.  
  60. static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
  61.                                AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  62.                                const uint8_t *buf, int len);
  63.  
  64. static int store_packet(AVFormatContext *ctx, PayloadContext *data,
  65.                         AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  66.                         const uint8_t *buf, int len)
  67. {
  68.     int interleave_size, interleave_index;
  69.     int frame_size, ret;
  70.     InterleavePacket* ip;
  71.  
  72.     if (len < 2)
  73.         return AVERROR_INVALIDDATA;
  74.  
  75.     interleave_size  = buf[0] >> 3 & 7;
  76.     interleave_index = buf[0]      & 7;
  77.  
  78.     if (interleave_size > 5) {
  79.         av_log(ctx, AV_LOG_ERROR, "Invalid interleave size %d\n",
  80.                                    interleave_size);
  81.         return AVERROR_INVALIDDATA;
  82.     }
  83.     if (interleave_index > interleave_size) {
  84.         av_log(ctx, AV_LOG_ERROR, "Invalid interleave index %d/%d\n",
  85.                                    interleave_index, interleave_size);
  86.         return AVERROR_INVALIDDATA;
  87.     }
  88.     if (interleave_size != data->interleave_size) {
  89.         int i;
  90.         /* First packet, or changed interleave size */
  91.         data->interleave_size = interleave_size;
  92.         data->interleave_index = 0;
  93.         for (i = 0; i < 6; i++)
  94.             data->group[i].size = 0;
  95.     }
  96.  
  97.     if (interleave_index < data->interleave_index) {
  98.         /* Wrapped around - missed the last packet of the previous group. */
  99.         if (data->group_finished) {
  100.             /* No more data in the packets in this interleaving group, just
  101.              * start processing the next one */
  102.             data->interleave_index = 0;
  103.         } else {
  104.             /* Stash away the current packet, emit everything we have of the
  105.              * previous group. */
  106.             for (; data->interleave_index <= interleave_size;
  107.                  data->interleave_index++)
  108.                 data->group[data->interleave_index].size = 0;
  109.  
  110.             if (len > sizeof(data->next_data))
  111.                 return AVERROR_INVALIDDATA;
  112.             memcpy(data->next_data, buf, len);
  113.             data->next_size = len;
  114.             data->next_timestamp = *timestamp;
  115.             *timestamp = RTP_NOTS_VALUE;
  116.  
  117.             data->interleave_index = 0;
  118.             return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
  119.         }
  120.     }
  121.     if (interleave_index > data->interleave_index) {
  122.         /* We missed a packet */
  123.         for (; data->interleave_index < interleave_index;
  124.              data->interleave_index++)
  125.             data->group[data->interleave_index].size = 0;
  126.     }
  127.     data->interleave_index = interleave_index;
  128.  
  129.     if (buf[1] >= FF_ARRAY_ELEMS(frame_sizes))
  130.         return AVERROR_INVALIDDATA;
  131.     frame_size = frame_sizes[buf[1]];
  132.     if (1 + frame_size > len)
  133.         return AVERROR_INVALIDDATA;
  134.  
  135.     if (len - 1 - frame_size > sizeof(data->group[0].data))
  136.         return AVERROR_INVALIDDATA;
  137.  
  138.     if ((ret = av_new_packet(pkt, frame_size)) < 0)
  139.         return ret;
  140.     memcpy(pkt->data, &buf[1], frame_size);
  141.     pkt->stream_index = st->index;
  142.  
  143.     ip = &data->group[data->interleave_index];
  144.     ip->size = len - 1 - frame_size;
  145.     ip->pos = 0;
  146.     memcpy(ip->data, &buf[1 + frame_size], ip->size);
  147.     /* Each packet must contain the same number of frames according to the
  148.      * RFC. If there's no data left in this packet, there shouldn't be any
  149.      * in any of the other frames in the interleaving group either. */
  150.     data->group_finished = ip->size == 0;
  151.  
  152.     if (interleave_index == interleave_size) {
  153.         data->interleave_index = 0;
  154.         return !data->group_finished;
  155.     } else {
  156.         data->interleave_index++;
  157.         return 0;
  158.     }
  159. }
  160.  
  161. static int return_stored_frame(AVFormatContext *ctx, PayloadContext *data,
  162.                                AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  163.                                const uint8_t *buf, int len)
  164. {
  165.     InterleavePacket* ip = &data->group[data->interleave_index];
  166.     int frame_size, ret;
  167.  
  168.     if (data->group_finished && data->interleave_index == 0) {
  169.         *timestamp = data->next_timestamp;
  170.         ret = store_packet(ctx, data, st, pkt, timestamp, data->next_data,
  171.                            data->next_size);
  172.         data->next_size = 0;
  173.         return ret;
  174.     }
  175.  
  176.     if (ip->size == 0) {
  177.         /* No stored data for this interleave block, output an empty packet */
  178.         if ((ret = av_new_packet(pkt, 1)) < 0)
  179.             return ret;
  180.         pkt->data[0] = 0; // Blank - could also be 14, Erasure
  181.     } else {
  182.         if (ip->pos >= ip->size)
  183.             return AVERROR_INVALIDDATA;
  184.         if (ip->data[ip->pos] >= FF_ARRAY_ELEMS(frame_sizes))
  185.             return AVERROR_INVALIDDATA;
  186.         frame_size = frame_sizes[ip->data[ip->pos]];
  187.         if (ip->pos + frame_size > ip->size)
  188.             return AVERROR_INVALIDDATA;
  189.  
  190.         if ((ret = av_new_packet(pkt, frame_size)) < 0)
  191.             return ret;
  192.         memcpy(pkt->data, &ip->data[ip->pos], frame_size);
  193.  
  194.         ip->pos += frame_size;
  195.         data->group_finished = ip->pos >= ip->size;
  196.     }
  197.     pkt->stream_index = st->index;
  198.  
  199.     if (data->interleave_index == data->interleave_size) {
  200.         data->interleave_index = 0;
  201.         if (!data->group_finished)
  202.             return 1;
  203.         else
  204.             return data->next_size > 0;
  205.     } else {
  206.         data->interleave_index++;
  207.         return 1;
  208.     }
  209. }
  210.  
  211. static int qcelp_parse_packet(AVFormatContext *ctx, PayloadContext *data,
  212.                               AVStream *st, AVPacket *pkt, uint32_t *timestamp,
  213.                               const uint8_t *buf, int len, uint16_t seq,
  214.                               int flags)
  215. {
  216.     if (buf)
  217.         return store_packet(ctx, data, st, pkt, timestamp, buf, len);
  218.     else
  219.         return return_stored_frame(ctx, data, st, pkt, timestamp, buf, len);
  220. }
  221.  
  222. RTPDynamicProtocolHandler ff_qcelp_dynamic_handler = {
  223.     .enc_name           = "x-Purevoice",
  224.     .codec_type         = AVMEDIA_TYPE_AUDIO,
  225.     .codec_id           = AV_CODEC_ID_QCELP,
  226.     .static_payload_id  = 12,
  227.     .alloc              = qcelp_new_context,
  228.     .free               = qcelp_free_context,
  229.     .parse_packet       = qcelp_parse_packet
  230. };
  231.