libavcodec/g729_parser.c

   1 /*
   2  * Copyright (c) 2015  Ganesh Ajjanagadde
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * G.729 audio parser
  24  *
  25  * Splits packets into individual blocks.
  26  */
  27
  28 #include "parser.h"
  29 #include "g729.h"
  30
  31 typedef struct G729ParseContext {
  32     ParseContext pc;
  33     int block_size;
  34     int duration;
  35     int remaining;
  36 } G729ParseContext;
  37
  38 static int g729_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
  39                      const uint8_t **poutbuf, int *poutbuf_size,
  40                      const uint8_t *buf, int buf_size)
  41 {
  42     G729ParseContext *s = s1->priv_data;
  43     ParseContext *pc = &s->pc;
  44     int next;
  45
  46     if (!s->block_size) {
  47         /* FIXME: replace this heuristic block_size with more precise estimate */
  48         s->block_size = (avctx->bit_rate < 8000) ? G729D_6K4_BLOCK_SIZE : G729_8K_BLOCK_SIZE;
  49         if (avctx->codec_id == AV_CODEC_ID_ACELP_KELVIN)
  50             s->block_size++;
  51         // channels > 2 is invalid, we pass the packet on unchanged
  52         if (avctx->ch_layout.nb_channels > 2)
  53             s->block_size = 0;
  54         s->block_size *= avctx->ch_layout.nb_channels;
  55         s->duration   = avctx->frame_size;
  56     }
  57
  58     if (!s->block_size) {
  59         *poutbuf      = buf;
  60         *poutbuf_size = buf_size;
  61         return buf_size;
  62     }
  63
  64     if (!s->remaining)
  65         s->remaining = s->block_size;
  66     if (s->remaining <= buf_size) {
  67         next = s->remaining;
  68         s->remaining = 0;
  69     } else {
  70         next = END_NOT_FOUND;
  71         s->remaining -= buf_size;
  72     }
  73
  74     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0 || !buf_size) {
  75         *poutbuf      = NULL;
  76         *poutbuf_size = 0;
  77         return buf_size;
  78     }
  79
  80     s1->duration = s->duration;
  81
  82     *poutbuf      = buf;
  83     *poutbuf_size = buf_size;
  84     return next;
  85 }
  86
  87 const AVCodecParser ff_g729_parser = {
  88     .codec_ids      = { AV_CODEC_ID_G729, AV_CODEC_ID_ACELP_KELVIN },
  89     .priv_data_size = sizeof(G729ParseContext),
  90     .parser_parse   = g729_parse,
  91     .parser_close   = ff_parse_close,
  92 };