FFmpeg
g729_parser.c
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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 {
34  int duration;
35  int remaining;
37 
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 
89  .priv_data_size = sizeof(G729ParseContext),
90  .parser_parse = g729_parse,
91  .parser_close = ff_parse_close,
92 };
AVCodecContext::frame_size
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:1035
G729_8K_BLOCK_SIZE
#define G729_8K_BLOCK_SIZE
Definition: g729.h:30
G729ParseContext::block_size
int block_size
Definition: g729_parser.c:33
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:284
ff_g729_parser
const AVCodecParser ff_g729_parser
Definition: g729_parser.c:87
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:311
ParseContext
Definition: parser.h:28
G729ParseContext::duration
int duration
Definition: g729_parser.c:34
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:2059
G729ParseContext::remaining
int remaining
Definition: g729_parser.c:35
s
#define s(width, name)
Definition: cbs_vp9.c:256
s1
#define s1
Definition: regdef.h:38
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:408
NULL
#define NULL
Definition: coverity.c:32
AVCodecContext::bit_rate
int64_t bit_rate
the average bitrate
Definition: avcodec.h:448
g729_parse
static int g729_parse(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: g729_parser.c:38
AV_CODEC_ID_ACELP_KELVIN
@ AV_CODEC_ID_ACELP_KELVIN
Definition: codec_id.h:525
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2960
G729ParseContext
Definition: g729_parser.c:31
ff_combine_frame
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:199
g729.h
parser.h
AVCodecParserContext
Definition: avcodec.h:2800
AVCodecContext
main external API structure.
Definition: avcodec.h:398
AV_CODEC_ID_G729
@ AV_CODEC_ID_G729
Definition: codec_id.h:488
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AVCodecParser
Definition: avcodec.h:2959
G729ParseContext::pc
ParseContext pc
Definition: g729_parser.c:32
G729D_6K4_BLOCK_SIZE
#define G729D_6K4_BLOCK_SIZE
Definition: g729.h:31