FFmpeg
libavcodec
amr_parser.c
Go to the documentation of this file.
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/*
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* Copyright (c) 2021 Paul B Mahol
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* AMR audio parser
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*
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* Splits packets into individual blocks.
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*/
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#include "
libavutil/channel_layout.h
"
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#include "
libavutil/intreadwrite.h
"
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#include "
parser.h
"
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static
const
uint8_t
amrnb_packed_size
[16] = {
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13, 14, 16, 18, 20, 21, 27, 32, 6, 1, 1, 1, 1, 1, 1, 1
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};
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static
const
uint8_t
amrwb_packed_size
[16] = {
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18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 1, 1, 1, 1, 1, 1
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};
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typedef
struct
AMRParseContext
{
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ParseContext
pc
;
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uint64_t
cumulated_size
;
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uint64_t
block_count
;
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int
current_channel
;
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int
remaining
;
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}
AMRParseContext
;
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static
av_cold
int
amr_parse_init
(
AVCodecParserContext
*s1)
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{
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AMRParseContext
*
s
= s1->
priv_data
;
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s
->remaining = -1;
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return
0;
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}
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static
int
amr_parse
(
AVCodecParserContext
*s1,
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AVCodecContext
*avctx,
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const
uint8_t **poutbuf,
int
*poutbuf_size,
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const
uint8_t *buf,
int
buf_size)
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{
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AMRParseContext
*
s
= s1->
priv_data
;
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ParseContext
*pc = &
s
->pc;
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int
next =
END_NOT_FOUND
;
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*poutbuf_size = 0;
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*poutbuf =
NULL
;
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if
(!avctx->
ch_layout
.
nb_channels
) {
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av_channel_layout_uninit
(&avctx->
ch_layout
);
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avctx->
ch_layout
= (
AVChannelLayout
)
AV_CHANNEL_LAYOUT_MONO
;
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}
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if
(s1->
flags
&
PARSER_FLAG_COMPLETE_FRAMES
) {
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next = buf_size;
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}
else
{
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int
ch,
offset
= 0;
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for
(ch =
s
->current_channel; ch < avctx->ch_layout.nb_channels; ch++) {
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if
(
s
->remaining >= 0) {
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next =
s
->remaining;
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}
else
{
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int
mode
= (buf[
offset
] >> 3) & 0x0F;
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if
(avctx->
codec_id
==
AV_CODEC_ID_AMR_NB
) {
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next =
amrnb_packed_size
[
mode
];
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}
else
if
(avctx->
codec_id
==
AV_CODEC_ID_AMR_WB
) {
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next =
amrwb_packed_size
[
mode
];
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}
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}
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offset
+= next;
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if
(
offset
>= buf_size) {
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s
->remaining =
offset
- buf_size;
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next =
END_NOT_FOUND
;
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break
;
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}
else
{
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s
->remaining = -1;
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}
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}
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s
->current_channel = ch % avctx->
ch_layout
.
nb_channels
;
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if
(
s
->remaining < 0)
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next =
offset
;
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if
(next !=
END_NOT_FOUND
) {
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if
(
s
->cumulated_size < UINT64_MAX - next) {
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s
->cumulated_size += next;
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/* Both AMR formats have 50 frames per second */
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avctx->
bit_rate
=
s
->cumulated_size / ++
s
->block_count * 8 * 50;
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}
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}
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if
(
ff_combine_frame
(pc, next, &buf, &buf_size) < 0) {
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*poutbuf =
NULL
;
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*poutbuf_size = 0;
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return
buf_size;
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}
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}
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s1->
duration
= avctx->
codec_id
==
AV_CODEC_ID_AMR_NB
? 160 : 320;
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return
next;
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}
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const
AVCodecParser
ff_amr_parser
= {
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.
codec_ids
= {
AV_CODEC_ID_AMR_NB
,
AV_CODEC_ID_AMR_WB
},
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.priv_data_size =
sizeof
(
AMRParseContext
),
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.parser_init =
amr_parse_init
,
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.parser_parse =
amr_parse
,
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.parser_close =
ff_parse_close
,
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};
AMRParseContext::cumulated_size
uint64_t cumulated_size
Definition:
amr_parser.c:41
AVCodecParserContext::duration
int duration
Duration of the current frame.
Definition:
avcodec.h:2862
mode
Definition:
swscale.c:52
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition:
parser.c:290
amr_parse_init
static av_cold int amr_parse_init(AVCodecParserContext *s1)
Definition:
amr_parser.c:47
AV_CODEC_ID_AMR_NB
@ AV_CODEC_ID_AMR_NB
Definition:
codec_id.h:427
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition:
channel_layout.h:327
AV_CODEC_ID_AMR_WB
@ AV_CODEC_ID_AMR_WB
Definition:
codec_id.h:428
ParseContext
Definition:
parser.h:28
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition:
avcodec.h:1071
av_cold
#define av_cold
Definition:
attributes.h:90
intreadwrite.h
s
#define s(width, name)
Definition:
cbs_vp9.c:198
AMRParseContext
Definition:
amr_parser.c:39
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition:
avcodec.h:461
NULL
#define NULL
Definition:
coverity.c:32
AMRParseContext::pc
ParseContext pc
Definition:
amr_parser.c:40
AVCodecContext::bit_rate
int64_t bit_rate
the average bitrate
Definition:
avcodec.h:501
AVCodecParserContext::flags
int flags
Definition:
avcodec.h:2781
amr_parse
static int amr_parse(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition:
amr_parser.c:54
AVCodecParser::codec_ids
int codec_ids[7]
Definition:
avcodec.h:2908
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition:
channel_layout.h:317
offset
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
Definition:
writing_filters.txt:86
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:203
ff_amr_parser
const AVCodecParser ff_amr_parser
Definition:
amr_parser.c:125
PARSER_FLAG_COMPLETE_FRAMES
#define PARSER_FLAG_COMPLETE_FRAMES
Definition:
avcodec.h:2782
AMRParseContext::remaining
int remaining
Definition:
amr_parser.c:44
parser.h
AVCodecParserContext
Definition:
avcodec.h:2748
AVCodecContext
main external API structure.
Definition:
avcodec.h:451
amrwb_packed_size
static const uint8_t amrwb_packed_size[16]
Definition:
amr_parser.c:35
channel_layout.h
mode
mode
Definition:
ebur128.h:83
AMRParseContext::block_count
uint64_t block_count
Definition:
amr_parser.c:42
av_channel_layout_uninit
void av_channel_layout_uninit(AVChannelLayout *channel_layout)
Free any allocated data in the channel layout and reset the channel count to 0.
Definition:
channel_layout.c:440
AMRParseContext::current_channel
int current_channel
Definition:
amr_parser.c:43
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition:
channel_layout.h:392
END_NOT_FOUND
#define END_NOT_FOUND
Definition:
parser.h:40
AVCodecParser
Definition:
avcodec.h:2907
AVCodecParserContext::priv_data
void * priv_data
Definition:
avcodec.h:2749
amrnb_packed_size
static const uint8_t amrnb_packed_size[16]
Definition:
amr_parser.c:32
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