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libavformat
adtsenc.c
Go to the documentation of this file.
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/*
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* ADTS muxer.
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* Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
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* Mans Rullgard <mans@mansr.com>
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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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#include "
libavcodec/get_bits.h
"
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#include "
libavcodec/put_bits.h
"
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#include "
libavcodec/avcodec.h
"
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#include "
libavcodec/mpeg4audio.h
"
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#include "
avformat.h
"
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#define ADTS_HEADER_SIZE 7
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typedef
struct
{
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int
write_adts
;
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int
objecttype
;
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int
sample_rate_index
;
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int
channel_conf
;
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int
pce_size
;
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uint8_t
pce_data[
MAX_PCE_SIZE
];
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}
ADTSContext
;
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#define ADTS_MAX_FRAME_BYTES ((1 << 13) - 1)
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static
int
adts_decode_extradata
(
AVFormatContext
*
s
,
ADTSContext
*adts,
uint8_t
*
buf
,
int
size
)
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{
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GetBitContext
gb;
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PutBitContext
pb;
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MPEG4AudioConfig
m4ac;
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int
off
;
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init_get_bits
(&gb, buf, size * 8);
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off =
avpriv_mpeg4audio_get_config
(&m4ac, buf, size * 8, 1);
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if
(off < 0)
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return
off
;
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skip_bits_long
(&gb, off);
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adts->
objecttype
= m4ac.
object_type
- 1;
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adts->
sample_rate_index
= m4ac.
sampling_index
;
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adts->
channel_conf
= m4ac.
chan_config
;
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if
(adts->
objecttype
> 3
U
) {
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av_log
(s,
AV_LOG_ERROR
,
"MPEG-4 AOT %d is not allowed in ADTS\n"
, adts->
objecttype
+1);
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return
-1;
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}
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if
(adts->
sample_rate_index
== 15) {
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av_log
(s,
AV_LOG_ERROR
,
"Escape sample rate index illegal in ADTS\n"
);
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return
-1;
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}
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if
(
get_bits
(&gb, 1)) {
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av_log
(s,
AV_LOG_ERROR
,
"960/120 MDCT window is not allowed in ADTS\n"
);
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return
-1;
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}
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if
(
get_bits
(&gb, 1)) {
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av_log
(s,
AV_LOG_ERROR
,
"Scalable configurations are not allowed in ADTS\n"
);
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return
-1;
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}
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if
(
get_bits
(&gb, 1)) {
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av_log
(s,
AV_LOG_ERROR
,
"Extension flag is not allowed in ADTS\n"
);
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return
-1;
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}
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if
(!adts->
channel_conf
) {
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init_put_bits
(&pb, adts->
pce_data
,
MAX_PCE_SIZE
);
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put_bits
(&pb, 3, 5);
//ID_PCE
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adts->
pce_size
= (
avpriv_copy_pce_data
(&pb, &gb) + 3) / 8;
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flush_put_bits
(&pb);
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}
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adts->
write_adts
= 1;
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return
0;
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}
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static
int
adts_write_header
(
AVFormatContext
*
s
)
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{
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ADTSContext
*adts = s->
priv_data
;
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AVCodecContext
*avc = s->
streams
[0]->
codec
;
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if
(avc->
extradata_size
> 0 &&
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adts_decode_extradata
(s, adts, avc->
extradata
, avc->
extradata_size
) < 0)
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return
-1;
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return
0;
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}
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static
int
adts_write_frame_header
(
ADTSContext
*ctx,
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uint8_t
*
buf
,
int
size
,
int
pce_size)
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{
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PutBitContext
pb;
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unsigned
full_frame_size = (unsigned)
ADTS_HEADER_SIZE
+ size + pce_size;
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if
(full_frame_size >
ADTS_MAX_FRAME_BYTES
) {
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av_log
(NULL,
AV_LOG_ERROR
,
"ADTS frame size too large: %u (max %d)\n"
,
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full_frame_size,
ADTS_MAX_FRAME_BYTES
);
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return
AVERROR_INVALIDDATA
;
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}
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init_put_bits
(&pb, buf,
ADTS_HEADER_SIZE
);
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/* adts_fixed_header */
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put_bits
(&pb, 12, 0xfff);
/* syncword */
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put_bits
(&pb, 1, 0);
/* ID */
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put_bits
(&pb, 2, 0);
/* layer */
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put_bits
(&pb, 1, 1);
/* protection_absent */
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put_bits
(&pb, 2, ctx->
objecttype
);
/* profile_objecttype */
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put_bits
(&pb, 4, ctx->
sample_rate_index
);
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put_bits
(&pb, 1, 0);
/* private_bit */
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put_bits
(&pb, 3, ctx->
channel_conf
);
/* channel_configuration */
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put_bits
(&pb, 1, 0);
/* original_copy */
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put_bits
(&pb, 1, 0);
/* home */
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/* adts_variable_header */
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put_bits
(&pb, 1, 0);
/* copyright_identification_bit */
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put_bits
(&pb, 1, 0);
/* copyright_identification_start */
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put_bits
(&pb, 13, full_frame_size);
/* aac_frame_length */
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put_bits
(&pb, 11, 0x7ff);
/* adts_buffer_fullness */
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put_bits
(&pb, 2, 0);
/* number_of_raw_data_blocks_in_frame */
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flush_put_bits
(&pb);
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return
0;
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}
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static
int
adts_write_packet
(
AVFormatContext
*
s
,
AVPacket
*
pkt
)
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{
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ADTSContext
*adts = s->
priv_data
;
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AVIOContext
*pb = s->
pb
;
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uint8_t
buf
[
ADTS_HEADER_SIZE
];
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if
(!pkt->
size
)
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return
0;
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if
(adts->
write_adts
) {
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int
err =
adts_write_frame_header
(adts, buf, pkt->
size
,
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adts->
pce_size
);
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if
(err < 0)
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return
err;
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avio_write
(pb, buf,
ADTS_HEADER_SIZE
);
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if
(adts->
pce_size
) {
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avio_write
(pb, adts->
pce_data
, adts->
pce_size
);
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adts->
pce_size
= 0;
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}
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}
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avio_write
(pb, pkt->
data
, pkt->
size
);
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return
0;
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}
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AVOutputFormat
ff_adts_muxer
= {
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.
name
=
"adts"
,
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.long_name =
NULL_IF_CONFIG_SMALL
(
"ADTS AAC (Advanced Audio Coding)"
),
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.mime_type =
"audio/aac"
,
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.extensions =
"aac,adts"
,
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.priv_data_size =
sizeof
(
ADTSContext
),
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.audio_codec =
AV_CODEC_ID_AAC
,
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.video_codec =
AV_CODEC_ID_NONE
,
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.
write_header
=
adts_write_header
,
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.
write_packet
=
adts_write_packet
,
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};
Generated on Wed Jul 10 2013 23:48:11 for FFmpeg by
1.8.2