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/*
* ADTS muxer.
* Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
* Mans Rullgard <mans@mansr.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/bitstream.h"
#include "avformat.h"
#define ADTS_HEADER_SIZE 7
typedef struct {
int write_adts;
int objecttype;
int sample_rate_index;
int channel_conf;
} ADTSContext;
static int decode_extradata(ADTSContext *adts, uint8_t *buf, int size)
{
GetBitContext gb;
init_get_bits(&gb, buf, size * 8);
adts->objecttype = get_bits(&gb, 5) - 1;
adts->sample_rate_index = get_bits(&gb, 4);
adts->channel_conf = get_bits(&gb, 4);
adts->write_adts = 1;
return 0;
}
static int adts_write_header(AVFormatContext *s)
{
ADTSContext *adts = s->priv_data;
AVCodecContext *avc = s->streams[0]->codec;
if(avc->extradata_size > 0)
decode_extradata(adts, avc->extradata, avc->extradata_size);
return 0;
}
static int adts_write_frame_header(AVFormatContext *s, int size)
{
ADTSContext *ctx = s->priv_data;
PutBitContext pb;
uint8_t buf[ADTS_HEADER_SIZE];
init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
/* adts_fixed_header */
put_bits(&pb, 12, 0xfff); /* syncword */
put_bits(&pb, 1, 0); /* ID */
put_bits(&pb, 2, 0); /* layer */
put_bits(&pb, 1, 1); /* protection_absent */
put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
put_bits(&pb, 4, ctx->sample_rate_index);
put_bits(&pb, 1, 0); /* private_bit */
put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
put_bits(&pb, 1, 0); /* original_copy */
put_bits(&pb, 1, 0); /* home */
/* adts_variable_header */
put_bits(&pb, 1, 0); /* copyright_identification_bit */
put_bits(&pb, 1, 0); /* copyright_identification_start */
put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
put_bits(&pb, 11, 0x7ff); /* adts_buffer_fullness */
put_bits(&pb, 2, 0); /* number_of_raw_data_blocks_in_frame */
flush_put_bits(&pb);
put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
return 0;
}
static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
{
ADTSContext *adts = s->priv_data;
ByteIOContext *pb = s->pb;
if (!pkt->size)
return 0;
if(adts->write_adts)
adts_write_frame_header(s, pkt->size);
put_buffer(pb, pkt->data, pkt->size);
put_flush_packet(pb);
return 0;
}
AVOutputFormat adts_muxer = {
"adts",
NULL_IF_CONFIG_SMALL("ADTS AAC"),
"audio/aac",
"aac",
sizeof(ADTSContext),
CODEC_ID_AAC,
CODEC_ID_NONE,
adts_write_header,
adts_write_packet,
};
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