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https://git.ffmpeg.org/ffmpeg.git
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119 lines
3.3 KiB
C
119 lines
3.3 KiB
C
/*
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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/bitstream.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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} ADTSContext;
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static int decode_extradata(ADTSContext *adts, uint8_t *buf, int size)
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{
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GetBitContext gb;
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init_get_bits(&gb, buf, size * 8);
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adts->objecttype = get_bits(&gb, 5) - 1;
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adts->sample_rate_index = get_bits(&gb, 4);
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adts->channel_conf = get_bits(&gb, 4);
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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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decode_extradata(adts, avc->extradata, avc->extradata_size);
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return 0;
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}
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static int adts_write_frame_header(AVFormatContext *s, int size)
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{
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ADTSContext *ctx = s->priv_data;
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PutBitContext pb;
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uint8_t buf[ADTS_HEADER_SIZE];
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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, ADTS_HEADER_SIZE + 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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put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
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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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ByteIOContext *pb = s->pb;
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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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adts_write_frame_header(s, pkt->size);
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put_buffer(pb, pkt->data, pkt->size);
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put_flush_packet(pb);
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return 0;
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}
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AVOutputFormat adts_muxer = {
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"adts",
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"ADTS AAC",
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"audio/aac",
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"aac",
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sizeof(ADTSContext),
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CODEC_ID_AAC,
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CODEC_ID_NONE,
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adts_write_header,
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adts_write_packet,
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};
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