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https://github.com/FFmpeg/FFmpeg.git
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103 lines
2.9 KiB
C
103 lines
2.9 KiB
C
/*
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* Raw AC-4 muxer
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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/codec_id.h"
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#include "libavcodec/codec_par.h"
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#include "libavcodec/packet.h"
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#include "libavutil/crc.h"
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#include "libavutil/opt.h"
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#include "avformat.h"
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#include "mux.h"
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typedef struct AC4Context {
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AVClass *class;
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int write_crc;
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} AC4Context;
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static int ac4_init(AVFormatContext *s)
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{
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AVCodecParameters *par = s->streams[0]->codecpar;
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if (s->nb_streams != 1 || par->codec_id != AV_CODEC_ID_AC4) {
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av_log(s, AV_LOG_ERROR, "Only one AC-4 stream can be muxed by the AC-4 muxer\n");
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return AVERROR(EINVAL);
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}
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return 0;
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}
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static int ac4_write_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AC4Context *ac4 = s->priv_data;
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AVIOContext *pb = s->pb;
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if (!pkt->size)
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return 0;
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if (ac4->write_crc)
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avio_wb16(pb, 0xAC41);
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else
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avio_wb16(pb, 0xAC40);
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if (pkt->size >= 0xffff) {
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avio_wb16(pb, 0xffff);
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avio_wb24(pb, pkt->size);
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} else {
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avio_wb16(pb, pkt->size);
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}
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avio_write(pb, pkt->data, pkt->size);
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if (ac4->write_crc) {
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uint16_t crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, pkt->data, pkt->size);
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avio_wl16(pb, crc);
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}
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return 0;
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}
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#define ENC AV_OPT_FLAG_ENCODING_PARAM
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#define OFFSET(obj) offsetof(AC4Context, obj)
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static const AVOption ac4_options[] = {
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{ "write_crc", "enable checksum", OFFSET(write_crc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, ENC},
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{ NULL },
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};
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static const AVClass ac4_muxer_class = {
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.class_name = "AC4 muxer",
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.item_name = av_default_item_name,
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.option = ac4_options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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const FFOutputFormat ff_ac4_muxer = {
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.p.name = "ac4",
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.p.long_name = NULL_IF_CONFIG_SMALL("raw AC-4"),
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.p.mime_type = "audio/ac4",
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.p.extensions = "ac4",
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.priv_data_size = sizeof(AC4Context),
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.p.audio_codec = AV_CODEC_ID_AC4,
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.p.video_codec = AV_CODEC_ID_NONE,
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.init = ac4_init,
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.write_packet = ac4_write_packet,
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.p.priv_class = &ac4_muxer_class,
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.p.flags = AVFMT_NOTIMESTAMPS,
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};
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