2020-09-03 22:32:37 +00:00
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/*
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* MCA demuxer
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* Copyright (c) 2020 Zixing Liu
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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 "libavutil/intreadwrite.h"
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#include "avformat.h"
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#include "avio_internal.h"
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#include "internal.h"
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typedef struct MCADemuxContext {
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uint32_t block_count;
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uint16_t block_size;
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uint32_t current_block;
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uint32_t data_start;
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uint32_t samples_per_block;
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} MCADemuxContext;
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static int probe(const AVProbeData *p)
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{
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if (AV_RL32(p->buf) == MKTAG('M', 'A', 'D', 'P') &&
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AV_RL16(p->buf + 4) <= 0x5)
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return AVPROBE_SCORE_MAX / 3 * 2;
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return 0;
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}
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static int read_header(AVFormatContext *s)
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{
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AVStream *st;
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MCADemuxContext *m = s->priv_data;
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AVCodecParameters *par;
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int64_t file_size = avio_size(s->pb);
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uint16_t version = 0;
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uint32_t header_size, data_size, data_offset, loop_start, loop_end,
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nb_samples, nb_metadata, coef_offset = 0;
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int ch, ret;
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int64_t ret_size;
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st = avformat_new_stream(s, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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par = st->codecpar;
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par->codec_type = AVMEDIA_TYPE_AUDIO;
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// parse file headers
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avio_skip(s->pb, 0x4); // skip the file magic
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version = avio_rl16(s->pb);
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avio_skip(s->pb, 0x2); // padding
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par->channels = avio_r8(s->pb);
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avio_skip(s->pb, 0x1); // padding
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m->block_size = avio_rl16(s->pb);
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nb_samples = avio_rl32(s->pb);
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par->sample_rate = avio_rl32(s->pb);
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loop_start = avio_rl32(s->pb);
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loop_end = avio_rl32(s->pb);
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header_size = avio_rl32(s->pb);
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data_size = avio_rl32(s->pb);
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avio_skip(s->pb, 0x4);
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nb_metadata = avio_rl16(s->pb);
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avio_skip(s->pb, 0x2); // unknown u16 field
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// samples per frame = 14; frame size = 8 (2^3)
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m->samples_per_block = (m->block_size * 14) >> 3;
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if (m->samples_per_block < 1)
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return AVERROR_INVALIDDATA;
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m->block_count = nb_samples / m->samples_per_block;
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st->duration = nb_samples;
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// sanity checks
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if (!par->channels || par->sample_rate <= 0
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|| loop_start > loop_end || m->block_count < 1)
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return AVERROR_INVALIDDATA;
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if ((ret = av_dict_set_int(&s->metadata, "loop_start",
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av_rescale(loop_start, AV_TIME_BASE,
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par->sample_rate), 0)) < 0)
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return ret;
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if ((ret = av_dict_set_int(&s->metadata, "loop_end",
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av_rescale(loop_end, AV_TIME_BASE,
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par->sample_rate), 0)) < 0)
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return ret;
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if ((32 + 4 + m->block_size) > (INT_MAX / par->channels) ||
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(32 + 4 + m->block_size) * par->channels > INT_MAX - 8)
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return AVERROR_INVALIDDATA;
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avpriv_set_pts_info(st, 64, 1, par->sample_rate);
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if (version <= 4) {
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// version <= 4 needs to use the file size to calculate the offsets
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if (file_size < 0) {
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return AVERROR(EIO);
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}
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if (file_size - data_size > UINT32_MAX)
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return AVERROR_INVALIDDATA;
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m->data_start = file_size - data_size;
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if (version <= 3) {
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nb_metadata = 0;
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// header_size is not available or incorrect in older versions
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header_size = m->data_start;
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}
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} else if (version == 5) {
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// read data_start location from the header
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if (0x30 * par->channels + 0x4 > header_size)
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return AVERROR_INVALIDDATA;
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data_offset = header_size - 0x30 * par->channels - 0x4;
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if ((ret_size = avio_seek(s->pb, data_offset, SEEK_SET)) < 0)
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return ret_size;
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m->data_start = avio_rl32(s->pb);
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// check if the metadata is reasonable
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if (file_size > 0 && (int64_t)m->data_start + data_size > file_size) {
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// the header is broken beyond repair
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if ((int64_t)header_size + data_size > file_size) {
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av_log(s, AV_LOG_ERROR,
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"MCA metadata corrupted, unable to determine the data offset.\n");
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return AVERROR_INVALIDDATA;
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}
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// recover the data_start information from the data size
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av_log(s, AV_LOG_WARNING,
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"Incorrect header size found in metadata, "
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"header size approximated from the data size\n");
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if (file_size - data_offset > UINT32_MAX)
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return AVERROR_INVALIDDATA;
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m->data_start = file_size - data_size;
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}
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} else {
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avpriv_request_sample(s, "version %d", version);
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return AVERROR_PATCHWELCOME;
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}
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// coefficient alignment = 0x30; metadata size = 0x14
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if (0x30 * par->channels + nb_metadata * 0x14 > header_size)
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return AVERROR_INVALIDDATA;
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coef_offset =
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header_size - 0x30 * par->channels + nb_metadata * 0x14;
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st->start_time = 0;
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par->codec_id = AV_CODEC_ID_ADPCM_THP_LE;
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ret = ff_alloc_extradata(st->codecpar, 32 * par->channels);
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if (ret < 0)
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return ret;
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if ((ret_size = avio_seek(s->pb, coef_offset, SEEK_SET)) < 0)
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return ret_size;
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for (ch = 0; ch < par->channels; ch++) {
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if ((ret = ffio_read_size(s->pb, par->extradata + ch * 32, 32)) < 0)
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return ret;
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// 0x30 (alignment) - 0x20 (actual size, 32) = 0x10 (padding)
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avio_skip(s->pb, 0x10);
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}
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// seek to the beginning of the adpcm data
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// there are some files where the adpcm audio data is not immediately after the header
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if ((ret_size = avio_seek(s->pb, m->data_start, SEEK_SET)) < 0)
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return ret_size;
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return 0;
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}
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static int read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AVCodecParameters *par = s->streams[0]->codecpar;
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MCADemuxContext *m = s->priv_data;
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uint16_t size = m->block_size;
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uint32_t samples = m->samples_per_block;
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int ret = 0;
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if (avio_feof(s->pb))
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return AVERROR_EOF;
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m->current_block++;
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if (m->current_block > m->block_count)
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return AVERROR_EOF;
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if ((ret = av_get_packet(s->pb, pkt, size * par->channels)) < 0)
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return ret;
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pkt->duration = samples;
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pkt->stream_index = 0;
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return 0;
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}
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static int read_seek(AVFormatContext *s, int stream_index,
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int64_t timestamp, int flags)
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{
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AVStream *st = s->streams[stream_index];
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MCADemuxContext *m = s->priv_data;
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int64_t ret = 0;
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2020-09-10 15:20:19 +00:00
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if (timestamp < 0)
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timestamp = 0;
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2020-09-03 22:32:37 +00:00
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timestamp /= m->samples_per_block;
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2020-09-10 15:20:19 +00:00
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if (timestamp >= m->block_count)
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timestamp = m->block_count - 1;
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2020-09-03 22:32:37 +00:00
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ret = avio_seek(s->pb, m->data_start + timestamp * m->block_size *
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st->codecpar->channels, SEEK_SET);
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if (ret < 0)
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return ret;
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m->current_block = timestamp;
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2021-06-05 14:09:03 +00:00
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avpriv_update_cur_dts(s, st, timestamp * m->samples_per_block);
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2020-09-03 22:32:37 +00:00
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return 0;
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}
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2021-04-19 17:45:24 +00:00
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const AVInputFormat ff_mca_demuxer = {
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2020-09-03 22:32:37 +00:00
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.name = "mca",
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.long_name = NULL_IF_CONFIG_SMALL("MCA Audio Format"),
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.priv_data_size = sizeof(MCADemuxContext),
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.read_probe = probe,
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.read_header = read_header,
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.read_packet = read_packet,
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.read_seek = read_seek,
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.extensions = "mca",
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};
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