87 lines
2.7 KiB
C
87 lines
2.7 KiB
C
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/*
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* PCM common functions
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* Copyright (c) 2003 Fabrice Bellard
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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/mathematics.h"
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#include "avformat.h"
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#include "internal.h"
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#include "pcm.h"
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#define RAW_SAMPLES 1024
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int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AVCodecParameters *par = s->streams[0]->codecpar;
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int ret, size;
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if (par->block_align <= 0)
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return AVERROR(EINVAL);
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/*
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* Compute read size to complete a read every 62ms.
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* Clamp to RAW_SAMPLES if larger.
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*/
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size = FFMAX(par->sample_rate/25, 1);
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if (par->block_align <= INT_MAX / RAW_SAMPLES) {
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size = FFMIN(size, RAW_SAMPLES) * par->block_align;
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} else {
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size = par->block_align;
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}
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ret = av_get_packet(s->pb, pkt, size);
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pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
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pkt->stream_index = 0;
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return ret;
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}
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int ff_pcm_read_seek(AVFormatContext *s,
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int stream_index, int64_t timestamp, int flags)
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{
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AVStream *st;
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int block_align, byte_rate;
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int64_t pos, ret;
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st = s->streams[0];
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block_align = st->codecpar->block_align ? st->codecpar->block_align :
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(av_get_bits_per_sample(st->codecpar->codec_id) * st->codecpar->channels) >> 3;
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byte_rate = st->codecpar->bit_rate ? st->codecpar->bit_rate >> 3 :
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block_align * st->codecpar->sample_rate;
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if (block_align <= 0 || byte_rate <= 0)
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return -1;
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if (timestamp < 0) timestamp = 0;
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/* compute the position by aligning it to block_align */
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pos = av_rescale_rnd(timestamp * byte_rate,
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st->time_base.num,
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st->time_base.den * (int64_t)block_align,
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(flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
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pos *= block_align;
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/* recompute exact position */
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st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
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if ((ret = avio_seek(s->pb, pos + s->internal->data_offset, SEEK_SET)) < 0)
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return ret;
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return 0;
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}
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