mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-28 20:53:54 +02:00
040b28aecc
Thanks for the discussion. Here's the next version, now with /25 and removed ff_log2(). The blocksize of the PCM decoder is hard-coded. This creates unnecessary delay when reading low-rate (<100Hz) streams. This creates issues when multiplexing multiple streams, since other inputs are only opened/read after a low-rate input block was completely read. This patch decreases the blocksize for low-rate inputs, so approximately a block is read every 40ms. This decreases the startup delay when multiplexing inputs with different rates. Signed-off-by: Philipp M. Scholl <pscholl@bawue.de> Reviewed-by: Paul B Mahol <onemda@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
/*
|
|
* PCM common functions
|
|
* Copyright (c) 2003 Fabrice Bellard
|
|
*
|
|
* 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 "libavutil/mathematics.h"
|
|
#include "avformat.h"
|
|
#include "internal.h"
|
|
#include "pcm.h"
|
|
|
|
#define RAW_SAMPLES 1024
|
|
|
|
int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
|
|
{
|
|
AVCodecParameters *par = s->streams[0]->codecpar;
|
|
int ret, size;
|
|
|
|
if (par->block_align <= 0)
|
|
return AVERROR(EINVAL);
|
|
|
|
/*
|
|
* Compute read size to complete a read every 62ms.
|
|
* Clamp to RAW_SAMPLES if larger.
|
|
*/
|
|
size = FFMAX(par->sample_rate/25, 1);
|
|
size = FFMIN(size, RAW_SAMPLES) * par->block_align;
|
|
|
|
ret = av_get_packet(s->pb, pkt, size);
|
|
|
|
pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
|
|
pkt->stream_index = 0;
|
|
|
|
return ret;
|
|
}
|
|
|
|
int ff_pcm_read_seek(AVFormatContext *s,
|
|
int stream_index, int64_t timestamp, int flags)
|
|
{
|
|
AVStream *st;
|
|
int block_align, byte_rate;
|
|
int64_t pos, ret;
|
|
|
|
st = s->streams[0];
|
|
|
|
block_align = st->codecpar->block_align ? st->codecpar->block_align :
|
|
(av_get_bits_per_sample(st->codecpar->codec_id) * st->codecpar->channels) >> 3;
|
|
byte_rate = st->codecpar->bit_rate ? st->codecpar->bit_rate >> 3 :
|
|
block_align * st->codecpar->sample_rate;
|
|
|
|
if (block_align <= 0 || byte_rate <= 0)
|
|
return -1;
|
|
if (timestamp < 0) timestamp = 0;
|
|
|
|
/* compute the position by aligning it to block_align */
|
|
pos = av_rescale_rnd(timestamp * byte_rate,
|
|
st->time_base.num,
|
|
st->time_base.den * (int64_t)block_align,
|
|
(flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
|
|
pos *= block_align;
|
|
|
|
/* recompute exact position */
|
|
st->cur_dts = av_rescale(pos, st->time_base.den, byte_rate * (int64_t)st->time_base.num);
|
|
if ((ret = avio_seek(s->pb, pos + s->internal->data_offset, SEEK_SET)) < 0)
|
|
return ret;
|
|
return 0;
|
|
}
|