avformat/pcm: decrease delay when reading PCM streams.

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>
This commit is contained in:
Philipp M. Scholl 2018-03-10 15:50:06 +01:00 committed by Michael Niedermayer
parent af7e953a59
commit 040b28aecc
3 changed files with 52 additions and 45 deletions

View File

@ -28,13 +28,20 @@
int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
{
AVCodecParameters *par = s->streams[0]->codecpar;
int ret, size;
size= RAW_SAMPLES*s->streams[0]->codecpar->block_align;
if (size <= 0)
if (par->block_align <= 0)
return AVERROR(EINVAL);
ret= av_get_packet(s->pb, pkt, size);
/*
* 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;

View File

@ -1,53 +1,53 @@
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:0 ts:-1.000000
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:1 ts: 1.894167
ret: 0 st: 0 flags:1 dts: 1.894150 pts: 1.894150 pos: 41766 size: 1024
ret: 0 st: 0 flags:1 dts: 1.894150 pts: 1.894150 pos: 41766 size: 882
ret: 0 st: 0 flags:0 ts: 0.788345
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ret: 0 st: 0 flags:1 dts: 0.788345 pts: 0.788345 pos: 17383 size: 882
ret: 0 st: 0 flags:1 ts:-0.317506
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:0 ts: 2.576668
ret:-EOF
ret: 0 st:-1 flags:1 ts: 1.470835
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ret: 0 st: 0 flags:0 ts: 0.364989
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ret: 0 st: 0 flags:1 ts:-0.740816
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ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:0 ts: 2.153336
ret:-EOF
ret: 0 st:-1 flags:1 ts: 1.047503
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ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 882
ret: 0 st: 0 flags:0 ts:-0.058322
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ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st: 0 flags:1 ts: 2.835828
ret:-EOF
ret: 0 st:-1 flags:0 ts: 1.730004
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ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 882
ret: 0 st:-1 flags:1 ts: 0.624171
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ret: 0 st: 0 flags:1 dts: 0.624172 pts: 0.624172 pos: 13763 size: 882
ret: 0 st: 0 flags:0 ts:-0.481678
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st: 0 flags:1 ts: 2.412517
ret:-EOF
ret: 0 st:-1 flags:0 ts: 1.306672
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ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 882
ret: 0 st:-1 flags:1 ts: 0.200839
ret: 0 st: 0 flags:1 dts: 0.200816 pts: 0.200816 pos: 4428 size: 1024
ret: 0 st: 0 flags:1 dts: 0.200816 pts: 0.200816 pos: 4428 size: 882
ret: 0 st: 0 flags:0 ts:-0.904989
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st: 0 flags:1 ts: 1.989161
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ret: 0 st:-1 flags:0 ts: 0.883340
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ret: 0 st: 0 flags:1 dts: 0.883356 pts: 0.883356 pos: 19478 size: 882
ret: 0 st:-1 flags:1 ts:-0.222493
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st: 0 flags:0 ts: 2.671655
ret:-EOF
ret: 0 st: 0 flags:1 ts: 1.565850
ret: 0 st: 0 flags:1 dts: 1.565850 pts: 1.565850 pos: 34527 size: 1024
ret: 0 st: 0 flags:1 dts: 1.565850 pts: 1.565850 pos: 34527 size: 882
ret: 0 st:-1 flags:0 ts: 0.460008
ret: 0 st: 0 flags:1 dts: 0.460000 pts: 0.460000 pos: 10143 size: 1024
ret: 0 st: 0 flags:1 dts: 0.460000 pts: 0.460000 pos: 10143 size: 882
ret: 0 st:-1 flags:1 ts:-0.645825
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882

View File

@ -1,53 +1,53 @@
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:0 ts:-1.000000
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:1 ts: 1.894167
ret: 0 st: 0 flags:1 dts: 1.894150 pts: 1.894150 pos: 41766 size: 1024
ret: 0 st: 0 flags:1 dts: 1.894150 pts: 1.894150 pos: 41766 size: 882
ret: 0 st: 0 flags:0 ts: 0.788345
ret: 0 st: 0 flags:1 dts: 0.788345 pts: 0.788345 pos: 17383 size: 1024
ret: 0 st: 0 flags:1 dts: 0.788345 pts: 0.788345 pos: 17383 size: 882
ret: 0 st: 0 flags:1 ts:-0.317506
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 1024
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st:-1 flags:0 ts: 2.576668
ret:-EOF
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ret: 0 st: 0 flags:0 ts: 0.364989
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ret: 0 st:-1 flags:0 ts: 2.153336
ret:-EOF
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ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
ret: 0 st: 0 flags:1 ts: 2.835828
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ret:-EOF
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