[FFmpeg-devel] [PATCH v4] avformat/pcm: decrease delay when reading PCM streams.
Philipp M. Scholl
pscholl at bawue.de
Wed Mar 7 16:30:37 EET 2018
Here is the fourth version of the PCM patch with updated testcases.
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 at bawue.de>
---
libavformat/pcm.c | 16 ++++++++++++----
tests/ref/seek/lavf-alaw | 42 +++++++++++++++++++++---------------------
tests/ref/seek/lavf-mulaw | 42 +++++++++++++++++++++---------------------
3 files changed, 54 insertions(+), 46 deletions(-)
diff --git a/libavformat/pcm.c b/libavformat/pcm.c
index 806f91b6b..1ea15a9e8 100644
--- a/libavformat/pcm.c
+++ b/libavformat/pcm.c
@@ -28,13 +28,21 @@
int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
{
- int ret, size;
+ int ret, size = INT_MAX;
+ AVCodecParameters *par = s->streams[0]->codecpar;
- 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 40ms. Clamp to RAW_SAMPLES if
+ * larger. Use power of two as readsize for I/O efficiency.
+ */
+ size = FFMAX(par->sample_rate/25, 1);
+ size = FFMIN(size, RAW_SAMPLES) * par->block_align;
+ size = 1 << ff_log2(size);
+
+ ret = av_get_packet(s->pb, pkt, size);
pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
pkt->stream_index = 0;
diff --git a/tests/ref/seek/lavf-alaw b/tests/ref/seek/lavf-alaw
index 4b1f8fbc0..b61e687a4 100644
--- a/tests/ref/seek/lavf-alaw
+++ b/tests/ref/seek/lavf-alaw
@@ -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: 512
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: 512
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: 512
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: 512
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: 512
ret: 0 st:-1 flags:0 ts: 2.576668
ret:-EOF
ret: 0 st:-1 flags:1 ts: 1.470835
-ret: 0 st: 0 flags:1 dts: 1.470839 pts: 1.470839 pos: 32432 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.470839 pts: 1.470839 pos: 32432 size: 512
ret: 0 st: 0 flags:0 ts: 0.364989
-ret: 0 st: 0 flags:1 dts: 0.364989 pts: 0.364989 pos: 8048 size: 1024
+ret: 0 st: 0 flags:1 dts: 0.364989 pts: 0.364989 pos: 8048 size: 512
ret: 0 st: 0 flags:1 ts:-0.740816
-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: 512
ret: 0 st:-1 flags:0 ts: 2.153336
ret:-EOF
ret: 0 st:-1 flags:1 ts: 1.047503
-ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 512
ret: 0 st: 0 flags:0 ts:-0.058322
-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: 512
ret: 0 st: 0 flags:1 ts: 2.835828
ret:-EOF
ret: 0 st:-1 flags:0 ts: 1.730004
-ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 512
ret: 0 st:-1 flags:1 ts: 0.624171
-ret: 0 st: 0 flags:1 dts: 0.624172 pts: 0.624172 pos: 13763 size: 1024
+ret: 0 st: 0 flags:1 dts: 0.624172 pts: 0.624172 pos: 13763 size: 512
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: 512
ret: 0 st: 0 flags:1 ts: 2.412517
ret:-EOF
ret: 0 st:-1 flags:0 ts: 1.306672
-ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 512
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: 512
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: 512
ret: 0 st: 0 flags:1 ts: 1.989161
ret: 0 st: 0 flags:1 dts: 1.989161 pts: 1.989161 pos: 43861 size: 239
ret: 0 st:-1 flags:0 ts: 0.883340
-ret: 0 st: 0 flags:1 dts: 0.883356 pts: 0.883356 pos: 19478 size: 1024
+ret: 0 st: 0 flags:1 dts: 0.883356 pts: 0.883356 pos: 19478 size: 512
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: 512
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: 512
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: 512
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: 512
diff --git a/tests/ref/seek/lavf-mulaw b/tests/ref/seek/lavf-mulaw
index 4b1f8fbc0..b61e687a4 100644
--- a/tests/ref/seek/lavf-mulaw
+++ b/tests/ref/seek/lavf-mulaw
@@ -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: 512
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: 512
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: 512
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: 512
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: 512
ret: 0 st:-1 flags:0 ts: 2.576668
ret:-EOF
ret: 0 st:-1 flags:1 ts: 1.470835
-ret: 0 st: 0 flags:1 dts: 1.470839 pts: 1.470839 pos: 32432 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.470839 pts: 1.470839 pos: 32432 size: 512
ret: 0 st: 0 flags:0 ts: 0.364989
-ret: 0 st: 0 flags:1 dts: 0.364989 pts: 0.364989 pos: 8048 size: 1024
+ret: 0 st: 0 flags:1 dts: 0.364989 pts: 0.364989 pos: 8048 size: 512
ret: 0 st: 0 flags:1 ts:-0.740816
-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: 512
ret: 0 st:-1 flags:0 ts: 2.153336
ret:-EOF
ret: 0 st:-1 flags:1 ts: 1.047503
-ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 512
ret: 0 st: 0 flags:0 ts:-0.058322
-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: 512
ret: 0 st: 0 flags:1 ts: 2.835828
ret:-EOF
ret: 0 st:-1 flags:0 ts: 1.730004
-ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 512
ret: 0 st:-1 flags:1 ts: 0.624171
-ret: 0 st: 0 flags:1 dts: 0.624172 pts: 0.624172 pos: 13763 size: 1024
+ret: 0 st: 0 flags:1 dts: 0.624172 pts: 0.624172 pos: 13763 size: 512
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: 512
ret: 0 st: 0 flags:1 ts: 2.412517
ret:-EOF
ret: 0 st:-1 flags:0 ts: 1.306672
-ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 1024
+ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 512
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: 512
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: 512
ret: 0 st: 0 flags:1 ts: 1.989161
ret: 0 st: 0 flags:1 dts: 1.989161 pts: 1.989161 pos: 43861 size: 239
ret: 0 st:-1 flags:0 ts: 0.883340
-ret: 0 st: 0 flags:1 dts: 0.883356 pts: 0.883356 pos: 19478 size: 1024
+ret: 0 st: 0 flags:1 dts: 0.883356 pts: 0.883356 pos: 19478 size: 512
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: 512
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: 512
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: 512
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: 512
--
2.16.2
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