[FFmpeg-cvslog] avformat/pcm: factorize and improve determining the default packet size
Marton Balint
git at videolan.org
Sat Mar 16 20:43:10 EET 2024
ffmpeg | branch: master | Marton Balint <cus at passwd.hu> | Sat Mar 2 22:56:35 2024 +0100| [9c2c0c37f8c775d2bdca1730789fbdae75922acd] | committer: Marton Balint
avformat/pcm: factorize and improve determining the default packet size
- Remove the 1024 cap on the number of samples, for high sample rate audio it
was suboptimal, calculate the low neighbour power of two for the number of
samples (audio blocks) instead.
- Make the function work correctly also for non-pcm codecs by using the stream
bitrate to estimate the target packet size. A previous version of this patch
used av_get_audio_frame_duration2() the estimate the desired packet size, but
for some codecs that returns the duration of a single audio frame regardless
of frame_bytes.
- Fallback to 4096/block_align*block_align if bitrate is not available.
Signed-off-by: Marton Balint <cus at passwd.hu>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9c2c0c37f8c775d2bdca1730789fbdae75922acd
---
libavformat/pcm.c | 41 +++++++++++++++++++++++++++++------------
libavformat/pcm.h | 1 +
tests/ref/seek/lavf-al | 46 +++++++++++++++++++++++-----------------------
tests/ref/seek/lavf-ul | 46 +++++++++++++++++++++++-----------------------
4 files changed, 76 insertions(+), 58 deletions(-)
diff --git a/libavformat/pcm.c b/libavformat/pcm.c
index 9741f73667..9676da3251 100644
--- a/libavformat/pcm.c
+++ b/libavformat/pcm.c
@@ -24,27 +24,44 @@
#include "internal.h"
#include "pcm.h"
-#define RAW_SAMPLES 1024
+#define PCM_DEMUX_TARGET_FPS 25
-int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
+int ff_pcm_default_packet_size(AVCodecParameters *par)
{
- AVCodecParameters *par = s->streams[0]->codecpar;
- int ret, size;
+ int nb_samples, max_samples, bits_per_sample;
+ int64_t bitrate;
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);
- if (par->block_align <= INT_MAX / RAW_SAMPLES) {
- size = FFMIN(size, RAW_SAMPLES) * par->block_align;
+ max_samples = INT_MAX / par->block_align;
+ bits_per_sample = av_get_bits_per_sample(par->codec_id);
+ bitrate = par->bit_rate;
+
+ /* Don't trust the codecpar bitrate if we can calculate it ourselves */
+ if (bits_per_sample > 0 && par->sample_rate > 0 && par->ch_layout.nb_channels > 0)
+ if ((int64_t)par->sample_rate * par->ch_layout.nb_channels < INT64_MAX / bits_per_sample)
+ bitrate = bits_per_sample * par->sample_rate * par->ch_layout.nb_channels;
+
+ if (bitrate > 0) {
+ nb_samples = av_clip64(bitrate / 8 / PCM_DEMUX_TARGET_FPS / par->block_align, 1, max_samples);
+ nb_samples = 1 << av_log2(nb_samples);
} else {
- size = par->block_align;
+ /* Fallback to a size based method for a non-pcm codec with unknown bitrate */
+ nb_samples = av_clip(4096 / par->block_align, 1, max_samples);
}
+ return par->block_align * nb_samples;
+}
+
+int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ int ret, size;
+
+ size = ff_pcm_default_packet_size(s->streams[0]->codecpar);
+ if (size < 0)
+ return size;
+
ret = av_get_packet(s->pb, pkt, size);
pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
diff --git a/libavformat/pcm.h b/libavformat/pcm.h
index 9af36d5a2e..1928497eed 100644
--- a/libavformat/pcm.h
+++ b/libavformat/pcm.h
@@ -24,6 +24,7 @@
#include "avformat.h"
+int ff_pcm_default_packet_size(AVCodecParameters *par);
int ff_pcm_read_packet(AVFormatContext *s, AVPacket *pkt);
int ff_pcm_read_seek(AVFormatContext *s,
int stream_index, int64_t timestamp, int flags);
diff --git a/tests/ref/seek/lavf-al b/tests/ref/seek/lavf-al
index 5a4085af4e..ebf7993425 100644
--- a/tests/ref/seek/lavf-al
+++ b/tests/ref/seek/lavf-al
@@ -1,50 +1,50 @@
-ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
+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: 882
+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: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
ret:-1 st:-1 flags:0 ts: 2.576668
ret: 0 st:-1 flags:1 ts: 1.470835
-ret: 0 st: 0 flags:1 dts: 1.470839 pts: 1.470839 pos: 32432 size: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
ret:-1 st:-1 flags:0 ts: 2.153336
ret: 0 st:-1 flags:1 ts: 1.047503
-ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 882
+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: 882
+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: 0 st: 0 flags:1 dts: 1.960000 pts: 1.960000 pos: 43218 size: 882
+ret: 0 st: 0 flags:1 dts: 1.987029 pts: 1.987029 pos: 43814 size: 286
ret: 0 st:-1 flags:0 ts: 1.730004
-ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 882
+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: 882
+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: 882
+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: 0 st: 0 flags:1 dts: 1.960000 pts: 1.960000 pos: 43218 size: 882
+ret: 0 st: 0 flags:1 dts: 1.987029 pts: 1.987029 pos: 43814 size: 286
ret: 0 st:-1 flags:0 ts: 1.306672
-ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 882
+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: 882
+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: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
ret:-1 st: 0 flags:0 ts: 2.671655
ret: 0 st: 0 flags:1 ts: 1.565850
-ret: 0 st: 0 flags:1 dts: 1.565850 pts: 1.565850 pos: 34527 size: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
diff --git a/tests/ref/seek/lavf-ul b/tests/ref/seek/lavf-ul
index 5a4085af4e..ebf7993425 100644
--- a/tests/ref/seek/lavf-ul
+++ b/tests/ref/seek/lavf-ul
@@ -1,50 +1,50 @@
-ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 882
+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: 882
+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: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
ret:-1 st:-1 flags:0 ts: 2.576668
ret: 0 st:-1 flags:1 ts: 1.470835
-ret: 0 st: 0 flags:1 dts: 1.470839 pts: 1.470839 pos: 32432 size: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
ret:-1 st:-1 flags:0 ts: 2.153336
ret: 0 st:-1 flags:1 ts: 1.047503
-ret: 0 st: 0 flags:1 dts: 1.047483 pts: 1.047483 pos: 23097 size: 882
+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: 882
+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: 0 st: 0 flags:1 dts: 1.960000 pts: 1.960000 pos: 43218 size: 882
+ret: 0 st: 0 flags:1 dts: 1.987029 pts: 1.987029 pos: 43814 size: 286
ret: 0 st:-1 flags:0 ts: 1.730004
-ret: 0 st: 0 flags:1 dts: 1.730023 pts: 1.730023 pos: 38147 size: 882
+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: 882
+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: 882
+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: 0 st: 0 flags:1 dts: 1.960000 pts: 1.960000 pos: 43218 size: 882
+ret: 0 st: 0 flags:1 dts: 1.987029 pts: 1.987029 pos: 43814 size: 286
ret: 0 st:-1 flags:0 ts: 1.306672
-ret: 0 st: 0 flags:1 dts: 1.306667 pts: 1.306667 pos: 28812 size: 882
+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: 882
+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: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
ret:-1 st: 0 flags:0 ts: 2.671655
ret: 0 st: 0 flags:1 ts: 1.565850
-ret: 0 st: 0 flags:1 dts: 1.565850 pts: 1.565850 pos: 34527 size: 882
+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: 882
+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: 882
+ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 0 size: 512
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