[FFmpeg-devel] [PATCH v3 7/9] avformat/pcm: factorize and improve determining the default packet size
Marton Balint
cus at passwd.hu
Sat Mar 16 10:45:07 EET 2024
On Fri, 15 Mar 2024, Marton Balint wrote:
> - 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.
Will apply the this and the rest of the series.
Regards,
Marton
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> 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
> --
> 2.35.3
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>
More information about the ffmpeg-devel
mailing list