highperfocused/ffmpeg
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

avformat/daudenc: force 2000 sample packet size with a bsf

Browse Source 
The samples I found all have 2000 sample packets, and by forcing the packet
size with a bsf we could automagically make muxing work for packets containing
more than 3640 samples.

Signed-off-by: Marton Balint <cus@passwd.hu>
This commit is contained in:
Marton Balint
2024-03-03 22:44:09 +01:00
parent 9eebeea4dd
commit 7196b12b2b
4 changed files with 22 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
doc/muxers.texi
View File

@@ -1397,23 +1397,17 @@ D-Cinema audio muxer.
It accepts a single 6-channels audio stream resampled at 96000 Hz
encoded with the @samp{pcm_24daud} codec.
In addition, each muxed packet size must not be greater than 65535 bytes.
@subsection Example
Use @command{ffmpeg} to mux input audio to a @samp{5.1} channel layout
resampled at 96000Hz:
@example
ffmpeg -i INPUT -af aresample=96000,pan=5.1,asetnsamples=3640 slow.302
ffmpeg -i INPUT -af aresample=96000,pan=5.1 slow.302
@end example
The @samp{asetnsamples} filter is used to reduce the number of samples
of each audio packet, with a size computed according to the formula:
@example
65535 / (@var{channels} * @var{encoded_sample_size}) = 655535 / (6 * 3) = 3640
@end example
The @var{encoded_sample_size} = 3 factor is due to sample size of the
@samp{pcm_24daud} encoder.
For ffmpeg versions before 7.0 you might have to use the @samp{asetnsamples}
filter to limit the muxed packet size, because this format does not support
muxing packets larger than 65535 bytes (3640 samples). For newer ffmpeg
versions audio is automatically packetized to 36000 byte (2000 sample) packets.
@section dv
DV (Digital Video) muxer.