[vlc-devel] [PATCH] audio_filters: add sample converter in pipeline

[Thomas Guillem]

On Fri, Oct 30, 2015, at 12:27, Rémi Denis-Courmont wrote:
> Le 2015-10-30 13:30, Thomas Guillem a écrit :
> > When creating a new chain a filter, the sample rate "audio converter" 
> > is not
> > added in the chain since a "audio resampler" is already added at the
> > end of the chain.
> 
> I think that is how it should be - except where the rate is known to 
> never change (e.g. unpaced sout).

In that case (unpaced sout), I think that the "/* Resample */" block
miss a aout_FormatPrepare (&output) to setup the
filter->fmt_out.audio.i_bytes_per_frame. Without that, resamplers "audio
converter" crashes.

> 
> Having two resamplers chained gives terrible results.

The two resamplers will be chained only when fixing a delay. Generally,
it happen less than 10seconds during a playback.

So, what should we do:
 - Having a good quality fixed resampler with good performances during
 the whole playback, and adding a ugly one to fix a delay (generally,
 less than 10seconds).
 - Having only one lower quality variable resampler.

> 
> > Unfortunately, we don't have any audio_filter modules that is capable
> > of doing a variable-rate resampling with good quality and good 
> > performances.
> 
> Hmm? SRC works fine here.

I'll do some test with fixed and variable rate with that one too. (I do
my test on Desktop and very old android devices).

> 
> -- 
> Rémi Denis-Courmont
> http://www.remlab.net/
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