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

[Thomas Guillem]

On Fri, Oct 30, 2015, at 14:05, Thomas Guillem wrote:
> 
> 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).

SRC seems to be the best for variable sample rate, but it handles only
float to float, that is useless for android.

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