[FFmpeg-devel] [GSoC] Qualification Task

[Mina Nagy Zaki]

On Thursday 24 March 2011 19:36:27 Stefano Sabatini wrote:
> On date Thursday 2011-03-24 10:59:16 +0200, Mina Nagy Zaki encoded:
[...] 
> > I have a working sox wrapper, but let me paste my commit message:
> > 
> > commit 9022e7cdb686c7397d82b00ee9c8e70ed7ddeef4
> > Author: Mina Nagy Zaki <mnzaki at gmail.com>
> > Date:   Thu Mar 24 09:21:49 2011 +0200
> > 
> >     Added a sox wrapper filter.
> >     
> >     Loads and initializes a single sox filter and passes samples to it
> >     during filter_samples.
> >     
> >     It is currently very limited due to several problems that need
> >     to be figured out, including:
> >     
> >     - Draining is not handled yet until I figure out finding EOF
> 
> Yes.
> 
> >     - Using config_props to set rate/fmt/etc from an output pad
> >     
> >       does not propagate the changes
> 
> This should work (at least for format and rate), check how it is done
> in aresample.

Well, aresample uses it, and it doesn't work there either. I think the problem 
is that the samplerate on the ost is not reset. It actually works in ffplay, 
but with ffmpeg the samplerate written to the file is the ist samplerate.

> 
> >     - No channel negotiation mechanism or means to choose between
> >     
> >       planar or packed data
> 
> Yes.
> 
> >     - No way to tell the filter system that we were unable to consume
> >     
> >       all the given input
> >     
> >     - ...
> > 
> > I have tested with the sox earwax filter and it works fine. Testing with
> > sox's rate filter though messes up the file due to the 2nd point above,
> > though I'm unsure if it's only me doing something wrong.
> 
> Post the patch so that we can comment on / review it :).

I hadn't posted because it's not nearly ready yet :D I have also hit a bug in 
aconvert: SoX deals with S32 samples, so I have two aconverts, one on input 
and one on output. After filtering I get one of the channels almost muted (very 
low volume). I have tested by doing my own sample conversion inside af_sox and 
things work properly then. I haven't investigated this yet.
Or maybe I'm doing something wrong??
syntax is simply -af "sox=earwax" / -af "sox=rate 8000" / etc

PS: My internet is out and I access the internet at uni currently, so no 
internet on days off (Friday and Monday). This will be resolved soon(-ish).

-- 
Mina
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