[FFmpeg-devel] Google Summer of Code Qualification

Justin Ruggles justinruggles
Tue Mar 11 05:40:34 CET 2008


andy g wrote:
> Hey everyone,
> 	I have been using ffmpeg for years now and every time I use it I like  
> it more. I know the C language (although I mostly program in Java  
> right now) and I think it would be great if I could work on it over  
> the summer in Google Summer of Code. Specifically, the ALAC-LC  
> implementation really interests me, as I was transcoding files from  
> iTunes before and I noticed that there was no ALAC encoder - something  
> I think I could fix.

That's great that you are interested.  Before you apply, I would highly
recommend spending some time looking through the FFmpeg source and
reading up on lossless audio in general.

As far as ALAC is concerned, it is not something I would implement
myself, but I would gladly mentor such a project.  I have considered
trying it myself in the past, but decided against it for silly
philosophical reasons. :)

I have added some very basic goals for an ALAC encoder to the Multimedia
Wiki page for SoC '08.  If you (or any other applicant) want to know
more specifics about what such a project might entail, feel free to ask.

> 	Regarding the qualification, I also noticed that ffmpeg doesn't have  
> the ability to pass along metadata tags when it transcodes music. I  
> was wondering if my qualification could be to write a metadata tag  
> reader/writer for certain media files. For mp3, the LGPL'd http://id3lib.sourceforge.net/ 
>   should probably do, but I could probably write my own implementation  
> if necessary (which I bet will probably be necessary for MP4/ALAC/AAC  
> tags).

FFmpeg already has very basic tagging support.  I don't know the full
list, but in a quick search I was able to find ID3 tags, Vorbis
comments, APE tags, and iTunes mp4 tags.  Granted, the current support
is very limited.  I'm not sure what the demand is for a more complete
metadata system. libavtag? ;)  To me that seems more like a full SoC
project, not a qualification task, but if a student has the time and
will to do it (and do it well), I would welcome it.

> 	If this is too simple for your test I could do something else, but  
> when I used ffmpeg last time this struck me as something that was  
> missing from ffmpeg that would probably be pretty useful in certain  
> transcoding operations.

As for me personally...what I am looking for in a qualification task,
beyond good programming skills, is clean, well-documented code, good
communication, and follow-through.  Having to clean up both the AC3
decoder and the E-AC3 decoder from previous summers has been somewhat

For example, something like cleaning up the MLP patch might have a
somewhat steep learning curve, but that's the kind of skills I really
want to see. :)


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