[FFmpeg-devel] [PATCH] Implement hdcd filtering

[Carl Eugen Hoyos]

Benjamin St <benjaminst123 <at> gmail.com> writes:

> I tried to test with the files sample.cdda.flac and
> > sample.hdcd.flac attached in the ticket.
> > The output is different and one possible reason
> > is the usage of floating point arithmetic in the
> > filter.
> 
> Did you compare flac files or raw audiodata (e.g. wav)?

I did compare wav but I probably made a mistake:
I can confirm that the output is bitexact with the 
Windows app and your patch.

> For me flac it is not identical but wav is.

> (probably due to different flac encoders?)

I also used the FFmpeg flac encoder when producing the 
sample file...

Not all of the comments on top of the filter file look 
very useful to me, what do you think?
In any case, I'd say a link to these should be useful:
http://www.audiomisc.co.uk/HFN/HDCD/Enigma.html
http://www.audiomisc.co.uk/HFN/HDCD/Examined.html
(Or only the second one.)

Please also add a fate test, since this is using floats, 
I would suggest to only compare pcm_s16 (instead of 24).

Carl Eugen