[libav-devel] [RFC] Cineform HD questions

Ganesh Ajjanagadde gajjanag at mit.edu
Thu Dec 31 05:28:44 CET 2015


On Wed, Dec 30, 2015 at 8:13 PM, Kieran Kunhya <kierank at obe.tv> wrote:
>
> This patch is the first attempt at getting a working Cineform HD decoder into avcodec
> It supports YUV422P10 files which are the majority of files in the wild
> There are some files not supported such as those from film scanners and some older files which do something unusual with chroma and the transform.
> Also files which are cut awkwardly will infinite loop in the coefficient decoding because of a lack of escape symbol.
>
> The big question is how to organise the coefficients - at the moment all the buffers are hardcoded.

I glanced at the patch, most of the tables seem trivially derivable at
runtime. I can help with more concrete ideas if you place a comment
above the tables with a link to where you got them: ideally a
mathematical/algorithmic derivation, but in the absence of that, a
link to where you got them from. On the plus side, this is nowhere
near as bad as dcadec tables, but we don't want to repeat such things
unless there is no alternative.

Apart from that, again from a quick glance, there are a ton of
mallocs/frees. Can these somehow get consolidated?

> If anyone has any suggestions about the best way to do this, that would be appreciated.
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