[FFmpeg-devel] [PATCH] nvenc: Compensate for hardware trying to mess with aspect ratio of DVD content.

[Philip Langdale]

On Mon, 19 Jan 2015 07:48:24 +0100
Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:

> On 19.01.2015, at 01:16, compn <tempn at mi.rr.com> wrote:
> > On Sun, 18 Jan 2015 18:41:09 +0100
> > Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:
> >> Oh my god, this is so horribly broken I vote for doing a "return
> >> -EBROKENAPI" and tell them we'll enable this when NVidia fixes
> >> their stuff.
> >> IMHO some features are not worth the hacks necessary.
> > 
> > [08:51] <compn> just let nvidia change aspect, its their crap, let
> > them fix it
> > 
> > [08:57] <kierank> compn: the nvidia behaviour is correct
> > [08:57] <kierank> so no patches are necessary
> 
> I don't really consider it "correct" if it doesn't do what a user
> expects, plus as I understood the discussion neither ffplay nor
> MPlayer nor VLC and probably WMP, flash player etc. will not show the
> video correctly if encoding e.g. a BluRay to DVD resolution via nvenc
> and playing it back. If they do I'll have to reconsider, but if they
> don't it isn't working, "correct" or not.

Right. And it's obviously wrong if you consider that trying to encode
any square pixel content at this size results in non-square output.

I'd also argue that bt.601 semantics come into play when you're
authoring the DVD, and any transcoding you do after that should
preserve the input characteristics - and that means the encoded SAR is
based on a 720 pixel width. Why on earth my transcoded file should have
a different SAR from the original when doing a digital->digital
conversion is beyond me.

--phil