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

Kieran Kunhya kierank at obe.tv
Sun Jan 18 12:16:04 CET 2015

On 18 January 2015 at 09:40, Nicolas George <george at nsup.org> wrote:
> Le nonidi 29 nivôse, an CCXXIII, Hendrik Leppkes a écrit :
>> nvenc should behave the same as libx264, or any other video encoder, if
>> this patch makes it do that, then it should be applied.
>> If bt601 needs special handling not yet present in avcodec, it should be
>> implemented in such a way that all encoders can benefit from it.
> That was one of the points I was trying to make, thanks for explaining it
> more clearly.
> Two additional points:
> According to Philip's tests, nvenc adds a 45/44 = 720/704 factor, not
> 720/702 = 40/39, so it does not conform to BT.601 anyway.

Why is it so hard for you to realise that the SARs are not
arithmetically derived?

> I have downloaded BT.601 from <URL: http://www.itu.int/rec/R-REC-BT.601/ >,
> both the most recent and the oldest versions, and I did not find any
> explicit reference of this 702 business, nor could I decipher indirect
> references, so I still wonder where it comes from exactly.

You can make the appropriate calculations *and simplifications* for
BT601. There are plenty of books with the appropriate derivations.


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