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

Agatha Hu ahu at nvidia.com
Thu Jan 22 06:12:59 CET 2015

在 2015/1/22 12:29, Philip Langdale 写道:
> On Thu, 22 Jan 2015 12:15:44 +0800
> Agatha Hu <ahu at nvidia.com> wrote:
>> We will fix the issue in driver, overscan compensation will be
>> applied to input DAR *only* if the DAR is 4:3 or 16:9, otherwise
>> won't unnecessarily modify the aspect ratio for resolutions like
>> 720x480 and 720x576.
>> The fix will be on future driver, I'll let you know when the branch
>> is released.
> Please, no. We do not want overscan compensation to be done by nvenc at
> all. The compensation makes nvenc inconsistent with *all* other
> encoders in ffmpeg. For every other encoder, if my input is 720x576 at
> [64/45], then my output is the same. It does not do anyone any favours
> for nvenc to implicitly alter the output DAR.
> There is a separate discussion about whether DAR 'compensation' is
> desirable in an encoder or not, but even if that discussion results in
> a decision to apply DAR compensation at encode time, it will be done
> globally in ffmpeg for all encoders - ie: at a layer above any
> individual codec.
> If nvidia feels it is important to offer this compensation 'feature',
> then I would ask for a configuration option to turn it off - otherwise
> we will need the 'de-compensation' logic in the patch I posted.
> Thanks,
> --phil
Disabling compensation is the best result, adding a flag is acceptable, 
but NVENC5.0 has just released, such option won't be available until 6.0 
is available, so...
Still waiting for nvenc teams feedback, the worst case is adding the 
'de-compensation' logic for 4:3 and 16:9

Agatha Hu

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