[FFmpeg-devel] [PATCH 2/5] avcodec/nvdec: Add support for decoding HEVC 4:4:4 content

[Timo Rothenpieler]

On 20.10.2018 23:52, Philip Langdale wrote:
> On Sat, 20 Oct 2018 22:58:34 +0200
> Timo Rothenpieler <timo at rothenpieler.org> wrote:
> 
>>>    
>>> +    // It it semantically incorrect to use AX_PIX_FMT_YUV444P16
>>> for either the 10
>>> +    // or 12 bit case, but ffmpeg and nvidia disagree on which end
>>> the padding
>>> +    // bits go at. P16 is unambiguous and matches.
>>
>> This comment seems redundant, since AX_PIX_FMT_YUV444P16 isn't even
>> used.
> 
> Yeah, that's outdated from the original version with no pix fmts. I'll
> remove it.
> 
>>> diff --git a/libavutil/hwcontext_cuda.c b/libavutil/hwcontext_cuda.c
>>> index 3b1d53e799..43337f14f0 100644
>>> --- a/libavutil/hwcontext_cuda.c
>>> +++ b/libavutil/hwcontext_cuda.c
>>> @@ -38,6 +38,8 @@ static const enum AVPixelFormat
>>> supported_formats[] = { AV_PIX_FMT_YUV444P,
>>>        AV_PIX_FMT_P010,
>>>        AV_PIX_FMT_P016,
>>> +    AV_PIX_FMT_YUV444P10_MSB,
>>> +    AV_PIX_FMT_YUV444P12_MSB,
>>
>> You are adding these to supported formats, but are not actually
>> adding support, so cuda_frames_init and cuda_get_buffer will both run
>> into the BUG case. Should be super easy, as they're identical to
>> 444P16.
> 
> This actually works fine. cuda_frames_init and cuda_get_buffer both use
> generic mechanisms that introspect the pix desc information.

Right, I had the 3.4 branch checked out when checking that...

>>>        AV_PIX_FMT_YUV444P16,
>> Technically, this can go now. But I guess removing it is an API
>> break, so it gotta stay I guess.
> 
> Right. And at the end of the day it works correctly in the context of
> the hwcontext. You might feed into some theoretical filter that would
> handle it appropriately. Just because nvenc can't actually consume it
> fully doesn't make it wrong.
> 
> --phil
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