[FFmpeg-devel] [FFmpeg-cvslog] lavc/qsvenc: add VDENC support for H264

[Carl Eugen Hoyos]

2019-01-11 3:28 GMT+01:00, Li, Zhong <zhong.li at intel.com>:
>> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
>> Of Carl Eugen Hoyos
>> Sent: Friday, January 11, 2019 1:06 AM
>> To: ffmpeg-devel at ffmpeg.org
>> Subject: Re: [FFmpeg-devel] [FFmpeg-cvslog] lavc/qsvenc: add VDENC
>> support for H264
>>
>> 2019-01-10 14:51 GMT+01:00, Linjie Fu <git at videolan.org>:
>>
>> > +#if QSV_HAVE_VDENC
>> > +    { "low_power", "enable low power mode(experimental: many
>> > +limitations by
>> > mfx version, BRC modes, etc.)", OFFSET(qsv.low_power),
>> > AV_OPT_TYPE_BOOL, {
>> > .i64 =  0 }, 0, 1, VE},
>> > +#endif
>>
>> This seems wrong to me: The visibility of an option should probably not
>> depend on configuration details (the effect can of course depend on many
>> details).
>>
>> Carl Eugen
>
> That's is just a remind that this feature has some limitations. The
> configures are just to make driver to support this feature.
> In ffmpeg level, the only thing we should do IMHO is to query MSDK/Driver
> capability and report an error message if not supported.
> And it was done:
> https://github.com/FFmpeg/FFmpeg/blob/395e8a53fa0266f26581f3e9752b0dbc93998a90/libavcodec/qsvenc.c#L376

That is probably helpful, but the issue I try to explain is unrelated
to the brokenness of the option:
Now, in some cases FFmpeg shows the option and in other cases
it does not. I believe that instead, the option should always be
shown, even if it does not work.

Carl Eugen