[FFmpeg-devel] [PATCH 6/7] libavfilter/vf_sr.c: Removes uint8 -> float and float -> uint8 conversions.

[Sergey Lavrushkin]

2018-08-15 1:49 GMT+03:00 Marton Balint <cus at passwd.hu>:

>
> On Tue, 14 Aug 2018, Pedro Arthur wrote:
>
> 2018-08-14 15:45 GMT-03:00 Rostislav Pehlivanov <atomnuker at gmail.com>:
>>
>>> On Thu, 2 Aug 2018 at 20:00, Sergey Lavrushkin <dualfal at gmail.com>
>>> wrote:
>>>
>>> This patch removes conversions, declared inside the sr filter, and uses
>>>> libswscale inside
>>>> the filter to perform them for only Y channel of input. The sr filter
>>>> still has uint
>>>> formats as input, as it does not use chroma channels in models and these
>>>> channels are
>>>> upscaled using libswscale, float formats for input would cause
>>>> unnecessary
>>>> conversions
>>>> during scaling for these channels.
>>>>
>>>>
> [...]
>
> You are planning to remove *all* conversion still, right? Its still
>>> unacceptable that there *are* conversions.
>>>
>>
>> They are here because it is the most efficient way to do it. The
>> filter works only on luminance channel therefore we only apply
>> conversion to Y channel, and bicubic upscale to chrominance.
>> I can't see how one can achieve the same result, without doing useless
>> computations, if not in this way.
>>
>
> Is there a reason why only the luminance channel is scaled this way? Can't
> you also train scaling chroma planes the same way? This way you could
> really eliminate the internal calls to swscale. If the user prefers to
> scale only one channel, he can always split the planes and scale them
> separately (using different filters) and then merge them.
>

If it is possible, I can then change sr filter to work only for Y channel.
Can you give me some examples of how to split the planes, filter them
separately
and merge them back?