[FFmpeg-devel] [PATCH v3 1/3] lavf/f_select: support scenecut with more pixel formats

[Marton Balint]

On Tue, 23 Jul 2019, Gyan wrote:

>
>
> On 23-07-2019 02:43 AM, Marton Balint wrote:
>>
>> On Sun, 21 Jul 2019, lance.lmwang at gmail.com wrote:
>>
>>> From: Limin Wang <lance.lmwang at gmail.com>
>>>
>>> This patch haven't make other pixel format usable yet to make sure 
>>> the test
>>> result is same with rgb32 format.
>>>
>>> Reviewed-by: Marton Balint <cus at passwd.hu>
>>
>> You should only add this if you got an explicit LGTM for a patch.
>>
>>> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
>>> ---
>>> libavfilter/f_select.c | 34 ++++++++++++++++++++++++++++++----
>>> 1 file changed, 30 insertions(+), 4 deletions(-)
>>
>> Ok, I applied the series with some minor fixes and rewordings of your 
>> commit messages, as they were a bit difficult to understand sometimes.
>
> "avformat/f_select: support scenecut with more pixel formats"
>
> This should have been avfilter/f_select.

Yes, sorry about that.

There is one more thing that we might consider. Now the scene change 
detection score uses all planes to detect scene changes. In this regard 
this is similar how the frozen frames detection works. However, in 
classic encoding scene change detection typically only uses the Y plane as 
far as I know, not the chroma planes.

We might get more resonable scores for scene change if we also use only 
the Y plane for calculating the score if the pixel format is YUV. Although 
this will require additional work once packed YUV formats are added, 
because for the moment the generic scene sad score calculation has no way 
to ignore some components in a packed format. Also it does not make a 
whole lot of difference, because chroma is usually subsampled anyway, so 
it is weighting less in the scene score. So I guess there are pros and 
cons for this.

Regards,
Marton