Re: [Mlt-devel] no alpha channel for video with PIX_FMT_YUVA420P pixel format

[Dan D. <da...@de...>]

2012/2/17 Maksym Veremeyenko <ve...@m1...>:
> 16.02.12 18:56, Dan Dennedy написав(ла):
>
>> 2012/2/16 Maksym Veremeyenko<ve...@m1...>:
>>>
>>> 02.02.12 19:03, Maksym Veremeyenko написав(ла):
>>>>
>>>>
>>>> Hi,
>>>>
>>>>
>>>> i am trying to decrease cpu usage, so i would like to use
>>>> PIX_FMT_YUVA420P animation instead of PIX_FMT_BGRA (or other rgb with
>>>> alpha channel) but has no luck..
>>>>
>>>> video with such pixel format in *nut* container has detected by ffmpeg
>>>> properly, but mlt did not use it alpha channel.
>>>>
>>>> i can provide a sample if required...
>>>>
>>>
>>> alpha been ignored for PIX_FMT_YUVA420P and PIX_FMT_YUVA444P pixel
>>> format.
>>> moreover current implementation of libswscale drop alpha channel if
>>> destination format has no alpha and not planar (even if buffer specified)
>>>
>>> attached patch extract alpha plane during image decoding. it works almost
>>> fine except moments when image fetched from cache (even if *noimagecache*
>>> specified). another problem is artifact that appear if last frame in
>>> movie
>>> is not transparent but producer specifies *out* out of animation.
>>>
>>> another attempt to fix this was to fix mlt_frame_clone (patch attached)
>>> but
>>> it has no luck too...
>>
>>
>> OK, thank you for the start of this effort. I will look at it this
>> weekend.
>>
>
> attached updated version that works with cache.
>
> second patch is optional but could be usefull if frame with alpha been
> cloned.

These look great, but I had to fix some minor formatting problems. We
tend to prefer C++ style comments in .c files (but not headers). Also,
some spacing around parenthesis. Sometimes I am OK to make these fixes
myself, which I have done here in my local repo. Now I just need to
figure out why this does not work:

melt -profile atsc_1080i_50 noise: -track
~/Videos/tests/now-main_aut_2011_fullHD.nut -transition composite

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