Do not forget to check libavutil version when adding more pixfmts.
On Fri, Mar 23, 2018 at 6:31 AM Brian Matherly <c...@brianmatherly.com>
wrote:
>
> On 3/23/2018 2:47 AM, Jean-Baptiste Mardelle wrote:
> > Hi all,
> >
> > In order to optimize performance, in the qtblend transition (in the qt
> > module), I try to detect if the top frame in the transition has
> > transparency, and if it doesn't, instead of performing the transition I
> > just return the top frame.
> >
> > However currently, to check if a frame has transparency I use the
> > following:
> >
> > if ( *format == mlt_image_rgb24a || mlt_frame_get_alpha( b_frame ) )
> > {
> > // The frame has an alpha channel
> > }
> >
> > However, some YUV formats with alpha, like AV_PIX_FMT_YUVA444P10LE,
> > don't obey these rules since the alpha buffer is not created.
>
> I predict the problme is not in the qtblend transition. The problem is
> probably that the avformat_producer is not creating the alpha channel.
>
> Maybe the problem is that AV_PIX_FMT_YUVA444P10LE is not handled here:
>
> https://github.com/mltframework/mlt/blob/master/src/modules/avformat/producer_avformat.c#L1391
>
> And/Or maybe it needs to be added here:
>
> https://github.com/mltframework/mlt/blob/master/src/modules/avformat/producer_avformat.c#L1184
>
> > Shouldn't the alpha buffer be created by default for this codecs, or is
> > there any other way to detect that the frame has alpha?
> >
> > Thanks for your advice.
> >
> > You can find sample video files in this bug report:
> > https://bugs.kde.org/show_bug.cgi?id=391963
> >
> > Regards
> >
> > Jean-Baptiste
>
> ~Brian
>
>
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