Change position with a dissolve

[Bill Hofmann]

Any thoughts on this? (see main q's)

1. Is RGBA in gstreamer limited to 8bit? If so, I'll need to figure another
way
2. Otherwise, it seems that there is a hole in the glcolorconvert
implementation


On Wed, Aug 10, 2022 at 12:17 PM Bill Hofmann <bill at theliquidview.com>
wrote:

> Thanks for your suggestion.
>
> That kind of works in general, but I'm running into an issue or two, no
> doubt for obvious to someone else reasons.
>
> First off (not burying the lede):
> 1. Is RGBA in gstreamer limited to 8bit? If so, I'll need to figure
> another way
> 2. Otherwise, it seems that there is a hole in the glcolorconvert
> implementation
>
> On Ubuntu 22, Intel 11gen NUC, using KMS/DRM, this graph has terrible
> performance (~ 4fps), no doubt because of multiple conversions:
>
> gst-launch-1.0 glvideomixer background=2 name=m ! kmssink connector-id=308
> plane-id=31 \
> souphttpsrc location="http://127.0.0.1//foo.m3u8" ! \
>  parsebin ! queue ! vaapih265dec ! video/x-raw,format=P010_10LE ! queue
> max-size-bytes=100663300 ! \
>  glupload ! glcolorconvert ! glshader fragment="\"`cat myshader.frag`\"" !
> m.
>
>
> Attempting to keep the conversion til later, this graph fails with the
> error "gstglcolorconvert.c:2656:_init_convert:<glcolorconvert2> Don't know
> how to convert from RGBA to P010_10LE"
>
> gst-launch-1.0 glvideomixer background=2 name=m !
> video/x-raw,format=P010_10LE  ! kmssink connector-id=308 plane-id=31 \
> souphttpsrc location="http://127.0.0.1//foo.m3u8" ! \
> parsebin ! queue ! vaapih265dec! queue max-size-bytes=100663300 ! \
> glupload ! glcolorconvert ! glshader fragment="\"`cat myshader.frag`\"" !
> m.
>
>
> Now, looking at gstglcolorconvert.c and at the glconvert element in
> general, it seems that while documentation (and caps negotiation) says that
> this conversion should be supported, the actual implementation doesn't
> support it (in _RGB_to_YUV). That said, also, I realize that the RGBA
> format is likely 8 bit, which would mean that this just wouldn't work for
> me (I'm delivering 10b HEVC video here).
>
> (Note the myshader.frag is straight from the glshader docs, just does a
> copy. First things first.)
>
> Yours in GL ignorance,
> -Bill
>
>
>
>
> On Fri, Jun 17, 2022 at 3:08 PM Jeff Shanab <jshanab at jfs-tech.com> wrote:
>
>> This sounds like a job for a shader. (that is how I did a fade on camera
>> disconnect)
>>
>> the shader has a single variable 0 to 100.  0 is stream old and 100 is
>> stream new.
>>
>> When value is not 0 or 100 you are in the transition zone.
>> decode both and pass both pixel values.
>> update the value and have it average the scaled pixel values into the new
>> pixel value passed on to the fragment shader.
>>
>>
>> Maybe pixel = factor * pixelFromOld + 100-factor * pixelFromNew as factor
>> runs from 100 down to 0
>>
>>
>>
>>
>>
>>
>> On Fri, Jun 17, 2022 at 4:49 PM Bill Hofmann via gstreamer-devel <
>> gstreamer-devel at lists.freedesktop.org> wrote:
>>
>>> All:
>>>
>>> I'm looking to be able to set position forward or backward (say, 5
>>> minutes, just for an example), but rather than a "hard cut", instead to do
>>> a 5 second dissolve.  That, to me, implies keeping 5 seconds of frames
>>> after the original position, and doing a ramped blend with frames from the
>>> new position. Or something like that.
>>>
>>> What's the best approach? I looked at the GstEdit functionality, but
>>> that seemed way overblown for what I need. Can imagine a way using the
>>> compositor, but I'd think I'd need a copy of the stream running in parallel
>>> (and switching back and forth). Could also do a custom filter in the path
>>> that queues the frames, maybe.
>>>
>>> Suggestions as to a way to attack this? I can't be the only one...
>>>
>>> -Bill
>>>
>>>
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