[LAU] composing for video

[Paul Davis]

On Tue, Dec 1, 2009 at 8:02 PM, Danni Coy <danni.coy at gmail.com> wrote:
> You would be suprised. RGBA32 is used quite commonly in the compositor
> world, usually stored as a sequence of images, with even higher precisions
> available. Raw RGB24 is reasonably common with the video professionals I
> know, when I questioned them about it they said that they could acheive more
> film like colour grading than they could in any of the YUV colour spaces.
>
> It's probably not the best format for realtime work given the amount of data
> that needs to be transmitted (or maybe it is), I have previously worked with
> piping raw YUV (yuv4linux) between applications and having something like
> jack to manage the connections would be a godsend.

my understanding is that one of the many problems that video faces is
that there truly is no equivalent to "32 bit floating point for
audio". whereas this format for audio samples is pretty much
acceptable for just about all purposes, and the ones not satisfied by
it are corner cases, in video there are many common cases that prefer
quite different data representations. for an audio analogy, imagine a
JACK world where some clients wanted FFT-bin data while others wanted
floating point encoding of PCM.

until or unless someone can step up and authoritatively say "the
interchange format for video is XXXXXX", its hard to imagine a "jack
for video" system really working very usefully for a significant
number of people. those who work entirely in the RGBA32 or YUV spaces
would be happy with just that format; anyone mixing processing that is
better suited to different formats is going to take a hell of a
performance hit.

--p