Re: [FFmpeg-devel] Request for assistance with adding new pixel format (NV12_8L128) in FFmpeg

[Devin Heitmueller <devin.heitmueller@ltnglobal.com>]

Hi Remi,

On Wed, Feb 8, 2023 at 12:38 PM Rémi Denis-Courmont <remi@remlab.net> wrote:
> Uh, not to deny that, but tiled formats are in no way an embedded thing, as
> you imply. They are also used by desktop GPUs. And that is not really
> relevant, I would argue, to the discussion, either way.

I don't disagree that tiled formats can be found on desktop GPUs.  My
only point was that the importance of being able to pass through the
native format is much greater with embedded SOCs since in many cases
on desktops you have enough CPU power to get away with doing a
conversion.

Also, you're more likely to find that desktop GPUs which support tiled
formats also support formats that are likely to be supported by ffmpeg
today.  This is less likely to be the case with embedded SOCs.

> > Of course ffmpeg could choose
> > to ignore them, but it would effectively prevent it from being used on
> > those platforms (and it's pretty essential to use the hardware blocks
> > to do any real video processing).
>
> Insofar as the format is *only* used by a single module, I don't see the need
> to assign it a pixel format in libavutil. You could just as well define a
> generic V4L format that would be used for all weird V4L formats that nothing
> other than V4L code understands.

In many cases the lack of support for a pixel format may be the reason
that more platforms aren't supported.  Somebody has got to be the
first.  Suggesting that it's only used by a single module may be the
effect of not supporting the pixel format, not the other way around.

This is not to suggest that like most developers I don't hate the fact
that there are so many different pixel formats out there, and with
each new format proposed for addition to ffmpeg we have the same
arguments.

> Ditto tiled DRM pixel formats for that matter. And while V4L is maybe not
> there yet, DRM has introduced format modifiers that anyway preclude any simple
> enumeration. My point being, there needs to be a way to further specify
> framework-specific formats outside of the avutil pixel format list, in any
> case.

I can't really offer an opinion on the implementation detail regarding
the avutil pixel format list.  I suspect the OP is open to alternative
approaches as long as the original requirement is met.

Devin

-- 
Devin Heitmueller, Senior Software Engineer
LTN Global Communications
o: +1 (301) 363-1001
w: https://ltnglobal.com  e: devin.heitmueller@ltnglobal.com
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