[FFmpeg-user] rgb8

[Roger Pack]

On Tue, Jun 20, 2023 at 8:28 AM Diederick C. Niehorster
<dcnieho at gmail.com> wrote:
>
> HI Michael,
>
> On Tue, Jun 20, 2023 at 9:14 AM Michael Koch
> <astroelectronic at t-online.de> wrote:
> >
> > Am 20.06.2023 um 02:53 schrieb Roger Pack:
> > > Can other apps use this dshow device?
> >
> > In VLC player it's incorrectly shown as a noisy rgb8 color video. Same
> > output as in FFmpeg.
> > In SharpCap I can open the camera directly (using the camera
> > manufacturer's API), that works without problems, the data is
> > uncompressed 8-bit or 16-bit grayscale.
> > If I open it in SharpCap as a DirectShow device, then the video is very
> > noisy but grayscale (no colors). Probably rgb8 converted to grayscale.
> >
> > >    If you plunk it into
> > > graphstudionext does it work, what media format do you see on the
> > > wires?
> >
> > See the attached screenshot.
> >
> > > I guess the only question is "is it actually palletized"?
> > > Based on the source it seems like we weren't sure...
> >
> > What else could it be? DirectShow doesn't support 8-bit gray.
> > It's sure that the pixel format is either 8-bit gray, or pal8 with a
> > palette which contains 256 levels of gray.
>
> I've only half been following this conversation, but i assume it must
> be palettized, since thats what the format says it is and how the
> other tools probably interpret it correctly.
> Your screenshot was helpful. It shows that biCompression is 0x0000.
> According to the docs, this value (BI_RGB, see
> https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/4e588f70-bd92-4a6f-b77f-35d0feaf7a57)
> means a palette is used:
> https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapinfoheader#color-tables.
>
> Now whether this can correctly be converted to a ffmpeg color format,
> and what needs to be done for that, i don't know ;)

Maybe it's PIX_FMT_PAL8, though implementing this might be a little
tricky...funding helps :)