About 16-bit RGB support:
I'd like to have some opinions here.
The fourccs I added to AviSource/DirectShowSource was based on what ffmpeg defined for them (bgr48le: BGR0 ie. BGR[48], bgra64le: BRA@ ie. BRA[64]):
https://github.com/FFmpeg/FFmpeg/blo...bavcodec/raw.c
Bottom-first vs Top-first
Currently, afaik, packed RGB (both 8/16-bit) is always stored inside avs+ upside down (bottom-first). This is OK (doesn't matter), the question is how to handle 16-bit RGB data when it enters/exits avs+. We all know for DIB formats inside avi/vfw/dshow the sign of the height matters: negative height means top-first, positive height means bottom-first.
BGR0 and BRA@ are basically the 16-bit equivalents of BI_RGB 24/32 bit, however it is unclear whether they should be treated as DIB or not (meaning: should the sign of the height matter or not).
We had a long discussion with shekh about this on how to interpret it, and we think these formats don't qualify for the DIB rule, so the sign of the height shouldn't matter (as they are separate fccs), or should it?
^Opinions needed here.
The reason fcc:BI_RGB with bits:64 doesn't work (when coming from a codec for example) is that it makes dshow croak. I believe it is because dshow tries to match to a mediasubtype, and there is none for BI_RGB 64bit, so it fails. So the only option is to use some fourcc, for which the only one existing is defined in ffmpeg (the fact that ffmpeg however cannot read back AVIs written by itself containing BGR0/BRA@ fourcc is another story).
Y8 as DIB
Avs+ AviSource/DirectShowSource treats Y8 as DIB meaning the sign of the height matters and also expects 4-byte boundary padding. Why is that (source)?
Greets,
I.