2019-03-11 11:37 GMT+01:00, Tomas Härdin <tjop...@acc.umu.se>: > fre 2019-03-08 klockan 21:39 +0000 skrev Matthew Fearnley: >> > On Fri, 8 Mar 2019 at 18:07, Carl Eugen Hoyos <ceffm...@gmail.com> >> > wrote: >> > 2019-03-08 15:04 GMT+01:00, Tomas Härdin <tjop...@acc.umu.se>: >> > > >> > > Maybe we could coordinate 1/2/4/24-bit support with the >> > >> > I believe FFmpeg cannot support 1/2/4 bit for encoding. >> >> As far as I can see, FFmpeg has very limited support for bit depths less >> than 8. I think there are basically two formats (plus variants), with >> fixed "palettes": >> 1bpp: MONO_BLACK / MONO_WHITE (black/white only) >> 4bpp: RGB4[_BYTE], BGR4[_BYTE] (RGB 1:2:1, 16 colours - I presume red/blue >> would be 0,255; green would be 0,85,170,255) >> >> If the ZMBV formats were defined, these might be worth encoder adding >> support for. >> (Practically speaking though, it would be a slight pain, because the >> encoder would do the work in 8bpp and pack/unpack as needed.) >> But with PAL8 being the only format allowing a free palette, all sub-8bpp >> formats would have to decode to that, so they wouldn't round-trip. > > There's some justification for adding sub-8bpp, like BMP. bmp.c > converts all of them except GRAY8 to PAL8. Bitdepths besides 1, 4 and 8 > don't work at all. > > One way to at least allow both the bmp and zmbv encoders to do sub-8bpp > from PAL8 would be to keep track of the maximum number of colors in > some appropriate struct.
bits_per_coded_sample Carl Eugen _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel