[FFmpeg-user] Trying to get lossless PNG -> VP9 (yuv) -> PNG

[Kirk Liberty]

On Tue, Jul 31, 2018 at 7:04 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>
> 2018-07-29 0:16 GMT+02:00, Kirk Liberty <kirk.liberty at gmail.com>:
> > My plan is to use the YCgCo
> > colorspace to get lossless conversion of rgb->yuv->rgb
>
> This conversion (may be lossless in theory but) is not lossless
> with FFmpeg, both x264 and libvpx-vp9 support encoding rgb
> which can be lossless.

Why is YCgCo not lossless in FFmpeg? Problem with using the
grba colorspace is that it is a fair bit larger than a lossless
WebP.

Someone on StackExchange pointed out that -color_range does not
affect the output. I was able to get the image to look right by
using -vf scale=out_range=pc and then -vf scale=in_range=pc for
for the reverse.

Kirk