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

[Carl Eugen Hoyos]

2018-08-01 21:24 GMT+02:00, Kirk Liberty <kirk.liberty at gmail.com>:
> On Wed, Aug 1, 2018 at 2:00 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>> 2018-08-01 6:12 GMT+02:00, Kirk Liberty <kirk.liberty at gmail.com>:
>>> 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?
>>
>> It is / can be.
>> What is not lossless is the conversion from PIX_FMT_GBR* (or RGB*)
>> to PIX_FMT_YUV*
>
> Are you referring to rgba2ycocg() in texturedspenc.c?

No.
You wrote above "lossless conversion of rgb->yuv->rgb" and i am
telling you that this is not possible with FFmpeg when using
libvpx-vp9 or x264.

Both libvpx-vp9 and x264 support rgb encoding and both can
encode in a lossless fashion.

If you have an additional question concerning FFmpeg usage,
please provide the command line you tested together with the
complete, uncut console output.

Carl Eugen