Lossless image compression

[birdie-github]

I've no idea how to make vvcenc losslessly compress images since I want to preserve the entire color space (RGB888). Any clues?

I'd love to use something like YUV444_10 which at least minimizes color space loss but even this format is not available:

Error parsing option "format,c" with argument "yuv444_10".

[adamjw24]

For now vvenc does not support either lossless compression nor other chroma subsampling than 420. The support is not planned in the near future.

[jungleboynx]

True lossless is usually Intra frames only (no P or B frames) at a low quantization in 4:2:2 or 4:4:4 and possibly 10bit as well.
Obviously non of this is possible with VVenC at present and is unlikely to be in future except for the 4:2:2 and 4:4:4.
The next best thing is to use a low quantizer like QP 10 - this should give an average I-SLICE quantizer of about zero.
If you want proper lossless then use x264 with 'I' frames only or 'I' and 'P' only (no 'B') and a very low CRF quantizer.

[ValeZAA]

True lossless is usually Intra frames only (no P or B frames)

That is false.

[birdie-github]

True lossless is usually Intra frames only (no P or B frames)

x265 has got a "true" (why do you call it "true"? It's either lossless or lossy, there's nothing in between) lossless mode and I've used it on several occasions.

[ValeZAA]

True lossless is usually Intra frames only (no P or B frames)

x265 has got a "true" (why do you call it "true"? It's either lossless or lossy, there's nothing in between) lossless mode and I've used it on several occasions.

VP9, AV1 (only aom), x265, and best of them x264 all have many different compression ratio true mathemtically lossless mode. AVIF too, you can spend more time encoding avif and it will be smaller AVIF that is same md5 of 420 plane.

[jungleboynx]

Having a ib-ratio parameter (similar to ip-ratio and pb-ratio in x264/5) would be useful to reduce the difference between B frame and I-SLICE quantizers. This would allow the ratio to be reduced to say 1.0:1

When --tune film or --tune grain is used in x264/5 then ip-ratio and pb-ratio are reduced along with aq-step to lower the difference in quantizer between frames but it also increases bitrate.

[adamjw24]

You could try playing with the IntraQPOffset parameter, which is the QP offset of I-frames (default =-3). If you set to closer to 0, the IB-ratio would get smaller.

[jungleboynx]

Thanks - I'll give it a go sometime when I get some nice grainy/noisy source.