Is H265 encoding via 01_video_encode really lossless?

[payton.rehl]

Hi! I am attempting to losslessly encode/decode Y444 video using 00_video_decode and 00_video_encode. I’ve been told its only supported for H265, however, whenever I try to generate a Y444 video, encode it, and then decode it, the original and decoded videos differ. I’ve posted my command line below, but am I missing anything – Are the tools actually byte-by-byte lossless? Any help would be much appreciated!

gst-launch-1.0 videotestsrc num-buffers=30 ! ‘video/x-raw, width=(int)1920, height=(int)1080, format=(string)Y444’ ! filesink location=~/origfile.yuv
./01_video_encode/video_encode ~/origfile.yuv 1920 1080 H265 ~/compfile.h265 --elossless
./00_video_decode/video_decode H265 --disable-rendering -o ~/decompfile.yuv ~/compfile.h265
diff ~/origfile.yuv ~/decompfile.yuv

[DaneLLL]

Hi,
Please check whether decompfile.yuv is in YUV444. It may be converted to YUV420.

[payton.rehl]

Thank you, according to the help message, decoding doesn’t actually support Y444 despite the encoder supporting it. I’ve used NV24 instead for both input and output and they match.

[DaneLLL]

Hi,
NV24 and YUV444 are identical in data bytes, but data layout is different. YUV444 has 3 planes and NV24 has 2 planes. The decoded YUV data is in NV24 and if you convert it to YUV444, the data is identical.