Mpeg1, vp9, theora and h264 intra lossless encoding strange results

Question

I tried lossless intra coding of a few sequences including this one from xiph.org: https://media.xiph.org/video/derf/y4m/foreman_qcif.y4m and strangely mpeg1video wins by a great margin sizewise. I used FFmpeg with these settings:

ffmpeg -i foreman_qcif.y4m -c:v mpeg1video -qscale:v 0 -intra foreman.mpeg
ffmpeg -i foreman_qcif.y4m -c:v libx264 -crf 0 -intra foreman.mp4
ffmpeg -i foreman_qcif.y4m -c:v libvpx-vp9 -crf 0 -intra foreman.webm
ffmpeg -i foreman_qcif.y4m -c:v libtheora -qscale:v 10 -intra foreman.ogg

And the sizes I've got: mpeg1video - 2643968; theora - 2949677; vp9 - 5636841; h264 - 5743014; So the question is: does mpeg1video really beats them all by such a margin in this mode ?

Answer 1

Apparently even on the max quality settings mpeg1video is far from being lossless. From ISO-IEC-11172-2_1991_MPEG1_Video:"algorithm is not lossless" and "The "quantizer size for the DC coefficients of the luminance and chrominance components is fixed at eight"