[FFmpeg-devel] FFV1: conspicious filesize oddities

[Peter B.]

Hello,

While creating FATE tests for FFV1, I've realized a peculiar filesize
difference when encoding a certain video in yuv444p.

"ls" output shows:
----------------------
1162564 Oct 29 19:35 yuv444p10.avi
265940 Oct 29 19:35 yuv444p16.avi
881960 Oct 29 19:35 yuv444p9.avi
265746 Oct 29 19:41 yuv444p.avi
----------------------

This seems strange to me:
1) 16bit version is only ~200 kiB larger than the 8bit version
2) The 10bit version is more than 4 times (!) bigger than the 16bit version

There seems to be a pattern:
The only exception in the expected filesize increase is the 16bit version.


All files play fine with "ffplay".
"ffprobe", however, shows that 9bit, 10bit and 16bit are all displayed
as "yuv444p16le".
Is that supposed to be so?


The command I've used to create those files was:
-----------------------
$ ffmpeg -i ffv1-yuv444p16.avi -an -c:v ffv1 -level 1 -coder 1 -context
0 -g 1 -pix_fmt $PIX_FMT $OUTPUT
-----------------------

I've uploaded a sample of the video I've used as source [1].


Thank you in advance,
Pb

== References:
[1]
http://download.das-werkstatt.com/pb/mthk/FFv1-Examples/ffv1-yuv444p16.avi