What steps will reproduce the problem?
1. ffmbc -i uncompressed.mov - vcodec prores -profile hq output.mov
2. calculate the PSNR for the given frames in accordance with ITU J.247
What is the expected output? What do you see instead?
For all videos, when the encoded video's PSNR is calculated in accordance
with ITU J.247 [1], the first 30 frames have a PSNR of 50 dB (the maximum
allowed in J.247). See image [2].
The first scene in this particular video is a complex scene containing lots
of multi-coloured elements lasting 250 frames, there is no significant
difference in the first 30 frames and the last 220.
I am wondering why the objective measurement of picture quality changes
after 30 frames? Could there be a fault with the allocation of bitrate
throughout the video
What version of the product are you using? On what operating system?
For further information, I've uploaded a graph of FFmbc Pro-Res HQ vs Apple
Pro-Res HQ. It can be seen that the overall quality seems to be
fractionally less, which could be accounted for by the (presumed) bitrate
spike at the start.
The psnr tool uses the first frame of motion video in the original file
($OFFSET) and hunts through the first 1750 frames of the encoded video file
for the frame that matches most. It then uses this frame to create the ITU
J.247 compliant PSNR output.
UYVY files are created using something like:
mencoder -demuxer lavf -nosound -ovc raw -of rawvideo "$WORK_FILE"
-o "$WORK_FILE".yuv
The graph shown contains the correct number of motion video frames (and
matches the number of Frames created when using the proprietary Pro-Res
encoder).
Ok, to compare accurately, I took the source file and encoded it using FCP.
I then encoded the same source file with ffmbc and then used calcpsnr.
I use ffmbc -i <file> -pix_fmt uyvy422 <file.yuv> to create yuv files.
FFmbc is constantly 1 db PSNR higher than Apple, so I cannot reproduce what
you are seeing.
The Apple encoded file you sent me if unaligned so is not suitable for
testing.
Actually I was wrong, apple encoder was better, but I fixed that and it is
now better
-- You received this message because this project is configured to send all
issue notifications to this address.
You may adjust your notification preferences at:
https://code.google.com/hosting/settings
-- You received this message because this project is configured to send all
issue notifications to this address.
You may adjust your notification preferences at:
https://code.google.com/hosting/settings
