VideoHelp Forum
+ Reply to Thread
Results 1 to 6 of 6
Thread
  1. Member
    Join Date: Mar 2008
    Location: United States
    Search Comp PM
    I'm searching for MeGUI presents that will allow me to convert my FRAPS captures to videos that strike a good balance between archival quality and manageable bit rate. I have found a few that seem to work well in lighter areas and in darker areas with strong color contrast. Finding presets that perform well in lighter scenes has been easy. However, using those same presets, I notice much lower quality in darker scenes that contain areas in which the color contrast is very low.

    I have included screen shot's below. This phenomenon can be seen on the wooden floor and the lower, wooden portion of the wall, even as upper portions of the images seem to remain much more true to the original. This is especially true of the "Low" quality x264, which is still about 7 GB per hour of video, before sound is added. The "High" quality x264 seems to produce a reasonably good, but not great, quality image, but the files using this preset tend to be about 25-30 GB per hour of video, before sound is added. This seems excessive. Is there a way I can clean up the quality in these types of dark scenes without resorting to extremely high bit rates?

    Thanks in advance.



    All of the x264 streams were encoded with 10-bit color, and the screenshots were taken using MPC-HC.

    I was able to see the differences best by putting each image into it's own layer on the same Paint.NET file. That way I could toggle between any two images for comparison.


    Original FRAPS Capture - 383 Mbps

    Click image for larger version

Name:	Outlast17_0_FRAPS Capture.png
Views:	112
Size:	12.63 MB
ID:	25433





    High Quality 10-bit x264 - 95.7 Mbps
    program --preset slow --crf 12 --output "output" "input"

    Click image for larger version

Name:	Outlast17_1_High Quality x264.png
Views:	196
Size:	13.26 MB
ID:	25430





    Medium Quality 10-bit x264 - 60.5 Mbps
    program --preset slow --crf 16 --output "output" "input"

    Click image for larger version

Name:	Outlast17_2_Med Quality x264.png
Views:	149
Size:	12.94 MB
ID:	25432





    Low Quality 10-bit x264 - 25.0 Mbps
    program --preset slow --crf 22 --output "output" "input"

    Click image for larger version

Name:	Outlast17_3_Low Quality x264.png
Views:	208
Size:	11.59 MB
ID:	25431
    Quote Quote  
  2. Originally Posted by Pilotwings_64 View Post
    Is there a way I can clean up the quality in these types of dark scenes without resorting to extremely high bit rates?
    No. You can try using higher CRF values and setting aq-strength around 1.8 to 2.0. But in the end the result is higher bitrates.
    Last edited by jagabo; 29th May 2014 at 14:23. Reason: changed qcomp to aq-strength
    Quote Quote  
  3. Member
    Join Date: Mar 2008
    Location: United States
    Search Comp PM
    Thanks for the reply.

    Is there any way I can set MeGUI to use one crf value when it encounters a scene like this and another value for all other scenes?

    Thanks again.
    Quote Quote  
  4. Member
    Join Date: Sep 2007
    Location: Canada
    Search Comp PM
    You can specificy zones in x264 (and megui) , so different CRF values (or bitrate multipliers), even some different encoding settings can be applied to different sections
    Quote Quote  
  5. Oh sorry, I suggested setting qcomp in my last post. I should have said aq-strength. Try setting aq-strength to a larger value than the default 1.0. Around 1.8 to 2.0.
    Quote Quote  
  6. Member
    Join Date: Mar 2008
    Location: United States
    Search Comp PM
    Thanks for the suggestions. I have not been able to get the quality I want by changing the aq-strength. After reading up on the subject, I think I'm going to have use zones, as poisondeathray suggested.
    Quote Quote