Question / Help What are Buffer Dimensions?

dot_Connection

New Member
I have been recording video using OBS(still learning and testing w/ different settings) and noticing all of my recordings are being output with a resolution of 1920x1088.
Here is an example of a remux'd .mp4(.mkv > .mp4) file's properties from File Explorer:
1589938053137.png

Here are my video recording settings (Replay Buffer is not enabled):
1589937843142.png

1589937879594.png

*I am scaling the output from 2560x1440 to 1920x1080 because I am recording off of a 2k monitor (MSI Optix MAG271CQR) and it helps reduce the file size.

Upon inspecting the file's information with VLC there is a "Buffer Dimensions" item in the Codec tab:
1589937500642.png


I can't find any info on this on the forums here, and the only relevant google result is from a post here with no answers. I can't seem to find any mention of this in OBS's settings either.
So what are the buffer dimensions? Why does it add 8 pixels to the height of my recording? Is there a way to change the buffer dimension so it actually matches the video resolution?

Here is my current log file: https://obsproject.com/logs/yznqEquW1lFOV7mI
 

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koala

Active Member
You're using a nonstandard encoder (hevc) with a nonstandard setup (color space RGB instead of NV12). It may be for this configuration, the encoder requires a resolution that is dividable by 16 to be able to use a block size of 16x16.

Try the standard x264 encoder with NV12 color space for testing purposes. This will work with a resolution of 1920x1080. Then change one thing at a time (first the encoder, then the color space if you absolutely must) and see with which configuration change will force the resolution to change.
 

dot_Connection

New Member
Thank you! I will try this out.
What is the difference between the H264 encoder vs the x264 encoder?
1589983785501.png


Do you have a link that explains the Color Formats and Color Space? I feel like I have a very surface level understanding of all these settings, so I would definitely like to learn more about how they work.
 

koala

Active Member
The topic color space is very broad, so I don't have just a link. You have to work out this yourself by googling. If you are only a surface level of understanding, I strongly recommend you use the OBS defaults. Use color format NV12. Very important, because this is where is OBS optimized for, together with Color Range partial. Color space 709 for output resolutions of 720p and above.

x264 is the software encoder that uses much CPU and produces the best quality. The AMD AMF encoders are hardware encoders on your GPU. These relieve the CPU from work but produce not the best quality. If you can afford the CPU load of x264, use this, but if you get encoder overload, try the AMD hardware encoders. Use H264, not H265. H265 is not widely supported in media players and postprocessing software and not at all by streaming providers.
 

dot_Connection

New Member
@koala so a bit of an update here - I tried out what you recommended: x264 encoding, NV12 color format, 709 color space, Partial color range. This seemed to have the desired effect (need to mess around with the rate control setting though, file sizes are a bit bigger than i would like), now the file properties list recordings as 1920x1080 resolution:
1590426405354.png

Oddly enough though, when looking at the .mkv & remux'd .mp4's media info through VLC there is still a setting for buffer dimensions that lists the resolution as 1920x1088:
.mkv file:
1590426450639.png

.mp4 file:
1590426487021.png


Do you have any idea why that would be?
 

koala

Active Member
Sorry, I don't know the meaning of the "Buffer dimensions" value. Perhaps some internal value how VLC will handle that video. It shows up on my system as well. It's no general property of the video. If you want to see the unbiased properties of a video file, don't use the VLC internal data viewer, use MediaInfo: https://mediaarea.net/en/MediaInfo
 

R1CH

Forum Admin
Developer
koala is correct, these are just size of buffers for decoding with alignment requirements. It has no impact on the actual video resolution. I would suggest ignoring the "buffer dimensions" here as it has no particular relevance, just an internal VLC stat.
 
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