Recording File Size Too Large

Hello,

I recently installed OBS (version 29.1.3) on a new pc running Windows 11. When using OBS Studio to record mkv files on this pc the resulting file sizes have been very large (500MB for a 30 second recording of Baldur's Gate 3). I have previously used OBS (version 21.1.2) to record numerous files on an older pc running Windows 7. These files were about half the size of those made by the new pc. The OBS recording settings for both computers are as close as I could get to identical barring differences between the OBS versions.

I was hoping that you could help explain what's causing the files to be so large. As a test I have recorded about 30 seconds of the video game Life is Strange on both computers. The same section of the game was used for both recordings. The Win 11 pc file size was 41.6MB, while the Win 7 file size was 20.0MB. The log files for each are attached. I would appreciate any help you can offer.

In both cases you used CQP 18 as quality target for the encoder. So dynamic bitrate and file size strongly depend on the actual gameplay and screen details and motion.

You may decrease the quality level but details in the video may got lost that way. Try what still works for you.

Baldurs Gate 3 on a powerful PC/GPU has extraordinarily high graphics detail and quality. You now compare some app or game rendered with a CPU and GTX 1070 from 8 years ago with a state of the art game rendered in 4K (downscaled to 1080p) on a top notch state of the art CPU+RTX 4080.
Better rendered and higher detailed graphics simply needs more space to store. CQP 18 isn't forcing the same average bitrate no matter the raw footage. It's just removing a fixed amount of detail for encoding, but if you start out with higher detail, it's still keeping at higher detail with higher disk space demand.

1. The Hardware-accelerated GPU scheduling ("HAGS") feature in Windows is currently known to cause performance and capture issues with OBS, games and overlay tools. It's an experimental feature and we recommend disabling it via these instructions.
2. You are running an old version of OBS Studio (29.1.3) which is not supported. Please update to version 30.1.2 or newer by going to Help -> Check for updates in OBS or by downloading the latest installer from the downloads page and running it.
3. You have a bit of rendering lag and encoder overload. Disable Look-ahead and Psycho Visual Tuning and set Multipass to Single Pass. Those all use additional GPU.
4. If you want consistent quality, use CQP. If you want consistent file size, use CBR or VBR.

You can also try adding a simple, static border. Static content, in general, uses less data.

I appreciate your replies. Unfortunately, none of them have fully addressed the issue yet. Despite trying most of the recommendations, so far we still haven't been able to find the answer - we're trying to determine why the OBS files in the Win 11 pc are so much larger than the OBS files in the Win 11 pc.

Sure I can always reduce file sizes by setting CQP to 30, but this doesn't fix the issue or explain the reason behind it. The Windows 7 pc has low file sizes while using CQP 18.

• As konsolenritter pointed out - CQP 18 was used for OBS in both computers. So the CQP setting cannot be the cause of the different file sizes.
  
  
• The actual gameplay and game settings were identical (30 seconds of the same Life is Strange dialogue choice prompt) for the test file created with the Win 7 pc and the test file created with the Win 11 pc. So the gameplay and game settings cannot be the cause of the different file sizes.
  
  
• Qhobbes had an excellent suggestion in recommending Disabling Hardware-accelerated GPU Scheduling. Hardware-accelerated GPU Scheduling could have potentially been the cause of the huge increase in file sizes because it's something that is completely different between Windows 7 and Windows 11. However, I disabled it and the result of the 30 second test was 39.7 MB. This is still double the file size of the Windows 7 pc OBS files.
  
  
• Look-ahead was already been disabled originally.
  
  
• Psycho visual tuning (aside from haivng the best name of any recording software feature) had an interesting effect. Disabling it decreased the file size for the 30 second Life is Strange test (from 41.6 MB to 29.2 MB). But it increased the file size for the 30 second BG3 test (from 509 MB to 589 MB). Not sure what to make of this.
  
  
• Setting Multipass Mode to single pass would not be the best solution because the OBS settings for both computers include using two passes. While this might reduce the file size, that's not the goal. I am trying to find out what specific differences are causing the huge OBS file sizes on the Windows 11 pc.

The majority of people on this site know OBS far better than me. I'd appreciate any help you can provide in identifying the cause of the different file sizes. I would like to use OBS to record gameplay using the Windows 11 pc. However, producing files that are over twice as large is obviously not ideal...

Files are different because you are using different encoders. Try same build of software x264 encoder (you may use "MediaInfo" util to get the build number that was shipped with OBS) and at same conditions - the result will be the same (for data block of media).

Also, because of few color planes conversion issues (artifacts, that were solved only after the https://github.com/obsproject/obs-studio/commit/164f731320c09ea6907c0a9f6a56528a10cd04fb was merged, Aug 10, 2019) it is not recommended to compare old builds of OBS against a newer ones (without some precautions or shader modification).

In short, comparison OBS v21.1.2 vs v29.1.3 is not correct, because everything is different.