Question / Help Inconsistent Recording Quality

[derklempner]

I just finished recording six 20-minute episodes of Minecraft gameplay. They were all downscaled from 1080p to 720p, but without video or audio stuttering. Very smooth video for the first time since I started using OBS MP in Linux (v0.11.2).

However, now I can't seem to replicate the results without the video downscaling. Here are my settings:

As soon as I disable downscaling (not shown here, it's set in the Video section), the video stutters. It doesn't matter what bitrate I use, either; the video saved is full of stuttering. It's rather annoying, mainly because I have no issues using OBS (with NVENC) and Fraps in Windows 8.1 without any of these issues. But Linux? No dice.

I'm wondering if anyone can give me some insight as to what I should be doing to make smoother, better-looking videos with OBS in Linux. I've tried changing bitrate, buffer size, keyframe interval, and CRF all to no avail. I'm no video expert, but I think my hardware (quad-core AMD A8-5500 and 8GB RAM) is more than sufficient for recording 60fps video, as I've had no trouble doing so whilst using Windows.

Please let me know what information you might need from me to assist with this issue.

 

[derklempner]

I also forgot to mention that in every video I capture, the last one or two seconds is always cut off, leading to a premature end to the video. Is this normal?

 

[Harold]

Change your buffer size to 0 and your cpu usage preset to ultrafast. Keyframe interval of auto is fine for recording.
Because "Use CBR" is disabled, the bitrate value above is ignored.

 

[derklempner]

Okay, so here's the new settings:

I've also disabled downscaling in the Video options. But before I make endless more attempts...

Should there be a change in CRF? And when you say the bitrate is ignored because CBR is disabled, does that mean I could put in 1000, 5000, or 10000 instead of 2250 and there would be no difference of quality? Also, what about the missing second or two of video after I stop the recording?

 

[Harold]

CRF values below 18 offer diminishing returns in image quality, and according to ffmpeg documentation:

Consider 18 to be visually lossless or nearly so: it should look the same or nearly the same as the input but it isn't technically lossless.

( reference: https://trac.ffmpeg.org/wiki/Encode/H.264 )

It doesn't matter what you put in for bitrate when using CRF based bitrate selection like you are, 1080p60 will, with those settings, typically land in the 40mbit range for video (you can only tell this after doing a ffmpeg remux of the file).

The missing second or two at the end of recording is being worked on.

Saving directly to mp4 isn't recommended. Although the situation is improved in multiplatform, any non-graceful shutdown of the encoding process will completely destroy the file. We still recommend saving to flv, but there are fewer instances where the encoding process will be shut down non-gracefully.

 

[derklempner]

Saving directly to mp4 isn't recommended. Although the situation is improved in multiplatform, any non-graceful shutdown of the encoding process will completely destroy the file. We still recommend saving to flv, but there are fewer instances where the encoding process will be shut down non-gracefully.

So saving to mp4 has issues with the videos being ended prematurely? Good to know. I only use mp4 now because I know I can record multitrack audio with the mic on a different track, making it easier to extract that audio and clean it up before re-merging it during editing.

I ran another test with the changed settings and it looked AMAZING. It was only at 30fps, so the next few tests will be 60fps and flv with the hopes it looks as good.

Seriously, this software is looking amazing so far. I'm fairly certain most of my issues are related to me being new to screen capture/recording in Linux, but OBS is making it easy. The more I learn about it and editing (I'm learning to use Kdenlive) the more I hope to be able to give back to the community in terms of support. Thanks for all your help!

 

[Harold]

If you absolutely need multitrack, I'd recommend mkv (matroska) as the container instead of mp4.

 

[derklempner]

If you absolutely need multitrack, I'd recommend mkv (matroska) as the container instead of mp4.

Not absolutely. I'm looking towards the future since I'm not that skilled at video editing (yet).

Moving on, my 1080p 60fps test using flv wasn't much of a success. The video looked good, but the stuttering returned. My settings now:

It was perfect at 30fps. It was stuttering badly (looked like maybe 2-3fps) at 60fps. This was using bicubic downscale filter, but since I'm not actually downscaling, does it matter what filter I use?

 

[dodgepong]

Can you post a log of the 60fps session?

 

[derklempner]

Can you post a log of the 60fps session?

Here you go!

The last test I did started at this line:

03:55:35 PM.283: ---------------------------------

EDIT: Changed code text to correct line info.

 

[derklempner]

Well, this was an eye-opener:

03:56:31 PM.740: ==== Recording Stop ================================================
03:56:31 PM.740: Output 'adv_file_output': stopping
03:56:31 PM.740: Output 'adv_file_output': Total frames: 1676
03:56:31 PM.740: Output 'adv_file_output': Number of skipped frames: 1487 (88.7232%)

 

[Harold]

Your processor may simply not be capable of 1080p60, even with the ultrafast preset.

720p60 maybe.

 

[derklempner]

Your processor may simply not be capable of 1080p60, even with the ultrafast preset.

720p60 maybe.

It's an AMD A8-5500, quad-core processor at 3.2GHz. I can do 1080p 60fps recording using OBS (not OBS MP) and Fraps in Windows, so I know it's not a processor limitation. (No, I'm not using the APU; I have a Geforce GTX 750 Ti graphics card.)

 

[derklempner]

But now that I think about it, I did have to use NVENC in OBS on Windows. Fraps still worked at 1080p and 60fps, though.

Maybe I'll just have to wait for NVENC to be added to OBS MP?

 

[Osiris]

Sorry, but you can't do 1080p @ 60fps and play a game with that CPU, certainly not when using OBS with x264.

 

[dodgepong]

FRAPS is completely different from OBS in terms of the way video is captured and recorded. FRAPS captures raw data and dumps it to a file. OBS captures, renders a whole scene with several captured elements, and then compresses and encodes using an encoder that is suitable for streaming or recording.