Smallest recording file size

S

S1ngler

New Member
Hi to all,

I 've read dozens different threads and yt videos how to optimize OBS recording settings to get the smallest possible video file size but without some success.
I want to record some Teams meetings and video quality isn't so important but in resolution settings below 720p I couldn't read power point presentations from video clearly. I've tried with 720p output resolution, bicubic downscale filter, 30 common FPS value, recording format MKV, Encoder x264, CBR Rate control and 1000kbps bitrate but video file was still about 500MB/hour and with 2500kbps bitrate about 1GB/hour.
Is it possible to get video file about 200MB to 300MB per hour in 720p resolution with decent quality to read presentation from screen?

Best regards!
 
Change rate Control to "CRF" then set it within 16 to 23 range (lower value = higher quality at the cost of filesize) and retest.
 
just divide by 8 and you have your Kb/s instead of kbps
because its kilo bits and 8 bit are one byte

sample 1000 kbit/s video + 160kbit/s audio = 1160 kbit/s in total divided by 8 is 145 kb/s or ~8,7MB/minute or ~522MB/hour

so first thing you could reduce audio bitrate to 64kbits/s that should be enough for voice and saves you a little
2nd if you change the preset from veryfast to fast or medium, you need more cpu power to encode but can use lower bitrate
3rd you could change to ABR (average bitrate) instead of CBR so if there are peaks in the video that need more bitrate the image will get it while images with less details need less bitrate

finally you have to decide what's your personal need of image quality vs file size.
if you want to save even more space you could change from x264 to x265 (only in custom ffmpeg mode) but that would be too mutch to explain here and even needs more cpu power to encode

I would not recommend to use CRF here because you have less control over file size
 
Thank you both for fast answers.
@Volfield
I've tried you advice to change rate control from CBR to CRF with 23 value and left other settings: CPU usage preset: superfast; Profile: high; Tune: zerolatency; Audio bitrate 160; Audio sample rate 44.1kHz; (1280X720) 720p output resolution; Lanczos downscale filter, 30 common FPS value, recording format MKV, Encoder x264. And with these settings in 720p output resolution, text from video was very hard to recognize in some moments and file size was great: ~180MB/hour.
But when I've changed output resolution to 1920X1080 (my monitor's resolution), video was much better and I could see clearly everything on the screen and file size was also great: ~220MB/hour.

P.S. I don't know is it because of installed video codecs on my computer, video player or something else but when I played above video with CRF rate control and 720p output resolution on another computer with Media Player Classic Black Edition player (MPC-BE) video quality was much better than the same video played on my computer with BS player!


@Schauerland
Yeah you've right I didn't remember to convert bits to bytes and to count output file size based on bitrate control value!
Bitrate CBR 1000kbit/s gives very poor output video file quality, but not too much small as you said with audio ~522MB/hour .
So CBR rate control doesn't suit me. I don't know should I listen to you and change from CRF to ABR rate control but definitely I would reduce audio bitrate to 64kbits/s or at least 128kbits/s. And for the cpu usage preset I don't know does it affect on video size and quality because my computer's hardware specs are poor?
 
Don't change the CPU preset, "very fast" is the default for a reason. "Super fast" leads to a fair bit chunkier final filesize. generally speaking, you only go below the default on lower end hardware that can't keep up with the workload.

Also, certain video players are recommended for those differences in playback of the same video file. MPC-BE is a very reliable media player.
 
OK. But what about Profile: high; Tune: zerolatency; Lanczos downscale filter? And should I leave 1920X1080 (my monitor's resolution) for output resolution? Also didn't notice any change if I put 30 common FPS value or 60 common FPS value !
 
You don't need to touch those settings, tune=zerolatency will absolutely kill your recording quality. Set your output to 1080p and increase the CRF value until you get the desired file size.
 
I didn't explain well, I've already set those settings: Profile: high; Tune: zerolatency; Lanczos downscale filter. Because I've followed the instructions of some guy from YouTube how to get best video with small file size with low end hardware. So I will turn off Profile: high to None; Tune: zerolatency to None; And what about: Lanczos downscale filter and 60 common FPS value should I change it to Bicubic and 30 common FPS value or leave it as it is? Also I've already set CRF to 23 value, I think it is the lowest recommended value.
 
Forget youtube videos unless you're willing to watch several and the author explains clearly why a particular setting may be helpful, as most just parrot outdated and overly hyped info that generally just makes a user feel they accomplished something without truly understanding "why" said setting may be useful or if it even did anything meaningful, at all.

Stick to OBS settings-->Video category set to 1080p output, 30FPS, "Bicubic" or "Lanczos" is personal choice then, in OBS settings --> Output, x264 encoder, CRF rate Control set to whichever value you found acceptable, "Very fast" preset, "High" profile (main no longer needed due to modern harware), "None" Tune and no x264 options, at all. if the filesize is still far too large, either increase the CRF value or reduce the resolution to 864p.

Without a logfile, these are the recommended settings for local recordings with minimal fiddling with more technical settings.
 
OK. Thanx for suggestions. I'll try these settings you recommended. One more thing - should I leave recording format MKV or to set something else?
 
If anything happens during the recording that results in the file not being finalized correctly, such as a crash, saving to.mkv container allows you to still recover what was already saved up to that point.

Unfortunately, .mp4 and .mov do not offer such an advantage.
 
Yeah, I read that somewhere that only mkv could recover from crash to the last saved point. Then definetely I'll stick to mkv format.
 
Оn more thing - I've noticed at another computer that in Output --> Recording --> Encoder settings beside x264 encoder I can choose Hardware encoder, but on my primary computer I have just x264 encoder option. Which determines if I have hardware encoder or not and is it better than x264 software encoder?
 
You must log in or register to reply here.
Back
Top