Optimal Configuration for Recording Long Videos

[nekovolta]

I need to record long videos, several sessions of 5-6 hours each. With the current configuration I have in OBS, it takes up a lot of space to record each session. I am trying to find a "sweet spot configuration" where the file size is significantly smaller without compromising too much on image or sound quality. I understand that reducing the file size often leads to lower quality, but sometimes, small adjustments can considerably reduce the size without sacrificing too much quality.

This is my current configuration in OBS:

Can you help me define such a configuration?

 

[AaronD]

All of your options are going to be on the Output page.

But I see that you're using Default for your audio device. That's a ticking time bomb. When it goes off, your audio will suddenly not work, without you having changed anything. The reason is that Windows changed *its* selection, probably because you unplugged something or plugged one in, or because a device with audio functions went to sleep or woke up. Any of those events can cause the Default audio device to change, and you probably won't know it until your audio suddenly doesn't work.

Always choose a *specific* device, *in OBS*. Never use Default.

 

[nekovolta]

Thank you AaronD. I chose "Default" actually because I thought it would be safer. For instance, if I choose my Headphones, which is what I usually use: I thought that if I ran out of battery, then the sound won't be recorded. Here you have the list of devices I can choose. Which one do you recommend then?

 

[AaronD]

Thank you AaronD. I chose "Default" actually because I thought it would be safer. For instance, if I choose my Headphones, which is what I usually use: I thought that if I ran out of battery, then the sound won't be recorded. Here you have the list of devices I can choose. Which one do you recommend then?
View attachment 99359

Ran out of battery where? And what actually happens then? If the entire device goes away, then that may or may not be a problem, depending on how Windows handles an app that is specifically told to go to that device.

My warning applies to all other apps too, not just OBS. If everything is hard-set for a specific thing, then you should never lose that connection.

But, having a critical device run out of battery is itself a problem that you need to get rid of. Just don't let that happen, and you'll be fine. If you need to make a fake battery to stuff in the compartment and plug into a "wall wart" power supply, so be it. I've done that for a few things myself. Or use something that's designed to plug in, or is completely passive.

At any rate, mid-session changes to the configuration are bad. Don't let it happen, whatever that takes.

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As for which device to choose, solve the config-change problem first, and then figure out which in that list corresponds to the device that you're actually using by then. If you really have no idea, it doesn't take long to trial-and-error all of them. :-)

 

[nekovolta]

Ran out of battery where? And what actually happens then? If the entire device goes away, then that may or may not be a problem, depending on how Windows handles an app that is specifically told to go to that device.

My warning applies to all other apps too, not just OBS. If everything is hard-set for a specific thing, then you should never lose that connection.

But, having a critical device run out of battery is itself a problem that you need to get rid of. Just don't let that happen, and you'll be fine. If you need to make a fake battery to stuff in the compartment and plug into a "wall wart" power supply, so be it. I've done that for a few things myself. Or use something that's designed to plug in, or is completely passive.

At any rate, mid-session changes to the configuration are bad. Don't let it happen, whatever that takes.

---

As for which device to choose, solve the config-change problem first, and then figure out which in that list corresponds to the device that you're actually using by then. If you really have no idea, it doesn't take long to trial-and-error all of them. :-)

HI. What I mean is that if the device is set to the Headphones, and the headphones run out of battery, it stops recording the sound, as the sound is set for a specific device that is OFF. The same if I set the sound card as a sound system for recording, if I then switch my headphones on, it does not record the sound at that moment. So it seems that the default changes automatically between the sound card or headphones: if I switch off the phones, continuous recording through the sound card of the PC automatically and vice-versa. That is why I thought (And still think) that was the safer option.

 

[AaronD]

So it seems that the default changes automatically between the sound card or headphones...

Yes, it does. The vast majority of the time, people *don't* want that switch to happen, don't know that it happens, and then complain that their audio suddenly broke when they didn't do anything. (because it's looking at a different device now than they expect)

...if I switch off the phones, continuous recording through the sound card of the PC automatically and vice-versa. That is why I thought (And still think) that was the safer option.

You're playing with fire, by changing the configuration mid-session. Again, whatever you have to do to not change configs, intentionally or not, do that.

It's like pulling the patch cord on this rig that feeds the main PA and plugging it in somewhere else, in the middle of a concert, and expecting the audience to not notice. Yeah, good luck.

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

 

[koala]

So it seems that the default changes automatically between the sound card or headphones: if I switch off the phones, continuous recording through the sound card of the PC automatically and vice-versa. That is why I thought (And still think) that was the safer option.

OBS will not follow the default device and change it on the fly. On OBS start or if you set some audio device to "default", OBS will determine the default device and use it until OBS terminates. This is different to common media players that change their output device on the fly, if they're outputting to the default device.
If your default device is a wireless headset, and it loses power mid-recording, OBS will continue to try to record it, even if it switches itself off. This will record silence. Because of this, you should not try to capture such volatile devices but instead choose devices that will not go away during recording.

About your initial question:
Audio is insignificant size compared to video, so focus on video and encoder settings to get a proper quality versus file size ratio.
Double the fps about doubles the file size.
Double the resolution increases file size about 4 times.
Encoder settings can vary the file size from nil (bloody mess) to insanely huge (as good as raw recording).

You didn't post a log and you didn't tell anything about the type of video you try to record (that matters!), so the encoder recommendation is generic:
For a long running video, choose advanced output mode and CQP/CRF/ICQ (depending on the encoder) as rate control for the recording encoder. Instead of bitrate, you're able to specify a quality parameter with these. It's called CQ level or CQP or CQP level or CRF.
This parameter is 0..50 and tells how much detail to remove. 0 = nothing, 50=all. Start with 25. A change by 3 about doubles/halves the file size. Make test recordings and choose the CQ/CRF value that produces the best quality/file size ratio for your type of recording. Before you do this, choose the lowest resolution and the lowest fps thats still acceptable to further shrink the amount of data to encode.