What does Recording Bitrate do if CBR is not checked?

[Jaxel]

I dont quite understand why the recording options in OBS Studio even have a field for bitrate if you haven't checked the "Use CBR" option. If you're not using CBR, then you're using CRF... Using CRF, it should alter the bitrate as needed to maintain and consistent quality setting.

For instance, I am using CRF=18 so that my local recordings can be as close to lossless without being too extreme. With that setting, the bitrate would probably end up being anywhere between 12k to 18k, depending on what game I am recording at 720p.

So whats the purpose of the bitrate option? Currently if I check the "Use CBR" option, the CFR field disappears. If I uncheck the "Use CBR" option, shouldn't the bitrate option disappear?

Constant Bit-Rate = alter the quality of the video to maintain a constant bit-rate.
Constant Rate-Factor = alter the bit-rate/compression of the video to maintain a constant quality.

 

[Sapiens]

Unchecking CBR and defining a bitrate without a custom buffer size of 0 will use VBR encoding with an upper limit of the bitrate you set.

 

[Jaxel]

Unchecking CBR and defining a bitrate without a custom buffer size of 0 will use VBR encoding with an upper limit of the bitrate you set.

Oh, so its just an upper limit? Ideally though, if you are using CRF, then the bitrate option shouldnt do anything.

 

[Sapiens]

In order to achieve that behavior with x264 you'll need to set a custom buffer size of 0.

 

[Suslik V]

When 'Bitrate' disappears then 'Use CBR' checkbox will 'jump' one level above, losing your mouse focus. Inactive, maybe it could become inactive (shaded grey). What do you think about this?

Edit: ...and it needs to be renamed to 'Maxrate' if custom buffer size=0 & CBR unchecked. That's will indicate VBR mode of the encoding. Yeah, sophisticated dependencies.

 

[Sapiens]

When 'Bitrate' disappears then 'Use CBR' checkbox will 'jump' one level above, losing your mouse focus. Inactive, maybe it could become inactive (shaded grey). What do you think about this?

Not sure what you're talking about here. When does the bitrate field ever disappear? Do you mean when the "Use Custom Buffer Size" box is unchecked that the buffer size field disappears and the other options are moved up? Nothing under the cursor moves at that point.

...and it needs to be renamed to 'Maxrate' if custom buffer size=0 & CBR unchecked. That's will indicate VBR mode of the encoding. Yeah, sophisticated dependencies.

If the custom buffer size is 0 then the bitrate value is ignored entirely. This suggestion doesn't make sense.

 

[Suslik V]

See? I messed up.

Let me alternate, second edition:

• [custom] buffer size>0 & CBR unchecked --> change text 'Bitrate' to 'Maxrate';
• custom buffer size=0 & CBR unchecked --> make 'Bitrate' field inactive (shaded grey);