Question / Help Still Confused About Buffer Size...

[Zero3ffect]

So I seem to find a lot of conflicting information about what to put for the value in buffer size. The tool tip tells you that if you don't know what to use then just set it to the same as the max bitrate. I've also seen some tutorials that say to set it to double what your max bitrate is. Finally, I've also seen tutorials that say you should set it to a value where "max bitrate" + "buffer size" = "the true max bitrate that it may spike to". So, which method is the true method?

I've got about a 3.5Mbit upload so I've set both values to 2500 but assuming the last tutorial is true it could spike up to 5Mbit, which I obviously don't have. Although, I don't think it ever has because I'm guessing that this would result in dropped frames and I haven't had that issue.

 

[R1CH]

A spike of 5Mbit is fine, your modem likely has very large buffers to handle situations like this. The downside is you will get latency spikes when queuing is taking place.

 

[gXxshock]

Sorry to dig this up again, but I was having a similar question. Is there a correct setting (i.e. same as bitrate or 2x bitrate) and what exactly are the effects of setting the buffer higher.

 

[Krazy]

It's generally recommended to have them set to the same value. This is fine in almost every circumstance. A higher buffer size will allow for more bitrate in high motion, but you will also spike higher and potentially clog your network too much.

 

[silverthorn99]

Go to http://obsproject.com/estimator

 

[Grimio]

vbv-maxrate
Sets the maximum rate the VBV buffer should be assumed to refill at.

vbv-bufsize
Sets the size of the VBV buffer in kilobits.

Quoted from: http://mewiki.project357.com/wiki/X264_Setting

If I understand it correctly, using a buffer larger than the maxrate will only increase the delay on the playback side.
Also it shouldn't spike as it says that it sets the maximum rate the buffer can refill. But there must be something wrong here as I always hear different thing when it comes to the bitrate and the buffer.

 

[gXxshock]

Thanks for the input guys, still not entirely sure whether a higher buffer would also mean that the upload speed needs to be as large as the buffer, but I'll just stick to the settings suggested by the estimator.

 

[MasterEvilAce]

I have the exact same question as stated in the original post, but nobody seems to be responding to the question itself, in the manner it's presented.

What does the buffer size have to do in regards to your actual upload bandwidth? This matters a lot when dealing with a low upstream limit. Whenever I stream the audio is fine, but the video starts breaking up after a bit. Determining the correct settings will remedy this, but without a straight answer I can't say what the settings need to be.

OBS itself says setting buffer = max bitrate is fine in most circumstances. The estimator however suggests a value lower than the max birate it suggests. Other sites suggest a larger buffer. It's all contradicting each other without stating specifically WHY.

Right now I see my stream occasionally consumes over the max bitrate, and i'm assuming that's because the buffer size is more of a headroom value. Something like Max Bitrate + Buffer + Audio Bitrate = Total upstream bandwidth consumed (which needs to be BELOW what your maximum upspeed is.) If, for example, I set the buffer size to 0, will my video stream only ever upload at the max birate, and never any more?

Knowing how these settings work will allow me to determine the correct ones for my connection. I also have to consider a game's networking needs, VOIP, etc.. and I just can't allow my stream to consume all of my upstream bandwidth.

 

[Pson]

Sorry if this is a bit of a hijack of the thread but it's a similar question.

I've got 100mbit upstream, what buffer size would you recommend me using if I'm using a bitrate of 3500-4000?
Also, people say that a higher buffer size = requires more bandwidth than the actual set bitrate. Now will that require my viewers to have more than 3500-4000 kbit download? Or does it just affect my upload speed?

Quite hard to explain but hopefully someone understands my question.