Question / Help Stream Settings -- "Warnings that stream is not set optimal"

[Chromatic]

Heya,

I've recently upgraded to 0.571b -- And now it gives me a "Warning: Your OBS settings are not optimized for use with Twitch/JTV. Please set the following: Encoding Settings: Enable CBR. And Advanced: Set Keyframe Interval to 2 Seconds."

I have been keeping CBR off,.. and letting the quality setting stay at 7.. I set the Max Bitrate to 2000 (even though it will exceed this at times so it isn't a LOCK) (I have 5Mbits to use), with Quality Balance at 7. Seems to work well.. but I'm always in favor of the best quality for the masses.

I could of course stream at 4Mbits a second and still have plenty of UL left for my 100Mbit connection.. but Wouldn't setting the CBR on cause it to stream at the maximum all the time?

Why is it recommended to use CBR for JTV/Twitch? Isn't it a better option to use a Quality balance.. so that regardless of people's internet connections they get the lowest bandwidth that is needed for any given second of video going out.. instead of forcing it to use 2000 kb/s in my example when it may not need it?

I'm more than happy to force it, but would like some explanation/reason to do so.. why would it help?

Also -- just curious, I set the keyframe interval to 2 as suggested,.. but what exactly does that do?

Further, I set the Scene Buffering time up from 300ms to the 'new default' I noticed in the changelog to 700ms --- Anyone care to elaborate how that helps ?

I've read the stream guides -- just wondering your input on what I've mentioned.

Further, what would be the ideal settings for a 5Mbit UL connection streaming 24/7 HD videos ? So that it doesn't cause lag to any majority of people,.. yet gives the best quality in video and sound and reliability?

Thanks!

 

[dodgepong]

Re: Stream Settings -- "Warnings that stream is not set opti

CBR and keyframe interval are new Twitch requirements: http://help.twitch.tv/customer/portal/articles/1253460

Without CBR, the bandwidth that is required to watch a stream is constantly changing. You might be streaming out at 1000kbps for a while, and then suddenly have a spike in activity on stream that demands 3000kbps. This kind of switching doesn't work very well with the internet's infrastructure, and can cause stream lag even if viewers have enough bandwidth to watch a stream. CBR streams are much more stable and easier for people to watch, due to their bandwidth requirements not constantly fluctuating.

Keyframe interval defines how long x264 can go before needing to send a keyframe. Twitch wants this at 2 seconds to aid in their HLS transcoding.

Scene buffering was increased because the default was not high enough for some people, causing them to have mic issues.

If you're streaming 1080p HD, I wouldn't go below 3000kbps bit rate. If you're doing that 24/7, then I hope you have a good relationship with your ISP...

 

[Chromatic]

Re: Stream Settings -- "Warnings that stream is not set opti

On average I stream at 720p.. occasionally I will run 1080p..

I don't bump the Bitrate to 3Mbit so I won't marginalize the viewers.. a lot of people watch my 24/7 stream with cell phones,.. and there is an even split of viewers across the world due to my content being what it is..

I've never had quality issues at 2Mbit.

I am using JTV, not twitch -- and Twitch (while the same company) -- receives FAR more attention on upgrades and fixing issues than JTV. JTV is working on implementing new video infrastructure -- specifically they are getting ready to implement HLS for JTV. Thus, at the moment, JTV is not HLS compliant. It is a future upgrade.

I will experiment with CBR -- Should I set my CBR at 2000 -- and Enable CBR padding,.. and with the Buffer size of the CBR,.. should it be equal to 2000, or greater?

Also looking at stats for the most common video's I play -- They are as follows:

H264 - 1280x720 - Planar 4:2:0 YUV - Audio - a52 - Stereo - Sample Rate - 48000 Hz - Bitrate: 192 kb/s - Frame rate 25 fps - Data rate 2012kbps - Total Bitrate: 2227kbps.

Now,.. given these stats -- I used to have the OBS framerate at 25fps.. but I moved it to 30fps,.. and it produces a smoother playback on the stream, despite videos being 5fps or so slower. (Any need to reduce this? Does the 30fps on OBS on a 25fps video help? Visually it seems so, ?)

Also the Audio is mostly at 192 kb/s -- Now you guys suggest 160 kb/s max.. is there any harm in pushing it to 192 kb/s to match video? Or will the server simply not accept it?

As you can see the bitrate is a bit higher than 2Mbit -- given this, should I increase my CBR to say 2.3 or so to keep up? And again as I mentioned, should I keep CBR padding on, and should I adjust a custom buffer size beyond the 2000 or 2300 bitrate,.. ?

I have 5Mbit on the UL, and 100Mbit on the downstream. My ISP has no problems with my 2-3Mbit 24/7 upstream and no problems despite how much of the downstream I use.. I pay $100 a month for it, so perhaps that is why..

Again, I always thought keeping the CBR off was of benefit to the viewers bandwidth so it wouldn't force them to sustain 2Mbit when many times only a fourth of that is being pushed.. ie: I see the stream pushing 500-700kbps during the stream with a quality balance of 7.

Lots of questions I know.. Dissect and respond at your leisure.. I am reading the twitch requirements now. Though JTV is not twitch,.. it is well behind, though such changes are coming to JTV just much, much slower. They have one engineer working on JTV and multiple engineers for Twitch.

Thanks for your time.

Thanks!

 

[dodgepong]

Re: Stream Settings -- "Warnings that stream is not set opti

I was giving 3000kbps as an example. 2000kbps is a good bit rate to stream at for viewers.

If JTV doesn't have the CBR/keyframe interval requirements yet, then I would expect then to enact them very very soon, especially switching HLS.

CBR at 2000 bitrate & buffer with padding enabled is correct.

 

[Chromatic]

Re: Stream Settings -- "Warnings that stream is not set opti

Thanks for the reply -- I've adjusted the settings and will see how it goes.

Anyone care to address my other question in the abovepost?

Also the Audio is mostly at 192 kb/s -- Now you guys suggest 160 kb/s max.. is there any harm in pushing it to 192 kb/s to match video? Or will the server simply not accept it?

Can I put it above 160 kb/s in OBS, and if I do will the sound quality increase? Or are the servers limited? IE: Some of my video's are above 160kb/s audio quality. If I set it at say 192 kb/s.. will JTV make use of it?

Thanks

 

[Krazy]

Re: Stream Settings -- "Warnings that stream is not set opti

I don't think they even accept streams with audio over 160kb/s anymore, no?

edit: just a note, JTV and Twitch are one in the same, as far as the tech side of things goes. Same ingest servers, etc, etc.