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Can anyone explain what the vbv buffer does and how changing it affects streaming?
Also, skype and/or ventrilo seem to lag my stream really badly (freezing every few seconds). I have a 2 mb upload internet, so I normally stream at 1500 max bitrate and 1500 or 3000 vbv buffer rate. But when I have skype or vent open, I can barely stream at 500 max bitrate. It doesn't seem like skype takes 1 mb of bandwidth. However, I just had some success by having vent open and streaming at 1000 max bitrate and 250 vbv buffer rate. The stream looked a little blocky, so I think I could do better.
Is there an optimal way to set this up? 1500 max bitrate, 100 vbv buffer? 750/750? 500/20000?
Also, what does the quality setting (1-10) affect? CPU, GPU and/or internet?
Thanks for your help! Let me know if you have any questions.
2 mb upload internet
Phenom II 940 cpu
Radeon HD 6970
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Although this doesn't answer your question, I have a 2mbit upload aswell, and streaming at 1500kbit goes without a hiccup with both vent and skype running at the same time.
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When your connection isn't sufficient to get the video stream up to the server(s) that you're streaming to, it starts creating a buffer locally, so that it won't interrupt the video, it will however lag up the stream on the viewers end for a split second, but once the buffer is created, the natural variance of your connection speed and the video bitrate will no longer cause these little stutters. Having too small of a buffer will cause tons of stuttering on the viewers end, having too large a buffer can be a problem on the streamer's side due to stressing the system.
Look up the x-split documentation if you want to know exactly what each of the settings do, don't use TL as your own personal search engine.
They do pretty much what the little descriptions say, quality alters the quality of the encoding, bitrate changes the target bitrate for the VBR encoder
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On September 28 2011 19:34 ruXxar wrote:
Although this doesn't answer your question, I have a 2mbit upload aswell, and streaming at 1500kbit goes without a hiccup with both vent and skype running at the same time.
What's your vbv buffer rate and your quality?
Also, what are your video card and processor?
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vbv buffer is a buffer (duh) for encoder before having to limit/raise momentary bitrate.
Example: 1000 kbps bitrate and 2000 kb vbv buffer means that encoder in xsplit has to maintain average bitrate of 1000 kbps during 2 seconds. Bitrate can be 15000 kbps in one frame but 2-second average has to be still 1000 kbps.
Low buffer makes bitrate more rigid and thus stream quality more uneven. In streaming conditions when bandwidth is limited, best quality is all the bandwith all the time (i.e. maximum possible bitrate and "0" or "no" vbv buffer) but most erratic then too.
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On September 29 2011 07:38 Cambam wrote:Show nested quote +On September 28 2011 19:34 ruXxar wrote:
Although this doesn't answer your question, I have a 2mbit upload aswell, and streaming at 1500kbit goes without a hiccup with both vent and skype running at the same time. What's your vbv buffer rate and your quality? Also, what are your video card and processor?
Buffer rate is 2800(double of VBV Max Bitrate)
Quality 10
i5 2500k
GTX570
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On September 28 2011 13:55 Cambam wrote:
Can anyone explain what the vbv buffer does and how changing it affects streaming?
Also, skype and/or ventrilo seem to lag my stream really badly (freezing every few seconds). I have a 2 mb upload internet, so I normally stream at 1500 max bitrate and 1500 or 3000 vbv buffer rate. But when I have skype or vent open, I can barely stream at 500 max bitrate. It doesn't seem like skype takes 1 mb of bandwidth. However, I just had some success by having vent open and streaming at 1000 max bitrate and 250 vbv buffer rate. The stream looked a little blocky, so I think I could do better.
Is there an optimal way to set this up? 1500 max bitrate, 100 vbv buffer? 750/750? 500/20000?
Also, what does the quality setting (1-10) affect? CPU, GPU and/or internet?
2 mb upload internet
Phenom II 940 cpu
So you can stream okay, when Skype or Vent isn't running?
When streaming and running Skype your need to lower it to 500 kbit/s?
When streaming and running Vent your need to lower it to 1000 kbit/s?
You haven't told us some very important figures which is needed to assess your setup: The desktop resolution, stream resolution and stream FPS, but using the bitrates you mentioned, I'm going to assume you stream in 720p at 25 or 30 FPS.
When I look at your specs, I'm going to say the problems stems from your CPU really isn't that powerful. Vent uses less resources than Skype, which explains the difference there.
Can you stream in 480p or lower while running Skype? Try it and report back 
Also, tell us the following settings: "location", "preset" plus your ingame FPS for each resolution tried.
Finally do note that the current XSplit seems to have a bug that might affect current performance (http://www.xsplit.com/forum/viewtopic.php?f=8&t=2280)
For more information about how and what the XSplit settings does, I really must direct you at the source of that information, being the XSplit website, ie. start here: http://www.xsplit.com/forum/viewtopic.php?f=2&t=1956
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Without skype or vent:
Desktop resolution: 1920x1200
xsplit stream resolution: 1280x800
xsplit framerate: 20 fps
xsplit Location: Default
xsplit preset: Xsplit Default (I live in Tallahassee, FL, should I change this?)
xsplit quality: 8
xsplit max bitrate: 1400-1500
xsplit vbv buffer: I haven't really decided what's best. I change it between 350, 700, 1400 & 2800. Lower values seem to have worse quality, but help with stream lag sometimes.
In game framerate: 20-50 fps.
So yeah, I already knew my processor sucked, but I didn't know that having skype or vent open could have such a drastic effect on stream lag (a seemingly bandwidth related parameter). I also didn't know that stream resolution was affected by CPU power, I thought it was mainly a GPU related thing.
So I guess my next question is how can optimize my stream for a crappy CPU with an awesome video card and ok upload speed?
Should I drop quality down from "8"? I don't know what things are CPU dependent.
Anyway, thanks for all the help guys. Sorry for using you as my "personal search engine" but google search for "xsplit vbv buffer" wasn't very helpful. I'm going to test lowering my streaming resolution now and I'll let you know how it turns out.
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Everything in xsplit should be CPU dependent and your CPU is decent. I would lower stream resolution for that bitrate,
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On September 30 2011 00:57 Cambam wrote:
Desktop resolution: 1920x1200
xsplit stream resolution: 1280x800
xsplit framerate: 20 fps
xsplit Location: Default
xsplit preset: Xsplit Default
xsplit quality: 8
xsplit max bitrate: 1400
xsplit vbv buffer: 700
In game framerate: 20-50 fps.
Weird. I just tested streaming with a skype call going with these settings and it was fine. Very smooth. The only difference from other times I've tried with skype is the buffer. Normally it's equal to or double the max bitrate. Either lowering the buffer to 700 fixed it or the other possibility is my internet upload bandwidth fluctuates with time of day. The other couple of times I've tested with skype were during "primetime" hours of like 7pm-10pm. Is this a possibility? And is there a way of testing this hypothesis? I have Comcast Cable internet 12 mb down/ 2 mb up.
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On September 30 2011 00:57 Cambam wrote:
xsplit framerate: 20 fps
xsplit Location: Default
xsplit quality: 8
xsplit max bitrate: 1400-1500
xsplit vbv buffer: I change it between 350, 700, 1400 & 2800.
I also didn't know that stream resolution was affected by CPU power, I thought it was mainly a GPU related thing.
I'm going to test lowering my streaming resolution now and I'll let you know how it turns out.
Ways to ease the stress of your CPU:
a) Lower your desktop resolution to ie. 1440x900 or 1280x800
b) Lower your stream resolution to 480p
c) OC the cpu.
Comments on your settings:
- 20 FPS is bad. On lower end CPUs there is a direct correlation between stream FPS and ingame FPS. The streams FPS literally caps the ingame FPS. I strongly suggest setting it to 30 for better ingame FPS *and* better viewer experience (20 FPS is noticeably lagging). I realize setting a higher FPS will put more stress on the CPU, but you'll need to compensate this in quality. No way around it imho. Low FPS is just worse than worse quality - for everyone.
- Location. Yes, do please experiment with other servers, as there seems to be congestion on different server at different times. Up until a week ago the choice "Main Origon Cluster" was the best, but look at this post for the latest info on 'location'.
- Quality. I would not go above 6 with your CPU
- Preset. Leave this a default (=veryfast)
- Max bitrate is fint! You need between 400 and 1600 for a 720p. But as I said above, if you've used a congested server for testing, you need to erase all results and start over.
- Buffer. This is an irrelevant setting for you. It only affects the viewer. See same post as above.
- The reason your desktop resolution matters is because there are more pixels in a 1920x1200 than in a 1440x900 frame, and when resizing (calculating) the frame to the stream resolution, CPU matters - simple as that.
- The test on 480p is still relevant - at least to determine that your cpu can handle that.
- Skype/Vent are not typically CPU heavy, you're right on that, but in your case your CPU is pretty much maxed out, and any resource stolen from the CPU by apps can/will affect the stream result.
All the above is what is supposed to happen - it's the logical reasoning behind XSplit and streaming. That said, I have heard of people adjusting their buffer size to suddenly be able to stream. There might be more going on in the back than we know/see .
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