Question / Help Pixelated webcam + not so pixelated game capture

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soulreaver2662

Member
Hello,

I've been lurking on the forums soaking up all the information you guys have been giving to others and i've benefited enough from them to even teach others how to get started on streaming with OBS.

Sadly, i've come across a problem that i'm still stumped by no matter how much i try to search for a solution without having to post about it.

I'm currently using 0.473b test build 11 and no matter what settings i use, my webcam almost always gets pixelated in high motion scenes. I remember having this fuzzy issue before with my game captures on quality 10 and a low max bitrate, but ever since i started streaming at 2500kbps and above, my games stopped blurring out.

For some reason though, my webcam continues to pixelate 10 times worse than the game capture during high motion scenes and i don't understand why.

Specs:
i5 760 (or 750 i can't recall)
HD 7970
12gb DDR3 ram
Xbox live vision camera (which i believe is VGA)
Upload speed with ShaperProbe is around 4900kbps
If you need more accurate specs, i'll post a log as soon as i get home.

To cut an already long story short, here are the video links of me broadcasting on twitch with these OBS settings:

Max: 2750kbps
Buffer: 2750kbps
CBR: ON
AAC 128kbps

Native resolution: 1920 x 1080
Downscale: 1.5 @ 1280 x 720
FPS: 60

Multithreaded Optimaztions: ON
Priority class: Normal
x264 preset: Veryfast
Force audio video sync: OFF
Mic QPC timestamps: OFF

Webcam settings:

Resolution: 640 x 480 (further edited and resized in the scene settings)
FPS: 30
Auto white balancing: OFF (as recommended by a forum post)
Auto exposure: OFF (as recommended by a forum post)

Video 1:
http://www.twitch.tv/thetissueissues/b/376456553
Maybe somewhere along the 21 minute mark where i'm doing the boss fight, or most of the video where i'm jumping around and moving a lot, my webcam starts to really crap out.

Video 2:
http://www.twitch.tv/thetissueissues/b/376737910
I think at 14:50 when i go up against the big daddy, the webcam starts to fuzz up a bit and it does the same thing further along the vid when there's combat going on.

Video 3:
http://www.twitch.tv/thetissueissues/b/376402035
I'm quite sure that my webcam does not pixelate at all for the entirety of this video. Could be due to the game not having many high motion scenes.

Does anyone have any idea what's happening here? Am i not streaming at a high enough bitrate? Should my webcam be set to 320x240 since i'm downsizing it anyway?

I've tried setting my cam resolution to 320x240 at both 60 and 30fps but it seemed to be of even lower quality once i downsized it to that tiny box. I've also tried streaming at 3000 and even 3500 max bitrate but i had the same results. Webcam getting pixelated, game capture doing fine.

This is mind boggling for me because Blackhive came up with a guide and i think he has streams running at 720p 60fps using game capture as well. For example: http://www.twitch.tv/blackhive/b/376695101 and his game is fine, webcam is clear. Assuming he's running at 2500kbps or even 3000kbps with the same settings.

Any thoughts would be extremely appreciated.

Thank you and apologies for wall of text.
 
L

Lain

Forum Admin
Lain
Forum Moderator
Developer
hilal - I tested out those values, and using a buffer size 3 times the bitrate with VBR causes some pretty huge spikes (upwards of 6000kb/s in a single second) in high motion scenes, it could potentially cause frame drops and/or client lag. The bitrate for the overall stream itself does remain the same, but it's much more prone to bandwidth spikes. I usually would say that 2x is like the maximum that anyone should ever take it, but anything over 1x still has that risk.

CBR should be fine, though feel free to try VBR as well. The entire scene in general can take a hit if there's a lot of motion in another part, so that's probably what's going on (as far as I can tell). If you have more bitrate to spare, try using some more if possible. You can also experiment with the buffer size if you really want, but just keep the above in mind.
 
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hilalpro

Member
using a buffer size 3 times the bitrate with VBR causes some pretty huge spikes (upwards of 6000kb/s in a single second) in high motion scenes
Click to expand...

yes, if the encoder tries to stick close to around the same less moving scene quantizer for too long because of how big the bufsize is it will not only cause a bandwith spike but also will result in it using a slightly more overall bitrate (because of how the quantizer have to progress). but that's not necessarily bad if the uploader has the quality bandwith to send stuff out.

it could potentially cause frame drops and/or client lag.
Click to expand...
yes i agree. most of the time this will happen if you've exceed your guaranteed bandwidth. but about the client lag no sir. the "up to 3 second" bufsize when assuming that there is not much underflow is beneficial for the viewer. from my experience and alot of viewers will tell you this. i've seen the difference in alot of 60 fps streams especially high action ones. the flash player will request about 3second's buffer length that is also known around here as "twitch buffering side". the viewer basically can have up to and sometimes more than just 3seconds to compensate for any yet unacknowledged data whereas if you request 3 you can only have for each one up to 1 second + a short decode time then you have to wait for the next one to get acknowledged . that and latency is also not in favor of the shorter buffer if you have to request the next buffer if the server doesn't sent/delay for some reason.

note that all the receiving buffers comes in huge spikes .
i wouldn't go against cbr here. you just have to use alot of bitrate to make that work as nice for action games. spikes can be a real problem for some type connections. but time is just the biggest factor when it comes to lag.
 
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soulreaver2662

Member
thank you guys for the help so far.
i tried out hilalpro's method of increasing buffer size. i asked a friend to watch my stream as i did these tests. he doesn't have a lot of download bandwidth so it was a good gauge of where i should set my bitrate at.

so this guy usually can't watch my streams at 3000:3000, he'd always complain about a jerky stream. but when i tried 3400:10000 Quality 9, he said the stream only jerked twice and he was able to watch it quite well.

the problem was that my webcam still got pixelated anyway. i even tried a bitrate of 4000 and it would still get pixelated whenever i stood next to a waterfall or NPCs that moved a lot.

i then tried to output to file instead of live streaming, and upon playback of the file, i realized that my webcam was also pixelating during high motion scenes. does this mean anything? i thought it was supposed to be a network issue.
 
Xphome

Xphome

Member
soulreaver2662 said:
i then tried to output to file instead of live streaming, and upon playback of the file, i realized that my webcam was also pixelating during high motion scenes. does this mean anything? i thought it was supposed to be a network issue.
Click to expand...

It's a bitrate issue, increase the bitrate and try again.
 
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