x264 live streaming parameter suggestions

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sean_malice
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x264 live streaming parameter suggestions

Postby sean_malice » 19 Feb 2008 14:28

As the title says, i'm streaming live h264 on a windows machine.
The problem is the bitrate keeps skipping way beyond my network upload capabilities (typically <1mbps DSL upload).
What parameters would you suggest to prevent this from happening while still maintaining best possible quality ?
I know most modern codecs rely heavily on VBR for quality. Some developpers don't even want to hear about
CBR anymore.
I heard about the qcomp=0 parameter within x264. I tried the various options suggested by people all over the forum. So far, i ended up with this :

:sout=#transcode{vcodec=h264,venc=x264{vbv-maxrate=512,qcomp=0,ratetol=0}vb=512,scale=1,acodec=mp4a,ab=64,channels=2}:duplicate{dst=std{access=file,mux=ts,dst="C:\Documents and Settings\Admin\Desktop\test5.ts"}

I input these in the "flux" field of the GUI. This should give me precise control other the desired bitrate. Well it doesn't.

When checking the bitrate during playback, the max bitrate is still sometimes twice as high as the desired bitrate.
(500kbps streams peaks at 900kbps, 700kbps at 1400...)

Any help would be REALLY apreciated.
I know many people are interested in this as well.

solelunauno
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Re: x264 live streaming parameter suggestions

Postby solelunauno » 05 Apr 2008 15:51

with the x264 encoder you have to specify first a preferred bitrate of at least 1/2 the target bitrate you want, for example: "vcodec=h264,vb=250" and after you can specify the max bitrate in vlc's preferences for x264 encoder (ex 500).
So you give to the encoder the ability to reduce bitrate peaks.
If you want more quality, I suggest you to reduce the scaling size of the movie (ex: scale=0.7) and operate some modifications in motion estimation in x264 preferences.


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