x264 Constant Bitrate

[mflopez]

(Constant Bitrate) qcomp=0.1 ratetol=1.0 works fine in 0.8.6i

Identical parameters does not work in Vlc 1.x.x

I've tried almost anything.....vbv-maxrate.....qpmax.....qpstep....but nothing happens with the bitrate....always variable in 1.x.x

¿Does anybody know the parameters for CBR with VLC 1.x.x?

[Lotesdelere]

IIRC:

Set qpmin to 1 and qpmax to 100
Set qcomp to 0.0
Set ratetol to 0.1 (0.0 is not a valid value)
Set vbv-maxrate equal to the desired bitrate (bandwidth)
Set vbv-bufsize as large as possible to prevent VBV underflows, but the streaming client must use the same buffer size. 1000 may be a good value if you don't know what the media player is using and assuming that you're going to use a lower bitrate than 1000, say 500

Notice that QPmax=100 is actually a bug in x264, which should be fixed soon, since the maximum value is 51 by design.

[mflopez]

Ok, thank you (according to the help of vlc 1.0.3, I use qpmax=51), those parameters work well as CBR.

[yuer1108]

mflopez：
could you post all your setting? and tell us the output bps range. thanks.
when I use 086 with qcomp 0 and ratetol 0.1. the bit rate still is choppy.
and 1.X result is worse then 086.
for example: 086 set 2000 K bps the output from 1900K to 2400K
1.x set 2000K bps the output: from 900K to 2600K

[ILEoo]

You shouldn't really fiddle with qcomp in 1.x series if you want cbr, you should be fine just setting bitrate

[yuer1108]

I just follow 2 floor indication: set qcomp = 0 and ratetol = 0.1
again, qcomp = 0 mean CBR in vlc-help.txt. {from 0.0 (CBR) to 1.0 (QCP)}
who can tell me the CBR result? how big +/- % of expected bit rate?