The VideoLAN Forums

Can anyone tell me what is the significance on x264 quality if the value of param->rc.i_lookahead is changed from 40 to 0??
or what is the effect of this change on x264?

http://mewiki.project357.com/wiki/X264_ ... -lookahead

rc-lookahead
Default: 40

Sets the number of frames to use for mb-tree ratecontrol and vbv-lookahead. The maximum allowed value is 250.

For the mb-tree portion of this, increasing the frame count generates better results but is also slower. The maximum buffer value used by mb-tree is the MIN( rc-lookahead, keyint )

For the vbv-lookahead portion of this, increasing the frame count generates better stability and accuracy when using vbv. The maximum value used by vbv-lookahead is:
MIN(rc-lookahead, MAX(keyint, MAX(vbv-maxrate, bitrate) / vbv-bufsize * fps))

On a sidenote, the higher the value of rc-lookahead the higher the use of RAM so be carefull especially with systems running 2 GB of RAM.

Hi I have one more question on x264..does it support slices in a frame?
Please note I am not talking about threads.

Yes it does support slices if you use enough new version of x264