Max Keyframe value for PAL?

[system]

Read this somewhere [can.t recall where]

".......If you are encoding a PAL movie, use a maximum of 250 keyframes. For NTSC use 300 frames (default)....."

Doom9's guide states that 300 is ok with 50% scene detection, no mention of PAL/NTSC, so is the above info legit? Thanks.

[zulu]

hi,
use the following rule of thumb:
max keyframe interval = fps*10

(pal = 25 fps, ntsc = 30 fps)

max keyframe interval is independent of scene change threshold.

[system]

thanks for clearing that up. I.ve encoded a few PAL films now using 5.0Pro and have left the key frame at 300. It does.nt seem to have effected the film, should it only have an effect on seeking and final file size?

[Acaila]

If the codec does it's work correctly you won't notice any difference with higher numbers. The only use of the max keyframe interval is to insert a keyframe after that many frames if the codec ommited it. As long as it's detecting every scene change correctly it won't use the maunal intervention.

[system]

got it, thanks.

[ppera2]

Too big max keyframe value will slowdown seeking by playback.