x264 cpu intensive options: In-Loop Vs. Cabac. Which Is More Efficient?

From a quality standpoint, which would be more efficient and why? In-Loop Deblocking or Cabac (Trellis 2 + all macroblock options)? Last night I did a crf encode at 22.0 with the cabac options first, then later did an encode with CAVLC with in-loop, and i've noticed the bitrate with cabac was smaller by roughly 33% but there was visible macroblocks (since i opted not to use in-loop for cpu purposes). Laters I did an encode at the same bitrate using cavlc & in-loop, and noticed it lacked as much detail as with cabac. My question is, if you could choose only one, which would you choose? Cabac + Trellis 2 + all macroblock options or CAVLC + In-Loop + All macroblock options except Adaptive DCT (which should only be used with CABAC) & I8x8? Also, is it just me, or does in-loop requires more cpu usage than cabac?

Note: CABAC is a lossless compression. It makes file ~15% smaller without any loss in quality. IMO you should use both, CABAC and In-Loop Deblocking, always! Why the heck do you want to disable one of them ???

huh? speed is cpu usage. All options that affect decoding speed, however minor: keyint (though only 1 vs >1. if it's a big number, 100 vs 200 doesn't matter.) bframes b-pyramid cabac ref deblock interlace bitrate (and all ratecontrol options insofar as they affect bitrate) partitions direct weightb 8x8dct fast-pskip (indirectly. it just changes the relative numbers of macroblock types.)

Thanks akupenguin, i'll see what kind of profiles I can generate using that information :)

only the first used B-frame is heavy @ decoding additional won't take much more decoding time anymore (1 ref) Code:

altough its not really new anymore, but still, for checking how specific encoding options affect decoding speeds in different decoders (yeah, different decoders are affected differently) look at the decoder comparison sticky

I would say have the normal features enabled (ie CABAC, in loop filter etc etc, you can have the settings quite good), then use a modern decoder. Note that as someone pointed out to me the deblocking occurs at both encoding and decoding, but if speed is a problem it can be disabled at the decoding stage, whilst still being on in the encoding stage without effecting the playback speed. This is the best way of doing it for quality as it seems the encoding deblocking is much more important (and more effective at deblocking then just at the decoder stage). The reason why you had blocking with CABAC and no filter is that the filter wasn't there to remove the blocks! The decoders seem to have improved significantly in the past year, ffdshow for example. Also with ffdshow you can set it to skip h.264 deblocking if there is a problem with playback speed. I use quite high settings (in terms of decoding performance): - Cabac (of course) - 16 b-frames (gives the encoder freedom. If 16 is never used then there's no loss, but at least if there's a situation where 10 is beneficial it can use 10)! - 6 reference frames (with mixed references). Stuff encoded with these setting can play back quite well even on older computers using ffdshow which automatically skips the deblocking as I said. If a trial encode doesn't work with those settings then try 3 b-frames and 3 reference frames. Don't change anything else. Now if you do disable CABAC to get the decoding performance like someone said you might as well use Xvid or something, because thats less CPU intensive to decode and using CAVLC etc negates any quality benefits that h.264 has over XVID file size wise in most cases. The latest builds of ffdshow are available from: There are still A LOT of old builds of ffdshow out there, and they can be slow for h.264!

That list is of features that are in x264, but not exposed in avidemux. Nonetheless, it's wrong: H.264 doesn't have 2x2 partitions.