Linux – x264 encoding speed, what should the expectations be

conversionffmpeglinuxvideox264

I am running Ubuntu 10.10 (maverick) on an HP Pavillion dv3 with core2duo 2.29 GHz, NVidia Geforce G105M (512MB) with CUDA and 4GB RAM. I have the latest versions of ffmpeg and x264.

I recognise that these aren't fantastic specs for encoding, but I am used to encoding with DIVX on a (different) single core PC with approx 2GHz processor, and being able to convert 10+ hour-long TV episodes overnight.

I have just started encoding with x264 and ffmpeg on the above HP laptop, and I was astounded to find a single 2 hr film taking 22 hrs to encode!

The command-Line I used was:

ffmpeg -i infile.mpg -vcodec libx264 -preset slow -profile normal -crf 24 -threads 0 outfile.mp4

Is this normal or do I have a bottleneck somewhere?

Thanks

Best Answer

Well, it's only a Core 2 Duo. The i7 would perform way better of course. Having CUDA doesn't help unfortunately, since x264 doesn't have GPU support. Also, encoding h.264 is computationally way more intensive than "just" into MPEG-4 Visual DivX.

That being said, x264 is a pretty fast encoder, and here's the thing. You see the -preset slow? You're actually telling the encoder to be slow.

Presets in x264 enable different algorithmic optimizations that yield better quality for the same amount of bits spent, or, less bits spent for a fixed quality. Thus: compression efficiency. Generally, the slower the preset is, the better the optimizations will be, but the more computation time they take.

You can choose other presets, as outlined in x264 --fullhelp, such as:

ultrafast
superfast
veryfast
faster
fast
medium (default)
slow
slower
veryslow

Pick the one that suits best, i.e. the one you can afford waiting for.

Related Solutions

Ny way to distribute x264 encoding jobs across multiple computers (to increase the encoding speed)

You could render separate chunks of the video, and use VirtualDub to stitch it all together with its Copy mode (where it does no encoding). It's not real distributed encoding or anything, but simplest solutions sometimes work the best.

FFmpeg x264 Tune – Detailed Explanation

This is what the modes do:

film – intended for high-bitrate/high-quality movie content. Lower deblocking is used here.
animation – intended for cartoons, etc., where deblocking is boosted to compensate for larger, flat areas. More reference frames are used.
grain – this should be used for material that is already grainy. Here, the grain won't be filtered out as much.
stillimage – like the name says, it optimizes for still image encoding by lowering the deblocking filter.
psnr and ssim – these are debugging modes to optimize for good PSNR and SSIM values only. Better metrics don't necessarily mean better quality though.
fastdecode – disables CABAC and the in-loop deblocking filter to allow for faster decoding on devices with lower computational power.
zerolatency – optimization for fast encoding and low latency streaming

You can see the detailed options applied with each tune with x264 --fullhelp:

--tune <string>         Tune the settings for a particular type of source
                          or situation
                              Overridden by user settings.
                              Multiple tunings are separated by commas.
                              Only one psy tuning can be used at a time.
                              - film (psy tuning):
                                --deblock -1:-1 --psy-rd <unset>:0.15
                              - animation (psy tuning):
                                --bframes {+2} --deblock 1:1
                                --psy-rd 0.4:<unset> --aq-strength 0.6
                                --ref {Double if >1 else 1}
                              - grain (psy tuning):
                                --aq-strength 0.5 --no-dct-decimate
                                --deadzone-inter 6 --deadzone-intra 6
                                --deblock -2:-2 --ipratio 1.1 
                                --pbratio 1.1 --psy-rd <unset>:0.25
                                --qcomp 0.8
                              - stillimage (psy tuning):
                                --aq-strength 1.2 --deblock -3:-3
                                --psy-rd 2.0:0.7
                              - psnr (psy tuning):
                                --aq-mode 0 --no-psy
                              - ssim (psy tuning):
                                --aq-mode 2 --no-psy
                              - fastdecode:
                                --no-cabac --no-deblock --no-weightb
                                --weightp 0
                              - zerolatency:
                                --bframes 0 --force-cfr --no-mbtree
                                --sync-lookahead 0 --sliced-threads
                                --rc-lookahead 0

Best Answer

Related Solutions

Ny way to distribute x264 encoding jobs across multiple computers (to increase the encoding speed)

FFmpeg x264 Tune – Detailed Explanation

Related Question