Why VC-1 encoding so slow(comparing to H264 encoding)?

Why VC-1 encoding so slow(comparing to H264 encoding)?


I use the latest Linux version ipp sample, the VC-1 encoding speed is too slow: 8.3fps under 720*576. But the same umc_video_enc_con program doing H264 encoding at 50 fps. Hardware is same(a double Quad-core Xeon). I tried different setting but did not make any difference. And I noticed that during encoding the CPU was near full. Anything wrong? How to improve?

Thanks in advance.


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Hi Peter,

What is your exact command when you run the VC-1 and H264 encoder?

As your hardware isdouble 4-core xeon, I doubt the threading is on in H.264 encoder, where VC-1 is not threaded, so you see the big difference on fps.

If you are running umc_video_enc_con, you may set-t 1- number of threads for encoding or export OMP_THREADS_NUM=1 and see if any changeifboth encoderrun in serial.(same starting line :)).

Best Regards,



The command line is:

LD_LIBRARY_PATH=/opt/intel/ipp/ ./umc_video_enc_con vc1 -t 8 vc1.par /tmp/a.vc1

The problem is, the speed does not change between "-t 1" and "-t 8". From 'top' command, I can see that almost all CPU cores are busy during encoding even when "-t 1" (722% cpu):


11138 peter 20 0 67748 15m 4156 R 722 0.5 0:40.27 umc_video_enc_c

Could you please help to use the umc_video_enc_con to do a comparation of H264 and VC1 encoding under linux?

Thanks a lot.



This is an interesting issue, the performance of the VC1 encoder (UMC implementation) seems to be quite lengthy, while the H.264 (UMC implementation) produces much more efficient results.

Basically, VC1 encoding algorithm complexity is expected to be similar to H.264 complexity.

This is not about the Linux version of ipp, the same experience appears on windows as well.

Here is another thread with similar extended discussion Problem in varying bit rate in Simple player (http://software.intel.com/en-us/forums/showthread.php?t=71023)



Looks like the VC-1 encoder has fundametal problems like performance and bitrate control. Any update on this, Intel experts?


I agree the VC-1 encoder could use some performance improvements. Despite all the SSE primitives, it's getting smoked by the Microsoft WMV9 encoder, even when the latter is set to maximum complexity/quality. Perhaps it's just a matter of better documenting the VC-1 encoder parameters to make it easier to achieve maximum performance while maintaining good quality.

I tried setting the MESearchSpeed to max 127, the speed is better but still far from H264. Anyelse I can tune to get better?

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