[FFmpeg-trac] #3651(avcodec:open): UT Video Codec is inefficient compared to libutvideo

FFmpeg trac at avcodec.org
Sun May 25 16:18:46 CEST 2014

#3651: UT Video Codec is inefficient compared to libutvideo
             Reporter:  Zerowalker   |                    Owner:
                 Type:  enhancement  |                   Status:  open
             Priority:  wish         |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  utvideo      |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |

Comment (by cehoyos):

 Replying to [comment:12 Zerowalker]:
 > Your UT Video Codec is faster cause of more threads, but slower on the
 same, meaning it has less efficiency overall (if i am not mistaken?)

 Isn't that what I wrote in comment:5?

 > Lagarith is slower cause of some issue, which i don't understand

 The original codec implementation uses floating point arithmetic which
 will fail on processors != x86 and might fail if you use another compiler.
 FFmpeg's implementation is fixed-point (which is what you expect for a
 lossless codec) meaning you can compile it for any hardware with any (non-
 broken) C compiler and you will always get correct (bitexact) output.
 Fixed-point arithmetic is often slower than floating-point on typical
 See also (for example):

Ticket URL: <https://trac.ffmpeg.org/ticket/3651#comment:13>
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