ffmpeg … -c:a flac -exact_rice_parameters 1 -multi_dim_quant 1 …

I was encoding wav to flac.

  • With default options, the result was almost instant
    • At > 500x speed
  • Used -compression_level 12, finished in ~ 7 seconds
    • speed = 48.9x
  • Then I used multi_dim_quant
    • After ~ 10 minutes, I checked the speed to be ~ 0.02x. So thought it would take an hour or so. 1.30 seconds worth of audio was encoded
    • It’s been over 2 hours now.
      • Shows 1.46 seconds of audio encoded with current speed = 0.00017x

Considering running it in a VM, so I can “pause” it whenever I need to restart my computer.

Update:
size= 123KiB time=00:00:02.82 bitrate= 356.3kbits/s speed=4.68e-05x
It stopped trying to use layman notation.
I’ll need to restart soon-ish, but I’ll see how far this goes and if the 2.82 seconds of audio is even listenable.

  • xxce2AAb@feddit.dk
    13·
    1 month ago

    Or, and hear me out, you could maybe reevaluate whether you really need the very marginal compression improvements offered by multi dimensional quantization.

    • ulterno@programming.devOPEnglish
      3·
      1 month ago

      Maybe it balloons RAM usage enough to trigger swapping?

      Well, my RAM usage doesn’t seem to have increased though (at least from this process).
      And I haven’t setup a swap.

      http://cue.tools/wiki/FLACCL

      Oh, it has a CUDA library!?
      Then this FFmpeg FLAC library is really basic, considering it has no parallelism. I was assuming that the algorithm itself is not parallelisable.

      • brucethemoose@lemmy.world
        6·
        1 month ago

        It’s OpenCL, so it should even run on integrated graphics.

        Yeah, it’s great! Extremely fast and marginally smaller than ffmpeg, last I checked, though I have not messed with those newer ffmpeg options. And cuetools has some other nice utilities anyway.

  • ulterno@programming.devOPEnglish
    2·
    1 month ago

    I realise I wasn’t able to make this look funny.

    BTW, the resultant bitrate from the same source file with:

    • default options : 706.8 kb/s
    • -compression_level 12 : 698.1 kb/s
    • with -exact_rice_parameters 1 -multi_dim_quant 1 that I am trying right now, it currently shows the bitrate to be 331.4 kb/s
      • but it’s only encoded the first 1.88 seconds yet, so no idea if it really will manage such an impressive compression.
    • solrize@lemmy.ml
      2·
      1 month ago

      I don’t see where the humor is, but I have an idle server so might let it run for a few days to compress a half minute of audio at .00017x. But are you sure it isn’t just stuck?

      • ulterno@programming.devOPEnglish
        1·
        1 month ago

        Well, the time value is definitely going forward, so I won’t expect that, but then a similar thing happens quite a bit with video stuff, so maybe you’re right.
        Similar, not same, because in that case, it starts showing speed=N/A

    • ulterno@programming.devOPEnglish
      2·
      1 month ago

      I am currently thinking that it might just be the problem with me having set too high parameters, but considering that mpv is unable to recognise the format even after 2 seconds of audio, perhaps there is some bug.