#35 audio split with clicks and rubberband time stretching strange behavior

svn_trunk
closed
nobody
None
2013-05-06
2013-01-20
Alex Chernyshoff
No
0 up votes | 0 down votes | 0%
23 comments

I do not know how to describe the problems exactly, but I'll try. (I apologize for my English)

  1. When you split a sound clip into parts - the next time you play, in some joints can be heard audibly click, which should not be. The situation depends more on the location in which the splitting was than the time and other factors. In the system there is no xruns. When playing material recorded without splitting sound is excellent.
    Clicks occur in a regular manner. Where they are - they are always the same every time you play.

  2. The "time stretching" by SHIFT-dragging mode something is not working on audio clips.
    The problem manifests itself in the mode "rubberband".
    The point of it is that - when I split in a few places the clip, and try to adjust the rhythm (to correct vocal tempo inaccuracies) by moving the joints (through a "shift-dragging" by the edges) - instead of the expected change in the length, the content of the sound clip unimaginable way changing. Content of parts are jumps and changes its position in time quite differently than expected - in some unpredictable manner. It is hard to explain, but it sounds awful.
    I tried to change the recording mode - 24 bit signed, 32 floating, all uncompressed, but the result is the same.

My system: Arch Linux x86_64 updated to the present day, qtractor-0.5.6 from the official repository, and qtractor-0.5.7 from sources (perfoms the same manner).

Discussion

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  • About implicit fade-in fade-out, I understand. But, I think it is not very useful to do it always at the split point of the arbitrary clip, as almost always leads to a click.
    The attached project is the case. There pure sinusoid.
    So, when we split the clip (logically), at split point there is almost unavoidable click. Of course, if at the point of splitting the signal amplitude is close to zero, a click will be less audible.
    It would be nice to have some opportunity to do a default "no-fading-in-out" at the split point. If at any split point (there can be many in the original clip) will be some amount of fading at edges, time stretching the complex rhythmic pattern will be almost useless.
    I do not know how else to explain :)
    Well ... this is so, for example, in Reaper. When we just split the clip, at this point the sound does not change at all. There is no any fading, unless of course it is not done manually later:)

     
  • I do it, Disabled SSE, recompile. Move the tracks here and there, listen - nothing has changed. Light distortions exactly in the same points of stretched fragment.
    (Yes, everything happens in the WSOLA mode)

    P.S. The distortions are relatively small - some kind of glitches (not a click) at fixed places of clip, regarding value and size of stretching.
    I tried recompile with more safe CFLAGS, and nothing was changed.
    P.P.S. Something strange appear. In the file "./configure" option "--disable-sse" is missing, only "--enable-sse" is present. It is possible that yesterday's experiment with recompilation is not quite correct. Or maybe I'm wrong?

     
    Last edit: Alex Chernyshoff 2013-02-07
    • status: pending --> closed
     
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