play~ audio quality problems
Hi,
I've been using play~ to play back sounds loaded into a buffer~, and
have discovered that the sound quality seems to be a problem. The
playback sounds like it is being slightly ring-modulated, or that it is
showing the effects of a sample-rate mismatch. In any case, to test out
the problem, I tried playing the buffer back with wave~, and the issue
did not occur. I am driving play~ with a line~ object, and thought that
that might also be the problem, so I replaced the line~ with a phasor~
but the problem persisted.
The attached patch demonstrates the issue. Load a 1 minute stereo sample
in the buffer, and then turn on the DAC. Both play~ and wave~ will
playback simultaneously, but you can x-fade between the two to hear the
sound quality difference. Any insight as to why this might be happening
and what I could do to prevent it would be greatly appreciated. Many
thanks in advance.
Best,
Peter Traub
Apologies. It seems the binary file I attached may cause some problems.
Here is a text version.
Best,
Peter
Hi Peter,
I tried the patch you sent and couldn't reproduce the effect.
Sometimes with long sound files there is a problem with the bit depth
of the playback signal that results in playback degradation, but "ring
modulated" isn't really how I would describe the sound... anyway, you
could try Joshua's hi-res objects
(https://cycling74.com/twiki/bin/view/Share/JoshuaKitClayton) to see if
that fixes your problem. Otherwise the only thing I can suggest is to
make your one minute sound file available somewhere on the web so that
we can test that.
Ben
Hi Ben,
Yes, I suppose bit-depth degradation might be a better description of
the sound, and it does happen over time. In my actual application, I'm
using a 10 min. buffer and not the 1 min. one in my test file, so the
problem is even more accute. In any case, I've uploaded a 1 min. test
sound to the web that you can download and hear the issue with. It is at:
After about 15 seconds of playback in the test patch, try hard x-fading
between the play~ and wave~ output (i.e., listen fully to one and then
the other), and the difference between the two should become quite
audible. It becomes more audible over time. I will check out the hi-res
objects you suggest, but I'm curious why this problem exists with play~
in the first place and if there is some sort of workaround? Many thanks.
Best,
Peter
You might compare it with the different interpolation modes on wave~.
(try interp 0, 1, 2) Mode 2 is high quality, mode 1 is default, mode 0
is off. Sorry, not a solution, but might reveal what's going on.
Peter McCulloch
Hi Peter,
Upon reading the docs for the hi.res objects, it seems that it is a bit
resolution issue. I have replaced my core playback module, that used
line~, play~, and pong~ with the hi.res objects hr.line~, hr.play~, and
hr.wrap~. They appear to do the trick in both the test application I
posted to the list and my main application. However, they do appear to
incur the cost of higher CPU utilization, meaning my poly~ instrument
that uses these playback objects can't have as many instances of them.
Btw, I did try playing with the interp modes for wave~, but interp 0,
while giving noticeably diminished quality, did not give the same sort
of effect as I was hearing with play~. Many thanks.
Best,
Peter
If you use the phase related playback methods on longer sound files than
ca. 6 min 20 seconds you will run into that problem, and ist obvious,
dealing with higher resolution will need more CPU.
Most things you can do with play~ and wave~, you could also do with
groove~. As you just start the playback, and then the object runs on its
own, sample by sample. I guess redoing your approach with groove~'s
might save you the missing CPU cycles. You could use the groove~'s sync
outlet as you master if you need one. Though the resolution problem
would then arise there as well, but you might not need the high
resolution there. Depends on what you're doing...
Stefan
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Stefan Tiedje
Klanggestalter
Electronic Composition
&
Improvisation
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