wwp@yahoogroups.com:
Re: Question about looped Sound
Markus Altendorff 2005-Oct-03 11:47:00
Dan Heimsoth wrote:
> --- In #removed#, "christian stehle" <#removed#> wrote:
>>I've just uploaded a sound-mov to the WWP server and want to loop
> the
>>playback.
>>But everytime the sound starts from the beginning, there is a
> short
>>break - very annoying. Is there a way to make a smoothly looped
> sound
>>or is it a general Quicktime problem?
>
> I don't have an answer, in fact I was about to post the same
> question when I saw your post. Since there hasn't been any response
> yet I'd guess it's not possible, but if you've found some way to
> create a seamless loop soundtrack for QTVR I'd appreciate it if you
> could post the answer here. There is at least 1 other person
> interested.
Hi,
sorry, had no luck either. I've tried it with a test tone,
and there's always some popping or scratching noise between
each pass - doesn't matter if the loop is happening during
zero transition of the waveform, or any other place. It
seems to be less audible if the loop length is a multiple of
1/30th of a second (guess that's the internal timebase,
since Quicktime does its work in "frames" of data). Another
thing i noticed is that the "pop" varies between each loop,
so maybe CPU load or RAM buffer or DMA audio output
interrupts or any other kind of digital voodoo does factor
into that, too...
You *can* avoid that noise by fading out and fading in the
sound (even over very short periods of time - i tried it
with as little as 2/1000 of a second for fade-in fade-out),
but that will cause an audible "gap" - not very strong, and
if you're playing back ambient "technical" machine noise, it
may be more tolerable than cracks and pops...
-Markus