On Thu, February 26, 2009 10:53 am, Mark Ruys wrote:
> Sometimes, when I mix two samples of different sampling rate, I notice
> that mixing fails:
> As a work around, I first downsample the 44 Khz sequence to 22 KHz, and
> then mixing works ok.
> Maybe you can take a look at it.
So did you produce the bottom track with Mix and Render to New Track (CTRL
+ SHIFT + M) with a project rate of 22050 Hz?
I can see what you mean from the zoomed in waveform (comparing 3.080 with
3.100), but I cannot reproduce a problem here with an arbitrary
experiment. If I create a DTMF tone at 44100 Hz and a music clip at 22050
Hz and render them twice to a new track, first with the music and DTMF at
their original sample rates, then with the DTMF resampled to 22050 Hz, the
two mixed tracks look identical even at high zoom levels. At high zoom it
does look "surprising" that the mixed waveform where DTMF and music
combines looks almost identical to that of the DTMF only, and barely
reaches any higher amplitude, but this (I think) may depend on the levels
of the tracks and what gain you were applying. In my case the DTMF was
loud and the music quiet, though with some gain applied. If I zoom out
horizontally to fit the tracks in the window, then both mixes look
perfectly correct (and sound so). Does the bottom track in your image look
wrong zoomed out, or sound wrong?
I have saved my experiment as an Audacity project and I'm forwarding this
to our developers' mailing list for any expert comment. If you believe
there is an issue and the first two tracks in your image mix "incorrectly"
when their sample rates differ, can you send them to me?