2x pitchshifting?

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picothinker
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I have been approached by a friend, that wants to rescue old 4-track cassette tapes. That's a pretty straightforward issue normally, just record 4 tracks in Ardour, mix as desired and export.

The problem will be, is that he does not have a similar 4-track as they were recorded on. They were recorded on a 1x speed machine, and all he has to play it on is a 2x machine. Aside from the unavoidable tape head alignment problems, what is the best way to do this?

One obvious thing that comes to mind is to set Jack for 88.1 khz to record it, and 44.1 khz on playback. The audio hardware is a Delta 66. Is there an easier way? Ecasound has good multitrack capabilities, and has a Jack plugin but I am more familiar with Ardour.

I guess it's better to be running the tape doublespeed, instead of half-speed and trying to speed it up, fidelity-wise.

thorgal
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just record each track into a wav file, open say audacity, import each file (you end up with 4 tracks), change the sample rate as desired for each of them (hopefully, they will align correctly in time and pitch with only one setting), correct for time alignment if needed, mix down, export.

Ardour is probably one of the greatest audio tools out there but for that kind of work, "minor" apps (or shall I say "pico" apps ? ;) can perfectly do the job.

lokki
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actually, as for my knowledge, it is better to run half-speed, because you will get more "data" from the tape-head. if you record in double-speed and then adjust it on the computer to halfspeed (the actual speed you want), you will loose quality because you stretch the soundfile and the information stored in it remains the same. if you record in half-speed and then adjust on the computer to double-speed (again the speed you want) you will have much better quality because you have more data per second stored in the soundfile...

picothinker
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And of course I meant 88.2 above. Thanks for the tips. I haven't used Audacity much, I assume you can record four tracks at the same time. I think I would rather do the actual pitch-shifting by manipulating the sample rate, than depend on any plugin.

I am locked into the concept of playing it 2x and slowing it down, because that's what we have available. In the bad old days of tape, faster was better while mastering because you had more storage per second. I'm not sure if that relates to playing something twice as fast. I guess I will find out!

lokki
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ok, i didn't read your post carefully...sorry

all you have is a tape machine that does 2x speed, right? so then your only option is to slow it down after recording... but quality-wise it would be better to do it halfspeed and then speed it up, for the same reason as you said, more storage per second (but on the computer-side this time)