tests performed doing basic resampling functions on an Akai MPC 2000 XL
The MPC 2000XL has a resampling / bit reduction algorithm built in to process your samples. This is not a real time process (just wait). Following is a collection of sound files, generated digitally, transferred to the sampler via flash card, then processed in different ways using the internal resampling and bit reduction algorithms at different settings.
Original sounds
Drum Loop 1 - Acoustic drum loop generated in Logic
Drum Loop 2 - 808 drum loop generated in Logic
Piano Loop - Electric piano loop generated in Logic (used occasionaly)
Sweep - Log Sine Sweep 20-20kHZ generated in Audacity
All files are 16 bit, 44.1kHZ sound files. The musical loops are the same BPM. The Piano loop
is twice as long as the drum loops.
The goal was to try to find a correlation between file size and processing time, and hear
the effect of the processing on different kinds of material.
16bit 44.1kHZ -> 16bit 11025HZ - Low Quality
Time to process a 4 second wave: 1:53 (28.25 x the original length of the sample)
Drum Loop 1
Drum Loop 2
Piano Loop
Sweep
16bit 44.1kHZ -> 16bit 11025HZ - High Quality
Time to process a 4 second wave: 8:44 (131 x the original length of the sample)
Drum Loop 1
Drum Loop 2
Sweep
16bit 44.1kHZ -> 8bit 44.1kHZ - Low Quality
Time to process a 4 second wave: 3:18 (49.5 x the original length of the sample)
Drum Loop 1
Drum Loop 2
Sweep
16bit 44.1kHZ -> 8bit 44.1kHZ - High Quality
Time to process a 4 second wave: 12:09 (182.25 x the original length of the sample)
Drum Loop 1
Drum Loop 2
Sweep
16bit 44.1kHZ -> 8bit 11025HZ - Low Quality
Time to process a 4 second wave: 1:53 (28.25 x the original length of the sample)
Drum Loop 1
Drum Loop 2
Piano Loop
Sweep
16bit 44.1kHZ -> 8bit 11025HZ - High Quality
Time to process a 4 second wave: 8:44 (131 x the original length of the sample)
Drum Loop 1
Drum Loop 2
8bit 44.1kHZ -> 8bit 11025HZ - Low Quality
Time to process a 4 second wave: 1:34 (23.5 x the original length of the sample)
Drum Loop 1
Drum Loop 2
8bit 44.1kHZ -> 8bit 11025HZ - High Quality
Time to process a 4 second wave: 6:58 (104.5 x the original length of the sample)
Drum Loop 1
16bit 44.1kHZ -> 12bit 13333HZ - Low Quality
Time to process a 4 second wave: 3:33 (53.25 x the original length of the sample)
Drum Loop 2
Piano Loop
Sweep
Ruminations
- Waiting 12 minutes just to reduce the bit depth of a 4 second file is insane.
- Also, why does the same file only take 8 minutes to reduce the bit depth and the sample rate at the same time?
- Reducing sample rate to some non-standard value (ie 13.3kHZ) has the most effect on the sound, I imagine
because there is no anti-aliasing filter built for non-standard frequency values.
- Why does it take so long to reduce sample rate anyway? That is very similar to what the machine is doing
when you play a sample an octave down, which it can do in real time.
- I will not use my MPC for resampling/bitcrushing.