0

This seems like such a trivial problem but there is no answer anywhere. I'm trying to convert a 16bit song to 8bit so I can play it with a microcontroller. This creates a lot of noise. Every time I filter the noise in adobe audition, audacity and goldwave, it sounds great until I try to export it. The file saves on my computer then it was as though the filter has had zero effect on it. I'm pulling my hair out trying to make it work and it just won't. Does anyone know what is going on?

  • Can you post samples? Most likely the noise is a result of the downconversion itself. – AJ Henderson Feb 10 '14 at 4:33
  • Yes, the noise is from the down conversion. Do you know of a way to down convert to 8 bit 16khz without noise? – Artemis N Feb 10 '14 at 7:11
1

This is because Audition (and others) is using temporary 32-bit float files for destructive editing. That's why you can't hear the "real" 8-bit sound after you process converted files further. They are just not 8-bit at this time.

As for the quantization noise you are trying to remove, it's not possible. Though you can reduce its amount by enabling dithering and noise shaping. In Audition's "Convert Sample Rate" dialog try these settings:

Dithering: Enabled
Dither Type: Gaussian
Noise Shaping: Weighted (Heavy)
Adaptive Mode: Dynamic (Extreme)

| improve this answer | |
  • Your recommendation does work.It reduces the noise quite a bit. However,the microcontroller can not read higher than 16khz and audition will not allow noise shaping under 32khz.Why is it impossible to filter out this noise?This particular song that I have can be easily filtered with a low pass filter around 1400hz.There has to be a way to make it sound ok.Otherwise there would be so many forum posts about it online.This is one of the only ways to play a song from an sd card using an arduino.Do you know of another way to turn a 16bit song into an 8bit 16khz one that won't produce so much noise? – Artemis N Feb 10 '14 at 7:10
  • By lowering the bit depth, you reduce the dynamic range of a signal. The smaller the dynamic range, the louder the quantization noise. This is unavoidable and absolutely normal. Techniques like dithering and noise shaping don't remove noise, they just help mask it using psychoacoustic algorithms, shifting the noise higher to less audible frequency range. That's why noise shaping won't work below a certain frequency. In short, in this imperfect world there's just no way you can make 8-bit audio sound as good as 16-bit, sorry. – Denis Druzhinin Feb 10 '14 at 9:45
  • Do you know how I can find songs that are already in 8bits? Every time I try to google it, 8bits come up a lot but they're always 16bit 44khz songs in 8bit style. – Artemis N Feb 10 '14 at 18:39
  • Just any audio files in 8-bit resolution or modern music distributed in this format or maybe authentic 8-bit chiptunes? I have a strong feeling there's some misconception in here. 8-bit format is obsolete, it's from floppy disk era. It reflects the audio hardware features and limitations of those days. To be good, 8-bit music for such hardware was written in a specific way using special software. Otherwise it sounded as bad as nowadays. If you're looking for 8-bit chiptune music, it usually comes in tracker formats (.mod, .ahx, .xm) which your microcontroller may not read. – Denis Druzhinin Feb 11 '14 at 3:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.