Hi. So a while ago I suddenly been having this issue where when I save a .Wav as an unassigned 8 bit PCM, some weird noise gets added to the file. Anyone know why is is happening suddenly, I have attached an audio recording with the sound.
At 8-bits you can hear [u]Quantization Noise[/u] which sounds like “fuzz” riding of top of the signal.
At 16-bits the quantization noise is below -90dB and inaudible under normal listening conditions.
Like regular analog noise, quantization noise is most noticeable with quiet sounds. But unlike analog noise it goes away completely with digital silence.
Audacity also has [u]Dither[/u] which I think is turned-on by default. Dither is added noise which is supposed to sound better than raw quantization noise.
I have Dither set to none. Is there a specific setting I should set it to?
8 bits per sample is not enough for good audio quality in uncompressed PCM. If you want better quality but need to keep the file size small, use a compressed format such as MP3 or OGG.
The thing is, what I am working on requires it to be unassigned 8 bit PCM for the project I am working on.
Then you have to accept that the sound quality will be quite poor.
The reason that audio CDs use 16 bits per sample is that 16 bits is just enough for audiophile quality audio (though some audiophiles claim that even 16-bits is not enough).
UPDATE: I tried another audio program with the same settings and it doesn’t have that noise.
Weird. I tried the same settings on another audio program called Goldwave and it didn’t have that noise. I just find it weird that Audacity is suddenly doing this even though it never did before.
Is Goldwave using dither?
Dither can make the sound subjectively better, though the downside is that for low bit formats (a small number of bits per sample), the dither noise will be noticeable in silences.
I think so. But it seems to be supported for mp3 files from what the text implies. I do see something involving triangular dither for 8 bit conversions. But that is disabled.
Please try this:
- Find a short bit of audio (just a few seconds) that produces this issue in Audacity.
- Select those few seconds (no more than 5 seconds), and export as “WAV, 32-bit float” - name this “original.wav”.
- Close and restart Audacity
- Import “original.wav”.
- Export as “Audacity8.wav” as an unsigned 8-bit WAV file.
- Open Goldwave
- Import “original.wav”
- Export as “Goldwave8.wav” as an unsigned 8-bit WAV file.
- Reply to this post and attach the 3 files: “original.wav”, “Audacity8.wav”, “Goldwave8.wav”.
Thanks.
The difference is that the Audacity8.wav file is using shaped dither, and the Goldwave8.wav file is using no dither.
Note that in the Audacity Preference settings, it is the “High Quality Conversion” settings that affect exports.
I am a long-time GoldWave user… Overall it’s a good program, stable and mature. And although it’s not free, upgrades are free (if you buy the $50 lifetime license) so the yearly cost has been almost nothing. Audacity has more features (and I think more built-in effects) but GoldWave also has a few features that Audacity doesn’t have.
I think so. But it seems to be supported for mp3 files from what the text implies.
The user manual is a little confusing, but no. dither is not applied to MP3, and it shouldn’t be since MP3 uses floating-point and MP3 doesn’t store individual samples so it doesn’t have a “bit depth”.
But that is disabled
Weird… That should be the same as disabling dither in Audacity.
Interesting. So I am guessing changing dither to none won’t change anything?
Yeah it is weird. I am Thinking a setting might be stuck.
Turning off dither in Audacity gives me the same sound as the Goldwave example.
When you said that you had turned off dither in Audacity, it appears that you haven’t - perhaps you turned it off in the “Real-time Conversion” settings but not in the “High-quality Conversion” settings.
The “Real-time Conversion” settings has dither set to “None” by default. This affects playback only.
The “High-quality Conversion” settings has dither set to “Shaped” by default. This affects exporting and mixing to a lower bit-depth.
Ref: https://manual.audacityteam.org/man/quality_preferences.html
You are right. My eyes mixed up “Real-time Conversion” and “High-quality Conversion”. This time I disabled dither in the “High-quality Conversion” section. I also did the process again (with a new recording) just in case but this time dither is set to none in “High-quality Conversion”. If you want I can make a recording in Audacity and a separate recording in Goldwave as well.
Also, I am attaching pictures of the settings I have in Audacity and Goldwave if it helps.
Do you agree that Original.wav, Audacity8.wav and Goldwave8.wav sound identical?
I don’t think that’s necessary, as we have now established that the “weird noise added” is “dither”, and it can be turned on or off in Audacity,