Resampler seems to be working but quality is unusable.

[70gto]

Trying to resample a 44100 mono s16 PCM file down to 8000.
The output file size is correct but has bad quality.
Any ideas?

See files attached in resampler.zip:
resampler.cpp - Console app written C which uses Miniaudio.
resampler.jpg - Audacity screenshot showing input file (top) vs resampled file.

resampler.zip

[mackron]

I haven't looked at your code yet, but are you aware that the reampler is just a simple linear resampler? Are you getting clicking noises or anything?

[70gto]

Yes, but wasn't sure what to expect. Not sure if there is a bug/issue, just not using the library correctly or the output is normal.

[mackron]

I had a look at your code. Open your file with "wb" instead of "w".

There's some other robustness issues with your code. In particular, if you were upsampling (going from 8000 to 44100, for example), the way you handle your input frame count is incorrect so you'll probably want to adjust that logic. There are cases where the resampler will not process the entire input buffer so you'll want to be careful about how you manage your input data. I think you might already know this just based on your comments, but just thought I'd mention it just in case.

Also, a bit of a side note, but I noticed when testing this that when the sample rates are the same (i.e. no resampling is actually happening), it'll produce bad output. This error is with miniaudio and I've pushed a fix to the dev branch. This is a separate issue though and only happens when the rates are the same.

[70gto]

Thanks for the help. It now works better than expected. The "w" vs "wb" was a copy mistake.
This app is currently written to just downsample. As you mentioned it would need changes to upsample as well.

[70gto]

With the resampler working well I moved on to the data converter to do channel conv., data format, and resampling in one shot. The converter is setup to do just resampling (only the in/out sampling rates are different). When I compare the outputs (with audacity) of the resampler and the converter there is an obvious difference. The converter output sounds worse and has an artifact at the end of it. I would expect them to sound the same.

Trying to resample a 44100 mono s16 PCM file down to 8000.
The output file size is correct. Any ideas?

See files attached in converter.zip:

resampler.cpp - Console app written C which uses Miniaudio.
converter.cpp - Console app written C which uses Miniaudio.
audacity.jpg - Audacity screenshot showing converter output file (top) vs resampler output file.
converter_casio_M.pcm_out - Converter output file
resampler_casio_M.pcm_out - Resampler output file

converter.zip

[mackron]

Just looking at the code now, it looks like the data converter is not setting the LPF order to the same value as the resampler by default. I'm not entirely sure why that's the case, but it might be an oversight. Something for me to look at. In any case, maybe try adding this to your data converter config:

config.resampling.linear.lpfOrder = MA_DEFAULT_RESAMPLER_LPF_ORDER;

[70gto]

I added the above code you suggested and it worked. Thank you.

[mackron]

I've updated the dev-0.12 branch so that the data converter uses the same defaults as the resamplers defaults.