Audio chunk size

[Knosys6]

Hi there,

Reading the configuration file explanations regarding audio i see this: "See documentation for recommended values for various Raspberry Pi models". And "Values: 2-2048 (256*)".

I cannot find the documentation anywhere, what would be the recommended chunk size for the Pi3? I was on the 256 and also tried 1024.

I'm using i2c innomaker dac, which is working on both 44.1k and 88.2k sample rates. In the FAQ it says it only works at 44.1k.

Thanks again for this amazing project!
Alfonso

[dwhinham]

I will remove that line from the config file; originally the plan was to exhaustively test different chunk sizes, see if it could be fine tuned for different models and document it. In the end it wasn't really worth it.

The recommended chunk size is the default, though as a rule of thumb, if you double the sample rate, you should double the chunk size, otherwise the Pi may not be able to handle it.

The innomaker DAC information simply suggests 44100, it does not say "only works at 44100". The information there was a user contribution from @alexras, who reported "sampling artifacts" (#215 (reply in thread)) at the default sample rate, which is 48000. Have you tried that?

I cannot independently verify settings for DACs that I do not own. If it works for you at other sample rates, then that's great, and I would encourage you to help improve the wiki.

Cheers,
-Dale

[Knosys6]

Thanks for you reply, just updated the wiki, tested at 44.1k, 48k, 88.2k and 96k. Higher than that it doesn't seem to work as I can only hear "bip" sounds.

No issues or atifacts at any of those sampling rates. The soundfont samples I tested were recorded at 48k.

Thanks

[dwhinham]

Thanks for confirmation and the wiki edit!

I've removed the recommended 44100 setting as it should be fine out-of-the-box at 48000 according to your test, and re-worded the comments slightly to clarify.

Cheers