analog input 88200 Hz (88.2 kHz, 2 channels) broken

[claudeha]

I am trying to do some experiments with ultrasound. I found that analog input 2 channels at 88200 was reporting the same block size as the audio at 44100, and analogRead() was returning 0 for the second half of the expected block size:

printf("%d @ %f | %d / %d @ %f\n", context->audioFrames, double(context->audioSampleRate), context->analogInChannels, context->analogFrames, double(context->analogSampleRate));

in setup() was printing

64 @ 44100.000000 | 2 / 64 @ 88200.000000

which is obviously inconsistent.

I made a small change to core/RTAudio.cpp and am now getting much more sensible behaviour:

root@bela:~/Bela# cat -n core/RTAudio.cpp | grep -C3 Claude
   677			gContext.analogInChannels = std::min((int)cfg.analogInChannels, settings->numAnalogInChannels);
   678			unsigned int numAnalogChannelsForSampleRate = gContext.analogInChannels;
   679			gContext.analogSampleRate = gContext.audioSampleRate * 4.0 / (float)numAnalogChannelsForSampleRate;
   680	//		// FIXME changed by Claude Heiland-Allen 2023-04-28
   681	//		gContext.analogFrames = gContext.audioFrames / (int)(gContext.audioSampleRate / gContext.analogSampleRate + 0.5f);
   682			gContext.analogFrames = gContext.audioFrames * gContext.analogSampleRate / gContext.audioSampleRate;
   683			gContext.audioExpanderEnabled = (settings->audioExpanderInputs & 0xFFFF) |

my setup() now prints

64 @ 44100.000000 | 2 / 128 @ 88200.000000

and the scopes look much more sensible.

(If you really want I could do a github pull request dance for your entertainment...)