Audio Capture

SinisterSoft

A simple (cross platform) command to capture audio would be great - it would be a good addition to some games...

Eg: structure=CaptureAudio(time,quality)

ar2rsawseen

There is a microphone plugin for that:
https://github.com/gideros/Microphone

SinisterSoft

That should do nicely. Thanks!

SinisterSoft

It appears that if you start the library with a sample rate that is not supported then then application exits without warning.

eg: It exits if you start it with 11025 as the sample rate on a HTC Sensation XE.

ar2rsawseen

@SinisterSoft oh yes, but this is stated at the readme, that this value should be between 4000 and 44100.

It will of course be added to the docs also, after the official release.

atilim

I've tried to catch all the exceptions while opening the audio capture device. Are you sure it doesn't give a proper Lua error message when you try to capture with 11025 hz?

And what happens when you try to capture 44100 hz. Android docs states that: 44100Hz is currently the only rate that is guaranteed to work on all devices, but other rates such as 22050, 16000, and 11025 may work on some devices. I usually cannot understand Android's weird limitations.

I'll fix it (by always recording in 44100 hz and downsampling by software).

@ar2rsawseen 4000 < 11025 < 44100

SinisterSoft

That should work - shame you can't compress the file whilst downsampling. Or can you?

atilim

@SinisterSoft I'm planning to implement compressed audio recording.

SinisterSoft

Possibly a quick improvement: When downsampling check a flag to also convert to 8 bits rather than 16 bits?

Edit: Just re-read the docs - this flag is already there. If you do sample at 44k and downsample, can you also sample at 16 bits and downsample to 8 if needed?
- this way 8 bit sample settings should work on all Android phones.

atilim

Although I don't recommend 8-bits for recording , it's a good idea implementing your suggestion.

ar2rsawseen

@atilim ah, automatically added one zero there

SinisterSoft

@atilim Oops, missed this: "I've tried to catch all the exceptions while opening the audio capture device. Are you sure it doesn't give a proper Lua error message when you try to capture with 11025 hz?"

Yes, on HTC Sensation XE (beats audio version) it just exists without warning - no crash, nothing, it just exits immediately. Change it to 22k and it works, back and it exits, to 22k it works...

On my samsung S3 and other some other HTC phones I've tried it works fine though, no problem at all at 11025. The downsampling should fix this though when it's implemented.

atilim

Hi @SinisterSoft,

I've implemented downsampling on Android (both for sample rate and bits per sample). Now, on Android, the plugin always records with 44100 hz/16 bit and downsample it automatically. You can update the plugin here https://github.com/gideros/Microphone

SinisterSoft

Thanks for this, I'll get it tested over the weekend for you.

atilim

thank you