Newbie Questions

loop

Hi. I am new to the Bela platform and after reading through most the documentation there are still some questions.

Is the render callback always using floats? (IEEE 754 single-precision)
How much memory is available for delays / loopers?
How big is the audio latency? e.g copy audio from in to out without processing?
Does bela offer an low level dsp api? Maybe something like Apples vDSP within the Accelerate framework?
Can I include 3rd party dsp libs?
Is it possible to read/write to SD while processing sound?
Is it possible to boot Bela from eMMC flash?
What is the input in and out level? Line level?

Thanks

LiamDonovan

loop welcome to the Bela forum!

To answer your questions:

The context struct which is passed into the render function contains the audio and analog i/o data as floats, and floats are often much more efficient than doubles with Bela because single precision multiplications are vectorised using the NEON unit. See here for more info on IEEE 754 compatibility.
The BeagleBone Black rev c which we sell as part of our starter kit has 512MB of RAM, most of which is available for use by your audio code. That's a lot of loopers!
Minimum roundtrip latency using the audio i/o is 1ms, using the analog i/o it is 0.1ms. More info here.
Not by default (yet) though any linux-compatible C++ DSP library can be used.
Yes, you can include libraries exactly as with any standard linux program.
Yes, we provide a class called WriteFile for doing this (see here for an example). You can also use any standard linux calls with Bela in conjunction with the Auxiliary Task API.
Yes, see here.
See here.

giuliomoro

Bela actually comes with the NE10 library, which has a number of DSP functions available, including FFT, FIR interpolators and decimators, vector/matrix operations.

6.: WriteFile writes in header-less binary format. If you are looking into writing audio files, then you could use the libsndfile API, using threads as WriteFile does. For reading audio files (using libsndfile), see the various sample- examples in https://github.com/BelaPlatform/Bela/tree/master/examples/04-Audio

loop

@LiamDonovan @giuliomoro Thank you very much. The links to the documentation helped a lot to better understand the capabilities of bela. Especially the NE10 library looks very promising.

I am looking for a platform to create a looper / delay / reverb / bbcut kind of realtime sound mangler for guitar. Do you think that the bela can handle this kind of stuff?

LiamDonovan

loop yes, that sort of thing is exactly what Bela is designed for! As well as using its C++ API you can also programme for Bela using Pure Data which provides lots of DSP functions for audio.

loop

@LiamDonovan Cool. Sound like I have to buy the bela board. :-) Regarding PD. Over the last 10 years i tried to like PD but somehow it never happened. For no special reason. Thats why I started do write my own dsp stuff. Now i have to get rid of some vDSP stuff and port it to ARM. Thanks for your support.