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A project log for Multichannel Audio DSP Field Mixer Recorder

USBmidi, bluetooth app controll 8 chan portable DSP mixer.balanced audio IO,phantom power,flexible routing,ISO recording. networked Timecode

ben bilesben biles 06/21/2018 at 13:580 Comments

https://soundcloud.com/benbiles/bbbox-proto1-recording-48khz16bitwav

The 1st test recording is here ! 16bits 2 channel recording from the master mix output. Sorry about the tired voice !

I had a few hours tough programing to make this work and was completely tired by the time I got it working!

You can here some audio click / jumps. This is because the ARM is master and generating its own clock with

the DSP in slave mode to it. The ADAU1446 doesn't have any ASRCs to sync the 2 clocks and doesn't like the clock mismatch :)

I had to battle with re-assigning SAI ( serial audio interface) pins on the stm32f7 demo board. I only have one SD pin available

on SAI_block_B and have to switch between player and recorder mode using the one SD pin and sharing the rest for FS and CLK.

I think I can can get 16 channels IO this way in TDM though so it should be enough for testing. Although it will be 16 channels in or out and not both at the same time ! or maybe they can be clocked in and out at the same time , not sure.

The next job is to get the SAI interface working in Slave RX TX Synchronious to the DSP MCLK then the whole system will be running off

the one high quality clock / fan out buffer. I already have the DSP setup for ISO recording.

I think after that my next coding headache will come from writing WAV poly. 8 channel WAV audio PCM files.

I will need to look up the spec of them and see how they are made. hopfully I can just write the TDM in slots and define in the header

in some kind of PCM descriptor ? anyone already know the answer? would be really helpful :)

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