Multiple audio streams

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Hello everyone,

I'm looking for some advice in using multiple audio streams. I'm fairly knowledgeable with AVR and FPGA but I've never dealt with audio before. The project I'm going to be working on requires the ability to play back samples whenever they're triggered. If a sample is currently playing and another sample is triggered, both samples will play concurrently (overlap). Would this be possible with one micro controller with one MP3 decoder (VS1011e for ex.). I doubt it but can I feed two digital audio streams to say the VS1011e or any DAC? Or would the approach be to use separate MP3 decoders or DACs for the number of channels (concurrent audio streams) I want to support with a mixer at the end mixing all the channels? Or even use separate AVRs with DAC for the number of channels / streams I want to support?

Regards,
David

edit: would multiplexing the digital input to a DAC work to produce the desired analog audio signal?

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You have a choice of either mixing in the digital or analog domain. The AVR would probably be pushed to do it in the digital domain, so you will most likely have to have multiple vs1011s and DACs and mix the audio at the analog end. To mix audio in the didital domain, you need to do the numerical average for each sample from all your sources. This means your sample rate has to be the same, otherwise you need to re-sample and it starts to get complicated. This is something you'd get a DSP to do or a fairly fast 'normal' processor or maybe a FPGA at a pinch.

Multiplexing to your DAC would not work - think of the issues involved.

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I'd use one of the new XMOS chips, it's the sort of application for which they were designed:

http://www.xmos.com

You should be able to do your development on one of the $99 XC-1 kits.

Leon

Leon Heller G1HSM

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Those Xmos chips look real nice!!

But I think now that I'm going to do the analog mix at the end. and support 4 channels of concurrent audio with 4 DACs..

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I have started to work on this project again and had a few questions, although not AVR specific, but about the VS1011e chip. The VS1011e has pins for digital and analog power and ground connections (AVDD / DVDD / DGND / AGND) and the datasheet states them as such with no further information. I'm not to sure on how to deal with the analog supply. Is this the analog supply that would drive speakers if I was to implement speakers? As stated earlier, I don't have much experience with audio / analog circuits. Any link / direction / suggestions would be greatly appreciated.

Regards,
David

edit:

came across this post:
https://www.avrfreaks.net/index.p...

Suppose my question is about the dual power supply system. Looks like I'm in the right direction now but if anyone else wants to suggest anything feel free.

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Google "Yammp" (specifically yammp-3) - Jesper's circuit shows a VS1xxx being used.

...

this in fact:

http://www.myplace.nu/mp3/images...

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Karnac The Magnificent divines that you are building a sounds effects box, perhaps for a simulator? Maybe 8 sounds and 8 inputs. Every time you see an edge on input 3, you conceptually dump all the samples for sound 3, maybe several K in a fifo feeding a dac. You could replicate this hw 8 times and have an 8 resistor mixer on the output.

Imagecraft compiler user