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Requesting clarifications on VS1005 capabilities..

Posted: Tue 2019-05-14 17:23
by msat
Hello VLSI staff and fellow members,

Maybe this is an obvious question, but gleaning over some of the available documentation as well as forum thread subjects, I found nothing on the topic, so I will ask here: Can the VS1005 simultaneously record one (or more) stream(s) while playing back another to and from an SD card? If so, what are the realistic limitations (supported file encodings, sample rates, # of channels, etc)? I have a basic grasp of the work that went into VLSI's HiRes 4-channel recorder system and why external SRAM was necessary, so I wonder how much having to frequently switch between SD reads and writes would negatively affect performance. Would it be to the point where it would be impossible, or at the very least, very difficult?


Re: Requesting clarifications on VS1005 capabilities..

Posted: Thu 2019-05-16 17:58
by Panu

These are just guesses, but I think it would depend heavily on which SD card is used. Different SD cards might have considerably different "turn-around" times to switch between reading and recording. I think the external SRAM is required in any case. It's difficult to give guess-based estimations without actually trying it and measuring. I think we've done such things mainly with PCM or ADPCM due to the memory requirements and encoding delays involved in the more complex codecs. But I think it depends quite a lot on the application and its realtime requirements. What kind of application are you targetting? A generic n-track recorder? How many channels would be sufficient?