Requesting clarifications on VS1005 capabilities..

Designing hardware that use VLSI Solution's devices as the system controller for the entire design.
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msat
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Requesting clarifications on VS1005 capabilities..

Post by msat » Tue 2019-05-14 17:23

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?

Thanks,
Mark

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Panu
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Re: Requesting clarifications on VS1005 capabilities..

Post by Panu » Thu 2019-05-16 17:58

Hi!

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?

-Panu
Info: Line In and Line Out, VS1000 User interface, Overlay howto, Latest VSIDE, MCU Howto, Youtube
Panu-Kristian Poiksalo, VLSI Solution Oy

msat
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Re: Requesting clarifications on VS1005 capabilities..

Post by msat » Wed 2019-06-19 17:27

Panu,

Thank you for your brisk response, and I apologize for my own delay. I have gone down the rabbit hole, so-to-speak, with regards to desired functionality and searched high and low for solutions from various vendors just to come full circle back to VLSI's very compelling offerings.

I've become lax in my requirements, in no small part due to cost sensitivities and packaging, but if possible I would like to be able to play back a stereo stream be it 16-bit 48kHz PCM or equivalent Vorbis (whether "dual stereo" or "lossless/phase stereo") while recording the same. Only one of those formats would need to be supported, especially if it allows for avoiding the need for external SRAM. Achieving this would be worth reducing internal SRAM usage by, say, limiting or eliminating things like display frame buffers. The points you make are valid and understandable, and seems to indicate that such a thing may not have been tried before on this product. I will study this problem and your product more closely in hopes that this capability can be attained. If it comes down to it, I can forego this functionality, but I'd rather not.

Thanks,
Mark

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Panu
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Re: Requesting clarifications on VS1005 capabilities..

Post by Panu » Thu 2019-06-20 14:00

Hi!

Great to hear that we have a good offering :)

Anyway, we'll do what we can to support you. Henrik has a better grasp than me about the performance of different SD cards with his Hi-Res Recorder. I think his code probably relies on the external SRAM, but I think that most SD cards work with just the single VS23S010 external RAM and do not require the full VS23S040.

Looking forward to hearing from you again!

-Panu
Info: Line In and Line Out, VS1000 User interface, Overlay howto, Latest VSIDE, MCU Howto, Youtube
Panu-Kristian Poiksalo, VLSI Solution Oy

msat
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Re: Requesting clarifications on VS1005 capabilities..

Post by msat » Thu 2019-06-20 17:28

Thank you, Panu. I'll be sure to ask more narrow questions as I study the problems some more.

Thanks,
Mark

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