USB data stream recorder – design idea ?

[fred_fraggleParticipant]

Whilst pondering why I stir my tea in a clockwise direction the other day I also wondered if anyone had invented a USB streaming data capture device. A sort of print buffer for audio recording ?

It would take the place of a high powered computer normally used to record your audio tracks and all the hassle it brings with setting up tracks, arming them, arranging ins and outs etc and just records the data stream to something like a buffered raid array for download later.

Does such a device exist, or have I just invented it?

[[XAP]BobParticipant]

A raspberry Pi zero would be sufficient I imagine.

But then QuDrive already performs this function ?

[airickessParticipant]

I think putting a USB stick into the Qu Drive or connecting a hard drive into the USB B port does this already.

[DoctorGParticipant]

Try stirring your tea in the opposite direction, and I’m sure the answer will dawn upon you.

[fred_fraggleParticipant]

I agree the QU records — but only 16 channels to the USB stick ? I was wondering if a device existed that could record all 32 channels via the USB socket on the back of the unit. A sort of data stream recorder black box – i.e. record without the need for a fully fledged computer at an event running pro tools or reaper.

[[XAP]BobParticipant]

18, not 16…

And an RPi Zero would probably be enough, so for £4/$5 and the cost of an SD card (I picked up a couple of decent 32GB ones for ~£6ea recently) you could get it working.

I suppose you might want to put an LED and a push switch on it as well (to show recording status and provide start/stop controls)

I might have to try to build an appropriate image…

[fred_fraggleParticipant]

Sorry xapbob my error with tracks– was late at night-

My idea was based on how a laptop works when you send something to print but have no printer connected. The file goes into a buffer area and awaits the next connection to a printer.

My thought was – I wonder if the 32 tracks of audio could be ‘buffered’ and then downloaded into Pro Tools / reaper etc at a later date ? Thus avoiding the need to have a full computer setup on site. It would also save time arming and setting up tasks when in the heat of battle… And the risk of a ‘hang’ whilst recording thus loosing everything and awaiting a restart etc…etc…

Not being a tecchie with such things might the zero ( or a full version Pi) also provide a cleaner stream for recording. i.e. could it have a larger buffer to avoid any dropped data and error trapping to ensure a complete recording… possibly to two flash drives/cards as a raid array?

Might it also save as you go along so if it did crash you would at least have something?

Your idea of feedback lights is great and the one press start stop is inspired

This sounds exciting — a crowdsourced Christmas project… thoughts anyone?

[[XAP]BobParticipant]

The Pi Zero would be limited to the onboard SD card – the USB interface would be used to connect to the QU.

A Pi B, or a B2, would be able to use additional USB cards, but beware, there is only a single USB connection from the SOC, there is a USB hub on board to provide the additional sockets.
The bandwidth shouldn’t be an issue, but it’s worth mentioning.

Of course the B could also be remotely started/monitored over the network…
(Obviously the PiZero could run an external USB hub as well – and these are available with NIC as well)

We wouldn’t “buffer” them so much as just record them straight. But yes, in theory it should be possible to dump them all to media, and with more RAM available than on the QU we might be able to deal with slightly less excellent USB devices (since we should be able to buffer over a longer wear levelling/internal check of the SSD.

Given ~£15 of hardware this should be possible – then you need a bit of a case to put it in – and of course a 5V PSU.

Maybe I should see if the QU is recognised natively by raspbian?

[fred_fraggleParticipant]

Wow xapbob you sound like a Pi expert…. even @ $50 it is cheaper than a $1k mac on site

For those of us not as familier with the Pi – Could you elaborate on the technical terms please
– what is the SOC – is that the brains of the Pi ?
– and the NiC?
– the SSD – taking a guess — solid state device – i.e. the flash card possibly?
– longer wear levelling/internal check — No idea on this one, sorry

[[XAP]BobParticipant]

SOC – System On a Chip – the Pi is basically a computer on a single chip, much like a phone’s brain.
NIC – Network Interface Card – the Pi doesn’t strictly have one, but some models have a 4 port USB and USB-ethernet adaptor on a second chip.
SSD – Flash card, the Pi boots from an SD card, but anything connected via USB could be used after the initial power up sequence (It’s a bit complicated: The GPU boots from the SD card then hands over to the CPU, which can be pointed at a USB device)

Wear levelling etc. is “stuff that storage systems do”. It’s one of the reasons we suggest formatting the QU disk each time data is deleted, you start with a fresh slate – the device has an easier time when it doesn’t have to juggle existing data. Depending on how good they are at it, they can do it really fast (like the SanDisk Extreme) or much slower – which can cause all sorts of devices which can in theory sustain the USB data transfer to have a “hiccup” long enough that the QU runs out of it’s own buffer, and you lose data.

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