why full speed usb 2.0?

[adrian23]

is there a reason why access went with 12mbit full speed usb 2.0 instead of hi speed 480mbit or even firewire on the ti (even firewire 800)? both usb hi speed and firewire been around for a long time...wouldn't hi-speed usb or firewire open up more bandwidth and give us more out ports and solve all those latency issues?

honestly, feels like 1.5mb/s (full speed usb 2) is slow as hell....

adrian

[Timo]

Hi Adrian,

Access recently announced they will be releasing OS v2.7 which adds 3 more stereo outputs through USB, using more of the available USB bandwidth. (12 megabits is equivalent to ~1.5 megabytes/second.)

Total Integration is a fairly new thing with synths these days. I can only think that the things Access wanted the TI to achieve (such as having the above 4 x stereo audio channels, Virus Control, and MIDI over USB) wouldn't require/necessitate a 480mbps chip, and also being business conscious decided to forego it for this round.

There could be other reasons. Maybe the available DSP isn't powerful enough for doing anything significantly greater than that, meaning it would make slightly bad business sense to get anything higher at that point.

Or, maybe they wanted to hold out until a TI mk2.

Or it could be a combination of the above.

Just my thoughts.

Timo

[adrian23]

fair enough but come to think of that, i highly doubt 480mbps chips are that much more expensive. Unless, as you said, the dsps on the virus cant really output more than full speed usb.
I'm not complaing, i love my virus. the only issue i have is latency, in other words i can't record through usb without editing every single note afterwards and was wondering if lag would have something to do with full speed usb.
adrian

[Doc Jones]

Originally Posted by adrian23

the only issue i have is latency, in other words i can't record through usb without editing every single note afterwards and was wondering if lag would have something to do with full speed usb.
adrian

Adrian, there might be something else going on here as I do all my recording through the usb connection and don't have any noticeable latency.

[adrian23]

Sir Doc Jones
it's a bit weird, this whole latency stuff. Perhaps there's something i need to tweak, adjust, click that i'm not aware of. The lag is quite noticeable when i play the keyboard. then again, arps are in sync when i play them back (99% of the time), and not once did VC crashed, even after 8 hours of non-stop usage.
I got the best (gold plated), shortest USB cable i could find, its plugged into its own usb port and is not being shard with other devices.

My setup is as follows (its plain as a white piece of paper)
Mac Pro, Logic 8, Leopard, M-audio Firewire solo, virus into its own usb port, m-audio trigger finger into its own usb port.

I tried to google latency with the virus and similar setup, but nothing really comes up. And speaking of m-audio. those bastards still didnt update their god damn driver for the firewire solo - i'm still on 10.4 drivers. I mean it runs fine, no problems, but i read a number of posts where people couldn't even get it running on leopard. I highly doubt my audio interface is the problem, but who knows?
dunno
any ideas Sir Doc Jones?
adrian

[Khazul]

The USB chip and driver set they use was bought in to save needing USB development expertise at a time when it was probably new to them.

I beleive its the same chipset and core driver code (both on the pc/mac end and on the DSP end) thats also used by novation and various others.

Also the USB 1.1 specification includes support for this type of device, whereas at the time, the USB 2 specification did not, so while USB2 is higher bandwidth, it was actually potentially less reliable than the slower USB 1.1 spec for streaming a small number of audio channels.

In reality, they should have gone for firewire on a purely technical level, however if you dont have in house firewire expertise, then that would have been far more risky as at the time I dont think there was any good off-the-shelf easy integration firewire chip+driver offerreing around. Im not even sure that there is even now.

Smaller companies are better off buying off the shelf support for things like this as developing reliable drivers at each end (pc/mac and the dsp) takes alot of time, even for a standard class device which this is at a basic level (if you hadnt noticed - Vista recognises the audio functionality of the Virus TI automatically, so no driver needed to use it as a standard sound card).

As for the latency, well TBH Ive never quite understood why it is so high, but then Ive not actualy written a USB audio device driver so have no idea what buffer sizes it is forced into using etc. For the latency to be that high then I'm guessing it must send/receive quite large audio data blocks over the wire along with alot of buffering in case your pc decide to ignore USB for a bit (as often happens with PCs and Macs).