Cockos Incorporated Forums - View Single Post

Philbo King · 02-13-2018, 03:00 PM

I see a lot of USB bashing, some of it deserved. But USB2 provides a theoretical bandwidth of 480 MB/Sec, which is easily enough for 250 mono audio streams at 44.1K/24 bit. This assumes nobody else is using that hub...

Math:
mono stream at 44.1K/24bit:
44100 words/sec x 24 bits/word = 1058400 bits/sec per channel

480 Mbits/sec divided by 1.0584 Mbits/sec = 453 channels
(theoretical limit, assuming only audio is using USB).

You can scale this; if you double the sample rate to 88.2KHz, you're limited to only 226 channels.

To be fair, 10 to 15% of this is devoted to things like transmission overhead (data packeting uses some of those bits to identify who the data came from and where it's going). So, knock 15% off of 226 channels, and you're down to only about 192 channels of 88.2K/24bit.

I've found that to be plenty for my work. If someone really needs more than 100 channels, they'd probably opt to get something more than a prosumer interface, like a MADI setup. At least in a rational sense...

02-13-2018, 03:00 PM	#45
Philbo King Human being with feelings Join Date: May 2017 Posts: 3,204	I see a lot of USB bashing, some of it deserved. But USB2 provides a theoretical bandwidth of 480 MB/Sec, which is easily enough for 250 mono audio streams at 44.1K/24 bit. This assumes nobody else is using that hub... Math: mono stream at 44.1K/24bit: 44100 words/sec x 24 bits/word = 1058400 bits/sec per channel 480 Mbits/sec divided by 1.0584 Mbits/sec = 453 channels (theoretical limit, assuming only audio is using USB). You can scale this; if you double the sample rate to 88.2KHz, you're limited to only 226 channels. To be fair, 10 to 15% of this is devoted to things like transmission overhead (data packeting uses some of those bits to identify who the data came from and where it's going). So, knock 15% off of 226 channels, and you're down to only about 192 channels of 88.2K/24bit. I've found that to be plenty for my work. If someone really needs more than 100 channels, they'd probably opt to get something more than a prosumer interface, like a MADI setup. At least in a rational sense... Last edited by Philbo King; 02-13-2018 at 03:08 PM.