[ubuntu-studio-users] Questions about production

[Ralf Mardorf]

On Sun, 2014-07-27 at 11:51 +0200, Thomas Orgis wrote:
> Am Sun, 27 Jul 2014 13:07:32 +0530
> schrieb Shubham Mishra <mishrashubham2007 at gmail.com>: 
> 
> > a first 
> > gen i3 and 3 GB RAM.

I didn't notice that this info already was provided.

> This is plenty of computing power for audio.

Indeed, I own an AMD 2.1 GHz dual-core, 4 GiB RAM, RAM, CPU load, DSP
load aren't an issue, anyway, chipsets and ugly Linux drivers could be a
PITA.

[rocketmouse at archlinux ~]$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: HDSPMx579bcc [RME AIO_579bcc], device 0: RME AIO [RME AIO]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: EWX2496 [TerraTec EWX24/96], device 0: ICE1712 multi [ICE1712 multi]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: EWX2496_1 [TerraTec EWX24/96], device 0: ICE1712 multi [ICE1712 multi]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

10.7 ms is the best latency provided by the PCI Envy24 cards (ICE1712)
to get no xruns, such a card is around 30,-€ at Ebay, it's prosumer
quality.

The professional PCIe RME HDSPe AIO costs more than 500,-€, recommended
by a LAD member, but it's not usable with Linux. It can't go under 10.7
ms and even with that latency or even a higher one, there are tons of
xruns. hdspmixer shows input for all 8 ADAT channels, but routed to
jackd are only 2 of the 8 channels. IOW for input and output only 2 of
the 8 ADAT channels do work. The card isn't broken and the developer of
the driver claims that I'm a liar.

You need good luck, not only good hardware!

> On the other hand ... I do wonder if there is a sync problem between a
> MIDI-only USB device and an audio USB device at all

I can not speak for USB audio devices.

For PCI/PCIe it should be the best to use one and the same sound card
for MIDI and audio, but since for serious MIDI work with external MIDI
gear we need several MIDI outputs, it's impossible to use just the MIDI
interface(s) provided by the audio card. Sync between the card I use for
audio and the cards I use for MIDI is the same good/bad as for audio and
MIDI using the same card. Even for PCI/PCIe cards MIDI jitter is an
issue. IT seems to interact with the audio latency, the lower the
latency, the better the audio to MIDI and MIDI to MIDI sync.

A note to the OP, this MIDI sync issue only is important, if you're
using external MIDI synth. But since you're using Qtractor, there's
another sync issue, in loop play mode audio and MIDI tracks get out of
sync after a few loops, this does effect internal, virtual synth too.