Clock, sample rate and a sync nightmare...

[Subsolo]

So if your just trying to fix the project audio, will you up-sample the 44.1 to 48k or the other way around?

Hi.
We tried your suggestions but nothing worked as expected. By using some import and convert options inside Pro Tools, my brother managed to convert some files and almost match with the project's tempo, but that wasn't perfect. Besides, we want to get the files back without any artifacts.

Yesterday he went to a famous mastering studio here in São Paulo to get a master from an album that he was working on and he explained our problem to the studio's engineer.
The Guy said that our problem was that we synced both computers using MTC but
the cloks were both set to "internal" and that was our mistake. He figured it out because it happened to him a several times in the past.

We used a Presonus Firebox as master and a Delta 1010 as slave.
If when the clock is set to internal we are actually using the "interface's clock", the only possible way to link and playback the files correctly once again is by linking a Firebox and a Delta 1010 (that's why we couldn't do it using a DigiDesign interface).
Regardless of software! They don't have any influence on the processing except by placing the files correctly in the project window, as you mentioned.

Cookie also mentioned: Midi may let you send start / stop commands etc, but it's no good for actual synchronisation. WordClock is what you really needed. Or when doing things really old-school: SMPTE.

So, now we are going back to the studio to link both interfaces once again. Then, when we got our system up and running, we'll just re-record the files into our master machine using the physical inputs, with the correct sample rate.
Which in this particular case will be 44.1! Damn it!

Regarding my next try on sync, I still have to do some research on the subject but I guess that probably the best way to go is by using SPDIF?? as the clock??
I don't know, the guy from the studio talked about a specific clock generator device like the one that Rangtangtang have.

I'm more interested in gather with a friend and link two computers to record our live band performance in a pub, for instance.

I'm gonna film the next "syncing session" and put it on YouTube as "How not to do midi Sync".
Cheers

[annode]

I believe the card that was connected to the Vegas system 'would' have been 'driven' to 44.1k from the master sound card, had they actually been clock connected. The system clocking for audio comes from the sound card and not the DAW software.
Even had you had both systems connecting MTC or/and MMC these would not align your two system's sample positions accurately. The cards are still running independent 'internal' clocks.

As you mentioned, s/pdif will have a clock signal on it. If both cards have s/pdif in/out, just connect the 2 ports with optical or short or heavily shielded coaxial cable if running over or near power cables. You don't need to set the cards to ADAT or set them up for optical or coaxial,(digital audio), in order to send and receive the master card's clock signal I believe. It's been along time so i'm not exactly sure about all that.

You'll have no use for SMPTE unless your encoding a SMPTE multi-track recorder tape track, then using that track to do what MMC/MTC will do in the digital world. SMPTE also is /was used in synchronizing TV frame rate and audio...the way MMC will control YOUR transport sync'g.

A clock pulse generator is not necessary.They are used more for clock distribution around multiple, driven/slaved equipment.
I want to have a look at your sound cards clocking options. (i'll write back about that)
Some cards won't be slaved...at least in my experience, they can only act as a master clock.
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Presonus Firebox from user manual;

7. Red-Blue Power/Sync Light. This light is a clock (sync) indicator. It lets you know if
your unit is receiving word clock correctly. Word clock is the manner by which digital
devices sync frame rates. Proper word clock sync prevents digital devices from having
pops, clicks, or distortion in the audio signal (due to mismatched digital audio
transmission).

Blue - solid sync
Red - sync not present.
Flashing Red and Blue - external sync not present
----------------------------------
MIDI and SPDIF I/O can be connected to this DB-9 connector breakout cable
(included). The S/PDIF I/O allows the FIREBOX to receive and transmit audio from/to
other digital audio devices. The S/PDIF standard allows for two channels of audio to
be transmitted at up to rates of 24bit/96Khz. Word clock is the synchronizing signal
that indicates the sampling frequency or rate of sample words over a digital audio
interface. Note: When using SPDIF In, you must select SPDIF in your FIREBOX
Hardware Control Panel.

---------------
From Delta 1010LT user manual;

Synchronization
For proper operation, the entire Delta 1010LT system is always synchronized to a single
master clock. The master clock is chosen via the Delta Control Panel software and this
clock may be derived from the Delta 1010LT's internal crystal oscillators, S/PDIF In, or
Word Clock In. Most of the time the master clock is taken from the internal crystal
oscillators. However, the S/PDIF and Word Clock options are used in situations where
the Delta 1010LT must be synchronized to external digital audio or sample rates derived
from an external device.
15

[Subsolo]

Hi annode,
thanks for the thoughtful advice. You're right about the clock issue.

For the following week, I'll try to sync my brother's computer and mine via SPDIF and do some scratch recordings to see how it works.
I'll let you know if you were right about the connections.

Best regards.