Synchronizing digital Audio
|Audio with Cubase VST and a Fostex D160...|
I visited your site after having read a message on a Mailing List (cubase, numerison or macmusic, I can't remember which one).One can find plenty of interesting stuff, and also in french, for a change, so : bravo ! I'm not against english, but it's easier for me to read french).
You offered to collect questions through the Tekno chat page, and I happen to have one : I've tried to find answers, but only find partial answers. My problem is in syncing my D160 (DtD fostex) and my PC (ISIS sound card) via midi time code. They sync up correctly, but after a while, a noticeable drift occurs. So my question(s) is(are) :
- What is wordclock ?
- Can it solve my problem ?
- What are the other types of sync (LTC, SMPTE ....) ?
To summarize : how can I sync two machines ?
If you have time to answer me, I thank you in advance.
My answer :
Sorry I couldn't answer sooner, I don't have access to the Internet on a daily basis.
I skipped through the owner's manual of a friend's D160.
Your problem is absolutely normal, and concerns any configuration where several machines are reading digital audio simultaneously. The clock driving the audio of the D160 and the clock of the sound card, driving the audio of Cubase VST are not synchronised.
Bad news for you : there is no simple solution other than buying the optional 8345 (TC/Sync) card that fits in slot B of the D-160. The card can send a word-clock that you must connect to the word clock input of the PC's sound card (if there is no WC input on the card, you're doomed).
You ask me to describe what word clock is all about : a good definition would be to say that it is an electrical representation of the sampling frequency, that you can then carry over to every other machine via a cable (coaxial video, BNC connectors), so that all the audio clocks run exactly at the same rate. You must of course configure all the machines so that their clock reference is sourced on that signal (except the machine that delivers the WC to the other machines).
Otherwise, 48 kHz in one machine is certainly not the same 48 kHz as in an other machine (the first is maybe really running at 47,996 kHz, and the other one at 48,002 kHz)
Thanks to a word clock link, the second machine will also be running at exactly 47,996 kHz, and its' audio won't drift.
Now if it's just the MIDI notes drifting (you didn't say if it was the audio or midi info in the cubase that was drifting. I assumed it was the audio), all you have to do is look in the Option/Audio Setup/System/ menu to set the parameter MIDI SYNC REF to Time Code, not Audio Clock.
There. I hope I met your expectations,
Best luck for the future !
|Clics with a Digidesign SDII and a Tascam DA30 DAT...|
Here is my problem :
I would like to record a digital DAT tape on Sound Designer II to do some editing. The tape was recorded using a DA 30 MKII Tascam recorder. The link I used to transfer the DAT sound to the SDII (via the interface) was an AES/EBU (XLR connectors). Until now, everything's fine, the problem occurs when I want to listen to the SDII : I chose to monitor via the headphone jack of the DAT recorder, by placing it in REC mode, and of course, selecting its' source to "digital". The recorder then asks me for a sampling frequency (44,1 or 48 ), that must mean that it needs to sync itself to the SDII is I'm correct !
I then hear clics while I read my audio file, which makes me think of a DAT player lagging behind a sync signal (the clic occurs regularly and rapidly, which is very ANNOYING !!!)
Question : Should I configure the SDII so that it becomes the master (is that possible ?) or is it the DAT that's supposed to be master ? And am I asking the right question... ?
thank you and goodbye.
My answer :
Oh boy ! Digital audio clock syncing problems again !
Normally, tell me if I'm wrong, you configured your SDII so that it's clock is synced to EXTERNAL (or digital, I don't remember exactly how they named that option) in the HARDWARE menu, so that SDII stays in sync with the clock present in the AES/EBU signal during the recording (we say that the SDII's audio clock is "genlocked" to the incoming signal, in tekno speak).
Now, when you wish to read audio with the SDII, in your configuration (using the headphone jack of the DAT player), you must set the audio clock of the SDII so that it syncs to INTERNAL ! I have the feeling, reading the symptoms you're detailing, that you leave your hardware (the I/O card) set to external clock, and your DAT being itself, not in a position to emit such a clock, but in a position of receiving one (which happens automatically on such a semi-pro machine when you set it to REC a digital source).... well : you've got a nice loop going on there !
When you record a digital source (DA30 or other) --> SDII audio clock set to external (digital)
When you read on the SDII, or when you record an analog source --> SDII clock set to internal.
Tell me if things keep going wrong. Normally, everything should go back to normal.