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steveschizoid 
Bobcat
Joined: January/19/2008
Location: Ohio
Points: 66
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 Topic: real time monitoring and overdubs
Posted: April/20/2015 at 10:17pm |
I believe I just had a rather huge epiphany.
I've been using real time monitoring all along, but I've just realized that every single overdub I've ever recorded was essentially tracked the input latency later than it was actually heard as performed.
For example, at a buffer of 1024 samples at 88.2 KHz, the input latency (according to the control panel) is 12.494 ms. So, if I wanted the playback to faithfully recreate the timing of the performance I would have to have the DAW play the track 12.494 ms early, right?
I don't know what to think about this. I guess it's cool for present and future projects, but it's a rather bleak thought that every project I've done up until now (except for the live stuff) could have been a little better....
thoughts anyone?
Edited by steveschizoid - April/20/2015 at 10:18pm
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David A Hoatson
Admin Group
Forum Administrator
Joined: October/01/2003
Location: Idaho
Points: 4993
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Posted: April/21/2015 at 9:00am |
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You didn't mention what DAW you are using. Most (if not all) DAW software knows what the latencies are and compensates for them. You can tell this by recording a square wave that you are playing back using analog loopback and you will see that the recorded track exactly aligns with the playback track (sample accurate). This is the driver reporting the latency and the DAW compensating for it.
Short answer: You don't need to worry about track alignment when you change buffer sizes.
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Thank you,
David A. Hoatson
Lynx Studio Technology, Inc.
Co-founder, Chief Software Engineer
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steveschizoid
Bobcat
Joined: January/19/2008
Location: Ohio
Points: 66
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Posted: April/21/2015 at 9:20am |
I didn't mention changing buffer sizes. I use Cubase by the way. I was just thinking about the differences between software monitoring and real time monitoring, and it occurred to me that when you are monitoring through the DAW (Cubase in my case) you are hearing the track as it will sound while you are are playing, but if you are real time monitoring you are hearing the audio pre conversion. Which is fine, and I've always done it this way, but lately I've had to work in a studio that is, long story short, set up to use software.
The question is, if you are overdubbing to prerecorded audio using real time monitoring for the overdub, aren't you essentially hearing the what you are playing earlier (by the amount of input latency) than it will actually be written?
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David A Hoatson
Admin Group
Forum Administrator
Joined: October/01/2003
Location: Idaho
Points: 4993
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Posted: April/21/2015 at 10:06am |
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There is no monitoring 'pre-conversion'. Direct Monitoring is basically a digital loop back from the input to the output, which still goes through the A/D and D/A process. Software Monitoring just means the audio must also go through the input and output buffer.
Does this answer your question?
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Thank you,
David A. Hoatson
Lynx Studio Technology, Inc.
Co-founder, Chief Software Engineer
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steveschizoid
Bobcat
Joined: January/19/2008
Location: Ohio
Points: 66
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Posted: April/21/2015 at 10:24am |
So when I monitor record in 1 through output whatever, what I am hearing has actually been through AD/DA? It always seemed zero latency to me; it is, right?
Are the input and output latencies reported in the cubase driver panel the time it takes for the audio to pass through the input and output buffers then?
So if I am monitoring as above, then Cubase automatically compensates for the buffer timing?
thank you for your time, by the way.
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PaulTech
Admin Group
Joined: August/13/2004
Location: United States
Points: 5495
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Posted: April/21/2015 at 3:24pm |
 steveschizoid wrote:
So when I monitor record in 1 through output whatever, what I am hearing has actually been through AD/DA? It always seemed zero latency to me; it is, right? |
Yes, but with hardware monitoring the amount of latency is imperceivable, well under 1 millisecond. With software monitoring the latency is relative to the buffer size
steveschizoid wrote:
Are the input and output latencies reported in the cubase driver panel the time it takes for the audio to pass through the input and output buffers then? |
Yes
steveschizoid wrote:
So if I am monitoring as above, then Cubase automatically compensates for the buffer timing? |
Yes, as do most DAWS.
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steveschizoid
Bobcat
Joined: January/19/2008
Location: Ohio
Points: 66
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Posted: April/22/2015 at 5:16am |
Paul, So, software or hardware, there's never any reason to worry about latency, except that with which the performers have to contend?
I personally don't understand the fact that software monitoring seems to be becoming the industry wide convention. I worked in a studio recently where the (fairly young) engineers involved in setting it up had not even considered hardware monitoring - it was a totally new idea to them.
One more question, and this one has nothing to do with the original topic: given that I am using an L22 alongside an aes16e and they seem to be working somewhat well together, might I be risking some unforseen issues if I upgrade to the newest driver? I'm on 2.0 19g. The new mixer (which I knew nothing about until today) looks very appealing.
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PaulTech
Admin Group
Joined: August/13/2004
Location: United States
Points: 5495
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Posted: April/22/2015 at 3:04pm |
You are correct, there should be no difference with SW or HW monitoring in terms of stream alignment, Only in terms of delay of input signals that the performer hears.
If you are using an AES16e with an L22 you should stay put at driver 19g, and keep the AES16e firmware at 12.11 or below. With the newer driver and firmware there is a different DMA engine being used that is not supported by the L22. Now the e22 is a different story...
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real time monitoring and overdubs