DX Track EFX and Time/Phase Shift?

MixNut wrote on 7/11/2000, 1:20 AM
Another fundamental I'm not certain has been covered yet...

Question: If I have several "phase locked and dependent
tracks" (i.e. drum iso's and overheads) in Vegas...And I
insert different and varying numbers/types of DX Track
effects/processes on some/all channels of this "phase
dependant" set of tracks...DOES VEGAS ACCOUNT FOR THE
LONGEST DX PROCESSING LATENCY AND REALIGN ALL TRACKS IN
TIME, POST DX EFFECT???

If not...This is a BIG problem...In my experimentation with
drum tracks this evening, it would appear that inserting an
EQ on the snare track changes is phase alignment with all
other non-effected tracks due to processing latency...

Am I punchy or is this the case?

If Vegas cannot properly delay all tracks in playback to
account for specific track DX processing delays, IS THERE A
WORKAROUND?

Thanks in advance...

David

Comments

darr wrote on 7/11/2000, 9:12 AM
Is this phasing you are noticing through a scope or by ear?
I have done two sessions with drums on VIDEO 2 without noticing this.
Please explain more?:-)
Another David.

David wrote:
>>Another fundamental I'm not certain has been covered yet...
>>
>>Question: If I have several "phase locked and dependent
>>tracks" (i.e. drum iso's and overheads) in Vegas...And I
>>insert different and varying numbers/types of DX Track
>>effects/processes on some/all channels of this "phase
>>dependant" set of tracks...DOES VEGAS ACCOUNT FOR THE
>>LONGEST DX PROCESSING LATENCY AND REALIGN ALL TRACKS IN
>>TIME, POST DX EFFECT???
>>
>>If not...This is a BIG problem...In my experimentation with
>>drum tracks this evening, it would appear that inserting an
>>EQ on the snare track changes is phase alignment with all
>>other non-effected tracks due to processing latency...
>>
>>Am I punchy or is this the case?
>>
>>If Vegas cannot properly delay all tracks in playback to
>>account for specific track DX processing delays, IS THERE A
>>WORKAROUND?
>>
>>Thanks in advance...
>>
>>David
pwppch wrote on 7/12/2000, 1:19 AM
>>Question: If I have several "phase locked and dependent
>>tracks" (i.e. drum iso's and overheads) in Vegas...And I
>>insert different and varying numbers/types of DX Track
>>effects/processes on some/all channels of this "phase
>>dependant" set of tracks...DOES VEGAS ACCOUNT FOR THE
>>LONGEST DX PROCESSING LATENCY AND REALIGN ALL TRACKS IN
>>TIME, POST DX EFFECT???
>>

Yes.

This is how Vegas does a mix.

Basic rule:
Sample x is mixed with sample x from all sources fed to a common bus.
This meaning that all sources are mixed sample accurately.

A source can be the file/event on a track, the output of a filter, or
the output of a gain stage. Some sources are sequential and others
are parallel. Depends on the routing.

However, sample 1 from a source will never be mixed with sample 2 of
another source.

When a buffer of audio data is streamed into a filter, the filter
will produce output(even if the output is silence). (If it doesn't,
then by definition it is not a filter, but a renderer.) Sample 1
going into a filter eventually produces a sample 1 on the output. The
output Sample 1 is mixed with sample 1 from all other sources tied to
the main bus. If the filter requires samples 1 thru N to produce
sample 1 on the output, we wait for sample 1 on the output before
mixing with all other sources. We never mix late. We will gap
playback if we can't keep up with filters like this.

Phasing can occur in a mix scenario if the same sample is run through
different processing stages. You end up mixing the original sample
with processed versions of that sample. This can produce phasing
effects. It is dependent on the filter, the source, and the mix path.
It also depends on wet/dry mix on the output of the filter.

Using different filters on different sources that were phase locked
before processing could produce phasing effects. This would happen
with external output gear just like it will occur with plugins. It
also depends on how a filter mixes its processed data with the dry
signal. If the filter does not mix sample accurately, then you could
get a phasing (among other) effect.

Peter

MixNut wrote on 7/12/2000, 9:20 AM


>>
>>Yes.
>>
>>This is how Vegas does a mix.
>>
>>Basic rule:
>>Sample x is mixed with sample x from all sources fed to a common
bus.
>>This meaning that all sources are mixed sample accurately.
>>


Excellent! Thanks for the detailed response. Your reply [above]
raises an additional question however:

If I were to route "phase dependent" tracks through multiple and
separate output busses (i.e. 8 mono drum tracks to 8 mono output
busses) would these tracks still remain phase/sample accurate? Would
they remain such with differing DX Track processes? Would they
remain such with differing DX Buss processes?

Thanks in advance.

David
pwppch wrote on 7/12/2000, 1:18 PM
>>If I were to route "phase dependent" tracks through multiple and
>>separate output busses (i.e. 8 mono drum tracks to 8 mono output
>>busses) would these tracks still remain phase/sample accurate?
Would
>>they remain such with differing DX Track processes? Would they
>>remain such with differing DX Buss processes?
>>

Yes, as long as the hardware does not do anything to the audio, all
of our busses are sample accurate between each other assuming that
the hardware keeps the different busses of a single physical card
sample accurate. Most hardware supports a sync start/stop mode
between the multiple stereo pairs they expose. As long as the
hardware/driver supports such a mode, then all buses will remain
sample accurate.

The hardware is the final "bus" if you will.

One cavet: If for any reason on hardware device glitches or gaps,
then you will get a out of sync condition between the output
hardware. This is a known issue that we are trying to resolve.

Peter