ADC & Post

[minister]

hi all,

i had been thinking about this. and i thought i would put it out there to see what others are doing.

i use ADC (Automatic Delay Compensation) for music mixing. it is a great tool to keep all those tracks phase-aligned when adding various amount of delay with plug-ins. i even put my hardware verbs on auxes as INSERTS and use an internal buss for effect routing. works great. makes a BIG difference.

in post, it does not seem to make sense to me... we are not so concerned about phase aligning sync dialogue, VO, music, Fx. bkdgs etc. they certainly didn't start that way. so what if they get delayed a few hundred samples. right?

if my math is right, in post, there are 48000 samples/sec, so, 1600/frame. {i should say for NTSC, for PAL, it's 1920/frame} most of my plug combinations -- de-ess, eq, comp, limit, don't add up to all that much, maybe 250-300 samples. now, if i use Noise Reduction, THAT is a different story. the delay there could be a frame or more. in that case, as much as i hate it, i slide my regions earlier (taking careful note, creating alternate playlists and noting the amount on the track in the comments.)

ADC works by identifying the track with the MOST delay (indicated by the orange in the display) and then matching the offsets on the other tracks to that slacker. i assume that it pushes the other tracks later in time to meet the delay of the longest. right?

all that said, anyone using ADC in their POST (not music) mixing? if you do, do you nudge your tracks? maybe it makes sense in design? but not mix? or, can you enlighten me further? or, do i basically have it?

constructive thoughts welcome.

[Brandonx1]

Actually, I think ADC makes the track with the longest delay start earlier in time. So, all the tracks aren't just aliened with each other, but the timeline as well. That being said, I would use it in post if it 1) were longer (compensate for the plug in hogs like the L3 of X-noise) and 2) didn't take up as much resources. I think the native DAWs ADC work much better. No limit to the time of ADC and uses the native recourses for the ADC.
Peace,
Brandon

[marty lester]

my understanding (from a Digi guy) is that ADC also aligns the movie
file...and in my experience, it does indeed.

in summary, if you use ADC while mixing to picture, you do not
need to move the picture.

hope i'm right,
marty.

[minister]

hi brandon,

thanks for the reply. so you say it moves it earlier.

then i am confused by this statement from page 469 of the manual:

To maintain time alignment, Pro Tools adds the exact amount of delay to each track necessary to
make that particular track’s delay equal to the delay of the track that has the longest delay.

that tells me it ADDS delay. so, later. or am i wrong?

[Brandonx1]

Hi Minster,
All I know is when I scrub with ADC on, the wave form is in front of the audio. I think the word add means adds delay between the tracks to time alien them but this also can be related to the timeline. I've been wrong before.
Brandon

[Frank Kruse]

The other tracks have to be aligned later to match the track with the longest delay. If an oudio track is late your picture has to be pushed later too. AFAIK the ADC doesn´t pull tracks earlier to compensate for the plug-delay, it will push the non-pulg-in tracks later to match the track with the plug-in, that´s why it´s problematic when you chase LTC to an external picture.

or am I wrong?

frank.

[filmixer]

> I would use it in post if it ... 2) didn't take up as much resources.<

This is the main issue I think. On a big 160 voice mix with lots of 5.1 mix engines, adding DSP usage for ADC doesn't leave much for plugins, even with 5 or 6 Accel cards. Being able to use RTAS on Auxes in PT7 will help though.

[minister]

SO...

we are not quite sure if it pushes the audio earlier or later. (i'd really suprised about earlier.) i can't locate the precise information on this in the manual. is it in there? but my reading of what i can find tells me that it aligns audio with the latest, which tells me that it would be later...

and it might be that it aligns with the movie? how? is this with a movie in the timeline? many of us do not have that. does it align with frame edge when we are ONLINE?

to be sure, in larger film mixes, the cost of the DSP may be too high, so many will not use it. and many will not even worry about it.

does it make sense to use in smaller mixes? does anyone notice a difference in their mix with it?

btw, i do not use it for post...seems too troublesome to me.

[marty lester]

does it make sense to use in smaller mixes? does anyone notice a difference in their mix with it?

to refine my post...yes, i am (nearly) positive ADC moves all audio later
to match the longest delay in a session...and it also moves
the movie later in the same manner...as if it's an audio track. i keep
my movie offset the same whether or not i use ADC, by the way.

since i mostly mix my audio post from an OMF file, i leave the audio
where it was in the time-line...find the visual 2pop (down to the
sample level), put a sync point there, and spot that sync point to
wherever the 2 pop should be...ie 00:59:58:00.
(using a DV movie and Canopus codec)

this makes my lip sync be as tight as it can be using the DV/Canopus
combo in conjuntion with ADC. mind you, my mixes up to this
point have been stereo and relatively small track counts.

i do wonder if things would change if i were syncing my PT session to
an external video/SMPTE source. i would have to believe it would
make the audio and video out-of-sync.

hope this doesn't cloud things further,
marty.

[Frank Kruse]

i do wonder if things would change if i were syncing my PT session to
an external video/SMPTE source. i would have to believe it would
make the audio and video out-of-sync.

hope this doesn't cloud things further,
marty.

As I said. If you lock to external picture source you will be out of sync when using plugs with high latency e.g. X-Noise etc. because with ADC on PT will delay all toher tracks to compensate for the longest plug delay in your session. Of course plugs that only use a couple of samples won´t harm lipsync.
Frank.