| Author |
Message |
eb7g
Guest
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 Posted:
Sun Sep 04, 2005 2:53 pm Post subject:
What is the latest word on Audio Drift in digitizing video? |
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Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all
as one file per tape.... at about 20 minutes in, the audio started to
drift and by the end of each tape the audio was out of sync almost a
full second of time.
Is this common? How do people without DVgate digitize their audio and
keep the sound in sync? If I digitize in Premiere, as one large file,
will the sound be out of sync as well?
I would have thought this would have been corrected by now. That
explains why DVgate splits up the video into chunks.
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Richard Crowley
Guest
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| Posted:
Sun Sep 04, 2005 7:18 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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"eb7g" wrote ...
| Quote: | There used to be the known problem of audio drifting out of sync on
long video files. I've been using Sony's DVgate for the last little
while, which will split the video into 10 minute segments, so I don't
get any drift. But the other day, I digitized 3 miniDV tapes and saved
them all as one file per tape.... at about 20 minutes in, the audio
started to drift and by the end of each tape the audio was out of sync
almost a full second of time.
Is this common? How do people without DVgate digitize their audio and
keep the sound in sync? If I digitize in Premiere, as one large file,
will the sound be out of sync as well?
I would have thought this would have been corrected by now. That
explains why DVgate splits up the video into chunks.
|
Dunno. I've always captured DV (or DVCAM) directly via
Firewire and in several hundred hours of captures (up to
2 hours long), I've never had a problem with A/V sync.
Are you talking about capturing analog into some cheap
graphics card with "VIVO"? There is unlikely any generic
answer to your question. |
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PTravel
Guest
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| Posted:
Sun Sep 04, 2005 10:32 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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"eb7g" <eb7g@shaw.ca> wrote in message
news:huzSe.369600$s54.356645@pd7tw2no...
| Quote: | Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all
as one file per tape.... at about 20 minutes in, the audio started to
drift and by the end of each tape the audio was out of sync almost a
full second of time.
Is this common? How do people without DVgate digitize their audio and
keep the sound in sync? If I digitize in Premiere, as one large file,
will the sound be out of sync as well?
I would have thought this would have been corrected by now. That
explains why DVgate splits up the video into chunks.
|
I'm unfamiliar with DVgate -- I use Scenealyzer Live or Premiere Pro for
capturing. However, I frequently have occassion to "bulk capture," and then
do after-the-fact scene detection and/or logging. I've never run into any
audio drift problems -- audio sync is rock solid.
Are you capturing using some odd codec? Are you sure there is nothing else
running on your computer? Has your computer enough power (it doesn't take
very much for capturing miniDV)? |
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Henry Padilla
Guest
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| Posted:
Tue Sep 06, 2005 7:24 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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"eb7g" <eb7g@shaw.ca> wrote in message
news:huzSe.369600$s54.356645@pd7tw2no...
| Quote: | Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all as
one file per tape.... at about 20 minutes in, the audio started to drift
and by the end of each tape the audio was out of sync almost a full second
of time.
Is this common? How do people without DVgate digitize their audio and keep
the sound in sync? If I digitize in Premiere, as one large file, will the
sound be out of sync as well?
I would have thought this would have been corrected by now. That explains
why DVgate splits up the video into chunks.
|
I'm with those other guys. I've _never_ experienced what you are talking
about.
I've had to deal with sync from simply having the camera far enough away
that they sound didn't reach it before the light did, but that's a different
phenomenon.
I guess I have the same question as the others, what the heck are you doing?
Are you using Firewire? (If not then we can stop now. Firewire is the best
way to import DV, period). Some weird codec or capture card?
I dunno.
Tom P. |
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William Davis
Guest
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| Posted:
Wed Sep 07, 2005 12:46 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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In article <eEhTe.299$nt1.40@newssvr33.news.prodigy.com>,
"Henry Padilla" <padillah@hotmail.com> wrote:
| Quote: | "eb7g" <eb7g@shaw.ca> wrote in message
news:huzSe.369600$s54.356645@pd7tw2no...
Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all as
one file per tape.... at about 20 minutes in, the audio started to drift
and by the end of each tape the audio was out of sync almost a full second
of time.
Is this common? How do people without DVgate digitize their audio and keep
the sound in sync? If I digitize in Premiere, as one large file, will the
sound be out of sync as well?
|
The problem often isn't with the equipment, it's with incorrect USER
SETTINGS.
It's reasonably common to see an audio sample rate that's incompatible
with an NLE's sample rate.
If that happens (AND if your software isn't designed to compensate) you
can easily get "audio drift."
The central fact of DV is that it expects an audio sample rate of 48Khz.
If you set your camcorder to something else (32Khz, is a common
camcorder choice (shudder) you'll likely get drift.
Also, if you're working on a 48Khz timeliine and drag a CD clip (the CD
standard is 44.1Khz) into the mix, you can also get audio drift.
(Imagine a band trying to simultaneously march to two different drum
sections, each playing at a different tempo!)
Smart NLE's can correct this on the fly. Inexpensive or free software
might not. If you're getting significant audio drift, the first thing to
do is check all your clips, and if necessary, resample the audio to the
48Khz DV standard.
Good luck. |
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Richard Crowley
Guest
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| Posted:
Wed Sep 07, 2005 10:12 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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"William Davis" wrote ...
| Quote: | The problem often isn't with the equipment, it's with
incorrect USER SETTINGS.
|
Do we even KNOW what equipment eb7g is using?
Dunno how we can determine it isn't the problem? |
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blackburst@aol.com
Guest
|
| Posted:
Thu Sep 08, 2005 1:08 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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eb7g wrote:
| Quote: | Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all
as one file per tape.... at about 20 minutes in, the audio started to
drift and by the end of each tape the audio was out of sync almost a
full second of time.
Is this common? How do people without DVgate digitize their audio and
keep the sound in sync? If I digitize in Premiere, as one large file,
will the sound be out of sync as well?
I would have thought this would have been corrected by now. That
explains why DVgate splits up the video into chunks.
|
I note that no other responders have experienced audio drift. I have -
not in digitizing, but in dubbing from DV tapes to DVD in an OUTBOARD,
STANDALONE recorder. Happens about 50% of the time, in either composite
or firewire. Pisses me off. Other pros may not have experienced it, but
it is a very real problem. |
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William Davis
Guest
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| Posted:
Thu Sep 08, 2005 4:41 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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In article <1126123690.629187.239950@o13g2000cwo.googlegroups.com>,
"blackburst@aol.com" <blackburst@aol.com> wrote:
| Quote: | eb7g wrote:
Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all
as one file per tape.... at about 20 minutes in, the audio started to
drift and by the end of each tape the audio was out of sync almost a
full second of time.
Is this common? How do people without DVgate digitize their audio and
keep the sound in sync? If I digitize in Premiere, as one large file,
will the sound be out of sync as well?
I would have thought this would have been corrected by now. That
explains why DVgate splits up the video into chunks.
I note that no other responders have experienced audio drift. I have -
not in digitizing, but in dubbing from DV tapes to DVD in an OUTBOARD,
STANDALONE recorder. Happens about 50% of the time, in either composite
or firewire. Pisses me off. Other pros may not have experienced it, but
it is a very real problem.
|
Well, outside of sample rate problems it shouldn't be.
I can see where a composite feed could be prone to timing errors - tho
I'd expect a constant offset, rather than progressive "drift." But in a
Firewire transfer, the video and audio information is locked into a
SINGLE multiplexed datastream.
(NOTE: remember that the AUDIO_TS folder on any common DVD is NOT your
DVD's audio! Unless you're one of the .0001% of the planet who messes
with DVD-AUDIO stuff it's useless. The Video_TS VOB files on any DVD
contain all the video AND audio information of your program - in a
single data structure with both video and audio info locked together. No
practical chance to induce drift that isn't already in the original
encoding.)
So again, if your audio drifts, it's likely because you've gotten
something wrong in data rate or perhaps fed the signal out of sync onto
the disc during encoding - because the DVD spec only has one drummer
and the video and audio MUST march to that drummer, in step.
Good luck solving your problems - but again, I'd START looking at the
data rates you've set for your shooting and/or sequence settings. In my
experience if the video and audio streams are ACTUALLY running at two
subtly different rates, it's a sampling rate problem nearly all of the
time.
FWIW. |
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Richard Crowley
Guest
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| Posted:
Thu Sep 08, 2005 4:42 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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blackburst wrote ...
| Quote: | I note that no other responders have experienced audio
drift. I have - not in digitizing, but in dubbing from DV
tapes to DVD in an OUTBOARD, STANDALONE
recorder. Happens about 50% of the time, in either
composite or firewire. Pisses me off. Other pros may
not have experienced it, but it is a very real problem.
|
Is there any pattern to which tapes stay in sync vs. not?
Most us were likely relating our experience with importing
DV footage into computers rather than using a standalone
DVD recorder. It is helpful to disclose exactly what
hardware/software/workflow you are using. |
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blackburst@aol.com
Guest
|
| Posted:
Thu Sep 08, 2005 6:35 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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William Davis wrote:
| Quote: | In article <1126123690.629187.239950@o13g2000cwo.googlegroups.com>,
"blackburst@aol.com" <blackburst@aol.com> wrote:
eb7g wrote:
Hi there,
There used to be the known problem of audio drifting out of sync on long
video files. I've been using Sony's DVgate for the last little while,
which will split the video into 10 minute segments, so I don't get any
drift. But the other day, I digitized 3 miniDV tapes and saved them all
as one file per tape.... at about 20 minutes in, the audio started to
drift and by the end of each tape the audio was out of sync almost a
full second of time.
Is this common? How do people without DVgate digitize their audio and
keep the sound in sync? If I digitize in Premiere, as one large file,
will the sound be out of sync as well?
I would have thought this would have been corrected by now. That
explains why DVgate splits up the video into chunks.
I note that no other responders have experienced audio drift. I have -
not in digitizing, but in dubbing from DV tapes to DVD in an OUTBOARD,
STANDALONE recorder. Happens about 50% of the time, in either composite
or firewire. Pisses me off. Other pros may not have experienced it, but
it is a very real problem.
Well, outside of sample rate problems it shouldn't be.
I can see where a composite feed could be prone to timing errors - tho
I'd expect a constant offset, rather than progressive "drift." But in a
Firewire transfer, the video and audio information is locked into a
SINGLE multiplexed datastream.
(NOTE: remember that the AUDIO_TS folder on any common DVD is NOT your
DVD's audio! Unless you're one of the .0001% of the planet who messes
with DVD-AUDIO stuff it's useless. The Video_TS VOB files on any DVD
contain all the video AND audio information of your program - in a
single data structure with both video and audio info locked together. No
practical chance to induce drift that isn't already in the original
encoding.)
So again, if your audio drifts, it's likely because you've gotten
something wrong in data rate or perhaps fed the signal out of sync onto
the disc during encoding - because the DVD spec only has one drummer
and the video and audio MUST march to that drummer, in step.
Good luck solving your problems - but again, I'd START looking at the
data rates you've set for your shooting and/or sequence settings. In my
experience if the video and audio streams are ACTUALLY running at two
subtly different rates, it's a sampling rate problem nearly all of the
time.
FWIW.
|
In the case of my work set-up (a small TV studio) and my home setup, I
have gone out-of-the-box: No setting of data rates on either camera or
DVD recorder. Straight firewire or comps cables.
The firewire run is very sensitive to any breaks in the "control
track". A slight blip (usually made when a volunteer switches to the
play mode on the camera to check their footage) will cause the audio to
unlock during the dub process.
One unrelated side note re: Katrina:
I've been working on a great historical documentary with a buddy who is
a producer at the PBS affiliate in New Orleans. He was missing for
several days, but I finally got him on his cel. He asked me to look at
satellite photos online to see if his house and station were still
there. I had the sad duty to tell him that both were there, but
underwater. And all the BetaCam master tapes of our project are gone,
as well as all his other work. I presume the station's FCP and Avid
suites are unsalvagable. This tragedy affected a lot of things. I count
my own blessings. |
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blackburst@aol.com
Guest
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| Posted:
Thu Sep 08, 2005 7:01 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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Richard Crowley wrote:
| Quote: | blackburst wrote ...
I note that no other responders have experienced audio
drift. I have - not in digitizing, but in dubbing from DV
tapes to DVD in an OUTBOARD, STANDALONE
recorder. Happens about 50% of the time, in either
composite or firewire. Pisses me off. Other pros may
not have experienced it, but it is a very real problem.
Is there any pattern to which tapes stay in sync vs. not?
Most us were likely relating our experience with importing
DV footage into computers rather than using a standalone
DVD recorder. It is helpful to disclose exactly what
hardware/software/workflow you are using.
|
Sure. I covered this in a thread a few weeks ago: Source is usually a
Panasonic PVGS15 or a later 3 chip model (number forgotten), in both
cases, the camera the tapes were recorded on. The tapes are usually
Fuji.
I record via either firewire or composite, to a GoVideo VR3930 or a
Sony DVD recorder/VCR combo, number forgotten.
No software or converters involved. These are original camera master
tapes dubbed to DVD. For some reason, the audio comes unlocked about
50% of the time. You would think that a simple machine-to-machine dub
would be no problem, but it is. A big problem. |
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Richard Crowley
Guest
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| Posted:
Fri Sep 09, 2005 4:41 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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blackburst wrote ...
| Quote: | I record via either firewire or composite, to a GoVideo VR3930
or a Sony DVD recorder/VCR combo, number forgotten.
|
If you are getting A\V sync problems with the analog inputs,
then your DVD recorder is broken. Can't think of any other
possible explanation. |
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blackburst@aol.com
Guest
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| Posted:
Sat Oct 01, 2005 6:54 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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I have the answer, finally.
I just bought 2 Sony DSR45 DVCAM decks. The manual clearly states that
while DVCAM audio is digitally locked to the video, DV audio is NOT
locked to the video and can cause drift. I'll post the section Monday
when I have time. |
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Richard Crowley
Guest
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| Posted:
Sat Oct 01, 2005 10:12 pm Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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blackburst wrote ...
| Quote: | I have the answer, finally.
I just bought 2 Sony DSR45 DVCAM decks. The manual clearly states that
while DVCAM audio is digitally locked to the video, DV audio is NOT
locked to the video and can cause drift. I'll post the section Monday
when I have time.
|
I've never seen a credible anecdote of "audio drift" caused
by the DV format. If you are having a problem with drift,
it is NOT because the audio on the tape is "unlocked".
All you have to do to check this is simply play the tape and
view the output of the camcorder. Does the audio "drift"?
No, I didn't think so.
I regularly use both mini-DV and DVCAM equipment
interchangably. I have never seen any difference in how
they handle video/audio sync. |
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blackburst@aol.com
Guest
|
| Posted:
Sun Oct 02, 2005 12:04 am Post subject:
Re: What is the latest word on Audio Drift in digitizing vid |
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Richard Crowley wrote:
| Quote: | blackburst wrote ...
I have the answer, finally.
I just bought 2 Sony DSR45 DVCAM decks. The manual clearly states that
while DVCAM audio is digitally locked to the video, DV audio is NOT
locked to the video and can cause drift. I'll post the section Monday
when I have time.
I've never seen a credible anecdote of "audio drift" caused
by the DV format. If you are having a problem with drift,
it is NOT because the audio on the tape is "unlocked".
All you have to do to check this is simply play the tape and
view the output of the camcorder. Does the audio "drift"?
No, I didn't think so.
|
Well, I do have several credible cases of such drift when dubbing. And
I work in a TV station and teach TV production in a college, so I'm no
neophyte.
| Quote: |
I regularly use both mini-DV and DVCAM equipment
interchangably. I have never seen any difference in how
they handle video/audio sync.
|
I'm just quoting what the manual says. I'll give a direct quote on Mon. |
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