Audio drift Sony vegas pro 12
- Thread starter mrpink89
- Start date
From what are you experiencing drift? I assume this comes from something like DSLR footage and audio from a separate recorder, but specific information would help. And how bad is the drift? After what amount of time are you experiencing it on any given clip?
You still didn't answer AcousticAl's questions.
1. Were you using a separate recorder?
2. How did you import the footage? (Both camera and audio)
3. How bad is the drift?
4. Is it simply out of sync, or does it start in sync and then drift?
1. Were you using a separate recorder?
2. How did you import the footage? (Both camera and audio)
3. How bad is the drift?
4. Is it simply out of sync, or does it start in sync and then drift?
If it starts in synch and then moves out, you may have a problem with audio timecode. Yes, I know a second is always a second, but I have seen clips getting flagged at the wrong "timecode."
Consumer and prosumer devices are nowhere near as precise - time wise - as professional gear. The only way to insure absolute locked sync is to use a common time code for all devices on the set, which is usually beyond the budgetary reach of most indie filmmakers.
Another possibility is a frame rate conflict - drop vs. non-drop, for example.
Actually, if you're in North America, unless you are working on a theatrical feature film (at 24fps "film speed"), then a second is never a second! SD and HD video runs at "video speed" in North America. SD is 30fps played 0.1% slower (which results in an actual speed of 29.97fps) and HD is 24fps played 0.1% slower (which results in an actual speed of 23.976fps). A second of timecode in either of these video speeds does not therefore equal a second of real time (it's 0.1% slower)! Try it for yourself, run timecode on your NLE and time it with a stopwatch; after exactly 1 hour of timecode your stopwatch will show about 1 hour 4 seconds.
Drift problems (due to timecode/frame rates) are always a video issue rather than an audio issue because audio is not played back in frames, the playback rate of audio is defined by it's sample rate, which for film and TV is always 48,000 samples per second (of real time) regardless of the time-code or frame rate. There have been issues with some NLEs (most notably FCP7), when editing at video speed they will sometimes try to slow down the audio by 0.1% to match the video speed. Of course, if you've recorded your footage at video speed and you play it back at video speed there is no need to slow the audio down and if you (or your NLE) does slow it down, it will drift (by about 4 seconds an hour).
On top of this there is the drift problem mentioned by Alcove, which is: Even if we are talking about real time (rather than timecode), a second according to the clock inside your camera is never going to precisely agree with a second according to the clock inside the digital converters of your recording device. So over time you will get drift and as Alcove states, the only way to avoid this is for the camera and audio recorder to both use the same clock rather than relying on two different clocks.
To the OP: There are a number of different reasons why drift occurs, each of which produce different amounts of drift and each of which requires a different solution. So unless you give us the exact details of the drift you are experiencing we cannot workout what's causing the drift, what the cure is (if there is a cure) and whether or not Vegas is capable of that cure.
G