OT: FX1--no audio first 4 frames!

riredale wrote on 4/2/2006, 4:53 PM
Has anybody else noticed that m2t files produced by the Sony FX1 HDV camcorder have muted audio for the first four frames, or about 130ms? It seems consistent no matter whether I capture the m2t file via Vegas or HDVSplit. If I make a GearShift proxy and if I load that proxy into Vegas4 I see the same thing. Since I've used Vegas4 for many projects and it has been very consistent, I assume that the idiosyncrasy lies with the FX1 and probably also with the Z1.

The audio track seems to be about in sync with the video. I use the term "about" because the audio from a clip seems to continue for about a half-frame past a video scene change.

All this means to me is that I can't use the first few frames of any HDV clip if I'm using the audio on the miniDV tape, so even though I'd rather have it behave more like DV, it's just one more thing to be aware of when assembling a project.

Comments

Serena wrote on 4/2/2006, 6:08 PM
I haven't seen this with my FX1E. Do you find this also when viewing on camera?
riredale wrote on 4/2/2006, 10:19 PM
Not sure I know what you mean. When I record to tape, it takes a short moment to get the red REC in the viewfinder, but I assume that's just because of all the MPEG2 processing involved.

Again, it's not that big a deal, since clips are usually cut down on both ends anyway, but only today did I notice that the first 4 frames (@ 29.97fps) had muted audio.
Serena wrote on 4/3/2006, 1:13 AM
I meant that if you play your tapes in your camera do you notice audio pauses between clips. This would be easily noticable. I don't get this in my audio.
riredale wrote on 4/3/2006, 9:12 AM
Good point. I had some time this morning to carefully listen to a few minute's worth of HDV video, and sure enough, there's that "blip" at the beginning of each clip.

I did a follow-on test where I pointed the camera at my PC and recorded 5 second's worth of video and audio (fan and hard drive noise, mostly), hit "stop" and then began recording again after maybe 5 seconds of stopping. I did this multiple times.

Then I repeated the above test, but this time recording in DV mode.

On playback, the difference was obvious. Each HDV clip's audio was definitely separated from audio before by a very brief gap or muting. In DV mode, by contrast, the multiple clips almost could not be distinguished from each other; each audio portion perfectly butted up against the next one.

Granted, it's only about 1/7th of a second of silence at the beginning of each clip, but that's enough to notice, and it means I need to trim the first 4 frames of every HDV clip I use.

Even so, as I've indicated earlier, this HDV stuff is really cool, and I plan to shoot in this format for all future projects, including those intended for SD results.
Spot|DSE wrote on 4/3/2006, 11:02 AM
Does the FX1 have quick rec on it? I don't believe it does, but if it does, you might want to enable it.
riredale wrote on 4/3/2006, 11:32 AM
Nope, I don't see any option for "quick record" in any of the menus or in the manual.
johnmeyer wrote on 4/3/2006, 11:36 AM
According to this:

http://www.advance-pro.com/downloads/whatsnew/Consumer%20-%20Pro%20Comparison.pdf

the FX1 does not have quick record; the Z1 does. However, if you stop and then re-start within a minute or so, my limited experience with the FX1 is that it restarts very quickly. In your test, did you re-start the camera within just a few seconds?

I happen to have a few m2t files lying around from an earlier shoot and just put them on the 6.0d timeline. This was from a stage production, and I started the camera just as the lights went down, so there is lots of chatter and background noise. It starts at frame 1.

I purchased my FX1 around the first of the year. It seems we are still getting stories from different people about the FX1, where some have a certain problem and others don't. I am still wondering if this could be due to firmware variations, but I still haven't found any site that describes how to display the firmware version. If anyone finds out how to do that, I think it would sure help tracking down some of these issues.
riredale wrote on 4/3/2006, 4:55 PM
This camera was bought in January of this year, so it's about the same vintage.

When I did my little test earlier today, I waited about 30 seconds between takes so that the camera would have time to do whatever it had to do when stopping the transport.

I would love to see a service manual or a back door into the firmware. I'm very happy with the camera, which appears to work perfectly otherwise.
Serena wrote on 4/3/2006, 5:41 PM
You will expect to hear a blip at the start of each clip (same as you will for a sharp cut in the audio timeline). I would expect you to notice 4 frames of silence as that rather than as a transient. This is a different issue to lag between button push and camera starting to record. Certainly your 4 frames silence isn't something I see on my timeline (using Cineform intermediates) and I just played some camera tapes to confirm that there is no silence at the start of my clips.

EDIT: I note that you're using Vegas 4. I think this was an issue prior to V6 (nothing to do with the camera).