PDA

View Full Version : MJPEG Sound Lag



RS-Colo
07-30-2009, 12:27 PM
I always seem to start my new threads on this site with "If this topic has already been covered, I apologize. Please point me to the right place". Consider this thread to have started the same.

When I record video in HD mode (MJPEG 720/60p) the sound lags behind over time. I understand this has something to do with the recording being 30fps and the standard being 29.97fps. But I have two questions. First, arn't I recording 60fps? Actually that question is more for curiosity. The main question is what can I do about the lag? Is it something that standard editing will correct for? Having sound and image not sinc up seems pretty serious. I can't believe the only solution is to record in AVCHD and then transcode for editing.

AdrianF
07-30-2009, 02:31 PM
The modes are PJPEG 720 30 or AVCHD 720 60. Are you trying to bring the footage into a 720 60 timeline for playback and then getting problems? I have the EU version 25/50, but PJPEG is the same @ 30p. One thing that could also cause sync problems is the sample rate being 16khz in this mode rather than the standard 48/44.1, so I wonder if this could be causing you problems in your NLE/Player?

RS-Colo
07-30-2009, 03:19 PM
I was wrong about the 60p, it is 30p. My camera and PC software are both NTSC. I don't know what PJPEG is. My manual calls it MJPEG. In any case it is HD mode on the camera. I am just playing the clip on my PC as recorded in the camera. I have made no modifications to the .mov file. I was also backwards about the lag. The video lags further behind as the clip plays. In other words, the audio finishes sooner than the video. The length of time it finishes early is larger as the clip is longer. I thought it had something to do with the 30fps versus the standard 29.97fps. But I may be wrong about this being the cause. But the lag is clearly there. I am trying to find out if there is a simple way to get rid of the lag. Videos that have this lag will not be anything I, or anyone else, will want to watch.

Ozpeter
07-30-2009, 04:44 PM
What happens if you play the clip IN the camera? What are you using to play the clip on the PC?

RS-Colo
07-30-2009, 06:13 PM
It plays fine in the camera. I'm using ThumbsPlus to play the video. It plays everything else I through at it. I tried Windows Media Player 11, but it doesn't recognize .mov files.

RS-Colo
07-30-2009, 06:24 PM
OK, you guys are great. I just tested with Nero ShowTime and it worked fine. So I went back and tried ThumbsPlus again and it worked fine. Before it was very consistant. The longer the clip the sooner the sound stopped. It was some consistant percent of the total. How did you guys fix it remotely?

As Emily LaTilla used to say, "Oh that's different. Never mind."

Sorry for the run-around.