Sync problem in rendered mp4 output.

wm_b wrote on 1/26/2009, 2:25 PM
I'm having a problem with audio being out of sync with video when rendering to MP4 using the MainConcept AVC codec. I had similar results with the Sony AVC codec.

I am doing some promotional material for a guitarist who has just released a record of speedy Joe Satriani instumental type stuff. I shot a video of him playing one of the songs, synced the camera audio with the multi track and rendered the performance so he could use it on his website. The rendered output isn't in sync but the playback on the computer is. The camera audio has the same problem if I render with it.

If I render a small portion or the whole thing it's also not in sync. The audio is ahead of the video slightly. I know I can move the audio around in Vegas but this just seems like the wrong solution.

Is this a normal thing for audio and video to be out of sync in mp4's? I haven't noticed this before. Is there a better delivery format for someone to post something on Youtube or other web uses?

Thanks for any ideas.

William

Comments

Zelkien69 wrote on 1/26/2009, 2:53 PM
Depending on how you captured the audio versus video, you may be noticing a slight drift in the audio's time clock (or vice versa). You may need to stretch or compress the audio to match the video. I use a Zoom H2 and H4 and always have to adjust it's sync versus my Canon XH-A1's.

and just in case it's something else, have you rendered to other formats? I've never seen a problem with just mp4.
wm_b wrote on 1/26/2009, 3:18 PM
The camera is a Canon HF100 and the audio is being recorded in Sonar 8 with the system clocked with an Apogee big ben. The audio doesn't drift in and out of sync between the camera and the multi track. The rendered output is always out of sync with the video being slightly behind the audio. We're going to try another performance tonight and I'm going to try printing audio from the console right into the camera even though I don't think it will make a difference.

I haven't tried another format yet.