24p music video falling out of sync. GH2

T

tylerindo1

Carbonite Member
Shot with a panny gh2 in 24p, notice the song falls out of sync 1 or 2 frames every few minutes. I've tried the avchd preset, the dslr preset with 24p mode, and even changed the pulldown method but to no avail....what am i doing wrong?
 
Jim Simon said:
Are you saying the audio recorded with the video in the same clip does not stay in sync?
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Hi, yes the live recording falls out of sync with the same cd track on timelime...i ripped the song from cda file someine said its probably a matter of converting THE song to 48khz but I ripped as wave so pretty sure thats not it...ill test that theory tonite
 
Do you loose sync randomly, or is it a consistent x number of frames every y number of minutes ?

I have found that most non-pro recorders / cameras will drift over a longer period of time ( say more than 10 minutes ), which is fine if the drift is consistent, as consistent drift can easily be corrected with a good audio editor.

i.e. My Olympus LS-11 recorder is always out 8 frames every hour, so I correct this by using the "TimeWarp" function in the low cost GoldWave audio editor, which does a great job of fixing this.
 
i tried converting to 48khz from 41khz and its still drifting 2 to 3 frames per 3 minutes....what settings do you use with the time warp function>?
 
tylerindo1 said:
i tried converting to 48khz from 41khz and its still drifting 2 to 3 frames per 3 minutes....what settings do you use with the time warp function>?
Click to expand...

Here's what I do:

1- Bring the audio and video clips in to my editor, then sync the clips at the beginning and make a cut so they both match at the start. This means cutting off the extra audio that proceeds the video clip.

2- Next sync the clips at the end and make a cut so they both match at the end. This means cutting off the extra audio the follows the video clip. With an hour long video clip that was shot at 24P I end up with an audio clip that is 8 frames longer. ( it will vary between different cameras and audio recorders )

3- Next I export the trimmed audio clip ( the one that is too long ) to a new audio file, and I note the full length of the video clip that I am trying to match the audio with. For example, lets say the video clip is 57:23:15, or 57 minutes, 23 seconds and 15 frames, which equates to 57 minutes, 23 seconds, and 0.6258 seconds. ( 15 frames divided by 23.97 = 0.6258 )

4- Next I load the new exported audio file in to the GoldWave audio editor, select the entire audio file and click on the "TimeWarp" function under the Effect menu. When the "TimeWarp" dialog opens I click on "Length" and then type in the time I want the finished audio clip to match, which in this example would be 57.23.6258. With the Algorithm set to the default setting of "Rate", I then click the "OK" button and in less than a minute my audio track has been resampled to the time I entered. I then click on the "Save" icon and quit the GoldWave editor.

5- When I bring the new "timed" audio file back in to my video editor and match up the synch with my video clip, the synch should now match for the entire video clip.

...It may take a little practice to get this process down, but once you do it's very quick to re-time just about any audio file to any video clip as long as the synch drift is NOT random. If the synch drift is random, then you are pretty much screwed as it will be next to impossible to properly correct this. Fortunately most digital audio and video gear on the market today shows a very consistent linear drift that is easy to correct.
 
Sheesh, Dingos's method sounds too complicated.

Just sync up the beginning of both tracks and adjust the speed of the audio clip until it also syncs at the end. The difference will probably not be significant enough to cause noticeable pitch shift.
 
tylerindo1 said:
Hi, yes the live recording falls out of sync with the same cd track on timelime...i ripped the song from cda file someine said its probably a matter of converting THE song to 48khz but I ripped as wave so pretty sure thats not it...ill test that theory tonite
Click to expand...

Uh? What to you mean you 'ripped the song from a CDA file?

If you are comparing a live performance to a 'cd' recording, there are often differences between 'timing' on live compared to recorded... most 'rock' musicians are not all that 'timing oriented'... and even the pros have differences having spent years listening to a metronome.... The differences can range from basic beat, to changes in speed through out the piece...

Often for 'music videos' there will be a sound system playing the 'recorded' track, and the performers lipsyncing to the song as it is played.

Taking a wild recording from a concert then matching it up with the 'recorded' version is... well... problematic...

Well, unless the 'recorded' version is the live concert version, just recorded on better equipment... even then there may be shifts due to slight timing differences between the equipment, unless everyone has 'sync'ed' up via some sort of master clock signal.
 
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Jim Simon said:
Sheesh, Dingos's method sounds too complicated.

Just sync up the beginning of both tracks and adjust the speed of the audio clip until it also syncs at the end. The difference will probably not be significant enough to cause noticeable pitch shift.
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With longer clips you may need to adjust the audio speed by 0.01 of a percent ( 0.0001 of the total time ) to get the timing to match, how many NLEs can do this ?
 
so the live audio, aka the playack on setis running a few frames faster per 3 minutes of the song. i've sped the song up in premiere to about 100.04% and it seems to be synced up to where it will stay in sync throughout for the most part but it's still falling out of sync. by 1 frame..
 
how many NLEs can do this ?
Click to expand...

Don't know how many, but Premiere Pro can. I do it all the time. My separately recorded audio is off by only .04%, so I adjust the speed of the audio clip by that much and it syncs up for the duration.
 
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