Redubbed audio/music track

[techmot]

This is really more to do with editing than capturing but thought post here anyway.

I've been doing some editing in Adobe Premiere of a TV show by redubbing the original music that was used in its original broadcast. In the DVD version the music in one scene was replaced with a different song, so I thought I would have a go at using an original broadcast recording I have (which I captured in Virtualdub from a VHS tape) that includes the original music from the TV broadcast. The other video I used the DVD version which had better video quality but uses a cover song. I have used Adobe Premiere many times and I'm quite familiar with the basics of video editing and trimming etc, so I though the redubbing of the music would be a piece of cake, but I soon discovered it wasn't. On the video timeline I unlinked the audio so that I could use the razor to cut the audio at the point where the music started and ended, leaving a gap where the audio was. I then imported the captured VHS file which had the original music that I wanted to add, used the In and Out trimmer and dragged just the audio to where the gap was on the timeline, but for some reason the audio didn't fill the space but went over by a few seconds. I checked the length of both files from the points where the music started and ended but they had different running lengths; the DVD version ran at 2 mins 12 seconds and the TV broadcast which I captured in Vdub ran at 2 mins 17 seconds, yet both are exactly the same scene and haven't been cut. I'm guessing one version is running at a different speed than the other., but visually there's no sign of the video appearing faster or slower. Both files (according to the file data) are at 25fps, so I wouldn't have thought different framerates where the cause. Stranger still though, that during the first couple of seconds with the added music dubbed over where the other music track was, the audio seems fine and in sync with the video, but a few seconds later before the scene and music come to end I noticed the audio is further ahead than the video as if the speed is different and making it appear as if it's out of sync.

I have done several edits like this with other episodes to redub the original music and they have all been fine.

[DB83]

Can I, firstly, ask how you got the dvd video and audio in to the Premiere time-line.

Many, many moons ago I did a variation on this which took video captured from official VHS and merged it with video privately shot (which had all the bits cut from the official release). Basically, I had to line up the video on a frame by frame basis so that what was not on the VHS was then incorporated in to the final video (Although the private audio was not as good as even the VHS it was used throughout so there would be no obvious 'spikes')


So what I am saying is it may be prudent to line up the video frames first (including some before the proposed substitution) before you cut any out. And with the frames lined up it would be easier to see if any have been duplicated on from the tv recording/capture. And that is possibly what has happened inasmuch that the vdub capture is not perfect (which, itself, is quite possible in the light of your previous topics)

[Brad]

The difference between 2m12 and 2m17 is 4%, which happens to be the difference between a "PAL speedup" conversion and a film source.

It would help if you uploaded samples, but it sounds like the DVD version went from 24 to 25 fps via speedup while the TV broadcast was converted to 25 fps by one of the methods that doesn't change duration (frame/field repetition or blending).

Since you only care about the audio, one solution is to speed up your TV track by about 4.2 or 4.3%. You'd also have to figure out whether or not to apply pitch correction, depending on whether the DVD used it.

[techmot]

The difference between 2m12 and 2m17 is 4%, which happens to be the difference between a "PAL speedup" conversion and a film source.

It would help if you uploaded samples, but it sounds like the DVD version went from 24 to 25 fps via speedup while the TV broadcast was converted to 25 fps by one of the methods that doesn't change duration (frame/field repetition or blending).

Since you only care about the audio, one solution is to speed up your TV track by about 4.2 or 4.3%. You'd also have to figure out whether or not to apply pitch correction, depending on whether the DVD used it.

I think you could be right about the framerate having originally being at 24fps and then was converted to 25fps, that may explain the difference in length to the TV VHS captured I did in Vdub. I went into Premiere again and trimmed down both files to the scene in question, trimmed both files, then exported them as H.264 files but changed both to 24fps. But the files still read at different lengths despite being exactly the same. I imported them both into the Premiere timeline and one was again shorter than the other. Changing the speed of the file or the pitch would probably just shorten or lengthen the clip. I wouldn't have though that one file being at 352x240 and the other at 576x432 would have any affect on the duration.

[techmot]

Only just realised that the reason for the difference in lengths is because the DVD version has had a few seconds cut. I hadn't noticed before until I imported both files into VSDC editor, overlayed both files above each and used the opacity level to try and determine where there may've been a difference in the framerate, but I noticed that part way through the scene that the DVD had been trimmed by about 4 seconds making the length appear shorter than the TV recording I have. Why the DVD version has been cut I do not know, but I suspect due to the use of the cover song which may've been too short for the original scene so they probably trimmed a few seconds off hoping noone would notice. I hate it when they do that. Alot of TV shows that have been released on DVD have had numerous changes made, either music changes due to rights issues or scenes trimmed or even whole scenes cut completely, sometimes for no apparent reason. That's why I think it's important to have an early broadcast recording your fav show on VHS, because there's always something that is changed for home video release.

[DB83]

Well you could get confirmation if you were to upload both clips as attachments - no editing or conversion pls

I am rather inclined to agree with Brad. It seems rather too much of a coincidence that the time difference is the same as the effect of a 24 fps original speed-up to 25 fps. I trust you do understand what PAL speed-up is. If not check PAL dvds you own to the quoted runtime on IMDB.


It has got more confusing lately since dvds can also show the correct run time due to methods beyond simple speed-up. Even tv companies have more sophisticated equipment at their disposal other than basic tele-cine.


I am still rather concerned that you do have two samples at 25 fps given the odd frame sizes you chose to capture at. But the samples will go a long way to settle that.

[hech54]

You're not trying WKRP are you?