Do video files contain VBR audio that will affect sequencing

[LightORamaJohn]

This sub-thread was moved to its own topic per Orville's request because it is important and needs to be resolved.

A problem occurs in the Sequence Editor when sequencing audio files that are encoded using VBR (Variable Bit Rate.) Windows Media Player (WMP) is used to play the audio. When you play an arbitrary section of your sequence, for example, Play -> Play Range -> Selection, WMP has to compute the position in the audio file. This is an approximation for VBR audio files. Because it is an approximation, it will most probably not line up with the position WMP will be at when playing the entire sequence from the beginning. This becomes more obvious the further you are into the audio file. This is a long time nuisance encountered with VBR MP3 files, it may also exist with the audio of video files, which is what Jeff brings up below.

Jeff Millard wrote:

So we're pretty sure that the reason the guy had problems with his timing moving too slow was due to VBR media files. Which begs the question, can the audio in video files also be VBR... or maybe the video compression could be incompatable... and toast the synchronization between sound and sequence editor? I want to eventually include a big TV with Santa in the window, but want to be sure this issue doesn't foul it all up before I settle on a specific type of file.

Jeff

GoofyGuy wrote:

Jeff Millard wrote:

So we're pretty sure that the reason the guy had problems with his timing moving too slow was due to VBR media files. Which begs the question, can the audio in video files also be VBR... or maybe the video compression could be incompatable... and toast the synchronization between sound and sequence editor? I want to eventually include a big TV with Santa in the window, but want to be sure this issue doesn't foul it all up before I settle on a specific type of file.

Jeff

Holy crud I didnt think of that Jeff.  That makes a great point about video if you have a VBR in a video?  Ive seen those Santa projections and thought about one on my house but it just wouldnt fit the display.  It wouldnt be overly difficult to strip the audio with some software, run it through audacity, then stitch them back together but I never thought about video needing this.

Steven wrote:

Jeff Millard wrote:

can the audio in video files also be VBR...

MP3 is short for MPEG Audio Layer III, meaning the audio part of a MPEG video file is an MP3 stream.  Since an MP3 stream can be VBR, I would bet that it could also be VBR when part of an MPEG video.

An AVI video file is a container that can contain an MPEG video (which in turn can contain an MP3 audio track).

So, I would say the answer to your question is "yes."

Jeff Millard wrote:

We've got to be very carful hijacking the subject like this guys...

I'm not up on all this compression, and wonder what the bulletproof answer is. For audio it seems to be WAV. For video...? I've no idea.

Jeff

Orville wrote:

Jeff Millard wrote:

We've got to be very carful hijacking the subject like this guys...

I'm not up on all this compression, and wonder what the bulletproof answer is. For audio it seems to be WAV. For video...? I've no idea.

Jeff

Depends on whether your video editing software allows for various sound compression object Jeff.   I actually strip the sounds from videos I create and put in an CBR MP3 track in it's place.

I do this by saving ONLY the audio portion of the video, if the track was already embedded, it can still be stripped out seperately and put back in, again, depends on your video editor.

I do this all the time for the on-line videos I create that the camera records the track, which is usually quite horrible in most cases, strip the audio and then add in an MP3 CBR audio track to the video and save it out in any format my video editor uses, MPG, AVI, RA, etc.

It's not difficult to do, but can get time consuming depending on how long the audio track actually is.


EDIT: p.s. maybe this would be a good one to open up a new thread on, as I'm sure others have not thought about this with Video options in their displays either.

[Guest guest]

Glad to see LightORamaJohn moved this thread to it's own area.

Thanks John!

[LightORamaJohn]

Jeff Millard wrote:

...and now it makes absolutely no sense, has no point and will eventually fall into the void of meaningless posts taking up space somewhere on the internet. I'm sorry I asked a question. Please feel free to ignore me in the future.
Jeff

I am very sorry Jeff, you are right. When you understand the context, you forget that others may not. I'll be more careful in the future. I have added a detailed description of the problem to the first post. Hopefully, it's no too late. The continued inconvenience this causes LOR in support is second only to the problem this causes users. We think there is a solution, but there's no way we will be able to spare the time this year to test it.