AC3 FPS problem after capturing - Please help!!

[bodybobo]

Hey, okay so I have a pretty big problem.
My capture card only records in 29.970 fps for some reason, not 29.976 but 29.970 and this makes the audio on files go out of sync, now I need a way to convert the ac3s to 29.970 from 29.976 but there is not a single software, gui or command line that seems to allow me to do so. Does anyone have ANY suggestions? I've tried absolutely everything.

[poisondeathray]

Why is this a problem ?

29.97 is standard (30000/1001 to be more precise). 29.976 is not standard. Why would you want 29.976 ?

Also, audio doesn't have a FPS . If something is out of sync, you can stretch/shrink the audio duration in an audio editor, or change the fps of the video


There can be other reasons for your sync issues e.g. dropped frames, maybe from too slow of a hardware setup

[bodybobo]

I don't want 29.976, I want 29.970, the audio is currently in 29.976. I appreciate the feedback but stretching/shrinking demands too much work to get it precise, I tried Ac3Machine but that just gave me white noise. This capture card has been nothing but a nightmare so while I appreciate all suggestions, I'm mainly looking for a way to just change the fps on the audio.

[poisondeathray]

I don't want 29.976, I want 29.970, the audio is currently in 29.976. I appreciate the feedback but stretching/shrinking demands too much work to get it precise, I tried Ac3Machine but that just gave me white noise. This capture card has been nothing but a nightmare so while I appreciate all suggestions, I'm mainly looking for a way to just change the fps on the audio.

How do you know the audio is 29.976? There is no fps on audio.

You stretch/shrink by the ratio of the fraction difference between audio & video. (Enter the value in an audio editor). There is no guesswork if you know exact duration in ms of video & audio .

If the sync issues were due to one of the other reasons (like dropped frames), it won't help to do this

[bodybobo]

Because I tried using the audio from a DVD as a source and that audio matched up with the one I recorded, and the DVD was in 29.976 fps.

[poisondeathray]

Because I tried using the audio from a DVD as a source and that audio matched up with the one I recorded, and the DVD was in 29.976 fps.

Unless that's a typo, it can't be.

NTSC DVD-video doesn't support 29.976 (and that's video, not audio, because audio doesn't have a "frame rate")

[bodybobo]

Okay, let's start from the beginning I would like an ac3 file to go 00.006fps slower than it currently is, does anyone know how to do this as eac3to and ac3machine won't let me - maybe there is a way to calculate how long 00.006fps is in seconds and then stretch the audio based on that information?

[poisondeathray]

Is it progressively out of sync? in sync in the begginnig, then gets worse and worse until the end ?

Lets' assume your values are correct . You would change the speed by the fraction 29.97/29.976 . or 0.9997998.....

E.g. in audacity you use effect=>change speed and would enter 99.97998... because it's expressed in percentage of speed , not decimal

But I'm still questioning how you got those values , and how "correct" they are

It's actually easier to change video fps. Depending on the video type/format, you can often do it without re-encoding

[bodybobo]

Thanks I'll try it and let u know how it works out, yes it is progressively out of sync btw =)

[bodybobo]

Hmm 99.97998 made the file waaaaaay too short, are u sure this is the correct setting I should use? It should be maybe around 20-30 seconds shorter than it is, this made it more like 40 minutes shorter.

[poisondeathray]

Sorry , you are right. It's expressed as "percent change", not "percentage of" .

100 - 99.97998 = 0.02002

So it would be negative 0.02002 if you are slowing it

[manono]

Because I tried using the audio from a DVD as a source and that audio matched up with the one I recorded, and the DVD was in 29.976 fps.

I hope stretching the audio works out for you but you've given out so much incorrect information that if it does, it'll just be a coincidence. Number one on the list is your claim above that your NTSC DVD outputs 29.976fps. I think you're getting the '976' from the frequent 23.976 framerate.

Your audio is not going out-of-synch because it's not being capped at 29.976fps. I don't doubt it's going out-of-synch, but that's not the reason. And you repeatedly spouting nonsense isn't going to gain you any fans.