3 Replies Latest reply on Sep 3, 2012 12:48 PM by dietermoreno

Confused how Key frame velocity works--want to make video faster

How do I make the video faster accurate to the hundredth of a second in AAE CS4?

I have taken audio out of a video by converting the avi into wav.

When I edited the audio in Audacity to improve the quality of the audio, in appears to have compressed the time of the audio track by about 0.8 seconds in a 4 minute 10.2 second long video.

When I add video and the edited audio onto the time line of a video editor that is not AAE CS4 that can support clips longer than 30 seconds and mute the video audio so can hear the new edited audio, it is extremely anoying that the new edited audio is out of sync with the video.

So I surmised that the solution to my problem would be to make the video faster in AAE CS4.  So each 30 second long clip I would make faster by (0.8 seconds)/(250.2 seconds/30 second clip) = 0.0585 seconds

However, when in AAE CS4 when I set a keyframe at the end of the video clip at time 30.00 seconds and drag the key frame to the left to make the video faster, the greatest accuracy that I can shorten the video by is from 30.00 seconds to 29.29 seconds, when I need to be accurate to the hundreth of a second.

What do I do?

EDIT: So if in the animation menu, I click on "Key frame velocity" and set it to a key frame velocity of "1.0585 seconds/second", would that speed up my 30 second clip by 0.0585 seconds?

EDIT 2: So more over, I am confused with how key frame velocity works since the changes can not be seen with the naked eye in trial and error on only a 30 second clip but are obvious on a 4 minute long video but AAE CS4 only supports 30 second clips.

So I mean to make it faster do I want to make the key frame velocity a higher decimal value than "1.00 seconds/second" to "1.0585 seconds/second", or do I want to make the key frame velocity a lower decimal value from "1.00 seconds/second" to "0.9415 seconds/second"?

And is it important that I also set a decimal value for "out going velocity" not just "in going velocity"?

And what does "influence" mean on the key frame velocity menu?

And what does "continuous" mean on the key frame velocity menu?

• 1. Re: Confused how Key frame velocity works--want to make video faster

Why not simply resample your audio and stretch it back to the original length? Seriously, what you are doing is like trying to re-use a crooked nail and spending hours on straightening it. You're looking for the solution on the wrong end. And depending on what you did to your audio, you may have simply done it the wrong way. I couldn't imagine why any audio editor on this planet would shorten a file unless you tell it to...

Mylenium

• 2. Re: Confused how Key frame velocity works--want to make video faster

When I add video and the edited audio onto the time line of a video editor that is not AAE CS4 that can support clips longer than 30 seconds and mute the video audio so can hear the new edited audio, it is extremely anoying that the new edited audio is out of sync with the video.

I'm not exactly sure what you mean that CS4 Cannot support clips longer than 30 seconds. You can change the length of an audio preview by editing the preferences. You can change the length of a composition in the composition settings. You can change the length of the available ram preview by previewing at a lower resolution or by skipping frames or by adding more ram. I've been cutting (editing) for more than 40 years and I can tell you that it's nearly impossible to detect audio that was slipping by 0.0585 seconds in 30 seconds unless there's a specific event at the end of that time. A frame is only 0.0333667 seconds long. Is your audio really off by less than 2 frames in 30 seconds.

Your audio probably did not change length. The only way to change the length of the audio is to resample it. You're probably not interpreting the timecode correctly.

Timecode does not display in tenths of a second, it displays in Hours;Minutes;Seconds;Frames

Non-Drop Frame Timecode displays time that is actually shorter than the real time because it counts by incrementing frames 30 times for every minute displayed. For Four Minutes ten point 2 seconds at 29.97 fps it is 7498.494, make that 7498 frames because there's no such thing as a half a frame.

7498 frames displays as 0;04;10;05 in Non-Drop Frame timecode displays and as 0:10:09:27 in Drop Frame timecode. Changing the timecode display from Drop Frame to Non-Drop Frame doesn't change the length of the clip by 8 frames. It doesn't shorten the clip. The clip still takes exactly, well exactly to the nearest whole frame, four minutes and ten point 2 seconds to playback. BTW, even though the numbers are different the same holds true if your footage is 24p video because 24p video doesn't playback at 24 fps, it plays back at 23.976 fps.

The way to tell if your audio has really changed length is to turn on both tracks and preview them together. Just go to the last 5 seconds of the comp and press the . key on the numeric keypad to preview audio. If you actually changed the length of the audio somehow you'll hear it in the audio preview.

If your audio did change length go back to your Audacity project and re-render the audio making sure that the settings match the original source. Make sure you render to .wav file. Do not render to MP3 or any other compressed format for production work.

If a ram preview is out of sync then you've probably got ram / resolution / drive speed playback issues.

I hope this helps.

• 3. Re: Confused how Key frame velocity works--want to make video faster

I compared side by side my original uneditted video side by side with the edited audio and I found that the audio waveforms match perfectly in the timeline, but the one compiled of 30 second video clips edited in AAE CS4 is out of sync, so the problem is not with the audio editing  or the video source, but the problem is with my video editting, probably misinterpretting the time codes causing me to not accurately clip it to exactly 30.00 seconds, or maybe the RAM preview was not accurate bc not enough RAM bc I only have 3 GB RAM.

So I will start over the video editing being sure to be accurate to frames not times, bc there is not such thing as "0.585 frames".

EDIT: Oh okay, now I realized that After Effects is not just an effects program, but can also edit a full video up to 3 hrs long simply by changing the default durration from 30 seconds to my duration of my video and then I don't have to worry about my human errors misinterpretting time codes when cutting clips and recombining clips.