20 milliseconds delay

[F31911627hlee]

Hi, friends. I use Premiere to synchronize audio and video (.avi) and I love this software, but there's a thing bothering me. I noted the sometimes a frame suffers a time variation of 20 milliseconds. The difference is always 20 milliseconds! For example: Before to repair the audio synchronization, I select a frame that begins at 00:03:11:43200. After I synchronize that and several others parts, I return to "frame 00:03:11:43200" in order to see it again, but, now, the same frame begins at 00:03:11:41200! I would like to know why it happens and if is there a way to avoid that variation, since it destroys the confidence on lipsync. Should I use mp4 intead avi?

[url=https://ibb.co/3fR3hyL][img]https://i.ibb.co/3fR3hyL/Adobe-Premiere-Sy.jpg[/img][/url]

Thank you very much in advance.

[F31911627hlee]

https://ibb.co/3fR3hyL

[Richard M Knight]

It looks like you are working with Audio units, there is a good chance Premiere is going to the nearest viseo frame.

[F31911627hlee]

I don't understand it. When I revisit  the same frame several times as I continue fixing other parts, it can return to normal or no. I would like to know a way to stop it, since I can't be sure about the timing. If I set some audio 5 miliseconds after the mouth opens, for example, and the same frame now starts 20 miliseconds earlier, sound will be produced 15 miliseconds before the mouth opening. And, sometimes, it returns to original timing when I revisit it. I have no confidence to do the job anymore. Do you have any solution?

[Remote Index]

Hello F31911627hlee,

"sound will be produced 15 miliseconds before the mouth opening"

What is the frame rate of the video material you are working with?

R.

[R Neil Haugen]

You need to understand working both in audio units and frames.

If your timeline is set for displaying audio units, you have control down to the millisecond, for sliding/adjusting audio tracks. And audio tracks only.

With the timeline time display set for audio units, you can micro-adjust sound tracks in tiny amounts.

Video tracks can never be changed by less than a full frame. Which is why the default working order for timelines is their video framerate. You can't move a video frame a partial frame either way.

So for say 23.976 timelines, each frame has a time length of 1/23.976th of a second. Which is 0.0417 seconds. And can't be subdivided.

48fps would be about 0.0208 seconds, so ... are you working with clips on a timeline of 48fps?

[F31911627hlee]

Yo. I'm working on such files:

Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
I think I was not able to convey my problem or I really don't understand what you are talking about. My problem is the timing of a same scene is changing. Characters mouth opens at 00:03:11:43200, I moce audio to fix the lipsync and after some time, when I revisit this scene, the mouth is opening at 00:03:11:41200. And, some time after that, when I turn to revisit it, mouth opens at 00:03:11:43200 again! Isn't a way to be sure mouth opens at 00:03:11:41200 and always will open at 00:03:11:41200?  I wonder if I change timeline from "audio samples" to miliseconds, it will enough... Thank you very much.

[Remote Index]

Hello F31911627hlee,

Thanks for the additional info you posted.

The behaviour you describe is, indeed, odd and I have no explanation for it. Clips should stay in the position they are placed in the timeline! It would be great to get an explanation of this behaviour from someone who knows.

However, it is important to realize that your video frames are changing only every 41.7 milliseconds. (At 23.976 seconds, 1 / 23.976 = 0.0417). This means that a change of 20 milliseconds is less than half the duration of a video frame, and it likely means that this change does not affect the video frame on which the sound occurs. There is a less than 50% chance that it does change the the video frame on which the sound occurs. Is this the case?

If so, I would do a larger change and move the sound another 20 milliseconds into the desired frame.

Again - it's strange that the sound is moving and that Premiere Pro is not keeping the sound where you place it. But you may be able to move the sound a bit a acheive a more stable sync relationship to the video frame which you are dealing with.

Hope that helps.

R.

[F31911627hlee]

Yo, friends. The sound isn't moving. It's the video. Weel, time the mouth opens at 00:03:11:43200 in the video, so I adjust the audion based in the information that mouth opens at 00:03:11:43200. When I revisit this part or open the software again, the mouth in video is opening at 00:03:11:41200. Depending on the time or occasion, when I turn to select this part, mouth opens at 00:03:11:43200 again. The fact is: if the time mouth opens in video changes depending on time, how can I know my adjust is good? I change timeline from "audio samples" to "miliseconds" and the same issue continues. For example, mouth of the character was opening at 00:04:38.194. Audio was coming out at 00:04:38.213. When I closed Premiere and opene it again, the mouth of character was opening at 00:04:38.154. I don't know what is the true when I watch the video on my TV.

[Richard M Knight]

What results do you get if you change the timecode to frames?

[Remote Index]

I think you need to investigate further.

If you are looking to indicate the position of a video frame with audio units, each video frame will cover a range of 41.7 milliseconds. Any position within that range will show that frame.

If you investigate further, find the position of the frame change. The next frame change should be 0.0417 seconds later.

R.

[F31911627hlee]

I don't understand. I always pick the first frame where the mouth opens, no?

Assuming I picked the first frame (using timeline "audio samples") and put the audio exactly 1 frame after, this frame could last for 0.0417, but it's a fact that audio will appears after mouth opens, no?

[Remote Index]

I'm having trouble following your description.

This speaks to R Neil Haugen's point: in the timeline you have video clips and audio clips. The smallest unit of video is one frame. When you enable audio units in your timeline, the smallest unit for audio is either audio samples or milliseconds, as you choose.

Thus, when you say "I pick the first frame where the mouth opens" - you are referring to a video frame. This will have a start time (in either timecode frames or audio units). And it will have a duration (of one frame or 0.0417 seconds). I presume you are referring to start time when you say "pick a frame" (though this is unclear).

When you say you "put the audio exactly 1 frame after" you are saying that you placed the audio 1 video frame later - or I don't understand what you are saying. Remember - in your timeline, a video frame has a duration of 41.7 milliseconds.

I don't think you are being precise with your language here and it is making it diffucult to understand your description of what is happening.

R.

[F31911627hlee]

Well, I think I don't understand it at all. I have a video and a audio. I select milliseconds instead audio samples. Forget frames language, please. Even I don't do anything, I see that character mouth opens at 00:04:38.194. I close Premiere. When I open it again e select the same scene. Character mouth now opens at 00:04:38.154. I didn't nothing. I just think character mouth should open at 00:04:38.194. But this time changes depending on the time I open the software.

[F31911627hlee]

R Neil Haugen, thank you very much for helping me. I'm trying to understand this program.

[F31911627hlee]

Remote Index, sorry. I changed your name.  R Neil Haugen, thank you too. Of course, I unlinked video and audio. What puzzles me is the fact that time where mouth opens change when I revisit the part. Thank you very much.

[Remote Index]

Hello F31911627hlee, I am sorry you have not found this more helpful.

"Forget frames language, please."

The thing is that you are talking about a video frame when you say "I see that character mouth opens." That's a video frame. So video frames are part of the discussion.

You are correct in assuming that clips should not move in the timeline if you have not touched them.

My inquiries above were to try to clarify the situation you are trying to describe (which remains unclear to me).

I have further ideas about how to problem-solve this. Let me know if you are interested.

R.

[R Neil Haugen]

As R notes, you are referencing audio against video.

If you want to move audio that is part of/linked to a video file, you need to first unlink them. Switch to audio units, then slide the audio to where it needs to be.

Then relink them, so they are again locked together. Now save the project. And on reopen things should remain as left.

[F31911627hlee]

Oh, I never linked video and audio again. I'll try it! Thank you very much, I'll let you know.

[F31911627hlee]

I tried to link the clips again, but I don't know if I did it right. I have a áudio with a hindred cuts. I selected the refered timeline section video and audio with shift and linked video and audio, but this function does not appear when I move to other sections. I wonder if all video and audio cuts were linked at once... I don't think so, because just the first section enables right-click "unlink"function.

[Remote Index]

Hello F31911627hlee,

re: Linking

The linking function is limited in certain ways, for example you can only link one video clip with one audio clip in serial (you can link several audio clips in parallel on different tracks, but not several one after the other, serially, on one track). Do a search for more explanation of this function if it is not clear.

re: Sync

I have a number of questions and suggestions to clarify:

1. I'd be interested to know why you're using audio units not frames.

2. How are you identifying points of interest in your sound - are you doing so visually / using the waveform or by listening / scrub?

These are my suggestions:

3. With "show audio time units" de-selected, find your reference video frame (you've described it as the first "mouth open" frame). Make a cut at the start of this frame in the video and the start of the next frame in the video. Make sure "show through edits" is enabled in your timeline. You should now see 1 frame of video clearly in the timeline - with a cut at the start and end of 1 frame.

4. With 'show audio time units' selected again, and "samples" not "milliseconds" selected, scrub and find the very first sample and find the precise start of the sound you are trying to sync. Make a cut at the start of this sound in the audio. You should now see a cut in the audio at the very beginning of the sound you are interested in syncing.

5. Align the cut in the audio with the cut in the video.

6. Test closing and opening the project. Observe if the "movement" you have been seeing is happening. If so, describe precisely where the cuts were when you place them in sync, and where they are after moving.

R.

[F31911627hlee]

Hi, Remote Index. Thank you for supporting me.

Originally, I worked based on "audio samples". When I select "show audio time units", looks timeline is more sensitive. For example, I can listen exactly when the following speech "contaminarion noise" begins.

I never changed to "miliseconds" before open this thread, but it looks still more sensitive than "audio samples".

Talking about this scene, for example, girl's mouth opened at 00:04:38:09340. "following speech noise contamination" begins at 00:04:38:10333 and audio wave begins around 00:04:38:12628. I was totally satisfied with this arrangement. Adjusting based on "audio samples" is wonderful. I really don't understand why the time on video is changing.

And, after I linked audio and video as R Neil Haugen said, but this event turned to happen again. There was an alteration of "20-units of audio sample". The same happened with miliseconds metrics. Without this disturbing fact, I think Premiere is wonderful for audio sync.

https://ibb.co/pxX02w9

[Using miliseconds metrics, girl's mouth opened at 00:04:38.194. "following speech noise contamination" begins around 00:04:38.206 and audio wave begins at 00:04:38.262. ]

When I say "following speech noise contamination", I mean the noise from following wave sound that we can hear before it.

When I open the software again, mouth opens at 00:04:38:07338 in video. It means "following speech noise contamination" and audio wave will spend more time to be produced.

[Richard M Knight]

I've been a video editor for 15 years and an audio mixer for 30 years before that and I only use audio samples when I am syncing two audi tracks together. When syncing video to audio I stick with frame timecode. The spec for broadcast audio sync used to be plus or minus one frame. Modern digital transmission is often worse than that. I agree you nay be seeing some issues but sticking to frame timecode will probably solve it.

[R Neil Haugen]

Richard is right ... you don't normally need the audio time units in editing. You do need to check and set the latency settings in Premiere or any other video/audio editing app, as that may actually be where your problem lies the more I read through this thread.

Your system's built-in latency may be the issue, not Premiere.

I only need audio time units when manually syncing separate sound tracks, or at times for placing sound effects tracks.

Neil

[F31911627hlee]

Neil, could you teach me how to set this latency in Premiere? I'm using an amateur PC, core5 with RTX 3060.