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A
AW_249415187cpq
Inspiring
December 4, 2022
Answered

Fixing 25p & 50p Footage Audio

  • December 4, 2022
  • 3 replies
  • 3580 views

dear community,

I have interview footage from two cameras A-Cam 50p and B-Cam 25p and now I have the problem that the audio track of the A-Cam in a 25p timeline is not lip synced.

 

I forgot to switch the A-cam to 25p and am now looking for a solution to synchronize the whole thing as the final product should have 25p.

 

1. does it make sense to convert the 50p footage to 25p with the media encoder so that both have 25p? or other around?
2. is there a solution within the sequence settings for audio?
3. or is there a simpler solution within Premiere?

 

A-Cam:
- 50p H.264/MPEG-4 AVC Long GOP High Profile 4:2:0
- 48000 Hz - 24 bit - 4 channels
- Good audio was recorded with Cam-A

 

B-Cam:
- 25p MP4/MOV H.264 4:2:0
- 48000 Hz - 16-bit - stereo

 

I would appreciate any tips as I have not been able to find a solution so far.

 

Thanks & Best regards
AW

 

This topic has been closed for replies.
Correct answer AW_249415187cpq
quote

Yes in a 50p Timeline is everthing fine. But then B-Cam (25p Material) is asynchron


By @AW_249415187cpq

 

It seems very odd since audio not have a frame rate, so it never matters. One second audio is one second at any frame rate so mixing frame rates should not matter. Different bit rates do often cause issues though. I see that one camera is set to 24-bit while the other is set to 16-bit.

 

One simple test you can do is to place the 50p footage on a 50p timeline and render out the audio to 16-bit/48Khz and import that audio while muting the original audio and see if that new 16-bit/48Khz audio behaves better. It´s often enough to render out 30-60 seconds to try it.

 

 


Good idea, unfortunately nothing helped.

 

My solution was to convert the 50p material (FX6) to 25p with Catalyst Prepare. Now it seems to fit.

Thanks for your quick help anyway.

3 replies

YANNA26705213grl5
YANNA26705213grl5
Inspiring
December 4, 2022

That was a good observation re: location of cameras ( as sound travels slower than light ).

Assuming there is no common slate for both cameras it might eventually become an issue of the length of the project regarding frame rates. Specifically constant frame rate vs. variable frame rate.

In that case it's  wise at this point to straighten out a slight confusion. 25 and 50 refer to frame rates ( FPS ) and NOT THE LETTER P.  When dealing with resolutions the LETTER P is often used to describe resolutions like 720P, 1080P and so on....so might as well get that down pat before it gets really confusing.

hehe... good luck and happy holidays.

 

    Z
    Zwea
    Inspiring
    December 4, 2022

    Wouldn't "interpret footage" do the trick? It also changes the audio as far as I'm aware.

    A
    AW_249415187cpqAuthor
    Inspiring
    December 4, 2022

    Nope, didnt work here! Thanks for yout suggestion.

    S
    smrpix
    Participating Frequently
    December 4, 2022

    Is the audio consistently out of sync the same amount of frames from the beginning of the take to the end or does it drift?  What is your reference, a clap stick?  What happens if you match up the clips in your timeline by audio rather than video?  Different cameras may record the audio in slightly different relation to the picture based on their own electronics -- or even by distance.  (For example, if one camera is at the back of an auditorium and another is near the stage.)

     

    Answer the first question first.

      A
      AW_249415187cpqAuthor
      Inspiring
      December 4, 2022

      Very good point with the spacing, but the cameras were about a meter apart. I only used hands clapping. The audio is the same from start to finish. no drift. 

       

      thank you very much for your suggestion.

      S
      smrpix
      Participating Frequently
      December 4, 2022

      No drift is the best answer.  Stack your clips in a timeline, unlink the audio and video on the clip where the clap does not match, and nudge the audio around until the waveform matches the correct track and the video.  Relink.

       

      Now save that corrected, relinked clip as a subclip and use that subclip as one of your multicamera sources.

       

      The 25,50 fps thing is a red herring.  They're the same time base.  You should be fine to make a timeline in either.

      Averdahl
      Community Expert
      AverdahlCommunity Expert
      Community Expert
      December 4, 2022
      quote

      I have interview footage from two cameras A-Cam 50p and B-Cam 25p and now I have the problem that the audio track of the A-Cam in a 25p timeline is not lip synced.

       

      By @AW_249415187cpq

       

      Is the 50p A-cam lip synced if you place it on a 50p timeline?

      A
      AW_249415187cpqAuthor
      Inspiring
      December 4, 2022

      Yes in a 50p Timeline is everthing fine. But then B-Cam (25p Material) is asynchron

      Averdahl
      Community Expert
      AverdahlCommunity Expert
      Community Expert
      December 4, 2022
      quote

      Yes in a 50p Timeline is everthing fine. But then B-Cam (25p Material) is asynchron


      By @AW_249415187cpq

       

      It seems very odd since audio not have a frame rate, so it never matters. One second audio is one second at any frame rate so mixing frame rates should not matter. Different bit rates do often cause issues though. I see that one camera is set to 24-bit while the other is set to 16-bit.

       

      One simple test you can do is to place the 50p footage on a 50p timeline and render out the audio to 16-bit/48Khz and import that audio while muting the original audio and see if that new 16-bit/48Khz audio behaves better. It´s often enough to render out 30-60 seconds to try it.

       

       

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