4 Replies Latest reply on Nov 7, 2013 8:33 AM by paddyirishman2005

    Why is audio rendered at the wrong position in the timeline?

    paddyirishman2005

      I have a video that fades in audio at the end of the clip (for about the last 20seconds of the video).

       

      When I render the video, the audio starts too early: about 10seconds too early, meaning the end of my video is silent.

       

      • I had the audio as part of a .mp4 file within the composition at first. The video played correctly, the audio was early.
      • Then I seperated the video and audio and I still got the same result.
      • Then I moved the audio +10 secs (to componsate for the early start), which worked, but clipped off the audio that passed the end of the timeline.

       

      I have checked and double checked that my audio is positioned at the correct time in the timeline.

      The only effects I am using are the audio level keyframes.

       

      I also have a audio file at the beginning of the video which seems to be working ok.

       

      Can anyone suggest a problem?  I'm pretty new at AE so I could be missing a config setting somewhere?

       

      Regards,

        • 1. Re: Why is audio rendered at the wrong position in the timeline?
          Mylenium Most Valuable Participant

          You are messing up your framerates. Check your footage interpretation, comp settings and render settings under that aspect.

           

          Mylenium

          • 2. Re: Why is audio rendered at the wrong position in the timeline?
            paddyirishman2005 Level 1

            Ok makes sense, but I'm still running into issues.

             

            My comp has a main video at 13fps, so I set my composition to a frame rate of 13.

            I have set all other video files to framerate of 13 (the originals are 30fps).  There is no such settings for the audio file.  In the render queue, I also checked that its at 13fps.

            Am I correct so far?

             

            It seems like the audio is now kicking in at the correct time, but the video layer at that point is off: The composition is exactly 4minutes long, with the last clip ending at 4.0mins.  But when I render, the video is 4min8sec long, and the last clip is pushed out (ending at 4min8sec).

             

            I think for now, *maybe* I will render the video as best I can, and then add in the audio after...

            Is it possible that because I created my composition before setting the framerate, that some of the layers are not updating to the new frame rate?  I don't want to start deleting and re-adding because I have quite a large project.  I'll be more careful in future

            • 3. Re: Why is audio rendered at the wrong position in the timeline?
              Mylenium Most Valuable Participant

              You will have to check the timebase in the project settings. Such odd framerates are not part of any SMPTE or other professional video and fim standards, so calculations may not be frame exact. Audio is calculated based on the files sample rate, so if it's an odd rate, there may be variations since samples will be quantized to whole frames. That could also be true for the video. Especially screen captures may use fractional framerates due to the performance and settings of the system they were captured on, but sell them as full frame rates. That's worth looking into as well and could explain your timing discrepancies.

               

              Mylenium

              • 4. Re: Why is audio rendered at the wrong position in the timeline?
                paddyirishman2005 Level 1

                Verry good insight.  The file was a screen capture (recorded in FLASH) and although it says the framerate is 13, its actual rate is 12.5!  I am using BB FlashBack Express Recorder which is great, but has little options.

                 

                Thanks a mill for your help Mylenium!