4 Replies Latest reply on Jul 24, 2013 4:28 PM by Rick Gerard

    Audio is slightly longer than video on export?

    jvknowles Level 1

      Anyone ever run into this?

       

      We just did a :30 commercial spot and delivered it to several outlets for regional broadcast. Most of them accepted our compressed output just fine (an H.264 QT,  1080 @ 29.97, PCM audio) but one outlet kept rejecting the file for being TOO LONG. We measured the file in several programs on the Mac (AE, FCP, QT 7, QT X) and it always came up as exactly 30 seconds every time. Even AE pegged it at 899 frames, so we definitely weren't over.

       

      Today we finally got someone on the phone and he said it was the AUDIO that was running long, not the video. He sent us a screenshot from Vegas Pro (I guess their system is all PC-based) and it showed the video stream at :30.00 and the audio stream at 00:30:29 -- nearly a full second longer than the video! How could this happen? I always thought the length of each stream was identical, so why woudl the audio come out slightly longer?

       

      One clue: the actual AIFF file used in the output comp is itself 00:31 long. I shortened it in the composition to fit within the time, and every setting for 'Duration' that I know of was set for 00:30, but it's like it just ignored the duration on output of the audio and exported the entire length of the track into the audio stream.

       

      Here's my workflow -- I did use other programs to make the file so maybe something else is the culprit:

      Finish in AECS6, render out to ProRes 4444 Master @ 23.98; re-import the file and drop into 29.97 comp to correct the frame rate for broadcast, render out to another 4444 Master file @ 29.97; dropped that into Apple Compressor to make H.264 file with PCM audio.

       

      TIA, JVK

       

      Vegas Pro error.jpg

        • 1. Re: Audio is slightly longer than video on export?
          Rick Gerard Adobe Community Professional & MVP

          Max audio has always been 28...

          Set an out point for your audio in the timeline. If you need to shorten the audio do that in an audio app like Audition and use a new file.

           

          How did you encode the file? You should be using the AME to get the best quality with multi pass rendering. I hope this solves your problem.

          • 2. Re: Audio is slightly longer than video on export?
            jvknowles Level 1

            Hi Rick, thanks for replying!

             

            >Max audio has always been 28...

             

            Sorry, 28 what?

             

            >Set an out point for your audio in the timeline.

             

            The audio layer is trimmed to fit within the work area which is :30 long; if I double-click on it then it confirms that the audio Out Point is already set to 29:23 (original comp was 23.98 time base).

             

            >If you need to shorten the audio do that in an audio app like Audition and use a new file.

             

            I would do that but I didn't think it mattered how long the source files were since they're being trimmed by the length of the comp. It would be just like inserting a video layer into a short comp but AE ignoring the comp length and exporting the entire thing.

             

            >You should be using the AME to get the best quality with multi pass rendering.

             

            I'm using Compressor because I have an MXO2 MAX box which allows for fast hardware rendering of H.264 files; the plugins in the driver I'm using only work with Compressor and not AME.


            • 3. Re: Audio is slightly longer than video on export?
              jvknowles Level 1

              UPDATE:

               

              Was just told by the outlet that my audio bit depth (24) may have caused the issue, and to use 16-bit audio.

               

              Really weird how the bit depth would add an extra second onto the audio stream length...

              • 4. Re: Audio is slightly longer than video on export?
                Rick Gerard Adobe Community Professional & MVP

                Yes all broadcast audio is 16-bit. That is probably the problem.

                 

                Oh, and 28 means 28 seconds. Fade in, audio up, play the spot, fadeout audio and video. Total 30 seconds. Total allowable audio track 28 seconds. It has been that way forever.