5 Replies Latest reply on Jun 14, 2014 11:45 AM by Seth Goldin

    Syncing by Audio

    Seth Goldin Level 1

      Hi there,

       

      When syncing by audio, what's happening when I offset the audio frames from the video frames?

       

      I was looking around for official documentation on this, but couldn't find any.

       

      I'm thrilled that the new Premiere Pro CC (7.0.0) can sync by audio. I can cut out PluralEyes from my workflow entirely. I'd just like to know what's happening when I modify the numerical value for "Offset audio by _ video frames" when I generate a new multi-camera source sequence.

       

      Operators of older DSLRs, like the T2i, 5D Mk II, and 7D, know that these cameras' own internal audio tracks are out of sync with their video, usually having their video tracks lag behind their audio tracks by a single frame or two, depending on the camera.

       

      Does this feature actually offset video and audio within a clip that has its audio and video tracks linked? Does it look for isolated audio tracks that have no video associated with them and simply offset those from the video clips that do have audio? I noticed that isolated audio tracks are automatically moved to A1 and are soloed, so they seem to have special priority.

       

      Also, which direction does the offset move the tracks? I'm assuming I can put in positive or negative values and get different results.

       

      Please help!

        • 1. Re: When syncing by audio, what's happening when I offset the audio frames from the video frames?
          Jim_Simon Level 8

          Runs some experiments.  Report back the results.  I'm sure others will want to know at some point.

          • 2. Re: When syncing by audio, what's happening when I offset the audio frames from the video frames?
            Seth Goldin Level 1

            OK, I ran some experiments. I started with a large absolute value of 24 so that I would really notice what was going on, hoping to see stuff about a full second out-of-sync.

             

            • Test 1:
              • Footage used:
                • Frame-accurate FS100 AVCHD MTS footage
                • Frame-inaccurate 5D Mark II H.264 MOV footage
                • No separate audio tracks unassociated with video
              • Operation:
                • Value set to 24 [positive]
              • Results:
                • FS100 audio was synced to 5D audio
                • FS100 video remained frame accurate with its own audio
                • 5D video remained out of sync by a frame with its own audio
            • Test 2:
              • Footage used:
                • Frame-accurate FS100 AVCHD MTS footage
                • Frame-inaccurate 5D Mark II H.264 MOV footage
                • No separate audio tracks unassociated with video
              • Operation:
                • Value set to -24
              • Results:
                • FS100 audio was synced to 5D audio
                • FS100 video remained frame accurate with its own audio
                • 5D video remained out of sync by a frame with its own audio

             

            At this point, I determined that no offsets were being manifested within the original clips themselves. Now it was time to add in an audio track unassociated with any video.

             

            • Test 3:
              • Footage used:
                • Frame inaccurate 5D Mark II H.264 MOV footage
                • One separate audio track unassociated with any video
              • Operation:
                • Value set to 24 [positive]
              • Results:
                • Lone audio track synced to 5D audio
                • 5D clip remained out of sync with its own video by a frame

             

            At this point, I thought I had done something wrong, or missed something, because even Test 3's lone audio track manifested no offset with the other clips. Just to make sure that I wasn't missing anything, I increased the offset to 48 frames in Test 4, hoping for the tracks to be a full two seconds out-of-sync.

             

            • Test 4:
              • Footage used:
                • Frame inaccurate 5D Mark II H.264 MOV footage
                • One separate audio track unassociated with video
              • Operation:
                • Value set to 48 [positive]
              • Results:
                • Lone audio track synced to 5D audio
                • 5D clip remained out of sync with its own video by a frame
            • Test 5:
              • Footage used:
                • Frame inaccurate 5D Mark II H.264 MOV footage
                • One separate audio track unassociated with video
              • Operation:
                • Value set to -48
              • Results:
                • Lone audio track synced to 5D audio
                • 5D clip remained out of sync with its own video by a frame

             

            So, as far as I can tell, the feature is actually completely non-functional. This is pretty annoying, Adobe! I still use these older DSLRs, and would love to actually be able to rely on this feature!

             

            I'll submit a bug report.

            • 3. Re: When syncing by audio, what's happening when I offset the audio frames from the video frames?
              Seth Goldin Level 1

              I submitted a bug report.

               

              Can other folks run some of their own tests to verify that the feature is not currently functional? If so, please submit a bug: https://www.adobe.com/cfusion/mmform/index.cfm?name=wishform

               

              Thanks!

              • 4. Re: When syncing by audio, what's happening when I offset the audio frames from the video frames?
                itsme_Bernie Level 1

                I am thanking your for your posting.  I am new at this, and just shot with an Mk III and Mkii at the same time, and am really PO'd to find out that the MkII footage sound, for my whole job, must have been off by two frames (as I now see, after reading this page and looking back).

                 

                It was driving me nuts exporting, and having the MKIII sync just fine, and JUST the MkII footage NOT sync.  I thought I was losing my mind.  ACK.

                 

                So thank you for your "as shooters of older HDSLR's" comment.  You saved my mind.

                 

                 

                Bernie

                • 5. Re: Syncing by Audio
                  Seth Goldin Level 1

                  Sure, absolutely. Glad to know this information was helpful for you.

                   

                  Here's the original forum thread that corroborated my suspicion, when I noticed it in my own 5D Mark II footage: Canon 5D Mk II Clap-Board Audio Sync Issue : Canon EOS DSLR

                   

                  What I've learned is that, even after having upgraded to using frame-accurate cameras and others systems with SMPTE timecode, you should always slate, even just as backup. If it was good enough for 1920s talkies, it's good enough for us now.

                   

                  Best,

                  Seth