10 Replies Latest reply on Jul 26, 2011 11:05 AM by Jim_Simon

    Audio Center Channel gone

    dave-h2

      Hi there!

       

      I have been trying to work this problem out for some time without success, so I hope somebody here is able to help me.

       

      I recently finished a project in CS 5.0.3 containing a lot of clips coming from DVDs which contain 5.1 sound which Premiere neatly converted to stereo tracks. Today I opened the project again to make some final changes only to find that the audio was not working as it did before. Suddenly the downmix Premiere does is missing the center channel. If I import a new clip an manually deselect all of the other channels only then I can hear the center. I tried creating a new project but it behaves just the same: the source monitor seems to playback the sound without the center, but if I drag the clip to a stereo track it the downmix seems correct.

       

      This is all very odd, considering that nothing was changed. Maybe some external codec that has to do with how Premiere downmixes the audio? Hope somebody can help me out with this.  

       

      Thanks, dave

        • 1. Re: Audio Center Channel gone
          Harm Millaard Level 7
          which Premiere neatly converted to stereo tracks.

           

          Since when does stereo sound have a center channel?

          • 2. Re: Audio Center Channel gone
            dave-h2 Level 1

            Harm Millaard wrote:

             

            which Premiere neatly converted to stereo tracks.

             

            Since when does stereo sound have a center channel?

            Well it doesn't. Maybe I didn't state my problem clearly enough. Dragging the clips which contained a 5.1 mix to a stereo track, Premiere did create a stereo mixdown of the original 6-track audio which contained all of its information. Suddenly the mixdown Premiere creates is lacking the original center channel and thus the main part of the original dialogue is gone.

            • 3. Re: Audio Center Channel gone
              Jeff Bellune Adobe Community Professional

              See if changing Edit | Preferences | Audio helps.  Like this:

              51Mixdown.png

               

              -Jeff

              1 person found this helpful
              • 4. Re: Audio Center Channel gone
                dave-h2 Level 1

                Hi Jeff,

                 

                as far as I see, this does not help, is it will only change how Premiere works in creating new mixdowns. If I open the Modify Clip dialogue I can see that the clips that are used in my project have only the L and R channel selected. This cannot be changed as long as the clips are used in a sequence...

                 

                The way the mixdown works in a new project has suddenly changed too. Listening to the 5.1 clip in the source monitor will give me only the left and right channels. Dragging it to the timeline suddenly produces multiple stereo tracks (regardless of the 5.1 Mixdown Type selected in the preferences). If (under Clip->Modify->Audio Channels) I select stereo, Premiere produces 3 stereo tracks on the timeline (probabyl L+R, LS+RS, C+LFE), if I select mono Premiere creates six tracks, only if I select 5.1 Premiere puts the sound on a single track. This is not as Premiere behaved before where it automatically created a stereo mixdown of the original 5.1 on a single track. O am beginning to think something in my installation got corrupted and I am thinking on trying out a fresh install of Premiere.

                • 5. Re: Audio Center Channel gone
                  Jim_Simon Level 8

                  Dragging the clips which contained a 5.1 mix to a stereo track

                   

                  To the best of my knowledge, that is not possible.  A clip will only go on a track of the same type.

                  • 6. Re: Audio Center Channel gone
                    dave-h2 Level 1

                    JSS1138 wrote:

                     

                    Dragging the clips which contained a 5.1 mix to a stereo track

                     

                    To the best of my knowledge, that is not possible.  A clip will only go on a track of the same type.

                    These are mpeg2 files containing an ac3 6-channel mix. Previously Premiere seemed to handle them as stereo tracks (the information on these tracks that I imported a month ago still reads "Compressed - Stereo", but Modify->Audio channels reveals there are 6 channels only two of them are selected L & R). If I now reimport any of these tracks Premiere suddenly says "Compressed - 3 Stereo". I suppose that this difference in handling the ac3-audio has resulted in the missing tracks.

                     

                    Could anybody tell me how their version of Premiere handles files with ac3 audio?

                     

                    Does Premiere rely on any extrenal codec to decode ac3 audio? It might have been that this codec was updated on my machine and now produces a different result?

                     

                    Thanks again, dave

                    • 7. Re: Audio Center Channel gone
                      dave-h2 Level 1

                      Okay, I found out that the behaviour of recognizing a 5.1 track as 3 stereo tracks was due to the option Source Channel Mapping - Default track format being switched to Stereo instead of Use File.

                       

                      If I now make a file offline and online again, Premiere recognizes it as 5.1.

                       

                      Still, the mystery remains: why did Premiere previously recognize these files as stereo tracks and now says they are 5.1?

                      • 8. Re: Audio Center Channel gone
                        Jim_Simon Level 8

                        why did Premiere previously recognize these files as stereo tracks and now says they are 5.1?

                         

                        Operator error would be my guess.

                        • 9. Re: Audio Center Channel gone
                          dave-h2 Level 1

                          JSS1138 wrote:

                           

                          why did Premiere previously recognize these files as stereo tracks and now says they are 5.1?

                           

                          Operator error would be my guess.

                          That's not very helpful. I previously exported the same timeline, with the same source material and it did have the information from the center and now a month later I reopen the project to find that things have changed, how could that be my fault?

                           

                          In the meantime I went ahead reimported the clips, dragged the audio to a new 5.1 track and manually realined the audio.

                           

                          I am still puzzled by this whole thing and if anybody still has an idea I'd be interested.

                          • 10. Re: Audio Center Channel gone
                            Jim_Simon Level 8
                            That's not very helpful.

                             

                            Well, it was just a guess.  Not being there to actually see what's going on and what you're doing, it's the best I can do with the info provided.