3 Replies Latest reply on Aug 7, 2009 7:59 AM by Doyle Lonnigan

    Compressing / Converting Audio

    Doyle Lonnigan Level 1

      I'm creating a video for streaming using After Effects, Premier, and Windows Media Encoder.  I don't know much about how we're streaming it, but the IT guys have asked for WMV with a maximum packet size of 1300 bytes.

       

      The workflow is thus:

       

      1 - Capture video from camera using Premier

      2 - Trim and export segments as uncompressed AVIs with uncompressed audio at 44.1K 16bit stereo

      3 - Import these AVI clips into After Effects to add animated slides synced with the video

      4 - Export these composited clips as uncompressed AVI from After Effects with same audio settings

      5 - Import these new AVIs into Premier to add titles and slates

      6 - Export final edited video as an uncompressed AVI, again with the same audio settings

      7 - Convert this final AVI into a Windows Media Video file using Windows Media Encoder.

       

      My logic is this: After Effects is necessary to add the animations, but it's easier to cut and splice the finished clips and add slates in Premier.  Premier doesn't seem to export very good WMV files, so I use Windows Media Encoder to compress which is giving me better results.  I try to maintain uncompressed audio with a high sample rate throughout, compressing it at the last step when I convert to WMV.

       

      My issue is this:  The audio in my final WMV file not great.  When I set it to compress to "FM quality" audio, it produces a shimmery warble in the high frequencies, almost like a subtle but bright flanging effect.  This effect is not present in the final AVI file I'm feeding to the Media Encoder.  So, as a test, I tried cranking down the audio export settings from Premier to 22K at 8 bit mono, which got rid of the shimmer but muddied my audio considerably.

       

      My question:  What exactly is "FM Quality" audio in terms of real export parameters?  I don't see it defined in the Windows Media Encoder anywhere, but if I knew I could try to maintain those settings from the beginning and perhaps WME wouldn't need to convert it.  Does this (as well as my work flow) make any sense?  Generally, I've been pleased with the results and if I can work out this audio issue I'll be golden.

       

      Anyway, I'd appreciate any feedback or suggestions to make this better.

       

      Thanks in advance for the typically stellar forum advice that's surely about to rain down.  I'm rarely disappointed here.

        • 1. Re: Compressing / Converting Audio
          Doyle Lonnigan Level 1

          Testing ... testing ...  is this thing on?

          • 2. Re: Compressing / Converting Audio
            Mylenium Most Valuable Participant

            FM audio applies a limiter/ compressor, which may have the ill effects you are seeing. It's realyl more menat for speech-only stuff, where you would want it to make the voice sound more voluminous. As for your otehr problems - well, whatever works. I've had no issues with Adobe Media Encoder and rendering directly from AE, but your mileage may vary.

             

            Mylenium

            • 3. Re: Compressing / Converting Audio
              Doyle Lonnigan Level 1

              Thank you, Sir.  I appreciate the response.  For anyone else that may be looking at this for some information, I've figured out a few things myself since I posted.

               

              First, I decided to cut Premier from the flow and just do my simple video edits in After Effects.  I rendered the final uncompressed AVI directly from AE, thus cutting out some steps.  This has saved time, but there is no noticable difference in quality.  Apparently, the extra pass through Premier didn't negatively affect anything.

               

              Secondly, I may have gotten a handle on the audio issue.  Since the anomaly sounded like a slight flanging effect, I started looking into the stereo characteristics and found that the original source audio is a mono signal, which AE was converting to stereo, which was again compressed in Windows media encoder.  I exported the audio as Mono from AE and this time there was no flange effect after "FM quality" compression.

               

              So there you have it.  Sorry to keep this question hanging out there so long only to answer it myself, but hopefully someone will find the thread useful.