Multichannel audio as an external essence

  • Serge Korolev

    Serge Korolev - 2008-03-18


    We've been evaluating the use of AAF to export EDLs into such editing systems as Adobe Premiere, Sony Vegas and others.

    The curious thing is that the AAF implementations don't seem to be working properly in both products. I didn't try Canopus' Edius yet and Apple's FinalCut doesn't seem to provide AAF support.

    In both systems, we've tried to create project containing AVI videos (pal, dvcam) with 8 audio channels (mono, pcm) incorporated.

    1) In case of Adobe, exported and then reimported AAF comes back with 1 channel audio in the media description (indeed, verifying an AAF's WAVEDescriptior there is 1 channel only mentioned). However, all audio clips on the sequence are reinserted detached from their video sources. I hope the latter should be related to the media file reimporting issue only which had been acknowleged by Adobe as a bug.

    2) But surprisingly, Sony Vegas works in a similar way. In other words, I created a project with the same video, put it on a timeline and exported into an AAF. Reimported AAF comes back with correct media information as expected but all audio clips on the timeline are detached and represent the first channel only.

    The question is am I right to suspect that there might be not a editing system around yet that would correctly implement AAF as if it were its native project file format?


    • Alexey Kharkevich

      I understand that you need Automatic Duck's plugins to have AAF support in FinalCut.

      Don't know much about Premiere or Vegas but it could be that they break an 8-channel audio track into 8 1-channel tracks as per AAF Edit Protocol:

          7.8 Multi-channel  audio
          [...] multi-channel audio (e.g. stereo audio or 5.1 surround) shall be
      represented using multiple tracks with mono sound Data Definition. [...[

      But then do they actually create 8 audio files to go along with the exported AAF? Or do they end up with 8 file mobs pointing to the same AVI file and then on import fail to properly map tracks to channels? Also, have you tried exporting AAF with embedded media? That may work better although probably won't help you with the EDL workflow.


    • Serge Korolev

      Serge Korolev - 2008-04-01


      We would want to avoid embedded media in AAF files at the moment. We were developing our own simple editing software with MXF support as an integral part of our automation system. Due to the limited resources we would not want to compete with the bigger players in the field and so we merely do a minimum of editing (mostly audio voice over) without special effects or titling. For those needs that exceed the capacities of our system we'd like to offer an integration with the applications dedicated to video editing.

      Previously, we used to export projects as a FinalCut's XML file, a format supported by Edius and, until some years ago, by Adobe via Automatic Duck's plug-in. Unfortunately, Automatic Duck abandoned Premier's project due to the continuous changes in SDK which resulted to high costs of support (or so I was told). About a couple of months ago I checked Premier's SDK, then communicated Adobe engineers and was told that there is no way to control a sequence from an importer plugin anymore.

      So, the natural solution seemed to be an AAF, a standard that's been around for some time already. Now, we checked it with Edius and this is the first system which worked right away and correctly re-read its own AAF. We'll continue to rely on Edius' AAF support for the moment and will see if the others catch up. Thanks for the tip about FinalCut's plugin, I didn't know of it.



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