Off-topic: Sounding like the Tin Man

One of the things I wanted to do in the last week was to publish samples of my webinars on YouTube. Sounds simple: you take the Webex recording, convert it to another file format, add an opening and closing slide and you’re done. Like always, the devil is in the details.

Webex has a standalone conversion utility that runs on Linux. The audio retrieval part reliably crashes on my Fedora, so I end up having the advancing slides video with no audio. The conversion process takes as long as the original recording; each try takes quite a long time. No wonder I gave up.

The Webex Windows player can also convert the proprietary ARF format into WMV format. Yet again, the conversion takes an awfully long time ... and here’s why: the conversion program plays the audio (in real time) and recaptures it through another codec. Converting a two hour recording thus takes two hours during which time you cannot work with your PC, as any other sound it generates is automatically mixed in. At least you can schedule the conversion process for night hours.

So, after several days of painful retries I ended with a WMV file that looked and sounded reasonably good in Windows Media Player. Next step: select a portion of the video and insert a few seconds of static text in front and at the end. I already have Camtasia Studio (one of the better programs on the market), so the next steps should have been pretty straightforward ... and they were, but the results were dismal: I sound like the Tin Man.

It took me a while to find a decently sophisticated transcoding program (currently I have both Avidemux and Handbrake), which helped me discover the root cause of the annoying sound: the audio track in the WMV file generated by the Webex conversion program has 8kbps (bits-per-second) bitrate with 8KHz sampling frequency. Obviously the Windows Media Player does a good job interpolating this miserable audio stream into something useful, while Camtasia expects a better input.

Next steps: trying to find a reasonable set of transcoding parameters. Till then, the audio quality of my YouTube videos will be awful.

4 comments:

  1. :)
    Links will be welcome, anyway.
    Search on YouTube yields nothing.

    ReplyDelete
  2. Sounds like vendor 'lock-in' - good luck

    ReplyDelete
  3. Ivan Pepelnjak21 March, 2010 17:51

    http://www.youtube.com/user/IvanPx#p/u

    ReplyDelete
  4. Ivan Pepelnjak21 March, 2010 17:52

    Oh, yes ... next time I'll do a workstation recording together with a Webex recording :(

    ReplyDelete

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Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.