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Transcribe screen freezes on Safari

ento

20 Aug, 2009 04:28 AM via

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When I click on the 'transcribe' link, Safari freezes for several minutes, taking up 100% of the CPU time. The video and the transcription log stays blank while it's frozen and after it comes alive, I can start to transcribe. The video I'm transcribing is:

• http://dotsub.com/transcribe/75a8d940-d901-4aa0-8d46-47d904f2b5c3

I'm using

• Safari 4.0.3
• Mac OS X 10.4.11
• MacBook 2.16 GHz Intel Core 2 Duo
• 2 GB RAM

When I try opening it with Firefox 3.0.10, it detects the page is unresponsive and gives me this alert:

Warning: Unresponsive script ... Script: http://ajax.googleapis.com/ajax/libs/prototype/1.6.0.3/prototype.js...

Any help appreciated.

1. Support Staff 2 Posted by brooks on 20 Aug, 2009 01:34 PM

   

   Odd I have the exact same Mac book here (with 4 Gigs of RAM)

   Do you have a lot of applications running? That warning shows when the browser has taken too long to finishing running javascript.

   Thanks,

   Brooks L.
   dotSUB.com

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2. 3 Posted by ento on 22 Aug, 2009 07:30 AM

   

   I tried restarting the mac and opened the problematic page but no improvement.

   Also, I have another video with no transcription yet and there is almost no noticeable lag when opening the transcription page.

   ---

   Back at home, I have another mac:

   • Mac OS X 10.5.8
   • MacBook Pro
   • 2.53 GHz Core 2 Duo
   • 4 GB RAM

   and when I try the problematic page with

   • Firefox 3.5.2: no noticeable lag
   • Safari 4.0.3: freezes for several minutes

   So as a workaround, I can use Firefox to transcribe videos at the moment. I'll try upgrading the copy of Firefox I have at work.

   However, I'd like to use Safari just like any other activity I do on the web so I tried investigating a little further:

   I turned on the profiler on Safari and got the following result.

   • the most heavy function was appendChild (self: 3.0min total:3.0min average:118.5ms calls:1539)
   • which is apparently called from: transcribeVideo.js::drawCaptionsTable > the line after createRowFromCaption

   If I may do a naive interpretation, perhaps it could speed up a bit by creating the entire transcription list on-memory and slapping it on to the actual DOM tree once it is complete?

   (In order to profile the initialization script, I created a small script that hooks the onload event with console.profile() and sets a timeout for console.profileEnd() and activated it by using GreaseKit.)

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3. Support Staff 4 Posted by brooks on 24 Aug, 2009 01:03 PM

   

   Thanks Ento,

   I am aware that the page loads slowly when there is already a large transcript. Sadly I inherited this page from another developer and the table that displays the transcription is derived at load time (this should be generated server side. )

   I will be fixing this very soon,

   Cheers,
   Brooks L.
   dotSUB.com

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4. brooks closed this discussion on 24 Aug, 2009 01:03 PM.

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