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Quicktime playback with audio drops video frames

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Mandie Clark
Quicktime playback with audio drops video frames
on Dec 23, 2009 at 7:54:40 pm

We are trying to playback .mov files from Blackmagic Media Express 2.0 to the SDI output of a Decklink SDI card on a Windows XP Pro (Service Pack 3) machine. We found that the Decklink SDI output drops video frames when playing back 1080i/29.97 files with audio (the SDI output momentarily goes to black, however the playback on the computer screen does not). The problem is intermittent and can happen 3 times during the playback of the file or not at all. When the audio is stripped from the files, the playback seems to be fine. Has anyone experienced this or have any idea what could cause video frames to drop out?

As for the computer itself, all drivers are up-to-date and we have no other applications running. The video files are playing off of a 640GB raid 0 hard drive (that has been recently defragmented) with a read speed of 380 MB/s. The files are using a Blackmagic 10-bit codec (4:2:2 RGB). The motherboard of the computer is a Asus P5E-VM-DO with an Intel Core 2 Duo E8500 Processor (3.16 GHz) and 2 GB of RAM (we have tried to increase the RAM with no success).


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Mandie Clark
UPDATE: Quicktime playback with audio drops video frames
on Jan 4, 2010 at 5:11:46 pm

After testing with 1080i/29.97 and 720p/59.94 media files (both with and without audio), we found that the SDI signal drops to black momentarily both during playback and while stopped/paused for all of our test files. The problem still appears to be intermittent, however it occurs more frequently after a cold start of the PC.


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