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Exporting an already compressed video

1160 Views 3 Replies Latest reply: Feb 1, 2011 8:21 PM by IlMolto RSS
IlMolto Level 1 Level 1 (5 points)
Currently Being Moderated
Jan 29, 2011 6:14 AM
Hey guys,

This is the scenario... I have a capture card that records my gameplay from my PS3. It captures in uncompressed video which is pretty much 1GB every 10 seconds for 720p. To preserve hard drive space, I always convert my captured gameplay (that is usually about 10 mins long, which is just over 60GB) to H.264 720p using Wondershare Video Converter Pro. So basically I have my video perfect in size and quality and now just want to record some commentary over the top of my gameplay.

Is it possible to import the already compressed video file into iMovie, record a voiceover and attach that audio that I've just recorded to the video without re-compressing? Basically I don't want to lose any quality through the export process. Anyone know what I mean?

Here's also what I want to know... If I export a movie from iMovie... So I go to Share -> Export Movie and choose HD 720p... And then create a new project, import that movie that I just exported and export it the exact same way again, will there be any quality lost? I tried doing some tests but it's hard to tell...

Thanks for reading. Any input appreciated.


Mac Pro 3.2GHz Quad-Core Intel Xeon "Nehalem" (Mid 2010), Mac OS X (10.6.4), 12GB 1066MHz DDR3 SDRAM
  • AppleMan1958 Level 7 Level 7 (27,335 points)
    Currently Being Moderated
    Jan 29, 2011 6:22 AM (in response to IlMolto)
    iMovie will recompress.
    If you cannot tell the difference, then keep doing what you are doing.

    For a slightly better workflow, convert your uncompressed video to Apple Intermediate Codec. This will be much smaller than uncompressed but 4 to 10 times larger than h.264. Then when you export to h.264, you will have more to work with and get better performance.
    iMac 24 2.8Ghz, iPhone, TV, Mac OS X (10.6.6), Panasonic HDC-SD5 iMovie 11


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