6 Replies Latest reply: Oct 18, 2011 10:19 AM by Brad Wright2
IlMolto Level 1 (5 points)
Hi,

I did some tests and it seems exporting to an .MP4 file using H.264 looks sharper and clearer than exporting to a .MOV file using the same codec and bit rate. The file size is almost exact as well. How is this possible? Shouldn't they look close to identical? It also took longer to export to the .MP4 file with my processor working harder. Interesting. Anyone have any idea why this is?

I think I might export to .MP4 from now on...

Mac Pro 3.2GHz Quad-Core Intel Xeon "Nehalem" (Mid 2010), Mac OS X (10.6.6), 12GB 1066MHz DDR3 SDRAM
  • Tom Wolsky Level 10 (115,510 points)
    QuickTime is a different format with the media built differently with separate tracks. MPEG-4 encodes differently. QT will usually require a higher data rate.
  • IlMolto Level 1 (5 points)
    Ok I think I found what I was doing different in the settings.

    When I exported to a .MOV file, I unticked Frame Reordering.

    When I exported to a .MP4 file, there was no option to choose frame reordering, but an option to choose to restrict profiles to either Main, Baseline or both. I left it on Main.

    Could this be why the .MP4 file looked better?
  • IlMolto Level 1 (5 points)
    Hi Tom,

    Thanks for your reply. I think it was because I had deselected Frame Reordering in the QuickTime Movie export. I did another test with Frame Reordering selected and I couldn't tell the difference between the two.

    Which makes me think using Main Profile is like using frame reordering. The video is going straight to YouTube and it is recommended by YouTube to keep Frame Reordering unchecked. So I need to be sure before I upload it.

    I did a Google search and found this page:

    http://rob.opendot.cl/index.php/useful-stuff/h264-profiles-and-levels/

    What are B slices? Are these the bidirectional frames that is used when frame reordering?
  • Tom Wolsky Level 10 (115,510 points)
    Depends on the original format you're exporting. No ideas what B slices are. Something to do with the compression algorithm.
  • rdkls88 Level 1 (0 points)

    I think I found what you're after, trying to export an mp4, with h264 encoding (iMovie '11)

    Share - Export using quicktime

      Export: Movie to MPEG-4

     

    (Options ...)

      File Format: MP4  (as opposed to "MP4 (ISMA)" which will be selected by default)

      Video Format: H.264 is now available

     

    Seems like a lot of steps, for what I would have expected to be a common use-case ....

    HTH

    Nick

  • Brad Wright2 Level 3 (700 points)

    H.264 can be encapsulated in Quicktime, MT2, MP4 and others.  The are just containers.  For video quality it shouldn't matter which container you use.  You can even transfer the H.264 video between containers without re-encoding.  I think the best H.264 encoder out there is still Apple's Compressor.