Skip navigation
This discussion is archived

harder & harder to remove unwanted video from HD

1313 Views 7 Replies Latest reply: Dec 7, 2007 4:20 AM by Karl Petersen RSS
Trevor Smith1 Calculating status...
Currently Being Moderated
Dec 5, 2007 12:38 PM
With each release of iMovie, Apple makes it harder to completely remove from the hard drive unwanted bits of video from long clips without disturbing the bits that I do want.

In iMovie 04 I could crop out bits at the end of scenes I had filmed that were just the camera jangling around or video of a bare wall or whatever. The useless bits were removed from my hard drive.

In iMovie HD this ability was removed for some reason and even after cropping scenes, the underlying file ALWAYS retained the useless bits. I got around this by cropping to keep just the bits I wanted permanently then exporting at Full Quality to create a new DV "original" without the footage accidentally shot up my nostrils or whatever.

Now iMovie 08 makes even this ability that much harder. I can still crop bits from my events and send those bits to the trash BUT doing so converts the underlying DV movies into .MOV files and DOES modify the quality of the video. I'm not sure if it's significantly worse quality, but I can do a side by side comparison of the original DV and the MOV file that iMovie 08 insists on making if I delete bits permanently from my events and there IS a difference. There is no longer any option that I can find to export Full Quality so I can't even use the kludge that I was forced to use in iMovie HD.

So I have now resorted to using a 3rd party application, MPEG Streamclip, that is really meant for converting video, but also allows me to crop and "save as" a full quality original DV clip. It's not ideal because I have to go outside of iMovie to do some editing and the interface of MPEG Streamclip is not the most user friendly.

I'm baffled by this. Does Apple think that no one ever overshoots a scene? Do they think hard drive space is actually free? I know it's cheap but it's NOT free and DV video takes up tons of space. Imagine when I get an HD camera! Do they think that we WANT to keep around 5 or 7 seconds at the ends of scenes -- or in the middle of them -- where we fumble with a lens cap or someone walks in front of our perfectly planned shot?

And why is no one else complaining about this? Do you all just not care? Do you want to keep minutes and hours of video that you will never use sitting on your hard drive?
MacBook 2Ghz Core 2 Duo, Mac OS X (10.4.10), 1 Gig RAM
  • Karl Petersen Level 6 Level 6 (15,170 points)
    Now iMovie 08 makes even this ability that much harder. I can still crop bits from my events and send those bits to the trash BUT doing so converts the underlying DV movies into .MOV files and DOES modify the quality of the video. I'm not sure if it's significantly worse quality, but I can do a side by side comparison of the original DV and the MOV file that iMovie 08 insists on making if I delete bits permanently from my events and there IS a difference. There is no longer any option that I can find to export Full Quality so I can't even use the kludge that I was forced to use in iMovie HD.


    Changing the split movie to a ".mov" file doesn't necessarily change the quality. (A ".mov" movie can haver essentially the same format as a ".dv" movie, which the split movie does.)

    I see no reduction in quality here after iMovie '08 splits the movie. The split sections look identical to the original imported movie, except they play as 720x480. (That shouldn't affect anything.)

    Make sure the General tab of your QuickTime Player preferences is set to "Use high-quality setting when available." That should cause both movies to play with high quality.

    Exporting any iMovie '08 source material that's DV WILL cause a reduction in quality, however. But that bug doesn't seem to affect split movies, at least not here.

    Not sure why you feel iMovie doesn't let you discard source material. Seems like it does exactly what you liked in iMovie 4. Or are you concerned only about the quality?

    Karl
    Dual-Core Mac Pro, Mac OS X (10.4.10), Sony TRV 900, HDTV, Cinema Displays
  • 42lanterns Calculating status...
    I think I have the same problem. I'm currently working on a multi-cam project but it's getting more and more difficult. I now only have 45 minutes cut and that with only two of the cameras and the project has taken up 87.59 GB! How was it that you saved space when you were cutting? I do a lot of cutting and pasting over playhead. I have both iMovie HD and iMovie '08.
    MacBook Pro 17 in, Mac OS X (10.4.10), 60 GB 5th gen ipod, Sony DCR-SR82
  • Karl Petersen Level 6 Level 6 (15,170 points)
    However, they get "squeezed" for some reason, as you pointed out, so that when played directly (i.e. from Finder in QuickTime) they get reduced from their real/original 853x480 to a smaller, squished 720x480.


    For NTSC DV video, the source material is imported as 640x480, then displayed as 720x480 after it's split.

    For PAL Dv video, it could very well be imported as 853x480.

    Your user profile doesn't say where you live. If you are part of "PAL world" that might explain what you see.

    Regardless, the change in the displayed size of the DV is not likely to affect quality. You're likely observing a playback feature, not a change in the underlying quality.

    Note that QuickTime Pro lets you change the size to 853x480 if you want to compare the clips at the same size.

    Karl
    Dual-Core Mac Pro, Mac OS X (10.4.10), Sony TRV 900, HDTV, Cinema Displays
  • Karl Petersen Level 6 Level 6 (15,170 points)
    QuickTime reports the raw DV files are:

    Format: DV, 720 x 480 (853 x 480), Millions
    DV, Stereo, 48.000 kHz
    FPS: 29.97
    ...
    Normal Size: 853 x 480
    Current Size: 853 x 480

    When iMovie crops the underlaying DV files, turning them into MOV files everything remains the same except all the 853s above turn into 720s.

    So QuickTime is reporting an actual change in the resolution, indicating it is NOT just a playback quirk. It appears that 853 pixels have been squeezed down into 720 for some reason.


    Sorry, I don't have widescreen video like yours to test, so I can't try it.

    For DV video, QuickTime always reports two dimensions, the native format size — 720x480 — and the playback display size, shown in parenthesis, e.g. "(853x480)". The native size is measured in non-square pixels and the display size in square pixels. (Or is it the other way around?)

    So long as QuickTime reports 720x480 for both the source video and the split video, my guess is everything is fine. iMovie may or may not be reporting the display size correctly for the display in QuickTime, but that probably doesn't matter.

    Throughout the history of QuickTime the playback of DV video has evolved from always displaying it as 720x480 — which confused viewers because the pixel shape of DV caused the video to appeared "stretched" — to adjusting the playback display to 640x480 for 4:3 video and 853x480 for 16:9 video. Sometimes QT doesn't choose the display size we expect, but that shouldn't affect the size or quality of the underlying video. (To force the video to use the aspect ratio we want so it looks right, QuickTime Pro lets us adjust the display size, just like we used to adjust all 720x480 DV to play as 640x480.)

    Illogical as it sounds, the test isn't whether iMovie's split movie uses the display size you expect when played in QuickTime. Rather, it's whether the split movie material continues to behave properly as iMovie edits the video. If the final product is okay you can ignore the rest.

    It's common as we work in DV to bump into the issue of square vs. non-square pixels. (Fortunately, iMovie protects us from that.) Google for "DV pixels" for more. Warning: it may make your head hurt.:-(

    Karl
    Dual-Core Mac Pro, Mac OS X (10.4.10), Sony TRV 900, HDTV, Cinema Displays

Actions

More Like This

  • Retrieving data ...

Bookmarked By (0)

Legend

  • This solved my question - 10 points
  • This helped me - 5 points
This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.