mpeg export file size question

Hi All,

Having a strange problem and can't find the answer in the FAQ or by searching past posts.

I have a need to output MPEG-2 files at 720 x 480 from a ProRes timeline in FCP. When I use Compressor or export using Quicktime, the settings say my file will be 720 x 480 but when I open the resulting .mov file in QT Player the size is reported as 640 x 480.

I've tried as many setting combinations as I can think of, I've exported directly to DV NTSC (which is 720 x 480) and then dropped that file into Compressor, and I've tried exporting from Quicktime Player itself and ALWAYS get 640 x 480 - no matter what the settings say.

When I read the specs of the MPEG-2 format it seems that a frame size of 720 x 480 should be possible. What am I missing?

Thanks, as always, for any help.

TJ Shank

When you exported via Quicktime Conversion, did you click SIZE / CUSTOM and actually type in 720 x 480? Works for me.

When life gives you dilemmas...make dilemmanade.

There's probably nothing going on here. 720x480 is the size of video (non-square pixels), but if you played that video clip in QuickTime Player on a computer monitor (which is square pixels), the clip will look horizontally stretched. To compensate for the difference, QuickTime Player can play the video back at 640x480 so that proportions look correct on a square-pixel computer monitor. If you press APPLE-I in QuickTime Player, DV clips that are 720x480 show up in QuickTime Player as "DV 720x480 (640x480)". That's normal.


www.derekmok.com

Yup, what Derek said. There's various terminology for this, but the one I think I've heard most frequently is "presentation size." On a square-pixel monitor (a computer monitor, in this case) the presentation size is 640x480, while the encoded size is 720x480.

Thanks Derek and Jeff. But...

Apple-I brings up the Movie Inspector, which STILL says the file is 640 x 480 (both the tab that says "Current Size" and the tab that says "Normal Size", and Apple-1 (Actual Size) also lists the file as 640 x 480 even though we selected 720 x 480 and that size appears in the Summary tab of the Inspector.
We used "Program Stream" as the file type and set the file image size in the Encoder Tab (as an NTSC output). The summary (in Compressor) says the file should be 720 x 480. The aspect ratio of the image is correct (not squeezed) - the file is just the wrong size.

Any further ideas?

TJS

I still ask: Are you sure you have a problem?

I just took a look at an old MPEG-2, converted from a 720x480, full-quality, self-contained DV NTSC file. QuickTime Player does show that file as 640x480, but once imported into DVD Studio Pro, that same file shows as 720x480, and when I burn a DVD there is no distortion.

Yep, just tested using QuickTime Player to convert a 720x480 DV file. The resulting MPEG-2 file also shows as 640x480 in QuickTime Player, but 720x480 in DVD Studio Pro. So, I'm suspecting that QuickTime Player is automatically adjusting its presentation size in response to the MPEG-2 format, and the usual "Conform aperture" option is greyed out. As far as I know, other movie files -- QuickTime Movies in DV and Uncompressed formats, MPEG-4s -- don't behave like this.

So, I suspect you're trying to fix a nonexistent problem.


www.derekmok.com

The problem is that these files aren't going to DVD Studio - they are being delivered to a client out of house. When he clicks on them, he sees them in Quicktime player and says (with some justification) that the files don't conform to his requested specs.

To rephrase the question - is there a way to get Quicktime player to display "720 x 480" rather than "640 x 480" so we can deliver these files to a happy client?

Thanks again for your time and attention.


TJS

> The problem is that these files aren't going to DVD Studio - they are being delivered to a client
> out of house.

This Creative Cow thread seems to support the theory that QuickTime Player is flat-out reporting the wrong frame size:

[forums.creativecow.net]

If that's the case, ask your client to use anything but QuickTime Player to view the thing.

I ran the same test, using a 720x480 Compressor preset (that I created -- and I checked all the parameters). The resulting m2v file not only displays in QuickTime Player as 640x480, but when imported into FCP, it also shows as 640x480, and square pixels -- not NTSC CCIR 601/DV, as set in the Compressor preset.

I checked Joe's method of using Exporting Using QuickTime Conversion from a 720x480 DV timeline. Same results -- the resulting file reports as 640x480, square pixels, in both QuickTime Player and Final Cut Pro.

So FCP isn't reading the file correctly, either...or something is preventing the correct settings from being used. Which is bizarre, since FCP usually reads files correctly for frame size.

Try using MPEG Streamclip to open up that MPEG-2 clip. It also reads the clip as 720x480 (correctly?), not 640x480.


www.derekmok.com

I've encountered the same thing. Compressor is converting the pixel aspect ratio from non-square to square pixels (720x480 to 640x480)! It goes in 720x480QT and comes out 640x480MPEG-2, which completely screws up my workflow of creating a DVD from QT movies.