[MEncoder-users] frame size confusion
Dave M G
martin at autotelic.com
Sat Dec 1 04:18:26 CET 2007
Forgive me if this question is very basic. I think it should be
something that isn't so confusing, and yet, I'm confused.
As described in an earlier post, I have a Sony HD camera that records to
an MPEG format. The camera connects by USB, and appears as a local hard
drive, so it does not require any DV capture utilities.
Just for reference, the specific camera is the Sony DCR-SR300.
I can record in two different formats which I'll refer to as "wide
screen" and "regular".
Here's where the confusion is. I thought "wide screen" was 720x480, and
"regular" was "640x480". When I transfer files over to my computer,
right click on them (I'm using Ubuntu 7.10 with Gnome Desktop) and look
at their properties, that's exactly what they say.
However, whenever I've been using Mencoder, or my preferred GUI editor
Kdenlive, I get all sorts of squashing and stretching of images with output.
So I took a "wide screen" video, rendered a screen shot, then opened it
in GIMP and the frame size was 720x405 pixels. Weird.
So then I did the same with a "regular" video, and the screen shot was
640x480 after all.
But, from looking at the video on the camera, it looks like all it does
when recording in "regular" is trim off the sides
So I'm confused. Why does the "widescreen" report itself as 720x480 when
it doesn't seem to be? Is the 640x480 actually that size? Am I not
taking something into account about how aspect ratios work?
Bottom line - how can I be sure of exactly what the details of these
files are? What their aspect ratio, pixel size, and everything else is,
so that I know where I'm starting from?
Thank you for any advice.
Dave M G
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