MPEG 2 Conversion to DV Video ruins aspect ratio

[dyoungiii]

Hello All...

I am trying to make an iMovie of my clips from a vacation, first time using the camera and first time using a Mac.

I can easily convert the movies to high quality DV, but it "shrinks" the video down to 640x480 and I don't know how to force it into 720x480.

If I convert via another codec, I get the 720x480 but the quality is much lower.

I'm using ffmpegx, and I've tried dvdrop - exact same results. I'm sure the video is widescreen because the source mpeg is identified as 720x480, and looks just wrong in 640x480 mode

Any help would be appreciated.

note: what's even weirder, is that in the ffmpegx status section, it says that it IS encoding to 720x480. What gives?

[jagabo]

Your DV files probably are 720x480 (640x480 isn't even legal for DV) and the display software is displaying at 640x480 because it "knows" DV is 4:3, not 3:2.

[edDV]

...

I'm using ffmpegx, and I've tried dvdrop - exact same results. I'm sure the video is widescreen because the source mpeg is identified as 720x480, and looks just wrong in 640x480 mode

For DV format, 720x480 is used for both 4:3 and 16:9 (wide) aspect video. The only difference is pixel aspect ratio and the wide flag.

When the 720x480 is viewed as square pixels, 4:3 video will appear slightly wide and 16:9 will look tall and thin. Square pixel display from a video player for 4:3 is 640x480 and ~854x480 for 16:9 (wide flag). If the video is 16:9 and the wide flag is missing, the video will be displayed as 640x480 and the video will appear very tall and narrow.

[dyoungiii]

Whats extremely weird is that one, and only one, of the videos DID convert into wide screen. Funny...

For now I'll settle for mp4, just because I wanna try out iMovie. But any further help... maybe things I'm missing, what not, would be appreciated.

THANKS!

[edDV]

Nothing unique about DV format. The same issues apply to DVD MPeg2, SD ATSC and SD DVB. Mpeg 4 (h.264 and VC1) at SD resolutions have the same PAR issues unless you retreat into SD square pixel or jump to HD. 1280x720 and 1920x1080 are square pixel formats but most HD recording formats (e.g. HDV, HDCAM, DVCPro, etc.) use non-square pixels as do most plasma HDTV sets.

They do this to increase picture quality for a given bitrate or display technology.