VIDEO_TS (852x480) -> MPEG conversion: Aspect Ratio?

[jswayze]

Hi,

I'm gradually ripping my DVD collection and converting several select titles to MPEG4. The goal is to have these available for viewing on AppleTV or some other yet unknown device that will someday hold all my movies.

I ran into trouble with "Miami Vice" - it has about a 2.4:1 aspect ratio, and the VIDEO_TS image is 852x400, including the black bars (actual image size is about 852x354.) I ran it through Handbrake first (which, as far as I can tell is just a front end for ffmpeg) and ended up with a *very* squished image. I then moved to ffmpegX using "autocrop" and it did better, but it was still not at the correct aspect ratio.

Any thoughts on how to maintain the same aspect ratio when converting very wide ratio movies?

Thanks!

[rumplestiltskin]

Sounds like the black bars are part of the source material. So include them in the calculations.

(I'm assuming the 852x400 size you mention is proportionally correct and doesn't appear stretched or scrunched.) If you have 852x400 and 46 pixels of the 400 make up the letterboxing, then let's do some math:

I use a video iPod connected to my TV so my destination file would be 640 wide. Pick the iPod H264 TV (640x) setting. (Gotta have some sort of destination in mind.)

640 / 852 * 400 = 300

You can see how my math works: Destination width divided by source width times source height = destination height.

304 is divisible by 16 and is pretty close to 300 so let's use 640x304 for the destination size. ("The rule of 16's") That will still leave the black letterboxing so you could, if you wish, crop about 16 pixels top and bottom (32 total) and this would make the file size a bit smaller. (I'm assuming the letterboxing you see is equally distributed.)

Try it and let us know how it goes.

[jswayze]

Hi, thanks for the response.

After about 3 tries (at about 2 hrs. each!) I finally found a combination that worked for me.

I used VisualHub, selected MP4 and H.264. I then fiddled with the crop settings using the Preview button in between tries. I must say that VisualHub's preview function is much nicer than straight ffmpegx - it actually updates when you make changes to your settings! It seems that the mplayer windows in ffmpegx just shows your crop results and nothing else.

I did the math like you suggested and ended up with a frame size of 640x272. That coupled with top and bottom crops of 62 and 64 seemed to do the trick and the result was very nice. A 995MB file for a 2hr 15min. movie.

Given that VisualHub uses ffmpegx (at least I assume it does) I'd be curious to see the settings necessary to replicate my result in ffmpegx. I tried several times and didn't have any luck.

Thanks again!

[rumplestiltskin]

Hi, thanks for the response.

snip...That coupled with top and bottom crops of 62 and 64 seemed to do the trick and the result was very nice. A 995MB file for a 2hr 15min. movie.

...snip

The 62 pixel crop may or may not result in a file that works in an mp4 player due to the "other-than-divisible-by-16" amount. Might want to check it before proceeding with additional conversions.

Otherwise, glad you found a setting that works.

[KBeee]

[quote="jswayze"]Hi,

I'm gradually ripping my DVD collection and converting several select titles to MPEG4. The goal is to have these available for viewing on AppleTV or some other yet unknown device that will someday hold all my movies.

I ran into trouble with "Miami Vice" - it has about a 2.4:1 aspect ratio, and the VIDEO_TS image is 852x400, including the black bars (actual image size is about 852x354.) I ran it through Handbrake first (which, as far as I can tell is just a front end for ffmpeg) and ended up with a *very* squished image. I then moved to ffmpegX using "autocrop" and it did better, but it was still not at the correct aspect ratio.

Any thoughts on how to maintain the same aspect ratio when converting very wide ratio movies?

Are you viewing your resultant AVI files on your TV or your computer? If your final viewing device is to be your TV, then that's what you should be checking the AR on.
An AVI that looks perfectly fine on a computer monitor, will often look vertically stretched on your TV.

[jswayze]

Thanks all.

I just got a video iPod so I'm converting everything to 640 x ???. I'm in pretty good shape except that a bunch of my movies have odd aspect ratios.

Is there a utility out there that will tell me the size, in pixels, of a particular video file? I suppose in my case that will always be a VIDEO_TS folder's contents. Once I know the true size I can figure the aspect ratio and calculate the proper height for a 640 px wide video.

Thanks!

[rumplestiltskin]

Thanks all.

Is there a utility out there that will tell me the size, in pixels, of a particular video file?

If you open the file in QT Player or MPEG Streamclip, you can "get info" (Command-i) and the resulting window will display that information (among other things, as well).

[jswayze]

Thanks - MPEG Streamclip seemed to have the most information. I also ran across Diva, which showed info as well.