640x360?

Discuss encoding for devices and presets.
Forum rules
An Activity Log is required for support requests. Please read How-to get an activity log? for details on how and why this should be provided.
Post Reply
cdb216
Posts: 6
Joined: Mon Jan 29, 2007 7:13 am

640x360?

Post by cdb216 »

I have a question about encoding 16:9 widescreen media. I can't seem to be able to get MediaFork to encode at 640x360, which seems to be the standard resolution for widescreen media on the iPod 5.5 (I've purchased a number of episodes off iTMS and all of them are encoded at 640x360).

As far as I can tell, I can only encode at 624x352 or 640x368. The former doesn't quit get the full resolution allowable on the iPod, while the later is slightly distorted.

I don't think I could really tell the difference between a media file that's 624x352 and 640x360, but it might be something to address in future releases (that is, if I haven't missed something completely obvious).

Congratulations again on the release of MediaFork!
baggss
Moderator
Posts: 886
Joined: Tue Jan 02, 2007 8:21 am

Post by baggss »

You can always uncheck the option to keep Aspect Ration and then custom crop to get it right.
dynaflash
Veteran User
Posts: 3820
Joined: Thu Nov 02, 2006 8:19 pm

Post by dynaflash »

Yeah, actually, it is a deficiency in the existing autocrop for some movies.
cdb216
Posts: 6
Joined: Mon Jan 29, 2007 7:13 am

Post by cdb216 »

Especially with the preference to "Reset picture width to 640 when x264 (iPod) encoder is selected," it would be awesome to have MediaFork automatically make 16:9 media 640x360. It would certainly save some time and ensure that I'm actually encoding at the best possible resolution for my iPod (plus, I bet a lot of people will check that preference box and not realize that it's slightly distorting their 16:9 media).

But as I said, I can't really tell the difference between 624x352 and 640x360 and it certainly won't stop me from encoding stuff in the meantime and being very happy with the result.
dynaflash
Veteran User
Posts: 3820
Joined: Thu Nov 02, 2006 8:19 pm

Post by dynaflash »

cdb216 wrote:But as I said, I can't really tell the difference between 624x352 and 640x360 and it certainly won't stop me from encoding stuff in the meantime and being very happy with the result.
Great, and just to let you know, we have a trac ticket on this already. Its affect varies from dvd to dvd and NTSC to PAL.

Hope you are enjoying MediaFork.
jbrjake
Veteran User
Posts: 4805
Joined: Wed Dec 13, 2006 1:38 am

Post by jbrjake »

cdb216 wrote:But as I said, I can't really tell the difference between 624x352 and 640x360 and it certainly won't stop me from encoding stuff in the meantime and being very happy with the result.
You do understand that 640*360 does not obey DCT rules, right? MPEG-4 requires video to be in 16x16 macroblocks. Apple, I guess, is cheating and allowing 8x8 values. While x264 can encode those, it will be at a loss of quality (or depending on how you look at it, an increase in file size). That's why the GUI height and width steppers move in increments of 16, in order to make sure the values are not going to cause extra work for the encoders.

Here's the word straight from the mouth of the man who actually created x264:
akupenguin wrote:5th April 2006, 01:23
In h264, if the resolution of the whole frame is not mod16, you basically pay the bit costs (and cpu-time) for the rounded-up resolution instead of the displayed resolution. So e.g. 640x368 ~ 640x352 > 640x364 > 640x360 > 640x356. (where ">" is "better")
atl
Posts: 2
Joined: Mon Feb 12, 2007 11:03 am

Post by atl »

Also, keep in mind that not all widescreen footage is precisely 16x9. A 1.85:1 aspect ratio is common in the cinema.
cdb216
Posts: 6
Joined: Mon Jan 29, 2007 7:13 am

Post by cdb216 »

Definitely didn't know about DCT rules. Good to know. I guess I'll just stick with what I've been doing then (or see if I notice any elongation of the picture at 640x368).

Thanks for the responses!
Post Reply