Just a little about iTouch video conversions

vbimport

#1

O.K. just wanted to collect some information for those that are backing up to there iTouch/iPhone. I think it does not matter because they seem to share the same screen. In the conversion process I want to make the file size as small as possible, but not to the point that one gives up video/audio quality for it. I also wish to maintain as close as possible to the original aspect ratio of the movie.

The iTouch/iPhone seems to have a screen size of 480 X 320 (1.5:1 aspect ratio), however it says it is capable of displaying resolutions up to 640 X 480(1.33:1). The typical big screen movies comes in either 2.35:1 or 1.85:1 aspect ratio. Yes, there are other ratios out there, but these seem to be the typical for US film makers. To keep things simple and not to get of on a tangent I wish for now to keep this thread related to the 2.35:1 aspect ratio movies converted to the iTouch/iPphone.

For 2.35:1 movie that is enhanced for 16:9 or anamorphic, the frame resolutions I have been looking at are 640 X 272(2.352) or 480 X 208(2.307). Both of these keep the aspect ratio very close to the original however with the iTouch/iPhone screen size limited to 480 X 320. So am I just wasting file size in converting things to the 640 X 272 resolution or do you think the difference in the two frame resolution will be visible on the iTouch/iPhone screen?


#2

I can’t speak for your i-Devices, but on my Archos (480x270, 4" screen) there is absolutely no difference in quality by encoding to a larger screen size. If you have a choice in the profiles for your devices (I haven’t looked at those recently) use one that has H264 video with AAC audio. To minimize file size, make tests of a single chapter starting with the bitrate slider set to produce about 0.08-0.1 bits/pixel. If that doesn’t look good enough, increase the bitrate slider to get a higher value until you find one that looks good to you. My new cellphone (LG Dare)has a screen about that size and I have been encoding at a video bitrate of about 280 kbps with good results using H264. If the conversions are 2.35:1, turn cropping to automatic and select the closest match to your screen size and cropped aspect ratio–this will help make the files smaller also.


#3

I haven’t done much with widescreen movies as of late, but as far as bitrates go. Iv’e been as low as 200 kbps (2 pass encoding) with my Family Guy episodes and they look perfectly fine on my iphone. On my laptop they look OK when set to full screen. I currently have my Family Guy shows encoded at 400 kbps 2 pass, and they look pretty good on the laptop as well. The scren resolution Iv’e been using is 432x320, and I like it a lot. When you go with a bigger resolution, one thing to keep in mind is it supposedly makes the processor work work harder to down convert to fit on your itouch screen. So it may use up more battery life possibly. How much? I don’t know my self, but I’d like to know.

Using the iphone tv out, my Family Guy shows look pretty good at 500 kbps 2 pass, and that on my Samsung 56" DLP. 400 kbps doesn’t look to bad either. On my 32" Westinghouse LCD they look ok, but definitely worse than on my bigger tv. -Still enjoyable though. I think it helps a lot that its a cartoon that doesn’t have a lot of animation/special effects that allow it to look pretty decent at those bitrates. Now if it was the new Star Wars Clone Wars it would probably look like crap.


#4

To further reduce the file size with animation, you can often reduce the frame rate to 15-20 fps. Looks OK in may cases and also speeds up the conversion. Stuff for bigscreen TV I encode at 1800kbps but usually just play the DVD. Looks better.


#5

I dropped the frame rate down to 23.97 and seemed fine still. I haven’t tried any lower.


#6

Try one at 15-20fps. The lower frame rate makes the bits per pixel number go up, which allows you to lower the video bitrate. You can do it with live action movies too, but sometimes they look a little jerky. With animation, the effect is almost invisible.


#7

Family Guy is a 1.33:1 aspect ratio, so 432 X 320 with auto cropping is would be fine, however that frame resolution is not good for 2.35 movies. I do agree with dropping the frame rate on animation, save space and no visible loss, however everytime I have tried that with regular movies they end up being very jerky looking to me.

I have noticed that doing 2 passes makes the file smaller as well, but encoding takes twice as long, not really sure what it is doing on the second pass that it did not do on the first pass but results in smaller file.

Now as far as using H264 video with AAC, I thought that was the default when selecting the iTouch from the drop down menu. There is also an option for H264G, but not familiar with that one.


#8

I noticed on most of these video files when I change the “Fix Bit Rate” number, it ends up changing it back next time I look at it. Is this normal or a bug in the software?

Let’s I choose “Frame Resolution” of 640 X 272, and I want the “Fix Bit Rate” to be 500 kbps istead of 626. I then select OK. If I know select the “Conversion Setting” button it has changed the “Fix Bit Rate” back to 626(the original number)?


#9

Do hit hit the icon in the upper right corner that says save as default?


#10

Do hit?

Not sure what you mean. Select the desired kbps the select default to save it that way? If thats what you mean then I have to select defualt everytime since I am doing movies of various aspect ratios. Everytime I switch the aspect ratio of the movie the kbps goes to a number I did not select. Even if I change it it goes back to its own original number.

Maybe if we had multiple default or user setting this would help. I could have a default for my 2.35 movies, a default for my 1.85 movies a default for my 1.78 movies.

Maybe this is something that could be added on for a future software upgrade???


#11

You can create custom profiles to do what you want already.

Have a read of the documentation under the profiles directory.


#12

Did you hit.

Download the profile editor thats located at the top of the forum. That will allow you to have multiple defaults to work with. Using beta 5.0.9.5 I was having problems that it sounds like your describing. I mentioned it to Fengtao(?), and I think he did something as now for the most part it only happens 1 out of 10 times maybe at the most using 5.0.9.8.


#13

Yes I did, and it created a defualt for my 2.35 movies that loads first when I select DVD to Mobile, but I do not see how to create a second profile for my itouch 1.85 movies. If I set it as default it simply replaces my original default.

I did see a DVD profile editor program that is seperate from the DVDFab. Does that mean I can not do this extra defualt profile with out it?


#14

You create multiple profiles with the setting that you require in each then add new devices to mobile so you just select the device on the sidebar.

You will have to work out a naming convention for your multiple devices, eg 235.xvid.avi.audiocopy, 185.xvid.avi.audiocopy and change the device name in the actual profile.

I still prefer use a text editor to edit the profiles over the profile editor.


#15

Ah I think I get it, will give it a try next time I get a chance.