DVD Movies!

MichaelX30 · 07-20-04, 09:17 PM

What movies do you watch on your Axim? So far just the only one I converted The Last Samurai, the video quality is ok, I just don't understand why it is more than 200 MBs, I hear people saying how they fit 2 movies on one 256 MB card! The resolution I have mine at is 320X144 ( I like keeping the widescreen aspect!)

hanna975 · 07-20-04, 09:35 PM

The only thing I can suggest is checking out BigD's guide. He's the best I found on converting movies to pocketPc and more.
Check out the link.

http://www.bigdsvideo.com

He'll hook you up

imf4 · 07-21-04, 06:35 AM

The resolution doesn't have much of an effect on the file size because it is compressed. The big part is the bit rate you encode it at. The best thing to do is take a 1 minute clip and compress it at 100k 150k and 200k using Windows Media Encoder and then you will see the file size differences.
Also pay attention to your audio bitrate. It will add a lot of space if you compress it at a high bitrate. If you do care about the audio quality(I do) I wouldn't go below 64k stereo.(or mono if you aren't listening through headphones) 48k would be resonable but the difference between 64/48 is very noticable.

MichaelX30 · 07-21-04, 09:44 AM

I am having such a blast with converting movies to PPC! I just converted Moulin Rouge at 170 kbps with audio at 80 kbps.

wmcjhi · 07-21-04, 09:54 AM

Quote:

Originally posted by imf4
The resolution doesn't have much of an effect on the file size because it is compressed. The big part is the bit rate you encode it at. The best thing to do is take a 1 minute clip and compress it at 100k 150k and 200k using Windows Media Encoder and then you will see the file size differences.
Also pay attention to your audio bitrate. It will add a lot of space if you compress it at a high bitrate. If you do care about the audio quality(I do) I wouldn't go below 64k stereo.(or mono if you aren't listening through headphones) 48k would be resonable but the difference between 64/48 is very noticable.

Actually, resolution has a TON to do with it...optimizing the res for the pocket pc screen (320*240) not only makes it look better on the PPC screen, it makes the file much smaller.

imf4 · 07-21-04, 12:57 PM

Quote:

Originally posted by wmcjhi
Actually, resolution has a TON to do with it...optimizing the res for the pocket pc screen (320*240) not only makes it look better on the PPC screen, it makes the file much smaller.

I totally agree with you on that it is best to optimize the resolution with the native one on your Pocket PC. BUT YOU ARE WRONG about the resolution making a alot of difference in size.

I just took a 1 minute clip and converted it to WM9 @ 200k with 96k audio @ 640x480 and 320x240.
the 640x480 file is 2.22 MB (2,338,070 bytes)
the 320x240 file is 2.20 MB (2,315,620 bytes)
I would hardly call that a major size difference.

wmcjhi · 07-21-04, 01:08 PM

Then you must be using some sort of compression that I have never used before (I mainly use divX)...because a single 640*480 frame is 307,200 pixels while a 320*240 frame is only 76,800...multiply that by 30fps, and you have a 6,912,000 pixel difference for 1 second...that should make a huge difference in size...particularly over a 2 hour long movie...

wmcjhi · 07-21-04, 01:17 PM

Here's proof: A chart from Canon's site detailing how much memory is needed to make a video clip at 640*480 or 320*240:

imf4 · 07-21-04, 03:16 PM

I don't know what to tell you. I used Windows Media Encoder and Tmpegenc. Both had the same results. Maybe you should try it if you don't believe.

Alric · 07-21-04, 03:43 PM

Look at the times. At 320 x 240 you get nearly four times more video time as opposed to 640 x 480.

A simpler test is to compare the size of a 640 x 480 jpeg to a 320 x 240 jpeg.

wmcjhi · 07-21-04, 04:07 PM

^^Thanks for the backup alric!

AMike · 07-21-04, 04:27 PM

If you compress using a certain bit rate, the resolution has no bearing on the size of the file. The size is defined by the bit rate times the length of the video. That's it. However, if you compress by a certain percentage for some reason (like the canon appears to do on a rough scale, and this may be roughly called perceptual compression for the purposes of this discussion) then the resolution will make a difference.

Now, for a practical clarification of the issue at hand. Say in a divx codec you compress to a certain quality. The resulting file will scale with the total number of pixels. Now, if you encode a wmv file, you usually choose a bit rate. In this case, the file size has nothing to do with resolution.

Also, if you choose a fixed-quality (perceptual) encoding technique, the size only scales by the resolution and complexity of the video, it has nothing to do with the length. I'm not sure what the "particularly over a 2 hour long movie" was about, because the 640x480 movie should be four times as large as the 320x240 movie, regardless of length, but maybe your point was just for clarification of some sort.

jledesma · 07-21-04, 04:30 PM

I also agree that the size resolution of the image is a factor (a big one) on the size of the resulting file. But also a good balance between bitrate and sound quality are important.

imf4 If the video you compressed has little or no movement in it the difference between size a resolution is very little due to the compression algorithms. The less movement on the image less information needs to be retained to reconstruct the image on decompression. Perhaps that's why your movie ends up with almost the same size once you compressed it

wmcjhi · 07-21-04, 04:30 PM

AMike: Essentially, what you are saying is that because the 640*480 WOULD take up more space than the 320*240, it is compressed more/quality is lowered more, etc...so in essence we were both right.

stuffer11 · 07-21-04, 04:36 PM

Agree with Amike.

the resolution has nothing to do with the final filesize as the bitrate at which you compress it with is used to draw up the whole screen, so if you have a file with 800kbps you will have
800/8 = 100KB per second, and at a fps of 25 that is= 4KB/frame

With a 640x480 resolution you then would have 4kb/frame to describe 307200 pixels but with a resolution of 320x240 you would still have 4kb/frame but just 76800 pixels per frame.

The quality on a 320x240 display would then be higher with the 320x240 file as each frame has more bits/pixel to explain what the hell it looks like :)

No, what he is saying is that at a Fixed bitrate the size is the same no matter if the resolution is 1024x768 or 320x240 (just as an example), But if you choose to have a perceptual encoding the resolution matters as it takes more bytes to explain how the frame is built, but then you won't have the same bit rate with the 320x240 as with the 1024x768