Resolutions and frame size when coding from DVD-sources

[tominator]

Hi
I encode DVD -> WMV.

Since my WMV-files are used for streaming Im using 1372 kbps WMV3 CBR with 128 kbps WMA2 44 khz as my bitrate settings.

I use 640px as width at the moment but Ive seen others using 720px. Im guessing this is because it's the same width as the source DVD.

Ive tried encoding files in both 640px and 720px width but I can't see a lot of difference.

Is there a right and wrong here? How does one generally determine what resolution to use for files encoded from DVD-sources? Is there some kind of calculator?

Any help much appreciated.

On a side note, does anyone have a clue what the image quality setting when encoding WMV-files does? Isnt it my bitrate and fps that determines the quality of my movies' images?

Thank you!

[dat720]

There's no right and wrong, for me it's simple, stick to the same width as the dvd, of course unless you need to crop horizontal, *you do notice the diff on a TV that runs at 1080 resolutions*

[tominator]

There's no right and wrong, for me it's simple, stick to the same width as the dvd, of course unless you need to crop horizontal, *you do notice the diff on a TV that runs at 1080 resolutions*

[rule 6 material removed]

[dat720]

If i would have to guess, i'd say it's to save space during compresion, it is hard to get a movie to 700mb and keep the quality of a DVD. Scaling down to 640px would afford a higher bitrate thus allowing them to keep the quality up, keep in mind i'm not refering to picture size as quality i'm refering to the actual image quality of the video.

As long as your not implying your downloading or trying to convert downloaded content i don't think the mods mind.

The 2 TV's i use in my house are a 60" rear pro and a 42" plasma, i couldn't give a toss about size.... i care much more about quality and would rather the picture be crisp and clear with no blokiness.

[Blue_MiSfit]

A common reason to encode at 640x... is because the content is 4:3. You can boost compressibility a little bit if you resize to 4:3 (640x480) ahead of time. The loss of horizontal resolution isn't such a big deal.

But, you can encode the full 720x480 - and encode anamorphically - I.E. stretch to 720x540 on playback.

WMV can be suited for streaming using CBR. No reason to limit yourself so dreadfully for local playback (or on a home network for that matter). VBR is always better, if your bandwidth is sufficient.

~MiSfit

[tominator]

A common reason to encode at 640x... is because the content is 4:3. You can boost compressibility a little bit if you resize to 4:3 (640x480) ahead of time. The loss of horizontal resolution isn't such a big deal.

Do you mean resize the source mpeg2 before transcoding? Why would that make a difference?

But, you can encode the full 720x480 - and encode anamorphically - I.E. stretch to 720x540 on playback.

Since my sources are PAL Im guessing you mean 576 and 625. But does WMP really take account to aspect ratio headers?

WMV can be suited for streaming using CBR. No reason to limit yourself so dreadfully for local playback (or on a home network for that matter). VBR is always better, if your bandwidth is sufficient.

I was under the impression VBR couldnt be used for streaming, that CBR was my only option. Is that not correct?

[roozhou]

WMP and WM Video Decoder DMO do respect PAR in asf header.

[tominator]

WMP and WM Video Decoder DMO do respect PAR in asf header.

Is PAR and DAR the same thing?

[ronnylov]

PAR = pixel aspect raio
DAR = display aspect ratio

A widescreen TV has DAR = 16:9 and non-widescreen TV has DAR = 4:3.
By setting DAR you tell the decoder to stretch the picture to the same width/height proportions as the DAR.
The resolution of your video may be for example 704x576 with DAR=16:9 which then will scale this picture to 16:9 format (no matter what resolution is of the video).

PAR is the aspect ratio of the pixels. Say you have 704x576 that you want to stretch to 1024x576 during playback. If you set PAR=1024/704 = 1.455 then you'll get correct aspect ratio.

So DAR and PAR is different settings to accomplish a stretching of your video as desired. You normally set one of them, not both at the same time.

I find this useful if I want to keep original video resolution and let the player do the scaling at playback.

[tominator]

thank you

[Chetwood]

The loss of horizontal resolution isn't such a big deal.
I've read similar statements before and I disagree: having 640px instead 720px makes for a lot of missing information. It's not degraded by compression, it's simply missing and why would I want that? I mean, it's better to stay on 720px and encode to more than 700 MB size. Since I'm doing backups for my media center file size doesn't matter that much anymore, still the question of what is the optimal size/quality trade off still remains.

[dat720]

Finally! nice to hear it Chetwood, trying to force a DVD to 700mb seems kinda pointless to me!