720p or 1080p Source? For converting to WMV-HD

[Mickey79]

Ave,

I have a 50" Panasonic 720p (1366 x 768 native resolution) Plasma TV. I'm trying to convert MKV Videos into a format (Most likely WMV-HD / WMA-HD 5.1) that can be burnt to DVD (Single or Dual) and played in my HD-DVD Add on for my XBOX 360. I need to retain the HD Resolution & 5.1 Audio.

My question is - the video file I have is 720p, but I can also attain the 1080p of that Video. Is it better to get the 1080p, process that & convert to WMV-HD, or will it not make any difference considering my TV is 720p native?

PS: Also - I'm still trying to figure out the best method for this conversion.

Thanks!

[jman98]

The smaller the resolution (720p is less than 1080p), the less bit rate you need for quality. So assuming the same quality, a 720p encode would need less bit rate and result in a smaller file than a 1080p encode.

The forums at http://www.doom9.net have a section called "New and alternative video codecs" that discusses how to encode stuff, including high def video, with Windows Media Video.

[JohnnyMalaria]

My question is - the video file I have is 720p, but I can also attain the 1080p of that Video. Is it better to get the 1080p, process that & convert to WMV-HD, or will it not make any difference considering my TV is 720p native?

Stay with the 720p. With LCD displays, it is alway best to use the native resolution. 1080p will just be downconverted anyway.

[Mickey79]

Well, I guess my argument comes from the fact that Downconversion will always look better then upconversion. In essence, the 1280 X 720 resolution in a 720p video, will be upconverted to 1366 X 720 on my Plasma TV. However, if I choose to convert the 1920 X 1080 (1080p) video, it will be downconverted. Won't the quality be better that way?

I'm not sure - I may be wrong.

[jagabo]

Well, I guess my argument comes from the fact that Downconversion will always look better then upconversion.

I generally agree with this. If your source is 1920x1080 you should probably leave it that way (if you can afford the bitrate). Downsizing to 1280x720 then having your TV upscale to to it's native resolution (probably larger because of overscan) will involve two resizings. Are you planning to keep these videos? What if you get a 1080p HDTV in the future? If you downsized to 1280x720 you've lost the additional resolution forever.

[aedipuss]

a dvd-r cost about 25 cents. try it both ways and see which you prefer.

[edDV]

Well, I guess my argument comes from the fact that Downconversion will always look better then upconversion. In essence, the 1280 X 720 resolution in a 720p video, will be upconverted to 1366 X 720 on my Plasma TV. However, if I choose to convert the 1920 X 1080 (1080p) video, it will be downconverted. Won't the quality be better that way?

I'm not sure - I may be wrong.

What are your sources?

1920x1080 has 2.073 MPixels per frame. 1280x720 has 0.922 MPixels per frame.

Other things being equal, saving at 1080p will take 2.25x the bitrate. That gets factored by frame rate to get minutes per DVD-5/9.

The quality difference on a 1366x768 display won't be anywhere near two times better. The only reason you would render to 1080p is for future use.

In theory, you might get a bit better quality and minutes rendering a 1080p source to 1366x768 wmv but that would be a non-standard size for future use.

[jagabo]

a dvd-r cost about 25 cents. try it both ways and see which you prefer.

And be sure to use something with high frequency content.

[Mickey79]

Well, I guess my argument comes from the fact that Downconversion will always look better then upconversion.

I generally agree with this. If your source is 1920x1080 you should probably leave it that way (if you can afford the bitrate). Downsizing to 1280x720 then having your TV upscale to to it's native resolution (probably larger because of overscan) will involve two resizings. Are you planning to keep these videos? What if you get a 1080p HDTV in the future? If you downsized to 1280x720 you've lost the additional resolution forever.

Well here's the thing - I have the same Video in both Sources, 720p & 1080p. I haven't started the conversion yet and that's why I'm trying to figure out which source to take. I can use either.

One question - you said "If you can afford the bitrate". What exactly do you mean by that?

Basic idea is to convert the MKV (coming from an HD-DVD/Blu-Ray) to a format that can be burned on a Dual or Single Layer DVD and played in the XBOX 360 (Or the HD-DVD Add On). I was recommended converting the MKV to WMV-HD VC1 / WMA-HD 5.1 to retain full resolution & audio, and burning it to disc which can be played in either XBOX 360 or it's HD-DVD Add On.

I have plenty of blank Single & Dual Layer discs - that is not the issue. My only issue is, with the video available in both 720p & 1080p, I'm trying to ascertain which is the best source to use in my case.

[JohnnyMalaria]

Well, I guess my argument comes from the fact that Downconversion will always look better then upconversion. In essence, the 1280 X 720 resolution in a 720p video, will be upconverted to 1366 X 720 on my Plasma TV. However, if I choose to convert the 1920 X 1080 (1080p) video, it will be downconverted. Won't the quality be better that way?

I'm not sure - I may be wrong.

The 720p conversion is from 1280 x 720 to 1366 x 768.

I have no idea why 720p displays are 768p. Seems stupid. I wonder if there are any true 1280 x 720 HDTVs.

[edDV]

I have plenty of blank Single & Dual Layer discs - that is not the issue. My only issue is, with the video available in both 720p & 1080p, I'm trying to ascertain which is the best source to use in my case.

The issue is whether you can live with 1/2.25 the minutes per DVD?

Another take is bitrate generally trumps resolution for perceived video quality. If you are talking movie lengths, that would lead you to trade resolution for minutes at constant bitrate.

Use the bitrate calculator to determine the bit rate needed for the minutes you want to record, then optimize resolution for perceived picture quality.
https://www.videohelp.com/calc

[edDV]

For example, the calculator shows a 2 hr recording requires max 4853Kb/s average bitrate.

Using your 1080p source, encode your most demanding clips (high action and/or high noise) to 4800Kb/s wmv at 1080p and 720p. Then see which looks better to you on your TV.

If you want to max for quality, use your 1080p mkv and encode to ~15,000Kb/s 1080p VC-1* (or the max playable Xbox360 decode rate) and live with the calculated minutes per DVD-5/9.


* That calculates out to around 39 minutes per single layer DVDR.

[jagabo]

Using your 1080p source, encode your most demanding clips (high action and/or high noise) to 4800Kb/s wmv at 1080p and 720p. Then see which looks better to you on your TV.

This isn't entirely fair. Most video has a mix of high and low complexity parts. Using a VBR encode the high complexity parts can be encoded at higher bitrates than the average, and the lower complexity parts at a lower bitrate. I know you, edDV, know this, I just want to make sure the OP is aware. In any case, he's using an HD-DVD drive so the 4.3 GB DVD limit isn't an issues.

[Mickey79]

jagabo - I understand your point about VBR vs CBR.

edDV, I think the problem is that you're extremely knowledgeable and unfortunately you're talking a little too technical for my understanding. I'm grasping the basic idea, but at the same time you're loosing me in bits & pieces.

Let me try and understand a little more - but let me ask you this - what would be the best tool/procedure to encode that MKV to VC-1 (retaining it's native resolution, i.e., 1080p or 720p, depending on the source I choose) and it's 5.1 audio?

Edit: We're definately talking movie length video. And I understand that to retain any good quality, I'll have to be picking up a Dual Layer disc as opposed to single layer in order to maximize bitrate/minute.

Thanks!

[jagabo]

Windows Media Encoder? Oh, except reading MVK will be a pain.

[Mickey79]

Windows Media Encoder?

I don't think Windows Media Encoder (I could be wrong) will take MKV source.
What about Encode 360 or TMPGEnc Xpress?

[edDV]

Using your 1080p source, encode your most demanding clips (high action and/or high noise) to 4800Kb/s wmv at 1080p and 720p. Then see which looks better to you on your TV.

This isn't entirely fair. Most video has a mix of high and low complexity parts. Using a VBR encode the high complexity parts can be encoded at higher bitrates than the average, and the lower complexity parts at a lower bitrate. I know you, edDV, know this, I just want to make sure the OP is aware. In any case, he's using an HD-DVD drive so the 4.3 GB DVD limit isn't an issues.

Yes VBR is fine tuning but I wanted to make the point that bitrate is generally more important than resolution for perceived picture quality, and that average bit rate is determined by the number of minutes to a fixed media capacity.

[edDV]

Taking VBR into consideration you might want to test the worse case clips at 150% average bit rate.

[jagabo]

Windows Media Encoder?

I don't think Windows Media Encoder (I could be wrong) will take MKV source.

Yes, you are right. I realized that would be an issues right after posting. It won't accept an AviSynth script either. I hardly ever encode anything to WMV so I can't give recommendations.

[edDV]

Ignoring the transcoder problem, our two hour example to dual layer DVD-9 calculates to an average bitrate of 9030Kb/s assuming 224Kb/s for audio.



So your ~25,000Kb/s MKV needs to be bitrate reduced to about 38% bitrate. Figure VC-1 or H.264 are good for half bitrate at similar quality. That difference between 50% and 38% may favor 720p over 1080p but that needs testing with your eyes.