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October 13, 2004

Quality of HDTV Xvids on XBMC?

I am thinking of getting an XBox just to get XBMC up and running. The XBMC FAQ and pretty much anything I've managed to google, say that XBMC can pipe out HDTV-quality picture only theoretically and that in practice the base XBox CPU is far too slow to decode an HDTV stream without jitter and dropped frames. Well, my question is this to those of you out there that do have XBMC installed: I don't get care about receiving HDTV itself, but I do download HDTV files from the 'net that are encoded in Xvid, DivX, etc. Does XBMC choke on those as well, or do they display OK?
-- costas

October 13, 2004 in media servers, Xbox

Answers

Most TV Shows that I see on the web are in xvid format and are not actually HDTV quality even though the title of the show may include HDTV in it. The only part of the HDTV that you get is the format 16:9. The picture quality is the same as any well encoded xvid show.

XBMC is what I use to watch all my downloaded shows from the web. I download a couple a day from the UK. My XBMC connects through SMB to my computer and I watch them directly from there without burning any CD's or ftping etc etc. Some say HDTV and some don't. They always look the same.

XBMC even understands CD images. I have a show I downloaded the other day that came across as a .bin/.cue file. A common format to burn to a CD. My XBMC recognized it and played it without doing anything special.

If you download shows and want to watch them on a tv then the price of an XBOX and a chip really can't be beat.

Posted by: Boyd at Oct 13, 2004 3:17:49 PM

It's all answered in the XBMC FAQ but let me try to clarify; XBMC/Xbox can playback 480p (720x480 progressive) HDTV files just fine (that's 720x480 progressive media files), XBMC/Xbox can even upscale 480p (and standard DVD-video) to 720p and 1080i without problems and at great quality, (as the upscaling gets done by the video-out chip and not the CPU). XBMC/Xbox only 'chokes' when you try to play media files that have 720p or 1080i in native resolution (that's 1024x720 progressive and 1920x1080 interlaced) as that is too much for the Xbox CPU, ...but fortunatly there are not many media files out there in native 720p or 1080i resolutions, (most HDTV media available for download on the internet today are 'only' in 480p resolution)

XBMC capability on a standard Xbox (Intel 733Mhz PIII CPU):
720x480p video output to 720x480p = OK! (eg not upscaled).
720x480p video output to 1024x720p = OK! (eg upscaled to 720p).
720x480p video output to 1920x1080p = OK! (eg upscaled to 1080i).
1024x720p video output to 1024x720p = FAIL! (eg native 720p).
1920x1080i video output to 1920x1080i = FAIL! (eg native 1080i).
Note! All above that sais FAIL don't actualy fail to play, it's just that the Xbox CPU is to slow to decode and render the high resolution so they will play so slow (dropped frames) making it unwatchable.

XBMC HDTV FAQ: http://www.xboxmediacenter.com/info_faq.htm#hdtv

PS! There are not many DVD-players out there that can upscale normal DVD-movies to 720p or 1080i and those that can are much more expensive than a modded Xbox ;-P

Posted by: Gamester17 at Oct 27, 2004 11:48:52 AM

While the official line holds true for most HD media (1080i), I've had marginal success watching 720p material (both mpeg4 .avi's and mpeg2 .ts's) viewed at 1080i; eg 720p ->1080i conversion.

While the result is far from perfect, it is mostly watchable. The Friendtech mod (replaces the cpu with a celeron @ 1480Mhz) would certainly be able to accomplish this, and probably 1080i as well.

Posted by: Jozzy at Jan 16, 2005 7:50:54 PM

just to clarify, 720p is 1280x720 not 1024x720

also any one see if xbmc could play HD WMV files?

Posted by: stizzo at Jan 26, 2005 3:18:19 PM

I have streamed a 1280x720 XviD movie from my PC.
It looks just great.
Having a problem though...
If I choose "Original Size" XBMC will scale the picture to 1170x720.
And picture looks no good at all. Downscaling to 720x576 looks fantastic.
I have no idea why - do you ?

I have a PAL xbox - but changing to NTSC makes scaling even worse.
I use a Panasonic AE700 projector (capable of doing 1280x720)

Posted by: Uffe at Feb 4, 2005 12:46:33 PM

A reply for Jozzy

I have Terminator 2 Extreme edition that has T2 in HD 1080i WMV format on disc 2. It does NOT play in XBMC. :(

Posted by: Shazad at Feb 11, 2005 3:45:58 PM

Has anyone got a configuration for xbmc that can support 720p playback of avi or mpeg formats? I have tried local playback of the files and it drops frames all over the place.

Posted by: mark at Mar 1, 2005 6:02:39 PM

stizzo, as far as i know in PAL mode an xbox wont do High definition (720p or 1080i) whereas in NTSC it is allowed. I have a 720p xvid of braveheart and have played that succesfully with xbmc at 1080i with no dropped frames. Unfortunately thats about as much as I've tried.

Posted by: lockie at May 2, 2005 8:52:10 AM

What about recoding to an intermediate resolution?

I just hooked up my XBMC my new 1080i set (sweet!) and got the Comcast dual-tuner HD PVR (see above) to boot.

The PVR has a FireWire port on it that'll digitally output full HD-resolution MPG video.

I had a thought ... I know the xbox doesn't have the processing power to play a full 1920x1080i video file, but do I have to convert all the way down to 480p to get a reasonable rate?

What if I downconverted to progressive 960x540, half the HD resolution? I'd get a better-than-DVD quality image, and since the resolution's an even multiple of the target screen, it'd scale up nice and cleanly, too.

Has anybody tried this? How big a video will XBMC play before it starts to choke?

Posted by: Adam Klein at May 6, 2005 2:57:52 PM

lockie..

i just did what you suggested (although time consuming/processor intense) these videos look great on my computer screen... 480 vs. 540 is very similar and im guessing my xbox will be able to play both (even if it only plays 480 the PQ is virtually the same).. will let u know when i get a chance to try it out

btw... my xbox is set to upconvert to 720p for my sammy dlp

Posted by: kman at May 18, 2005 9:30:18 AM

oops i meant what "Adam Klein" not "lockie"

Posted by: kman at May 18, 2005 9:31:32 AM

If your gonna play a 720p avi file with XBMC make sure you turn of post processing!

After I realized this, frames were only dropped during fast motion scenes, it was quite watchable! Plus, choose low quality pixel shader or hardware overlay as your video display mechanism (something like that) as that uses less memory and processing. Try it out. You can see how many frames are dropped by pressing 'white' while a video is playing too.

It's kind of a bummer that the xbox isn't quite fast enough for 720p display, guess we need the xbox 360 + hacks soon!

Posted by: Jonny_eh at May 23, 2005 7:42:25 PM

If you encode 1280x720 @ 30fps (not 60fps! like it is broadcast) with all the extra options (QPEL and GMC) within XVID off = XBMC performs like a champ! I have encoded several programs and they playback without any dropped frames. I didn't re-encode the audio and left it as AC3. I don't have the link but I did a Google search for something like XVID XBMC HDTV and you can find a few guides. WM9 and VP6 use way too much cpu and the xbox chokes.

BTW - I am running the Xbox to a 1280x720 lcd.

Posted by: Rob at Jul 8, 2005 1:04:24 PM

Hi,
I can not play HDTV wma files, frame drop is to big.
There is one important thing that is not said here, and that is that you have to have component conection from the box and that the box has to be in the NTSC mode, and that you should setup resolution in msdashboard to 720p or whatever you want it to be.
There is also a possibility to change xbox cpu to 1,4GHz and then it should play anything.

Posted by: Esmir at May 27, 2006 6:38:27 AM

Also, be aware that it will not play .264 video very well. I have had some success, but only with video I've encoded specificaly for playback on xbmc. I'm very happy with the quality I'm able to get from even the x264 codec, but most .264 encoded videos you find on the internet will most likely seem quite choppy

Posted by: Terc at Jul 15, 2006 10:38:27 AM

There are quite a few nero digital x264 files floating around out there that were specifically made to play well with xmbc...and they do!

Posted by: me at Aug 28, 2006 2:19:21 PM

I have had success encoding 720p 24fps material with xvid for xbmc playback.

A few key points - use the XVID "HDTV" profile; set max consecutive b-frames to one; set target bitrate no higher than 4800kbps. (Note: You MUST do two-pass encoding for the profile's "video buffer verifier" limits to be applied.) This combination constrains the output stream to avoid spikes in data volume and complexity during 'hard' segments with a small loss in quality during those segments.

For playback, only do from local hard disk (or dvd-r with a slight performance hit), NOT smb; use hardware overlay video; use digital audio output with an external ac3/dts decoder (no software audio decoding); turn off extraneous functions (ftp server, rss feed, etc). This setup eliminates 99.999% of frame drops and great quality.

Posted by: me at Sep 25, 2006 8:43:57 AM

960 x 544 HR eps of prison brake upscailed to 720p look really good through an xbox gonna try 720p native tonight.

Posted by: pezza at Nov 1, 2006 9:11:03 AM

Hi.. i only want say. i try to play matroska files.. and many frames dropped..

then i play the same file at 720p in xvid and divx and play with no dropped frames.. very ok..
:)

Posted by: infiernet at Nov 13, 2006 10:29:48 AM

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