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Discussion Starter · #1 ·
What's the current state for HD stream playback in software?


Will a 2.0 GHz P4 playback 1080i, or do you need a beefier machine?


(I tried searching for the info, but I couldn't hit upon the magical keywords to find the info I'm looking for)
 

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A 1ghz Pentium3 works fine if you have the right video card. The video card is most important when trying to play HD in software. I'm using Radeon 64 VIVO's.


For raw (HiPix) TS files, I use XP, ZoomPlayer, Elecard demuxer with PowerDVD4 video filter, DXVA enabled, MoonLight or Intervideo audio.
 

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There is a related issue that I have trouble understanding: I was looking in to HDTV cards for HTPC use. It seems that to view (in real-time) HDTV content you must hook up your TV to the card's output (component or otherwise). They won't play through the PC's video card. The reason for this, or so I'm told, is that the HD stream uses more bandwidth than the PCI bus has.


That may be so. However, HDTV is simply MPEG2 encoded, just like DVD. We know an average PC has no problem at all decoding MPEG2 in software in real-time. So, why don't these things just send the MPEG stream through the PCI bus for decoding by the PC?


Point being that I'd like to keep things simple and have just one set of component outputs hooked up to the TV (ie. from the video card).


I know some cards will play 480p through the video card. I know some cards support pass-through of the video card through the HDTV card, but they only support very specific resolutions. It should go the other way around.


I guess there's not really a question in this, unless someone knows a more elegant way of doing it. I just don't understand why it has not been implement better.


- Rob -
 

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GaryHDTV,


I have a 2GHz P4 and AIW Radeon, but I can't play 1080i. I don't have a HDTV card, so I tried the 400MB crawford clip, which, I believe, is the same as a .ts file.


I am running windows XP and catalyst 2.3 drivers.


What's going on?
 

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camoura, I don't know about the crawford clip. All my files come from a HiPix. What software are you playing your HD files with?
 

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That stream is 30Mbs, quite a bit higher than normal ATSC video. I would try it, but it's just too slow a download.


I have yet to get WinDVD Directshow filters to function in hardware assist mode, only the WinDVD3.1 player app itself under Win98SE (not XP).


The Sonic filter should work in XP, but you must go into the registry and set UseDXVA to 1. I haven't used Sonic, but the older Ravisent filter that came with ATI7.6 worked, however it would not display video initially when play is pressed. I had to hit the position slider before the video would appear. If you don't have Zoom Player, I recommend it as you can build your own custom filter graphs. The PowerDVD video filter is working the best for me right now.
 

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> What is the bitrate of a normal ATSC video? I could try to reencode at that bitrate.


It's roughly 19MBps. You can download the ATSC specification from http://www.atsc.org, and find the exact bitrate constraints.


GaryHDTV, interesting...I have to do the *exact* same thing to play my WinTV-D TRP files with ATI7.6+elecard. Furthermore, I was only able to make this work with the older Win98SE drivers (before 'Catalyst'), and with a specific version of the elecard demuxer (10/2001.) If I update anything to more recent (display driver, elecard demux), nothing works.


I recently suffered a bout of stupidity (deltree \\windows ... opps!), and reinstalled Win98SE. Now I can't get the ATI7.6 player to play any TRP files, even though I've done my best to restore my previous system-config. PowerDVD-XP's MPEG2-video decoder works almost as good. It can play 720p (from ABC) with almost no stuttering on my Celeron 1.33GHz and Radeon7200. Unfortunately, I can't get 1080i clips to play properly, and I think this is a someware issue.


Just about all 1080i recordings from KCBS/2 (Los Angeles) suffer severe stuttering. 1080i Jay Leno recordings from KNBC/4 (Los Angeles) play with momentary glitches every 30-35 seconds. Old 1080i recordings from KCET/28 (PBS) play almost perfectly. All three stations broadcast at the full 19MBps ATSC rate, no multicasting. (Well KCET now multicasts, but I'm using older recordings that ran at the full bitrate.) For some reason, KCBS's encoder really gives the elecard demuxer fits and spasms.


And when I open KTLA/5 (WB)'s recordings, elecard scans the *entire* file before returning control to WMP. This takes up to a minute. Afterward, I can play the clips about as well as my KNBC stuff.


...


When I had the ATI7.6 + elecard combo working, CBS 1080i clips required some fancy/schmancy mouse-clicking to play properly. Opening the file gets a blank screen, so I hate OPEN -> STOP -> PLAY. That gets apicture on my window, but the playback stutters severely ( less than real-time playback.) To fix this, I seek through the clip (FF/REW), causing the demuxer to internally empty/refill its buffer, until the playback resumes smoothly. Most of the time, it only takes 5-6 attempts or so (hehe.) Once it achieves 'smooth', it stays that way until I pause or FF/REW again (or open a new file.)


The old ATIDVD 4.1 had no problem opening/playing 1080i files at full-speed, every time. Unfortunately, the player had a tendency to crash, the 1080i playback wasn't correct (the chroma and luminance fields were out of alignment), and I don't think it works with the newer Catalyst drivers.
 
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