[mythtv-users] Can't Do HD ATSC Playback

[Robert Current]

Just did another "test" and tried to play a ATSC HDTV show at time
stretch 0.5x, and it it works... (everyone sounds drunk, but no
choppyness!)

So, I'm wondering still, would a new video card solve it?

And...  Meanwhile, can I set up different transcode jobs defined
specifically to HDTV shows only automatically (globally, only if it's
an HDTV show, but all HDTV shows, not per-show).  Or at least, for one
specific tuner?


On 4/24/07, Robert Current <robert.current at gmail.com> wrote:
> My system completely falls over when I try to do HD ATSC playback.
>
> Just got an antenna today, and started using my air2pc card for the
> first time (in addition to my PVR-150).  Now I've learned that my
> system can't handle "real" HDTV.  I was surprised, because it will
> play what I thought were HD recordings, but not recordings of my
> own...
>
> Here is what I've managed to figure out, and why I think it might be a
> video card issue:
>
> I can record ATSC HDTV with the air2pc card, and record MPEG-2 encoded
> standard definition shows from cable TV on the PVR-150, and play back
> one of the standard definition shows, while doing 1-2 commercial flag
> or transcode jobs, all at the same time without problem.
>
> PBS broadcasts an ATSC "SD" channel, I watched it, and it seemed fine.
>  I tried recording that to for testing.  File size was big, but it
> managed to play that back fine.  It even plays that back while
> recording two shows at once and doing a transcode job.
>
> But, I can't watch live ATSC HDTV, I get pauses and jumps at about 1
> per second.  The same thing happens when I try to watch a ATSC HDTV
> recording.
>
> When watching ATSC HDTV recordings, I ran top in an ssh session, and I
> saw that the mythtvfrontend was using 75% to 90% of the CPU.  It only
> uses about 25% for SD shows.  So, I started to feel confident it was
> PLAYING the recording, not the encoding or recording of the file.
>
> So, I ran a transcode on one of the ATSC HDTV recordings, hoping to
> make it smaller, quicker to display, hoping I could watch that.
> Unfortunately, the and the file size didn't reduce much, and I still
> got the pause/skip thing happening.
>
> Since my transcode experiment didn't help much, I just started
> watching the same 5 seconds of a ATSC HDTV show over and over and
> over.  I was trying to see if the skips were always in the same spots,
> indicating a problem with the recorded file.  But, I'm fairly
> confident the skips were not always the same, telling me the recording
> was fine, but I couldn't play it back on my system.
>
> Does this seem like a reasonable conclusion?  Does it sound like only
> a playback issue, and not related to any other step?
>
> And IF that seems to be the issue, what do I need to upgrade to watch ATSC HDTV?
>
> I'm guessing the CPU, drive speeds, and RAM aren't the bottleneck,
> because it can do so much I/O in the background if I'm not trying to
> display the image... so I'm thinking video card only maybe?
>
> My system is a Compaq Presario SR1500NX 2GHz Desktop, with AMD
> SempronT processor 3000+ 2.0GHz processor, upgraded to 1GB RAM, 80GB
> hard drive for /myth (recordings only) and 40G / (everything else),
> DVD/CD-RW combo drive, 9-in-1 flash card reader, blah, blah, blah...
> The video seems weak, I'm using the "Video Graphics Integrated
> graphics with 64MB of shared video memory."
>
> As near as I can tell, it's an ASUS A7V8X-LA motherboard, so it uses
> "Via Unichrome KM400 graphics" but I'm not sure what that means.  It
> does have one One AGP 8x/4x (1.5V) slot that I'm not using.  I'm
> hoping I can just stick a card in there and move on?
>
> Does this sound right?  If so, I'd like to get something that has DVI
> out, and S-Video out, and is really inexpensive.  I don't really care
> about noise, a fan is ok, this system makes a bit of noise anyway.
> Any recommendations?
>
> Thanks in advance,
> Rob C.
>