Basic questions about pc video

[Guest]

Archived from groups: rec.video.desktop (More info?)

Experienced in computers, but new to PC video. Questions about playback of
MPEG2 files on computer and TV screen.

I record TV using WinTV PVR-250; the mpegs it produces look slightly jittery
when viewed on my PC screen, but perfect if I burn them to a DVD and play
the DVD back on a standalone DVD player. So I presume that the recording
and encoding are fine, it's just a playback problem on the computer.

The computer is a newly purchased e-machines T2742 (Celeron 2.7 GHz; 256 MB
RAM; Windows XP; on-board video Intel Extreme Graphics 3D 64 MB Shard
Memory)

I have been able to reduce/eliminate the jitter using a utility called
reclock, but can't use it with BeyondTV. From reading the stuff that comes
with reclock, my understanding is that much of the problem is related to the
fact that mpeg's play back at a certain frame rate, which does not exactly
correlate with the computer monitor's refresh rate, and this dis-synchrony
causes the jitter (I do have my monitor set to 60Hz, and the video is NTSC).

Is this a known and common issue? Do I understand the problem correctly?
And mainly, if I purchase a video card with a TV output, does this solve the
problem at least as far as outputting mpeg video directly on to the TV
screen? What refresh rate do these video cards use for the TV output (60Hz
or 29.97 interlaced or what?).

This video stuff is fascinating, but much more complicated than I imagined
(and I majored in electrical engineering / computer science many many moons
ago).

Michael Jacobson

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

Michael Jacobson wrote:

> I record TV using WinTV PVR-250; the mpegs it produces look slightly jittery
> when viewed on my PC screen, but perfect if I burn them to a DVD and play
> the DVD back on a standalone DVD player. So I presume that the recording
> and encoding are fine, it's just a playback problem on the computer.

Correct.


> I have been able to reduce/eliminate the jitter using a utility called
> reclock, but can't use it with BeyondTV. From reading the stuff that comes
> with reclock, my understanding is that much of the problem is related to the
> fact that mpeg's play back at a certain frame rate, which does not exactly
> correlate with the computer monitor's refresh rate, and this dis-synchrony
> causes the jitter (I do have my monitor set to 60Hz, and the video is NTSC).

Also correct. If you have you monitor set to a frequency which is not a
multiple of the video standard, the playback will not be as smooth as it
could be. 60Hz, though? I think my eyes would be bleeding before
too long. 90 or 120 would be much nicer, assuming your monitor
supports it.


> Is this a known and common issue? Do I understand the problem correctly?
> And mainly, if I purchase a video card with a TV output, does this solve the
> problem at least as far as outputting mpeg video directly on to the TV
> screen? What refresh rate do these video cards use for the TV output (60Hz
> or 29.97 interlaced or what?).

The key is to get a card that supports 59.94 Hz, interlaced. I'm told
that with the proper drivers and configuration, the Geforce cards can do
this under Linux. The Geforce4 MX cards are a favorite among the
MythTV bunch. (For those who haven't opted for the PVR-350 that has
built-in TV-out capabilities)

In the Windows world, I'm not sure what cards do proper TV-out.


-WD

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

Thanks very much. If anyone has any comments about cards that support TV
output 59.94 Hz, interlaced for Windows XP systems, info would be
appreciated.

MJ


"Will Dormann" <wdormann@yahoo.com.invalid> wrote in message
news7FAc.124794$DG4.5877@fe2.columbus.rr.com...
> Michael Jacobson wrote:
>
> > I record TV using WinTV PVR-250; the mpegs it produces look slightly
jittery
> > when viewed on my PC screen, but perfect if I burn them to a DVD and
play
> > the DVD back on a standalone DVD player. So I presume that the
recording
> > and encoding are fine, it's just a playback problem on the computer.
>
> Correct.
>
>
> > I have been able to reduce/eliminate the jitter using a utility called
> > reclock, but can't use it with BeyondTV. From reading the stuff that
comes
> > with reclock, my understanding is that much of the problem is related to
the
> > fact that mpeg's play back at a certain frame rate, which does not
exactly
> > correlate with the computer monitor's refresh rate, and this
dis-synchrony
> > causes the jitter (I do have my monitor set to 60Hz, and the video is
NTSC).
>
> Also correct. If you have you monitor set to a frequency which is not a
> multiple of the video standard, the playback will not be as smooth as it
> could be. 60Hz, though? I think my eyes would be bleeding before
> too long. 90 or 120 would be much nicer, assuming your monitor
> supports it.
>
>
> > Is this a known and common issue? Do I understand the problem
correctly?
> > And mainly, if I purchase a video card with a TV output, does this solve
the
> > problem at least as far as outputting mpeg video directly on to the TV
> > screen? What refresh rate do these video cards use for the TV output
(60Hz
> > or 29.97 interlaced or what?).
>
> The key is to get a card that supports 59.94 Hz, interlaced. I'm told
> that with the proper drivers and configuration, the Geforce cards can do
> this under Linux. The Geforce4 MX cards are a favorite among the
> MythTV bunch. (For those who haven't opted for the PVR-350 that has
> built-in TV-out capabilities)
>
> In the Windows world, I'm not sure what cards do proper TV-out.
>
>
> -WD

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

On Fri, 18 Jun 2004 16:42:50 GMT, "Michael Jacobson"
<mjmd@journalclub.org> wrote:

>Experienced in computers, but new to PC video. Questions about playback of
>MPEG2 files on computer and TV screen.
>
>I record TV using WinTV PVR-250; the mpegs it produces look slightly jittery
>when viewed on my PC screen, but perfect if I burn them to a DVD and play
>the DVD back on a standalone DVD player. So I presume that the recording
>and encoding are fine, it's just a playback problem on the computer.
>
>The computer is a newly purchased e-machines T2742 (Celeron 2.7 GHz; 256 MB
>RAM; Windows XP; on-board video Intel Extreme Graphics 3D 64 MB Shard
>Memory)
>
>I have been able to reduce/eliminate the jitter using a utility called
>reclock, but can't use it with BeyondTV. From reading the stuff that comes
>with reclock, my understanding is that much of the problem is related to the
>fact that mpeg's play back at a certain frame rate, which does not exactly
>correlate with the computer monitor's refresh rate, and this dis-synchrony
>causes the jitter (I do have my monitor set to 60Hz, and the video is NTSC).
>
>Is this a known and common issue? Do I understand the problem correctly?
>And mainly, if I purchase a video card with a TV output, does this solve the
>problem at least as far as outputting mpeg video directly on to the TV
>screen? What refresh rate do these video cards use for the TV output (60Hz
>or 29.97 interlaced or what?).
>
>This video stuff is fascinating, but much more complicated than I imagined
>(and I majored in electrical engineering / computer science many many moons
>ago).
>
>Michael Jacobson
>

Try viewing your Mpegs with a programme such as Video Lan
Client www.videolan.org You can right click on the playing
video and select different deinterlace options (blend, bob
etc) to smooth the picture playback. Also handy for TV
output from the PC.

slippery

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

Thanks. Tried VideoLan, it's a nice program. Changing the various
interlace settings doesn't reduce the "jitter", however. Only using reclock
helps, so far.

MJ



"slippery" <slippery@invalid.invalid> wrote in message
news:rtd7d0dpsm577mqgdnkudbnhpss9vci0s3@4ax.com...
> On Fri, 18 Jun 2004 16:42:50 GMT, "Michael Jacobson"
> <mjmd@journalclub.org> wrote:
>
> >Experienced in computers, but new to PC video. Questions about playback
of
> >MPEG2 files on computer and TV screen.
> >
> >I record TV using WinTV PVR-250; the mpegs it produces look slightly
jittery
> >when viewed on my PC screen, but perfect if I burn them to a DVD and play
> >the DVD back on a standalone DVD player. So I presume that the recording
> >and encoding are fine, it's just a playback problem on the computer.
> >
> >The computer is a newly purchased e-machines T2742 (Celeron 2.7 GHz; 256
MB
> >RAM; Windows XP; on-board video Intel Extreme Graphics 3D 64 MB Shard
> >Memory)
> >
> >I have been able to reduce/eliminate the jitter using a utility called
> >reclock, but can't use it with BeyondTV. From reading the stuff that
comes
> >with reclock, my understanding is that much of the problem is related to
the
> >fact that mpeg's play back at a certain frame rate, which does not
exactly
> >correlate with the computer monitor's refresh rate, and this
dis-synchrony
> >causes the jitter (I do have my monitor set to 60Hz, and the video is
NTSC).
> >
> >Is this a known and common issue? Do I understand the problem correctly?
> >And mainly, if I purchase a video card with a TV output, does this solve
the
> >problem at least as far as outputting mpeg video directly on to the TV
> >screen? What refresh rate do these video cards use for the TV output
(60Hz
> >or 29.97 interlaced or what?).
> >
> >This video stuff is fascinating, but much more complicated than I
imagined
> >(and I majored in electrical engineering / computer science many many
moons
> >ago).
> >
> >Michael Jacobson
> >
>
> Try viewing your Mpegs with a programme such as Video Lan
> Client www.videolan.org You can right click on the playing
> video and select different deinterlace options (blend, bob
> etc) to smooth the picture playback. Also handy for TV
> output from the PC.
>
> slippery

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

By jitter I mean what is probably dropped frames. When I view a "news
crawl" at the bottom of the screen, where writing is supposed to scroll by
smoothly, it scrolls with fairly frequent little jerks. Not noticeable in
the picture above, usually, just in the writing. Sometimes something
similar when a picture pans -- there are very small but noticeable
hesitations or jumps.

Michael Jacobson


"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:40d48b8e@post.usenet.com...
> **** Post for FREE via your newsreader at post.usenet.com ****
>
> On a sunny day (Sat, 19 Jun 2004 16:24:18 GMT) it happened "Michael
Jacobson"
> <mjmd@nospam.journalclub.org> wrote in
> <SMZAc.5646$z24.3232@nwrdny01.gnilink.net>:
>
> >Thanks. Tried VideoLan, it's a nice program. Changing the various
> >interlace settings doesn't reduce the "jitter", however. Only using
reclock
> >helps, so far.
> Not exactly clear what you mean by 'jitter'.
> You are right about the frame problem monitor vs movie.
> There exist video cards that sync (in Linux at least).
> The other thing is interlace, I have ever seen only one (Chinese) program
> that did true interlace on a PC monitor.
> It should be no problem actually.
>
> But please describe 'jitter' a bit more.
> JP
>
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