[mythtv-users] am i dropping frames?

Steve Peters - Priority Electronics steve at priorityelectronics.com
Fri Jan 18 05:06:51 UTC 2008


 

-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Steve Smith
Sent: Thursday, January 17, 2008 1:13 AM
To: Discussion about mythtv
Subject: Re: [mythtv-users] am i dropping frames?




On 17/01/2008, Steve Peters - Priority Electronics
<steve at priorityelectronics.com> wrote: 

 

-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Steve Smith

Sent: Wednesday, January 16, 2008 1:14 AM
To: Discussion about mythtv
Subject: Re: [mythtv-users] am i dropping frames?





On 15/01/2008, Steve Peters - Priority Electronics <
<mailto:steve at priorityelectronics.com> steve at priorityelectronics.com> wrote:




-----Original Message-----
From: mythtv-users-bounces at mythtv.org
<mailto:mythtv-users-bounces at mythtv.org> 
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Jesse Burt 
Sent: Tuesday, January 15, 2008 9:53 AM
To: Discussion about mythtv
Subject: Re: [mythtv-users] am i dropping frames? 



On Tue, 2008-01-15 at 10:33 -0700, Brian Wood wrote:
> Steve Peters - Priority Electronics wrote: 
>
> > ____________________________________________________________
> >
> > 
> > Beww, so are you saying that this might be normal for myth
> > recordings? Is everyone using mythtv stuck with this kind of 
> > playback problem? It's not the artifacts that are the problem, it's 
> > the lack of smooth playback that is the problem. I just don't see
> > how any sports fan could put up with this. I go to other people's 
> > houses and watch sports there and I think to myself...I'd better not 
> > invite them over to my place to watch sports, cause that will make
> > my mythtv setup look really bad. -Thanks 
>
> No, you should be able to get a recording (and playback) that most
> viewers would not be able to tell from "live" TV, unless you have some
> very critical (and observant) viewers.
>
> If you are not, the first thing to do is determine if the problem is
> with the recording or the playback. Try playing back a known good
> recording, then try playing back a Myth recording with something other 
> than Myth.
>
> The recording you posted looked pretty good to me except for the 
> interlace artifacts.
>
> beww
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> mythtv-users mailing list 
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

I agree with beww that with the right settings it would be difficult to tell
the difference unless, as stated, someone is very critical or observant or 
the difference is being looked for. With the right settings, I find that
image impurities that are easily noticeable on my 15" Laptop LCD or 22"
Desktop LCD wind up looking perfectly normal on a plain old 29" CRT TV. Also

is that channel (in your example clip) available as a digital channel on
your service (probably encrypted if it is)? If so, and your TV is connected
to a cable/sat box, perhaps when watching TV through it, you are watching a 
digital version of the analog-encoded clip you posted. If so, that could
account for a difference in quality.

Cheers,
Jesse Burt


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----------------------------------------------------------------------- 

Jesse, Steve, Mitch, and Brian, thanks for the replies,

I have to agree with Steve... Bob is the problem :) 

I think if I can figure out why it is not working, I'll be set. That was
recorded from espn analog. Time warner cable in my area has teriffic quality

digital cable, where it looks way better than analog. On my espn digital 
(still in sd), I get the same effect. On my espn hd channel I get the same
effect. So I don't think it's the signal that is the issue here. 

I'm not so concerned with the image artifacts... when I watch on my 14" 
widescreen laptop, I see them, but on my 55" 480p tv, I don't notice them at
all, probably cause of the resolution of the screen I am viewing. 

As to figuring out if the problem is with the recording or the playback, 
Brian recommended playing back a know good recording, then try playing back
a myth recording with something other than myth. ----well...that video I 
uploaded, I played back on my windows laptop, and it looked pretty decent. 
Also, what is a known good recording? Something downloaded from the web
perhaps? Maybe one of you guys can upload or email me a known good recording

(preferebly sports) and I can play it back on my laptop and then on my 
mythtv.....? :)

Also, is there a way to find out if I am indeed dropping frames? Because if
that is the issue, then all this other troubleshooting is for naught. 

Lastly for now, any ideas on how to fix Bob? Could it be related to an 
nvidia drivers setting or something like that?

-Thanks so much for the help/tips.


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Steve,
 
Well the first thing to do is to get some log output:
 
mythfrontend -v playback  >/tmp/frontend.log
 
Should put some useful output in /tmp/frontend.log....
 
I'm guessing you'll see something along the lines of....."Refresh too low
for bobdeint defaulting to onefield..."
In which case you'll need "Viktor's Patch"... search this list for posts
from me mentioning Viktor & bob and you'll find it.
 
(You could also try  mplayer -vo xvmc:bobdeint  FILE.mpg,  this may or may
not work depending on your setup. But if it works you'll be able to see what
bob should look like)
 
Cheers
 
Steve
  
 
 
 
OK, it seems like there is some bad stuff happening in the log file. What i
did was  run that command you said for the frontend with linear
deinterlacing, then one just for bob setting. I ran the video (live tv) only
for around 15 seconds at each command line. I have two files on my site,
both around 12k in size. 
 
here are the files:
 
http://www.penguinframe.com/frontend.log --uses kernal
http://www.penguinframe.com/frontend-bob.log
<http://www.penguinframe.com/frontend-bob.log> --uses bob
 
Let me know what you guys think.
-Thanks


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Steve,
 
 
Looking at your BOB log:
 

2008-01-16 15:33:26.599 Using deinterlace method bobdeint

****************************************************************************
*************************************************

*******2008-01-16 15:33:26.701 nVidiaVideoSync: VBlank ioctl did not work,
unimplemented in this driver?****

****************************************************************************
*************************************************

2008-01-16 15:33:26.701 DRMVideoSync: Could not open device /dev/dri/card0,
No such file or directory

2008-01-16 15:33:26.701 RTCVideoSync: Could not set RTC frequency,
Permission denied.

2008-01-16 15:33:26.701 Set video sync frame interval to 33366

2008-01-16 15:33:26.701 Using audio as timebase

2008-01-16 15:33:26.701 Video timing method: USleep with busy wait

2008-01-16 15:33:26.701 Refresh rate: 16679, frame interval: 33366

 

The line I've highlighted suggests that Sync to VBlank might not be enabled
on your  video card. Try running

nvidia-settings             (I can't actually remember the name of the
program at the moment I think its called this!)

Play with the Sync to.... settings to see if this helps! (You'll have to
keep restarting the playback on mythfrontend).

(I wouldn't worry about the dropped frames reported at the moment I always
expect playback to stutter a bit in the first couple of seconds)

Cheers

Steve 

 

 

OK, i played around with all the sync settings i could find in the
nvidia-settings program, and in mythtv as well, but i could not get the bob
deinterlace setting working. I have an hp dv1040 laptop with intel graphics
and using the standard drivers from ubuntu feisty, now gutsy after the
upgrade, i was able to set bob just fine and i noticed a HUGE improvement in
the video playback during a Lakers game. 

So now i'm convinced that the Bob setting is my issue on my main frontend. I
even reinstalled my nvidia drivers using a program called Envy.

Any ideas on what i can do now?

-Thanks

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