[mythtv-users] Can't get a good Playback Profile

Brad DerManouelian myth at dermanouelian.com
Mon Dec 8 15:01:43 UTC 2008


On Dec 8, 2008, at 12:45 AM, MythTV wrote:

> In the previous incarnation of my MythTV install, I used the generic
> "nv" X11 driver to watch my HD shows.  The newest version of MythTV
> shows a blank screen if the "nv" X11 driver is used; thus, I have to
> use the proprietary driver "nvidia", which is suppose to be better...

>
> Well, I can't get my Playback Profiles to work without artifacts,
> dropped frames, loss of sound, etc.  "Mac Hardware acceleration"
> Decoder with "2" Max CPUs work okay for very slow motion, but a pan,
> or sports, or even the actor's eyes blinking are beyond the capacity
> for my system now.  "libmpeg2" Decoder with "quartz-blit" Video
> Render sometimes works too on certain types of reality TV.  But, I
> can't find any setting that is near as decent as that generic "nv"
> X11 driver I use to use.

Weird. nv never worked good for me. "Mac Hardware Acceleration" is  
meant to be used on Macintosh OS X. Not sure why you're using that.

> I have read the Playback Profiles page multiple times:
> http://mythtv.org/wiki/index.php/Playback_profiles
>
> The idea behind Playback Profiles seems cool but it also assumes that
> you know the resolution of your shows.  How do I find out what the
> resolutions are on my shows?

http://www.gossamer-threads.com/lists/mythtv/users/328485#328485

> Because you can have 5 or more profiles, I don't know which profile
> is selected when playback is occurring.  Is this mentioned in /var/
> log/mythtv/mythfrontend.log?  How do I know which profile setting is
> being use?

You log will definitely give you information about what library is  
being used along with the deinterlacer and other good information. The  
profile being used is the one selected. The specific settings used in  
the profile are not named so you get that information but not a name  
associated with it. You could just look there and see if your  
questions are answered.

> I have created a Test profile that has only one setting.  Thus, I
> assume that that's the setting being used.  Is this a correct
> assumption?  What happens when the setting doesn't work or my
> hardware doesn't support the setting?

If you have an unsupported setting, you will get an error and likely  
get kicked back to the main menu.

> There are probably a hundred different settings I can try thus time
> consuming and tedious.  This is standard technology; there has got to
> be a more scientific way to know what profile setting to use.  Is
> there another location to go to learn more about configuring Playback
> Profiles?

This is not standard technology. There are many resolutions, playback  
libraries, hardware configurations, progressive or interlaced video,  
deinterlacers, etc. that all produce different playback video. For an  
example of just how not standard this is, take a look at what is  
considered "standard" HDTV here: http://en.wikipedia.org/wiki/High-definition_television

If we all used the same hardware it would be a matter of getting a  
consensus of what everything thinks is "best", default to that and  
leave it there (like Tivo - and even they offer different "quality"  
modes). However, since you have built your system with the processor,  
video card, output method (svideo, dvi, hdmi, etc.) of your choice  
there's no way to set a "standard" that will work for everyone. Also,  
video output is VERY subjective to the viewer so what I think looks  
good may not look good to you. That's why there are profiles.

The plethora of choices is why there are default profiles. One of them  
will get you close to what you need then allow you to fiddle with the  
settings when you have a problem with one particular resolution or  
deinterlacer.

> Rob
> My configuration is:
> MythTV version: 0.21.20080304-1 18722
> Ubuntu 8.10, kernel version: 2.6.27-9-generic
> CPU: Intel Pentium 4 CPU 3.2GHz Socket 775 800 FSB w/Hyper Threading
> Technology
> Memory: 1Gig DDR 333 Memory 180 Pin
> Motherboard: ASRock 775i65G Mother Board
> Optical Drive: LG 18X DVD RW + Dual Layer
> Hard Drive: 1 Western Digital 250 Gig HD contains the OS and 1
> Western Digital 1 TB 7200 RPM Cache Serial ATA contains the video data
> Video onboard: Integrated SiS Ultra256 2D/3D Graphics
> Video card: Micro-star International (MSI) AGP GeForce FX5200-
> TD128LF, 8X, 128M, DDR1, D-Sub, DVI-D, TV-out
> Audio onboard: AUDIO ADI AD1888 6-channel audio CODEC
> Audio card: Riviera C-Media CMI 8738 (Connected to my entertainment
> center via the optical cable)
> Network Card: Onboard 10/100 Network Card
> Tuner cards: 2 pcHDTV HD-5500

You didn't mention your output resolution and device. I assume you are  
outputting to a progressive display and I'm guessing 1920x1080? Or  
maybe something else? In any event, I recommend starting with the  
"Slim" profile since that tends to work best for most people (it  
matches the default settings used before there were playback profiles).

In the end, if you're trying to match the happiness you experienced  
when using the generic "nv" driver, why don't you just use the generic  
"nv" driver? It doesn't make sense to me to try to fix something that  
wasn't broken.

-Brad



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