[mythtv-users] All profiles the same as default?

[Ryan Steffes]

Bruce Markey wrote:

> Dave Bush wrote:
>
>> Darryl Okahata wrote:
>>
>>> Dave Bush <statman at twcny.rr.com> wrote:
>>>  
>>>
>>>     Why don't you try various settings, and decide what you like?
>>> Start with 2200 and go up from there (as you're happy with Tivo basic
>>> quality, don't go above 4400 (~2-2.5GB/hr) or so, as I think that's
>>> somewhat similar to Tivo high quality).
>>>  
>>>
>> Okay - this may be a dumb question, but I assume that you mean that I 
>> should be using the MPEG-4 codec instead of the default RTjpeg codec?
>
>
> That's correct. RTjpeg compresses each frame individually whereas
> MPEG-4 compares the frame with the previous one and only needs
> to encode the differences so it is much more space efficient.
> Also, see the howto section on resolutions:
>
> http://www.mythtv.org/docs/mythtv-HOWTO-21.html#ss21.3
>
> --  bjm
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>
The one question I've been trying to get answered is how all these 
settings work together.  I actually have a pretty bad and old capture 
card, so I'm kinda stuck on the settings I can use but I'm having 
trouble figuring out what they do since very little I change seems to 
have a ton of effect.

Any chance you can help me come up with a pseudo doc that perhaps can be 
used to better explain what every setting actually DOES?

First screen:

Profile Name:  (Duh)
Autotranscode: [] (Ok, even after DOING it I haven't entirely figure out 
what the POINT of transcoding does. Has something to do with file 
formats.  Seems to make file smaller, and will remove the parts of the 
stream in the cutlist)


Second Screen:

Width: [ ]    Height: [ ]

Ok this is the lines of resolution as explained 21.3 of the docs.  Width 
is vertical scan lines, height is horizontal scan lines.  Normal TV 
seems to be about 480x480.  Lowering these numbers makes the picture 
more [ Blocky? Fuzzy? Descriptive word needed here! ]


Third Screen:

Codec: MPEG-4  ( Selected because it seems to be smaller at the cost of 
CPU )

Bitrate: ( Controls how sharp the focus is? Relates to video size in 
some way? No idea what "standard" numbers are.  People seem to run 
anywhere from 2200 to 5000)

The next three options are labeled something along the lines of "Don't 
EVER touch" which makes me wonder why they are there.

These next ones never seem to come up in anyone's advice, I can't tell 
what effect they have at all, but it could be because my card sucks.

[]Scale bitrate
[] Enable High Quality   [] Enable 4MV Encoding
[] Enable Interlaced DCT encoding [] Enable interlaced interface estimation


Fourth Screen:
Sound people don't seem to ever mess with.



The questions I'm trying to answer are what settings have the most 
effect, and how trade offs work.  For example, is there really any 
visible difference at 480+ if NTSC only has 480 lines of picture?

What has the biggest effect on picture quality, lines or bitrate?  How 
about CPU?  Can any of these settings lock your computer up messing with 
them? Will they cause video to skip if they are set too high?  Is there 
anyway to tell BEFORE you botch a recording?

Basically I randomly bump numbers around and go back to live tv and see 
if I can tell the difference, which is a VERY unsatisfying way to try 
and test.

Any help or even just links would be appreciated.

-Ry