[mythtv-users] quality question.. ways to make it better?

[Johnny Lee]

I was playing with my colors,brightness,contrast after adding these filter
settings you gave and this is what I got that looked almost identical to
what my TV was showing...

update channel set contrast=30000,brightness=37500,colour=32768,hue=32768; 

The same video filter settings since I have no clue what they do

update channel set videofilters='adjust=34:253:1.0:23:232:1.0';

Seems to work great for me! Thanks a lot Bruce.


Johnny Lee

-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Johnny Lee
Sent: Thursday, May 20, 2004 12:46 AM
To: 'Discussion about mythtv'
Subject: RE: [mythtv-users] quality question.. ways to make it better?

Bruce, So what kind of card do you currently use? I've played only with my
color/brightness/contrast settings and I seem to like everything default
other than changing the contrast to 25000. I currently run a Winfast Deluxe
BT878A card w/ dbx stereo. So what does the filter do exactly? I am going to
run it now to see if I can see a difference or not...


Johnny Lee

-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Bruce Markey
Sent: Wednesday, May 19, 2004 5:49 PM
To: Discussion about mythtv
Subject: Re: [mythtv-users] quality question.. ways to make it better?

Craig Tinson wrote:
...
> I've set the recording profile for LiveTV to mpeg4 and set it to pretty 
> much maximum quality.. but its still quite "bitty" (not a lot.. but you 

The "bitty"ness has to do with bitrate and the compression
factors. Ironically, if you use a higher resolution at the same
fixed bitrate, the "bitty"ness gets worse. What you need is
a moderate resolution and a higher relative bitrate.

For example, for my Default profile, I use 480x480 (480x576
for PAL) and a scaled bitrate of 4000. For low bitrates like the
default 2200, it is best to set the "Maximum quality" at 2 so
that it doesn't waste precious bits on frames that are almost
perfect anyway. However, at 4000 and above, setting the Max
limit at 1 will reduce the blockiness in the background.

> can see it).. and the colors just seem really dull.. it seems to lose 
> the vibrant quality from the original..

Yeah, there are some silly problems with the luma and chroma
values for bttv cards that make bright colors washed out and
pale even when the saturation is set high enough to make the
dark colors bleed. Because of the 'out of the box' picture, most
people assume PVR cards are superior even though they use the
same chip for video capture. With the correct adjustments, a
bttv card can look even better than a hardware encoder card.

There is a new filter added after the 0.14 release in CVS that
fixes an outright mistake for bttv luma. It also has parameters
that allow you to make further adjustments that you can't do for
the hardware cards. I've played with this over the past few months.
By comparing direct cable on one input and myth on another, I've
got the color reproduction almost identical. Even though the
myth input is a little fuzzier, the picture is otherwise as
vivid. To set these parameters, run your mysql client and
enter these two lines.

update channel set contrast=21500,brightness=37500,colour=32768,hue=32768;
update channel set videofilters='adjust=34:253:1.0:23:232:1.0';

If your worried that you might have to undo this, these will
reset the defaults:

update channel set contrast=32768,brightness=32768,colour=32768,hue=32768;
update channel set videofilters='';

Also, especially if you have an AverTV card, they tend to over-
saturate quite a by default. Hauppague tend to under-saturate.
If you have v4l2 support in your kernel, v4lctl can normalize
the chroma levels with Automatic Gain Control (AGC).

: bjm at moktoo ; v4lctl -c /dev/video0 setattr 'chroma agc' on
: bjm at moktoo ; v4lctl -c /dev/video0 list
attribute  | type   | current | default | comment
-----------+--------+---------+---------+-----------------------------------
--
norm       | choice | NTSC    | PAL     | PAL NTSC SECAM PAL-Nc PAL-M PAL-N
NTSC-JP PAL-60
input      | choice | Televis | Televis | Television Composite1 S-Video
audio mode | choice | lang1   | mono    | mono stereo lang1 lang2
bright     | int    |   37500 |   32768 | range is 0 => 65535
contrast   | int    |   21500 |   32768 | range is 0 => 65535
color      | int    |   32768 |   32768 | range is 0 => 65535
hue        | int    |   32768 |   32768 | range is 0 => 65535
mute       | bool   | off     | off     |
chroma agc | bool   | on      | off     |
combfilter | bool   | off     | off     |
automute   | bool   | on      | off     |
luma decim | bool   | off     | off     |
agc crush  | bool   | on      | off     |
vcr hack   | bool   | off     | off     |
whitecrush | int    |     207 |     207 | range is 0 => 255
whitecrush | int    |     127 |     127 | range is 0 => 255

If your output is missing "chroma agc" and some of the others
then you do not have v4l2 support.

> Is there anything fundamentally wrong with this setup? is there anything 
> I can do to make it better without shedding out tons of cash?

Yes and yes.

--  bjm