[mythtv-users] Some questions about HDTV recording

Brad Templeton brad+myth at templetons.com
Sun Dec 12 07:38:24 UTC 2004

On Sat, Dec 11, 2004 at 11:51:11PM -0600, Nate Carlson wrote:
> So basically write a shell wrapper that gets called for transcode, and 
> looks at the channel number or something?

Well, I would actually look at the resolution of the stream if you can
extract that.  You want to transcode a 480i differently from a 720p or
a 1080i.  Since most HDTVs are really only 1280x720, that sort of resolution
reduction from 1080i makes a lot of sense as the TV is going to do it
> >Tons of them.  HD is new to MythTV.  AC-3 audio also creates problems in 
> >myth and its sound drivers.
> Well, doesn't sound too horrible, at least.  :)

I'm finding it to be a pain.  Here are some pains I have seen:

a) Getting your video card to display on the HDTV can be a lot of work,
requires pushing the edge, newer drivers etc.   Often this leads to
hard crashing and upgrade troubles.
    a2) Many HDTVs won't actually take input at 720p.
    a3) DVI can be harder to get going than other output forms.

b) Many xv drivers won't actually drive at 1920 wide.  Some even say they
do but can't.

c) Most HDTVs have overscan problems when computer driven

d) DVD playing needs to be modified to understand 16:9 TVs

e) The drivers for the HDTV cards can be a pain to work with, and
they can crash your machine.

f) Myth TV front end crashes when it tries to tune a channel with a
poor signal.

g) Myth TV back end gives up recording a show if there is bad signal,
and doesn't retry if the signal gets better, and thinks it recorded the
show so refuses to record a later timeslot.

h) When you record 1080i, you can get a lot of interlacing artifacts if
you don't get your redisplay just right

i) As noted, problems with transcode, recording of non-HD shows using disk

j) AC-3 sound is not handled well.  The center channel will be missing
sometimes.  Alsa drivers have bugs, and can cause jittery audio or

k) I haven't looked to hard, but it's not so clear how to use the
non-ATSC features of the PC-HD3000.

l) Did I mention it can be a bitch to get your card to drive your HDTV
at 1920 x 1080?   Many people give up and drive at 1920 x 540p (but then
you get interlace artifacts if not careful.)

m) Sometimes the NVIDIA drivers will flake out doing xv, and it goes
all blue, and you have to take the module out of the kernel and back in,
or reboot.  But NVDIDIA are still the best at it.

n) HD takes a lot of CPU to play, and if anything else pops up on your
machine, it can cause troubles.

o) xvmc seems like a win for HD, but reports are it causes a lot of
problems, and crashes in certain circumstances.

p) Getting stuff OTA with an antenna is a real pain, we have forgotten why
we took the antennas down to get cable.  And a rotor (the old solution to
stations in all directions) doesn't work for a PVR, unless you had a rotor
aware PVR!

q) I see some strange display bugs in how the borders are drawn in the
program menus at 1920 x 1080 res.  The box around the list of programs
sometimes looks like it's coming from bad memory.  But this is cosmetic.

r) Some featurs of myth just arnen't ready to be on an HD display, like
the web browswer and news, the text is too small.

s) Channel changing is intolerably slow in live viewing (you pretty much
want to swtich to the guide browse mode for channel change.)

And I have heard more.

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