[mythtv-users] HD Playback Problems

Larry T larryt at gmail.com
Fri Dec 29 23:57:54 UTC 2006

I purchased a pcHDTV 5500 card and installed it into an established SD
system. As an SD system, it was functioning perfectly. I decided to upgrade
the system to FC6 while I was taking it down to install the HD card. I
successfully got the system working up to the previous level and got the HD
input functioning and channels mapped. However, I have scoured google and I
have reached an impasse on the following issues which as far as I can tell
may not be resolved. Most of the relevant threads seem to be abandoned in
the end with no resolution.

My system specs are:
NF7-S (onboard sound with optical out), Athlon XP 3200+, 512MB RAM, GF4 MX
420, Hauppauge PVR150 MCE, pcHDTV 5500, FC6 kernel-2.6.18-1.2868.fc6.i686,
ALSA 1.0.13, nvidia 9629, connected to a 32" 1360x768 LCD monitor by VGA
cable, all the rest of software is the latest version from yum installed per
Jarod's howto.

1) I have been unable to output Dolby Digital sound through my SPDIF. I can
output digital sound however only digital stereo. If I attempt to output
48kHz Dolby Digital through the SPDIF, I get silence. If I attempt to output
44.1kHz Dolby Digital sound, I get noise (as expected). In either case, my
amplifier never identifies the input as Dolby Digital. This problem is not
limited to Myth and I have observed it in mplayer using an AC3 sound file as
well. I am using the asound.conf from here:
. My default is the digital-hw connection and I modified it to be device 2
as appropriate for my SPDIF connection.

When attempting to output Dolby Digital sound in either mplayer or Myth, I
receive no indication that it has failed other than the apparent lack of
sound. I have tested the source AC3 file on a different computer and
verified that it is indeed a valid sound file. If I use software AC3
decoding, I get a functioning digital stereo output. Here is a sample
mplayer run: http://pastebin.ca/296144 . I also have modified iecset to both
audio and non-audio in an attempt to get it working but had no success with

2)  My HD playback is stuttering and unwatchable. I believe I have
successfully enabled XvMC (and have grayscale OSD ) and that the problem
lies on the sound output as supported by the output from mythfrontend but I
am uncertain: http://pastebin.ca/296145 . I have no vsync options marked (in
Myth settings or nvidia-settings). I have played with audio buffering and
deinterlacing options.
I have modified options per every web page I can find and I am completely
stumped and would appreciate any help. I would be glad to provide any
additional information as requested. Thanks.
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