[mythtv] QAM tuning problem with HD-3000 & kernel DVB drivers

Chuck Lloyd chuck.lloyd at gmail.com
Sat May 28 22:17:32 UTC 2005


Bruce,

I've had a similar problem. I think the cause is that your cable provider
is not providing the standard PSIP data. I have a similar problem
with Comcast here in Boston.

I have been able to find a few stations, but I have not tried putting them
into the Myth database yet.

I noted which channels myth seemed to find a frequency lock on
and then did a little probing.

For example:

Myth found something on channel 84 so I tuned to that channel.
azap -r C84

using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 585000000 Hz
video pid 0x0000, audio pid 0x0000
status 1f | signal 0977 | snr fde5 | ber 00000000 | unc 00000000 | 
FE_HAS_LOCK
status 1f | signal 0977 | snr fdfd | ber 00000000 | unc 00000000 | 
FE_HAS_LOCK
status 1f | signal 0394 | snr fdfd | ber 00000000 | unc 00000000 | 
FE_HAS_LOCK
status 1f | signal 0394 | snr fdb3 | ber 00000000 | unc 00000000 | 
FE_HAS_LOCK
status 1f | signal 0977 | snr fdb5 | ber 00000000 | unc 00000000 | 
FE_HAS_LOCK
......

Then I ran dvbtraffic to look at the pids:

dvbtraffic
-PID--FREQ-----BANDWIDTH-BANDWIDTH-
0000 3 p/s 0 kb/s 5 kbit
0030 19 p/s 3 kb/s 29 kbit
0031 19 p/s 3 kb/s 29 kbit
0800 9362 p/s 1718 kb/s 14081 kbit
0801 261 p/s 47 kb/s 393 kbit
0802 88 p/s 16 kb/s 133 kbit
0840 11093 p/s 2036 kb/s 16685 kbit
0841 260 p/s 47 kb/s 391 kbit
1fff 4718 p/s 866 kb/s 7096 kbit
2000 25830 p/s 4742 kb/s 38848 kbit

>From above it looks like there is a hi-bitrate signal at PID 800 (2048)and a 
low 
one at 801 & 802. ( 2049 & 2050 )

I leave dvbtraffic running and then I run mplayer:

mplayer -vid 2048 -aid 2050 -vc ffmpeg12mc -vo xvmc /dev/dvb/adapter0/dvr0

Viola, WGBH in HD.

Just need to figure how it all works into the database. (and maybe automate 
it.)


On 5/28/05, Bruce Pennypacker <bruce at pennypacker.org> wrote:
> 
> Hi all,
> 
> I've been unable to tune QAM channels on my HD-3000 with mythtv despite
> being able to extract it using the azap, dtvscan, etc. tools. In
> searching around I've come across many similar reports of problems with
> this combination. I've tried both the 0.18.1 release and the CVS tree
> from yesterday with the same results - doing a channel scan simply
> results in all of the channels resulting in "Timeout Scanning Channel"
> when it's able to lock onto a channel.
> 
> I was wondering if anybody knows about this problem and/or may be
> working on it. It's been years since I've done any serious c/c++
> development/debugging and I know next to nothing about DTV, QAM, etc.
> but I was thinking of firing up gdb to see if I could figure out why
> this may be happening. Of course I don't want to expend the effort if
> somebody else is already looking into it, hence my query here before I
> take the plunge.
> 
> -Bruce
> _______________________________________________
> mythtv-dev mailing list
> mythtv-dev at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
>
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