DVB-T tuner loses lock when starting omxplayer


3 posts
by madman_xxx » Thu Jan 10, 2013 1:21 pm
Hello everyone,

I am running raspbian 3.6.11, omxplayer compiled from source downloaded a week ago, the DVB-T tuner is IT9135-based and generally this works, but not all altogether.
I use tzap to tune, it works, I can for example do:
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tzap -p -r -S 'somechannel' &
cp /dev/dvb/adapter0/dvr0 /mnt/res/test.ts

The above records the currently tuned channel, which can be later successfully watched:
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omxplayer /mnt/res/test.ts

The problem is to watch it directly:
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omxplayer /dev/dvb/adapter0/dvr0

It works for a few seconds, then the tuner loses lock, so the omxplayer stops, then the tuner acquires lock again, so the omxplayer plays again, so the tuner loses lock and so forth...
Furthermore, this behaviour is not limited to playing /dev/dvb/adapter0/dvr0, the same thing happens whenever I play any video file with omxplayer when tzap is running!
Here is an excerpt from tzap log:
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status 1f | signal 0f5c | snr 6c46 | ber 0000b6f2 | unc 000632bc | FE_HAS_LOCK
status 1f | signal 0f5c | snr 6aee | ber 0001c089 | unc 000639da | FE_HAS_LOCK
# I start omxplayer here #
status 1f | signal 0f5c | snr 4127 | ber 0009c400 | unc 000687fa | FE_HAS_LOCK
status 01 | signal 11eb | snr 0000 | ber 0009c3b4 | unc 0006d616 |
status 00 | signal 0f5c | snr 391f | ber 0009c3b4 | unc 00072432 |
status 00 | signal 11eb | snr 0000 | ber 0009c3b4 | unc 0007724e |
# I stop omxplayer here #
status 01 | signal 0f5c | snr 0000 | ber 0009c3b4 | unc 0007c06a |
status 1f | signal 0f5c | snr 5f9e | ber 000816d7 | unc 0007fbfe | FE_HAS_LOCK
status 1f | signal 0f5c | snr 5e45 | ber 0007a1a2 | unc 00083384 | FE_HAS_LOCK

What's even more interesting - when a movie is played in omxplayer, pausing it may cause locking again, but doesn't have to - this is quite random. A stable lock is acquired only when omxplayer is not running.
At first I thought it has something to do with a power supply. Did the measurements: 5.00 V when tuner locked, 4.99 V when omxplayer is running.
Posts: 37
Joined: Tue Dec 18, 2012 5:03 pm
by nickon314 » Mon Apr 07, 2014 4:04 pm
I know this is an old thread, but I see the same behaviour as you using the same type of DVB-T USB adapter.

Did you ever get a fix for this sorted out?


Regards

Nick
Posts: 103
Joined: Tue Jul 03, 2012 12:11 pm
Location: West Yorkshire
by madman_xxx » Mon Apr 07, 2014 9:05 pm
Well, I've solved it partially - it turned out the aerial cable was damaged and attenuated the RF signal. After cutting it short, the tuner stopped losing lock. And by "partially" I mean no thorough tests were made - I am no longer using my Pi to watch TV.
Conclusion: make sure the reception is good enough.
Posts: 37
Joined: Tue Dec 18, 2012 5:03 pm