Opened 15 years ago

Closed 15 years ago

#1513 closed defect (fixed)

Channel change problem with cinergyt2 dvb-t

Reported by: parasonic666@… Owned by: danielk
Priority: minor Milestone: 0.20
Component: mythtv Version: 0.19
Severity: medium Keywords: dvb tune channel livetv
Cc: Ticket locked: no



I have yet another channel change problem with 0.19. Since I have overcome my recent channel-scan issues with the 0.19 scanner (finally I have all my channels detected after letting the scans run a dozen times with incredibly high timeout values), I still have persistent channel-change problems during live tv using my terratec cinergyt2 usb 2.0 dvb-t device. I had no such problems with 0.18, and this device also works great in e.g. kaffeine.

Using the latest mythtv-0.19-fixes livetv works great in general, but i have strange tuning behaviour with one of my two dvb cards. It seems it depends on which channel i change *from*, so e.g. a change from German "VOX" to "Kabel1" *always* fails, ending up in the well-known osd message that the channel should already been tuned...

Some specific channel changes (e.g. from VOX to Kabel1 (Germany, NRW) are *never* successful with my cinergyT2, the OSD shows (L) partial lock instead of (LAM) lock, if the osd shows up at all. I am still able to tune back to VOX then, and escape also brings me back to the menu. Scheduled recordings *always* work.

When I switch from VOX to a channel of a third (different) transponder (e.g. ARD), and then again switch to the previously failed one, it works like a charm, in my example Kabel1 appears always when switched-to from ARD, but never when from VOX... strange. Maybe this is a dvb driver problem or specific to the cinergyt2, but in kaffeine all channels including all channel hops i ever tried work fine (and much quicker btw), just as they did in myth 0.18.

I definitely notice this since upgrading to 0.19 (7 weeks ago?) up to now (9348). Although the channel scanner has become better in the last weeks of svn upgrades, the scanner still makes trouble with my cinergyt2 and this channel change problem persists totally repeatable for me :-(.

I also noticed other dvb-t users on the mythtv-users mailing list also having trouble getting other "non-mainstream" devices to work flawlessly, some of them are also still reporting strange tuning problems after upgrading to 0.19. I have no such problems using my dvb-c.

That all being said, I today noticed ticket #1502, which definitely sounds very related! Is there a way to get the fix (the tuning delay) into the 0.19-fixes tree or is it already in there? I can't find the corresponding setting within my mythtv-setup after moving to 9348, so I guess this is in head only, right?

Some additional info (not sure if important):

  • athlonxp 2400/1gb
  • nvidia 5200 onboard (xv i think - where can i see that?)
  • using ALSA:hw for sound
  • Mandriva 2006
  • kernel 2.6.12-5mdkcustom with latest dvb-patches from

In case it is unrelated to ticket #1502 can I provide any information to assist debugging this? Sorry, I can handle diffs and patches, but I've never used a debugger before and am not a programmer ;-)

Please request any logs / files / output needed, I'll do my best to provide them.

Anyway thanks for your great work folks!

Attachments (5)

mythbackend-delay1000.log (19.7 KB) - added by parasonic <parasonic666@…> 15 years ago.
Using dvb tuning delay 1000
mythbackend-delay300.log (133.7 KB) - added by parasonic <parasonic666@…> 15 years ago.
Using dvb tuning delay 300
mythbackend-delay200.log (201.2 KB) - added by parasonic <parasonic666@…> 15 years ago.
Using dvb tuning delay 200
mythbackend-delay100.log (147.3 KB) - added by parasonic <parasonic666@…> 15 years ago.
Using dvb tuning delay 100
mythbackend-delay0.log (55.7 KB) - added by parasonic <parasonic666@…> 15 years ago.
Using dvb tuning delay 0

Download all attachments as: .zip

Change History (13)

comment:1 Changed 15 years ago by parasonic666@…

Same behaviour in 9360 just for completeness.

comment:2 Changed 15 years ago by danielk

Can you try setting "DVB Tuning Delay" in the "Recording Options" pane of the card setup in mythtv-setup (in SVN). Set it to something like 1000 to start with, if that works lower the value until it doesn't work and report the smallest working value along with a backend log with '-v channel' enabled.

comment:3 Changed 15 years ago by justifiably@…

Just to remark that I also have a cinergyT2 USB device and experienced very similar trouble, LiveTV has been quite unreliable compared to 0.18. In the hope of improving things (as well as upgrading my second card from analogue to digital), I bought a PCI card with a cx88 chip (KWorld/VStream XPert DVB-T), but tuning has been similarly bad there.

Anyway, anecdotes aren't much use, but I have just tested the new setting briefly and found that I can tune channels successively more reliably on both devices, although I still get some tuning failures. This was with a setting of 250 for Tuning Delay, I'm willing to try a larger value but maybe you're making further changes to match scan.c as suggested by Doug Scoular?

I can also provide logs if the OP does not (mine are cluttered with Jobqueue and other stuff at the moment). I'm using the latest FC4 kernel, 2.6.15-1.1833_FC4.

comment:4 Changed 15 years ago by parasonic666@…

The delay option is not available in my 0.19-fixes install i did svn update and recompiled. Then I did a fresh checkout of the head (trunk) files on my workstation (was afraid of doing harm to my "production" mythbox ;-) I started with a new master backend / new db on this machine, so my "production" mysql database would be untouched also.

But with myth (trunk 9409) I'm unable to successfully find my channels using mythtv-setup anymore, no matter if I use 0, 250 or 1000ms delay :-( Although it gets a lock on all transport ids, I always get "no tables" and some bogus channels are added into the db, named "C1#1", "C1#2" and so on. However these are not tunable/watchable within the frontend. Kaffeine scans quickly and find all channels with names.

I'll try to dump the channels/multiplexes out of the "production" db and insert them by hand, and will report to see if that gives me some live-tv for testing channel changes ... Is it possible to port this delay option back into 0.19-fixes? That would make testing a lot easier.

comment:5 Changed 15 years ago by danielk

Resolution: invalid
Status: newclosed

parasonic, the bogus channels from the scan are a seperate problem, but you should be able to use the DB from your production system to get the proper tuning params for your channels. If you back up the DB, run MythTV from SVN HEAD, then restore the DB, you should have no problem running 0.19-fixes again.

reopen the ticket when you have the proper timeout, along with the "mythbackend -v channel" log of a short recording. Once I stop getting these types of error reports with SVN head, I plan to backport the needed fixes to 0.19-fixes.

comment:6 Changed 15 years ago by parasonic666@…

Milestone: 0.20
Resolution: invalid
Status: closedreopened

After intensive testing I found that a dvb tuning delay of 200ms is the optimal value for my cinergyT2 device. Had no unsuccessful tunings or freezes anymore.

Using other values (1000, 500, 300, 0) made more trouble:


  • tuning was unsuccessful (partial lock) but successful after switing to another channel (as in 0.19)


  • livetv freezes, osd fades away leaving an empty screen, ending up with an "error during video display".

I'll attach the backend logs "-v channel".

Changed 15 years ago by parasonic <parasonic666@…>

Attachment: mythbackend-delay1000.log added

Using dvb tuning delay 1000

Changed 15 years ago by parasonic <parasonic666@…>

Attachment: mythbackend-delay300.log added

Using dvb tuning delay 300

Changed 15 years ago by parasonic <parasonic666@…>

Attachment: mythbackend-delay200.log added

Using dvb tuning delay 200

Changed 15 years ago by parasonic <parasonic666@…>

Attachment: mythbackend-delay100.log added

Using dvb tuning delay 100

Changed 15 years ago by parasonic <parasonic666@…>

Attachment: mythbackend-delay0.log added

Using dvb tuning delay 0

comment:7 Changed 15 years ago by parasonic <parasonic666@…>

After more testing I must say there is still some occasional bad tuning in live tv, but with 150-300 ms delay I have the most reliable results.

comment:8 Changed 15 years ago by danielk

Resolution: fixed
Status: reopenedclosed

(In [9535]) Closes #1513 by adding cinergyt2 to list of broken DVB drivers.

In order for this to apply to your cinergyt2 card, delete and reinsert it, or manually set the DVB tuning delay to 200 ms.

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