Black screen after channel change... (1 Viewer)

argypak

Portal Pro
November 21, 2007
62
0
Berwick
Breakthrough!!!



I have tested and tested and now I think I have found the reason that the problem occurred more frequently under 1.0 than earlier.

I recently bought a new TV-card (leadtek 1000S) and with that one I changed the priority for my FloppyDTV (used to have highest priority).

I've done som extra testing now and it seems like it is much easier to trigger the problem when switching channels that are on different TV-cards. I now changed so that I am only using the channels from one TV-card and now I had to really push it to be able to trigger the black screen (managed to do it though by selecting some channels that I have no subscription for). However when changing channels (with subscription on all of them) randomly including switching MUXes all the time, I did not manage to trigger the problem even once.

The reason I am having two TV-cards is that I have three clients and on top of that recording in the server. I have used the Leadtek card with highest priority to be able to use the floppyDTV for the encrypted channels when watching unencrypted on another TV-set.

This also explains why it sometimes has been harder to trigger the problem - If I have two clients active it is almost impossible to trigger the problem, because then one card will be locked to one TV-set (as long as I am not watching channels on the same MUX on both TVs).

I have had preloading active. When I turned it off, every channel change I did that triggered a new TV-card to be selected gave black screen. And when I turned it back on and changed the priority of the TV-cards the problem was gone!

I am later going to set up a channel-group with only the free channels to try to see if it is possible to trigger the problem while only using the Leadtek card...

Conclusion:
Switcing channels on multiseat (separate client and server) with different TV-cards being used before and after the channel change is the easiest way to trigger the problem...


Previous post that got automerged...

I've tried to change the time-shift buffer...
...it was already a specific location, but now I tried with another without luck.

I tried changing recording format from TS to MPEG, but that didn't help when trying to play recorded TV (recorded in MPEG instead of TS format) after the black screen has occurred.

BTW, in my prevous post I forgot to mention that I haven't changed anything from default in Catalyst. I double-checked it and when I did I got straight into the "first time guide".

I now understand what you mean with how bug-reports are to be handled. It is however not crystal clear when entering the forum...

Regarding to be able to reproduce the problem:
- I have no problem doing that. The problem occurs when changing channel in every 1/1 to 1/50 times. For most of the time the problem occurs before 10 channel changes have been done, but once in a while the problem takes up to 50 times or more before happening. This makes it hard for me to say whether it is fixed or not...
...it might occur again after rather a long time. And then the next time I turn on the client it occurs immidiately and almost every time a channel change occurs.

Another thing that might be of interest is that I have rather poor TV reception (have already the biggest antenna with the best amplifier ;-). I have 80km to the transmitter and a few trees rather close. Could it be disturbancies in the signal while changing the channel that makes the reader/codec to take a leave? I know that the quality of my TV-reception varies a lot over time and with the wheater...
I'd just like to point out that although the above observations may be true, and he can now recreate the problem more readily, it doesn't explain why it happens on one client and not on the other client.
 

jhb

Portal Pro
September 19, 2006
121
2
Gothenburg
Sweden Sweden
More news:

I have tried using the same configuration as before (the one that gave black screen when changing between cards), but shifted channels so that I was entirely within the leadtek card. No blacks screen! Did the same with the same configuration but stayed entirely within the floppyDTV card - no black screen.

Then I realized that one of the few things in common in the TV-server is the folder where I store the timeshifting buffers...
...so I changed to use separate folders for the the timeshifting of the two cards and it seems to help for some strange reason (the files are named differently when using the same folder - I've checked that). I haven't had time to test it thoroughly yet, but I couldn't trigger the problem when trying roughly 30-35 channel switches in a row.

I'm now suspecting that this has something to do with the access to the filesystem in the server and how the problems that causes are handled on the R1.0-client on Vista. Remember that I am still running RC4 on my other XP-based client. I have a rather old (5 year old P4@3GHz) server with XP Home. It could be that there is some kind of temporary "deadlock" in the filesystem when switching from one TV-card to another...

Parameters that are related to the TV-server and this phenomenon are:
- 70GB left on a 200GB disk
- using the c:\ disc, where both windows and mediaportal server runs
- storing the timeshifting in a new timeshifting-folder in the same directory as MP stores its own (under the name timeshifting).

I think I'll move the timeshift to another disk (as recommended for speed) to see if that helps when using the same timeshift folder for both TV-cards. This is now getting more interesting than frustrating (since I seem to have a work-around). But I am getting closer and closer to the real problem.......
 

jhb

Portal Pro
September 19, 2006
121
2
Gothenburg
Sweden Sweden
Even more progress:

I have finally managded to recreate the problem on my other client running RC4 on XP!!!

There I got "Can not start timeshifting" as an error. Searching the forum lead me to this thread:
https://forum.team-mediaportal.com/...rtsp-multiseat-mode-test-plz-36735/index.html

and also these threads:
https://forum.team-mediaportal.com/...anby-hibernation-41368/index2.html#post375177
https://forum.team-mediaportal.com/.../no-tv-unable-start-timeshifting-error-53354/
and more...

Where I find most of my problems very well described (especially in the first thread), except for the fact that the screen for me goes black while audio is still working on R1.0. But on RC4 they fit perfectly!!!

I have not yet managed to test the SMB-disk workaround and have yet all the posts in the thread to read....
 

Union

MP Donator
  • Premium Supporter
  • January 23, 2009
    6
    0
    United Kingdom United Kingdom
    All my clients are ASRock K7S41GX motherboards which have onboard graphics which I am not using, all have agp MSI FX5200 graphic cards.

    I agree the easiest way to trigger mine is by switching cards I have 3 DVB-S cards and 1 dual DVB-T all installed in my server.

    I had previously tried the timeshift buffer on different hard drives, however I always used the same directory for all five cards, and the problem was always there, since reading your post I have tried your “work-a-round” and created a different folder for each card timeshift buffer. This created a new fault for me every time I changed channel the video goes back to the start of the timeshift buffer making channel changing get longer each time a channel is changed, not a workable solution. Although I did not reboot my server after I had made the change but the change was implemented because I looked at my timeshift buffer folders and could see the new files. I did not get a blank screen but only did 5 channel changes.
     

    jhb

    Portal Pro
    September 19, 2006
    121
    2
    Gothenburg
    Sweden Sweden
    Well...
    ...my workaround didn't help it just decreased the probability. My wife managed (as usual) to trigger the problem anyway...

    I am now trying out the solution with mounting the timeshift buffer over the network and using it as if it was local. So far so good, but haven't had time testing it that much, it is a production-server you know...
    ...it is the solution used for watching TV and as such, you can't fool around whenever you like to...
     

    Union

    MP Donator
  • Premium Supporter
  • January 23, 2009
    6
    0
    United Kingdom United Kingdom
    Yes I understand what you meen "production server"........ Its hard to find time to mess with the system because someone is either watching someting or recording!!!! I wish to have a spare server so I can mess around off line.

    I am not convinced about sending the timeshift buffer around the network but we do stream video so I guess there is not much diferance.

    Have you tried a RAM drive on your server for the timeshift buffer?
     

    argypak

    Portal Pro
    November 21, 2007
    62
    0
    Berwick
    If anyone is interested try this.
    Start TV client on client
    start channel
    disconnect network switch (client should show loss of connection)
    navigate client back to main menu
    Start TV client on client. - (Should produce sound but no video.)
    navigate back to main menu
    restart MP
    Start TV client on client. (video will return)

    My questions are:,
    Does this relate to the problem in this thread and also other similar threads?
    Is the problem a connectivity problem rather that a video or codec issue?

    My previous thoughts were that is relates to the videocard driver, but I have now managed to recreate the problem on another system with an 9500GT nvidia which always works fine.
     

    frenzy

    Portal Pro
    April 29, 2008
    228
    10
    France France
    Country flag
    If anyone is interested try this.
    Start TV client on client
    start channel
    disconnect network switch (client should show loss of connection)
    navigate client back to main menu
    Start TV client on client. - (Should produce sound but no video.)
    navigate back to main menu
    restart MP
    Start TV client on client. (video will return)
    If that happens there are at least about 5 different things that will go wrong on the pc including some MP functions.
     

    jhb

    Portal Pro
    September 19, 2006
    121
    2
    Gothenburg
    Sweden Sweden
    Frenzy:
    Yes there are several things that will go wrong, but messing up the TSreader is the only one thing that MP does not recover from when I am doing this.

    Argypak:
    I don't have to test this, it is already verified on my system...
    ...it has happened already when the Ethernet cable slips out of the switch (broken connector lock)! ;-)

    My conclusion is that it is yet another way to reproduce exactly the same problem. I am aware of these scenarios when the problem occurs:
    - switching channel with multi-seat and RTSP, more frequently when the new and the old channel are on different TV-cards
    - loosing network connection with multi-seat and RTSP
    - resuming from stand-by with multi-seat and RTSP
    - going to live-TV from recorded TV (or vice versa) with multi-seat and RTSP

    All these have in common that the RTSP signal is abruptly broken, where-after the screen goes black and audio continues (MP1.0final) or a message "Can not start timeshifting - no audio or video available" (Free translation of the Swedish error message on MP1.0RC4).

    There are also other situations where there are problems with multi-seat and RTSP, like:
    - contiguous stuttering
    - intermittent stuttering (mainly when timeshift buffer is changed)
    - slow channel changes
    - problems with FFWD/REW
    - etc

    Most users are using MP in single seat with live-TV and recordings being exchanged over the harddrive and there these problems are not existing...

    ...I am now running with the fix in this thread (TVplugin - avoiding RTSP in multiseat mode (test plz). - Page 17 - MediaPortal Forum) and things are working quite good. It works for now and I can maybe even live with that solution for my main TV and RTSP for my secondaries for quite a while, but I don't like the fact that multi-seat is so poorly tested by the community... :-(
    ...what happens the next time? I will definitely be reluctant to upgrade a working system after this...
     

    jhb

    Portal Pro
    September 19, 2006
    121
    2
    Gothenburg
    Sweden Sweden
    Found yet another situation when this appears and it even appears when not using streaming with RTSP!!!

    Today the same problem occured with Samba file sharing of the time shift buffer!!!

    In Sweden we have regional news breaking the national transmission of a TV channel. This can be seen as a disturbance to the TV-signal. I have previously had problems with this, the audio reception has stopped working. Using another audio codec than MPA solved that issue.

    Today I realized (I am rarely watching the regional news) that the problem I have with black screen after channel changes also may happen when the regional transmission breaks the national one. The same situation also occurs when the regional transmission is terminated and the national transmission takes over again. When I were about to watch the regional news today, the screen went black due to the disturbance in the signal. And when the national transmission started again (I had restarted MP in-between), the screen went black again!

    This bug has to be recognized so that it can be solved. Based on this I definitely can say that it may appear in single seat MP setups also!
     

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