Opened 9 years ago

Closed 7 months ago

#9954 closed Bug Report - General (Works for me)

Bad channel crash loop - Problem since v 0.18

Reported by: al5121024@… Owned by: sphery
Priority: minor Milestone: unknown
Component: MythTV - General Version: 0.24
Severity: medium Keywords: channel starting channel
Cc: Ticket locked: no


Minor Problem: Channel scan finds 100s of invalid, non-existent channels. Tuning to an invalid channel in LiveTV crashes to main menu.

Major problem: No fast way to recover. Fastest way is to close down, run backend setup and manually change the starting channel. No big deal if it's one channel, one time. 5 minutes or so to fix. Major problem is that if you are trying to label 500 channels, 200 crashes are going to add an extra 16 hours to the time it takes.

I regret to report that this has been a problem since at least version 0.18 (see link). I have seen lots of people asking for this to be fixed.;#196477

Forget about fixing the "crash when the data is bad" problem.

The real problem (can't quickly recover from crash) is an incredibly simple problem to make a good workaround. Please accept my suggestion for one or more of the following seven ways to workaround it.

1) On crash, return to last working channel 2) On crash, return to a pre-set channel (e.g., channel 2_1) 3) On crash, tune to analog tuner (for those of us with analog and digital tuners) 4) Option for a "what channel do you want" to pop up when selecting live TV, before trying to turn to TCC (the Crash Channel). 5) An option to have a fixed starting channel rather than a variable one. 6) A simple command line program to change to another startup channel while frontend is running. 7) Let us tune to a channel from the channel guide in "schedule recordings" instead of only live TV (which crashes before we can get there). 8) When it crashes, offer the option to delete the channel then and there (then tune to default channel when starting).

In short, if you can't stop the thing from crashing on particular channels, please provide some very fast way to get away from a bad channel. I would be happy to tab to a terminal, then re-run a command line every time it crashes.

If it matters, I have HDhomerun. Oh, and this isn't the SD/HD bug. It happens regardless of what channel you start from, only the destination channel matters.

So could somebody please, please fix this so that those of us whose cable company shuffles the channels from time to time don't have to spend days weeding out the bad ones?

Change History (12)

comment:1 Changed 9 years ago by stuartm

Keywords: Bad bug crash removed
Severity: highmedium
Type: Bug Report - CrashBug Report - General

FWIW 'Crash' doesn't mean what you think it means, exiting playback is not crashing. The entire application exiting suddenly and without being asked would be a crash.

comment:2 Changed 9 years ago by Raymond Wagner

Status: newinfoneeded_new

Duplicate of #4515. For reference, what version of MythTV are you using?

comment:3 Changed 9 years ago by al5121024@…

Ticket #4515 was closed but it hasn't been fixed. Someone named markus.ingalsuo posted an updated report with the exact problem I am having and it was re-closed by danielk, who said it was an unrelated problem. Since this has been declared an unrelated problem, this ticket is not a duplicate of that one.

As for the version: at various times IIRC I have used v .18, .19, .20, .21, and .24. I am using .24 now, same problem on every version, just that the number of channels found and number of bad channels found has gone up over the years.

I saw a post that suggested this could be caused by running out of disk space and having a different user for backend nad frontend. The frontend says "myth" for user, the backend says "mythtv" for user. There is only one user account on the system. There is plenty of disk space.

comment:4 Changed 9 years ago by al5121024@…

I should have said this before, it sometimes crashes to desktop either on the first change to bad channel or on later tries to "watch TV".

comment:5 Changed 9 years ago by al5121024@…

OK, I misunderstood the symptoms. It isn't starting on the originally crash-to-menu channel. Instead once it has been on any crash-to-menu channel, every channel on the digital tuner turns crash-to-menu.

It actually is reverting to the last non-crash-to-menu channel. Unfortunately that channel is now a crash-to-menu channel too (unless it is an analog channel, which is how I realized what was happening). Unfortunately, starting from analog doesn't fix the problem, it just crashes-to-menu as soon as you switch from the analog to any digital channel. Stopping myth frontend in system monitor eliminates the "all digital channels are crash-to-menu" problem until the next time you tune to a bad channel. Frontend automatically reboots so this fix is fast enough to work with. Still, it would be nice if the underlying problem of "all digital channels go bad after one bad channel" or the problem of bad channels causing an "error opening jump program file".

comment:6 Changed 9 years ago by sphery

So, it sounds like you're reporting 2 issues:

a) MythTV saves "last channel" even on channels it cannot tune

b) can't change from SDTV channel to HDTV channel in Live TV ( #9177 )

comment:7 Changed 9 years ago by al5121024@…


It's more complicated than that. There is one serious problem, compounded by a minor problem that I just found out about and have not previously reported. The more I experiment, the more quirks I find. My initial ticket was wrong about the cause of the serious problem. I incorrectly thought it was caused by the digital tuner going from good channel 171 to bad channel 174 (for example) and then "watch TV" trying to tune to bad channel 174 ever after. Instead mythtv tunes to 171, which has gone bad, corrupted by the previous attempt to tune to 174.

So the serious problem is that once the digital tuner has been on certain bad channels, all digital tuner channels (even on a second digital input) are bad.

The "can't change from SD to HD" is a red herring. First, it isn't SD to HD, since some digital channels are broadcast in SD. It is analog to digital. Second, it isn't changing from analog to digital that's the problem. Its that all digital channels have gone bad.

Examples are the best way to show this:

Channel 777 is good digital Channel 1313 is bad digital Channel 2 is analog

Example 1) Start on channel 777. Change to 1313=crash to menu. "Watch TV" takes you directly to 777, but now 777=crash to menu.

Example 2) Start on channel 2. Change to 1313=crash to menu. "Watch TV" takes you directly to 2, which still works, but all digital channels are now bad.

It's not going from analog to digital that kills it, its just that starting over at analog is the only way to avoid instakill by the bad digital channel.

The only reason it looks like going from analog to digital kills it is that analog is the only safe place once digital goes Hal9000 on you.

Not all bad channels trigger "all bad". At least one crashes-to-menu but doesn't have further results. That one has content that can be recorded but not watched on live tv. At least one of the really bad channels can't be recorded.

comment:8 Changed 9 years ago by beirdo

Status: infoneeded_newnew
Version: Unspecified0.24

comment:9 Changed 9 years ago by al5121024@…

Still "freezing" (not "crashing") to menu constantly. Since TWC just shuffled their QAM channels again this is a problem. Does anyone have an efficient way to deal with re-identifying the digital channels despite the "not crashing" or does everyone just use this program half-crippled?

comment:10 Changed 9 years ago by sphery

FWIW, the description in comment:7 sounds a lot like broken capture card hardware or drivers that result in a card becoming unusable if it ever attempts to tune a "bad" channel (i.e. when the broadcaster/re-broadcaster shuffles channels around and the old scanned channel is no longer valid). This happens for me with my pcHDTV HD-3000 cards, but doesn't happen with Avermedia A180 or Hauppauge HVR-2250. It seems to be independent of MythTV.

comment:11 Changed 7 years ago by stuartm

Owner: set to sphery
Status: newassigned

comment:12 Changed 7 months ago by Klaas de Waal

Resolution: Works for me
Status: assignedclosed

This ticket is really old and the problems mentioned here cannot be reproduced on today's master. Analog TV is gone so that is not an issue anymore. Also, the channel scanner has now an option "Complete scan data required" that is checked by default and which insures that all the malformed channels are discarded, leaving only the tunable channels. I cannot rule out that it is possible to make the tuner fail on a malformed channel but at this moment I do not see a problem. Therefore this ticket is now closed.

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