[mythtv-users] A little help clarifying dummy tuners and HD ringbuffers
Cody Hofstetter
codyhofstetter at gmail.com
Fri Aug 7 04:06:08 UTC 2015
Thanks for the info Michael, very useful!
Since you were able to answer the ringbuffer question, I hope you could
answer the other one I referenced:
If you have a large amount of system memory is there any downside
whatsoever to increasing the ringbuffer? Does increasing the buffer
increase time between switching channels or have any negative side effects
at all (assuming you're not coming close to swapping)? I'd like to add this
answer to the MythWiki if I can find it.
Thanks again Michael, big help. Best of luck in all your Mything adventures.
On Thu, Aug 6, 2015 at 11:44 PM, Michael Watson <
michael at thewatsonfamily.id.au> wrote:
> On 7/08/2015 12:47 PM, Cody Hofstetter wrote:
>
>> Thanks Mark!
>>
>> I am receiving channels and can view them completely fine using the
>> Prime's GUI/VLC. I can open LiveTV and watch channels in LiveTV. The issue
>> only occurs when watching a channel and I switch to another (only some of
>> them though which is what I find weird). Mythfrontend then gives the "error
>> opening jump program file buffer" and completely crashes. I got the thought
>> about the dummy tuners after reading this post:
>> http://www.gossamer-threads.com/lists/mythtv/users/504473 in which
>> Mitchell Gore says
>>
>> "Also, if you follow those instructions (he is referring to the
>> HDHomerunPrime setup instructions in the MythWiki - the one you just
>> mentioned) you first attach the tuner to adummy recorder. That way you can
>> fetch the listings. WHen doing this itwill pause for a bit and look like
>> nothing is happening. but if you gotothe channel editor you can see the
>> channels it grabed. Next you attach thetuner to the Prime and delete the
>> dummy."
>>
>> The OP goes on to say "On that page it said that using the dummy was for
>> 0.24-fixes but I'musing the 0.25 branch. I'll give that process a shot
>> though and see ifit makes a difference."
>>
>> Next post by OP: "In case anyone following along ran into the same issue
>> despite the factthat you are running Master or 0.25 go ahead and follow the
>> instructionsfor 0.24-fixes and it should work. Even in 0.25/Master (at
>> least fromthe mythbuntu repos) the channel numbers will not be fetched
>> unless youfirst configure the dummy recorder."
>>
>
> Dummy tuners are now called Demo Tuners. Whilst the name in the setup
> menu's may have changed, internally Myth my still use the name dummy. This
> looks like a hack to get Myth to populate the channel / schedule data in
> the video source prior to the tuners being properly configured, make it
> like a chicken and egg process - to get the tuner working properly you need
> channel data - to get channel data you need a configured tuner.
>
> I couldn't find any reference to a dummy recorder whatsoever in the
>> MythWiki Prime install guide or when looking for the .24-fixes. This leads
>> me to believe it was there at one point but has since been removed. I've
>> searched through the last 20+ mailing list archive pages, plus forum
>> posts/pages and still couldn't find anything. My guess is perhaps that the
>> "virtual" Prime tuners are these dummy tuners, but I don't know for sure
>> because I can't find any other references.
>>
>> As for the ringbuffer question, if you know how it works and can explain
>> it to me in detail it would be */greatly/* appreciated. I'm relatively new
>> to Myth and trying to understand as much as possible in as much detail as
>> possible. I also try to research as much as possible before asking any
>> questions because I feel it helps me learn better by having to go through
>> the wiki/archives first and try to figure it out myself (trial by fire
>> so-to-speak). Which, unfortunately on the only hand means that if I'm
>> asking questions it's because I couldn't find the answer myself after quite
>> a bit of digging haha. That's one of the reasons I appreciate */any/* input
>> anyone has so much. Maybe I just missed something really simple.
>>
>> Thanks again Mark. I've already deleted and re-added the tuners, but if
>> no one else has any suggestions I might just try it again.
>>
>> On Thu, Aug 6, 2015 at 9:48 PM, Mark Perkins <perkins1724 at hotmail.com
>> <mailto:perkins1724 at hotmail.com>> wrote:
>>
>>
>>
>>
>>
>> On 7 Aug 2015, at 7:40 am, Cody Hofstetter
>> <codyhofstetter at gmail.com <mailto:codyhofstetter at gmail.com>> wrote:
>>
>> Hello all!
>>>
>>> Still trying to fix a LiveTV "error opening jump program file
>>> buffer" when switching programs and am hoping for a little
>>> clarification on dummy tuners and HD ringbuffers.
>>>
>>> I'm using Mythbuntu 14.04 and .27 with a HDHomeRun Prime in
>>> CableCard mode.
>>>
>>> First, my searching through the forums/archives has led me to
>>> find that dummy tuners were originally designed for use as a
>>> development tool for those without the hardware wishing to
>>> contribute to Myth (e.g. on a laptop, no tuner card, etc) and for
>>> use on backends with no tuners.
>>>
>>> I've come across some errors indicating dummy tuners (I believe)
>>> that I was unaware were set up. Which lead me to wonder if MythTV
>>> automatically sets up dummy tuners and if so, why?
>>>
>>> E CoreContext fileringbuffer.cpp:300 (OpenFile)
>>> FileRingBuf(/var/lib/mythtv/livetv/1043_20150805170925.mpg):
>>> OpenFile(): File too small (0B).
>>> E CoreContext mythplayer.cpp:2718 (JumpToProgram) Player(1):
>>> JumpToProgram's OpenFile failed (card type: HDHOMERUN).
>>> E CoreContext mythplayer.cpp:2719 (JumpToProgram) LiveTVChain has
>>> 6 entries#012 DUMMY: 1026 (17:08:58 to 17:08:58)#012 HDHOMERUN:
>>> 1026 (17:08:59 to 17:09:06) discontinuous#012 DUMMY:
>>> 1028 (17:09:06 to 17:09:07) discontinuous#012 HDHOMERUN: 1028
>>> (17:09:07 to 17:09:24) discontinuous#012 DUMMY: 1043 (17:09:24
>>> to 17:09:24) discontinuous#012* HDHOMERUN: 1043 (17:09:25 to
>>> 18:30:00) discontinuous
>>> E CoreContext mythplayer.cpp:2960 (EventLoop) Player(1):
>>> Unknown recorder error, exiting decoder
>>>
>>> The MythWiki "Dummy Tuner" page says it's been outdated since .24
>>> and Myth now has a dedicated "demo tuner". Hence the wondering if
>>> they automagically setup or I'm getting this error because of the
>>> Prime tuner.
>>>
>>>
>>> Second, I understand the HD ringbuffers are, to paraphrase " to
>>> weather moments of stress and too large a ringbuffer will result
>>> in swapping" (description used in backend). So my question after
>>> searching through everything is, let's say most modern systems
>>> have at least 2/4gb of memory. Even if the swappiness is set to
>>> 60 as the default for most Linux distros, you still have plenty
>>> you could add before running into a problem (since the default is
>>> 9600kb). Please correct me if I'm wrong, but increasing the
>>> ringbuffer size won't increase the amount of time between
>>> switching programs in LiveTV (it should actually decrease it if
>>> switching for example from channel 2 to channel 3 and then back
>>> to channel 2?). From one of the many many posts I read somewhere
>>> I got that the live-tv chain ID is sent from the frontend to the
>>> backend and this is when the ringbuffer is assigned. Then the
>>> frontend loads the first channel in the chain to the ringbuffer.
>>> When the program guide data is changed (when you switch
>>> channels), it automatically creates a new file/chain entry. Is
>>> the only possible issue that would result from setting the
>>> ringbuffer higher is that it could get swapped?
>>>
>>> With the "RingBuf: Taking too long to be allowed to read.."
>>> error, where would you increase the timing to allow it to wait
>>> longer? Unless I'm completely off and that's not the way you
>>> solve this error.
>>>
>>
>> Use of LiveTV is fraught with peril, for some it works, for others it
> doesnt. Many threads on here about issues with LiveTV.
> The "RingBuf: Taking too long to be allowed to read" error basically means
> there is nothing in the buffer to read, and process has thus timed out.
> Common when changing channels in LiveTV. No real fix AFAIK - Myth does
> recording/scheduling well, LiveTV not so good.
>
>
>>> *http://pastebin.com/rWvzir9s --- Backend/Frontend Logs*
>>> *
>>> *
>>> If anyone could even give me a partial answer it would help so
>>> frigging much! It's a nightmare trying to troubleshoot things
>>> after spending hours searching and still not finding a simple
>>> answer as I'm sure everyone can attest to. You guys are immensely
>>> helpful when stuck!
>>>
>>> Thanks again!
>>>
>>> P.S. Gary already helped me solve one previous error and I find
>>> the troubleshooting guide with the errors section of the MythWiki
>>> easiest to understand when looking for a particular error. I know
>>> there has been talk of restructuring the wiki and I would like to
>>> put the errors I have as I solve them in the troubleshooting
>>> guide to help anyone else who has the same issue. I wouldn't mind
>>> lending a hand in helping reorganize the wiki either if someone
>>> has taken a lead and can point me who to talk to.
>>> _______________________________________________
>>>
>>
>> I don't think the issue is in the ring buffer. The presence of a
>> dummy tuner suggests to me that the tuners have not been setup
>> correctly because MythTV doesn't create dummy tuners by itself.
>> Waiting longer won't help if nothing is coming from the tuners.
>>
>> I don't have a HDHomeRun so won't be able to help troubleshoot but
>> if it were me I would delete all capture cards on all hosts in
>> mythtv-setup and redo the HDHomeRun setup from the wiki.
>>
>>
>
>
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>>
>>
>>
>>
>> --
>> If you have any questions feel free to contact me at this email, or at
>> the phone number listed below.
>> *
>> *Thanks,
>> *Cody Hofstetter*
>> *CodyHofstetter at gmail.com <mailto:CodyHofstetter at gmail.com>*
>> *CodyHofstetter.com <http://www.CodyHofstetter.com>
>>
>> *
>>
>>
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>
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Thanks,
*Cody Hofstetter*
*CodyHofstetter at gmail.com <CodyHofstetter at gmail.com>*
*CodyHofstetter.com <http://www.CodyHofstetter.com> *
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