1.11.0 - Video & Audio Stuttering for short period of time for LiveTV only after S3 or S5 | Page 3

Discussion in 'Archive' started by marttoma, June 28, 2015.

  1. marttoma
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    Hi mm,

    New surprise:) Does it mean if I set up to grab EPG while timeshifting the TV Server just grab EPG while timeshifiting only from TV channel, which is currently active? I had a feeling TV server grabs EPG from all channels, which are checked (if Store data only for the selected channels is checked) or from all TV channels, which contains EPG (if Store data only for the selected channels is unchecked).

    I am testing stuffering in case I jump to Barandov HD channel, but so far no stuffering (I checked only to grab EPG from full EPG channel - i.e. from Barandov HD channel).

    Yes, this is comming from current wiki, but I would remove this as well:)

    I would like to ask you to explain the definition of timeout for EPG in idle and EPG while timeshifting as I am not sure if I wrote down in wiki proposal right information.

    Thank you & best regards,
    marttoma


     
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  3. mm1352000
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    mm1352000 Development Group

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    I think you need to understand the difference between grab and store.

    EPG must be grabbed first. Grabbing requires that TV Server must tune a channel. The idle EPG grabber automatically tunes every channel that you tick when all tuners are not in use; the timeshifting EPG grabber is activated when you tune a channel that is ticked. To be clear: in both cases the channel must still be ticked. EPG is never grabbed from channels that are not ticked.

    After a ticked channel is tuned successfully, EPG grabbing (data collection) commences.

    After some time TV Server will determine that EPG grabbing (data collection) is complete. The 2 possible completion conditions are:
    1. All available EPG data has been collected.
    2. Timeout (maximum time for grabbing) has been reached. Note that the idle and timeshifting grabbers have their own timeout settings.
    Now the EPG that has been grabbed must be stored in the TV Server database.

    If "grab EPG only for channels on same transponder" is ticked, EPG for channels from other transmitters will be thrown away.
    If "store data only for selected channels" is ticked, EPG for channels that are not ticked with be thrown away.
    All remaining data is stored in the database.


    An example...
    For grabbing, you have only one channel - Barandov HD - ticked. That means the timeshifting EPG grabber will only grab EPG when you select "Barandov HD". It is not active when you select other channels. The idle EPG grabber will also tune "Barandov HD" automatically when all tuners are idle.

    For storing, you have both "grab EPG only..." and "store data..." unticked. This means all EPG data that is received will be stored.

    Your provider is broadcasting EPG for all channels on the Barandov HD transmitter. This means you will receive EPG for all channels even though TV Server only grabs for one channel.

    Timeout means: "maximum time" or "time limit".

    As explained to CyberSimian:
    The timeout is the maximum time that the grabber can use for collecting the available EPG data.
    If the timeout expires (ie. the grabbing time limit is reached) before the grabber receives all EPG data then TV Server stops grabbing and stores the data that was received/collected. As always, the data that is stored depends on the "grab EPG only..." and "store data..." settings.
    The same meaning is applied to both the idle and timeshifting EPG grabbers.
     
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  4. marttoma
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    Yes, sure:) Thank you for your patience.

    Here I would have question - which sentence is incorrect?:
    1. EPG grabbing for idle is grabbing (when it is activated) EPG from all checked channels from whole TV channel list?
    2. EPG when timeshifting is grabbing only EPG from current activated TV channel (if this channel is checked)?
    3. EPG when timeshifting is grabbing only EPG from current activated TV channel (if this channel is checked) and for all other channels from same MUX (if these channels are checked)?
    BTW what is not clear to me is why in my case EPG grabbing when timeshifting took too much time as the grabbing was based on sence #2 or #3 -> it seems to me not so many data (as in one MUX is ~8 channels) ...

    Default time for idle is 10 min, for timeshifting is 2 min -> Why this default time is not the same? Is it due to fact EPG grabbing when idle in general should take more time as it in general will grabb EPG from more channels (based on assumption more TV channels are checked)?

    Is this sentence valid for EPG when idle as well? Or just for EPG while timeshifting?


    EPG when idle - which TV channel is going to be grabbed first? What is the order of TV channels of EPG grabbing when idle?


    Dont spend time with the reading of proposed Wiki text as I would like to prepare new version - based on your information - if this could help others...
     
  5. mm1352000
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    <sigh>
    I don't think I can explain any better than I already have. :(

    Incorrect.
    The "whole TV channel list" has zero connection to EPG grabbing. The idle (and timeshifting) EPG grabbers only grab from the checked channels in the DVB EPG -> TV Epg grabber and DVB EPG -> Radio Epg grabber channel lists.

    Correct.
    ...if the channel is checked in the DVB EPG -> TV/Radio Epg grabber channel lists.

    When you mention "MUX" you start to make it complicated to explain. :(
    This one is both correct and incorrect.

    If you want to understand the full situation properly then my advice would be to think of the EPG as like a "hidden channel" in the MUX. The grabber always grabs from the "hidden channel", not actually from the channel that was tuned. That means that the grabber will get the same data regardless of which channel on the MUX is tuned.

    So, for example...
    If the grabber tunes a channel that is from the same MUX as Barrandov HD, the grabber will find the same EPG data as if it had tuned Barrandov HD. It really makes no difference.

    I don't understand.
    Why do you think EPG grabbing when timeshifting took too much time?

    I have no idea. These settings were added before I joined the team. If you ask for my opinion, I think the idle and timeshifting grabbers could use a single timeout setting.

    No. Grabbing when idle and timeshifting will take the same time (...because it is exactly the same thing).

    The only difference between idle and timeshifting EPG grabbers is:
    With the timeshifting grabber, you decide which channels to tune.
    With the idle grabber, all checked channels are tuned automatically.
    There is zero difference in the grabbing or storing part (except maybe the timeout value).

    Yes, of course.
    As above: the difference between idle and timeshifting is very small.

    It is not defined/deterministic... and it shouldn't matter.
     
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  6. marttoma
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    marttoma MP Donator

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    Thank you, fortunatelly this is clear to me (I had same view just I did not write it in proper way):)

    Here I would have one question. Let estimate you have 5 MUXs, on each MUX 6 TV channels with one hidden EPG channel. In case of EPG while timeshifting (triggered via channel change) TV Server will grabb EPG only from this MUX and only for checked TV channels, right? It means it does not grabb EPG from other EPG hidden channels on other MUXs, right?
    In case of EPG when idle it will grabb EPG for all checked channels from all MUXs. right?
    So if grabbing take same time for idle and timeshifting, it is valid only for case of full PEG channel (as in my case Barandov HD channel), right?

    Let estimate I have my wrong setting (as at the beginning of this thread) and I have only EPG when timeshifting and I jump to CT1 channel for example, it should grabb EPG from this MUX only(there is no full EPG - just EPG for channels on this MUX) and in this case I had stuffering - this is a reason I think EPG took too much time:)[DOUBLEPOST=1436423471][/DOUBLEPOST]I was googling litle bit and found out this documet, here are list of EPG channel types:
    • This Channel EPG
    • Multiple channel EPG
    • Full EPG
    When you mentioned some EPG, which contans just sgort data, did you mean "this channel EPG" and near area?
     

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  7. mm1352000
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    Yes, the timeshifting EPG grabber only ever grabs from the MUXes that you tune, and it only grabs if the channel is checked.

    Yes, I suppose... but it will if you change to a checked channel on another MUX, or if a recording starts on a checked channel on another MUX. I don't understand your point.

    No. If you uncheck all channels from a MUX then the idle EPG grabber will not grab from that MUX. However, you may still get EPG for those channels (depending on provider and settings) when the grabber grabs from other MUXes. For example, with your new configuration, the grabbers are only grabbing from the Barrandov HD MUX and not from any other MUX... but you have seen you still get EPG for all channels.

    You have misunderstood.

    The timeout settings are for grabbing from a single MUX. So, what I was trying to say is that grabbing for a single/same MUX always takes the same length of time, regardless of whether the grabber is timeshifting or idle.

    Of course grabbing from 10 MUXes will take longer than grabbing from 1. However as I said above, the timeout settings are not applied to the full grab time for all MUXes.

    Sorry, but this is wrong.

    CT1 HD seems to have full EPG for all channels just like Barrandov HD:
    Show Spoiler
    [2015-06-28 11:00:21,168] [Log ] [12 ] [INFO ] - dvbc: Tune:DVBC:tv:UPC CT 1 HD Freq:730000 ONID:1 TSID:112 SID:1202 PMT:0x7A0 FTA:True LCN:10000 SymbolRate:6900 Modulation:Mod64Qam
    ...
    [2015-06-28 11:02:12,064] [EPG ] [24 ] [INFO ] - dvb:dvb ready.EPG 183 channels
    [2015-06-28 11:02:15,168] [EPG ] [24 ] [INFO ] - TimeshiftingEpgGrabber: OnEPGReceived got 183 channels
    [2015-06-28 11:02:15,185] [EPG ] [EPG Update thread] [INFO ] - TimeshiftingEpgGrabber: CT 1 lastUpdate:27.6.2015 23:31:54
    [2015-06-28 11:02:15,807] [EPG ] [EPG Update thread] [INFO ] - - Inserted 247 epg entries for channel CT 1
    [2015-06-28 11:02:15,810] [EPG ] [EPG Update thread] [INFO ] - TimeshiftingEpgGrabber: CT 2 lastUpdate:27.6.2015 23:31:55
    [2015-06-28 11:02:16,503] [EPG ] [EPG Update thread] [INFO ] - - Inserted 265 epg entries for channel CT 2


    ...and so does CT1 [SD]:
    Show Spoiler
    [2015-06-28 16:35:03,076] [Log ] [scheduler thread] [INFO ] - dvbc: Tune:DVBC:tv:UPC CT 1 Freq:658000 ONID:1 TSID:101 SID:1 PMT:0xB0 FTA:True LCN:10000 SymbolRate:6900 Modulation:Mod64Qam
    ...
    [2015-06-28 16:36:54,056] [EPG ] [21 ] [INFO ] - dvb:dvb ready.EPG 183 channels
    [2015-06-28 16:36:57,096] [EPG ] [21 ] [INFO ] - TimeshiftingEpgGrabber: OnEPGReceived got 183 channels
    [2015-06-28 16:36:57,096] [EPG ] [EPG Update thread] [INFO ] - TimeshiftingEpgGrabber: CT 1 lastUpdate:28.6.2015 13:03:25
    [2015-06-28 16:36:57,766] [EPG ] [EPG Update thread] [INFO ] - - Inserted 280 epg entries for channel CT 1
    [2015-06-28 16:36:57,766] [EPG ] [EPG Update thread] [INFO ] - TimeshiftingEpgGrabber: CT 2 lastUpdate:28.6.2015 13:03:26
    [2015-06-28 16:36:58,506] [EPG ] [EPG Update thread] [INFO ] - - Inserted 304 epg entries for channel CT 2


    So, I still don't understand what you're talking about.
     
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  8. mm1352000
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    No.
    That document is from 1996 - ancient! ;)
    If you want to read standards them maybe look at ETSI EN 300 468 and/or TS 101 211.
     
  9. CyberSimian
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    I thought that I would add this update for anyone else who is curious about the way that the EPG operates and who has been following this thread.

    Today I switched off the TV and expected the HTPC to run for circa 7 minutes (it was overdue for an EPG grab), and then hibernate. Instead it ran for 30 minutes :eek:, and then hibernated. Looking at the TV Server log showed that the EPG grab had occurred for the full 30 minutes from a single channel and then timed out -- the smart limiter never operated.

    Although I have only three examples, I am beginning to wonder whether the ordering of the transmitted EPG in the UK varies between daytime and nighttime:

    (1) During the day, the ordering of the EPG is optimised for the large number of TV sets that do not retain the EPG when in standby, and so gives preference to EPG entries for today and for the next 2-3 days, and reduces the occurrence of EPG entries for days that are 7 days in the future. These "distant" EPG entries are not absent, but they occur so infrequently in the datastream that from the point of view of the EPG grabber, the EPG never stops changing (even after 30 minutes!), and so the grabber eventually times out.

    (2) During the night, the ordering of the EPG is optimised for DVRs that wake up during the night to grab the EPG, and so there is a more uniform distribution of EPG entries for different days, allowing the entire EPG to be grabbed within 7 minutes (in the UK).

    That is all speculation, of course. However, the reason for doing a frequent EPG grab (whether using the idle grabber or the timeshift grabber) is to receive last-minute EPG changes for programmes that are broadcast later the same day. A short grab would be sufficient to receive these last-minute changes. In the UK, a 30-minute grab serves no purpose, so I shall revert to the default idle grab of 10 minutes. So it seems (cough) that MP had it right all along. :D

    -- from CyberSimian in the UK
     
  10. marttoma
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    There is no point;) Just I am trying to understand advantage of EPG while timeshifting for case there is no full EPG channels, all channels are checked in TV EPG grabber and you have let say 10 MUXs. In this case is probably better to use EPG when idle as it should grabb all checked channels on all MUXs and you should have EPG data for all channels, for EPG when timeshifting if this just grabb channels from current MUX, you can be in situation to have EPG data only for some channels (from MUX you tunned for TV watching/recording) and missing data for channels from MUXs, which were not in use...

    I see, but I would have question here - if you have timeout of 2 min for example and EPG grabbing from 1st MUX takes 1,5 min, and TV Server should grabb EPG from 2nd MUX as well (lets estimate this option), what happens after 2 min of timeout?

    How can I find how much time EPG grabbing takes from e.g. CT1 HD channel? Are there any triggers in the log, wher eyou can find this information from? Sorry, may be stupoid question, but log is quite long and I would like to be sure I know how to check it.


    Thank you. To be open, it is strange as I was testing to grabb EPG from CT1 HD channel only before I opened this thread and I just got EPG for CT1 HD channel, not for others, but may be I did something wrong, anyway I have to tested again:)

    I am talking still about the point in first line of this message:)

    BTW, was the stuffering (I had with my old settings) created during the EPG grabbing or during EPG data saving in to the SQL database?

    Thanks:) I did not notice it is too old:) Anyway I am not guy how can read ETSI specifications,I would prefer to read some more simple documenst, would you know about something, where this EPG is explained in more simple way as in ETSI?:) Mr. google did not find such document on internet:(
     
  11. mm1352000
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    There are 2 advantages:
    1. The idle EPG grabber won't be activated if TV Server is constantly timeshifting or recording. Therefore you won't get any EPG at all unless you enable the timeshifting grabber.
    2. The timeshifting grabber is more likely to receive last minute updates than the idle grabber, because the idle EPG grabber may only run once every 24 hours whereas the timeshifting grabber runs every time you tune a checked channel.

    Again, you have completely misunderstood how the grabber works. :(
    This is the last time I can explain.

    Timeshifting:
    1. Channel is tuned (timeshifting or recording) => grabber starts.
    2. EPG data complete or timeout reached => grabber stores EPG.
    Nothing else happens after this unless you change to a different channel. Grabbing for additional MUXes won't ever happen unless you change to a channel from a different MUX.

    Idle:
    1. All tuners become idle => grabber activated.
    2. The grabber gets the list of channels for grabbing (checked channels).
    3. Repeat for each channel in the list, until any tuner is needed for timeshifting/recording or the list is complete (grabbing complete for all channels)...
      1. Grabber tunes channel.
      2. EPG data complete or timeout reached => grabber stores EPG.

    The timeout is always applied for each channel/MUX. There is no grabbing timeout for all MUXes.


    As I said to CyberSimian, the time varies from provider to provider, channel to channel, and grab to grab. My point is: you cannot expect grab times to be consistent.

    Tuning:
    [2015-06-28 21:10:50,177] [Log ] [22 ] [INFO ] - dvbc: Tune:DVBC:tv:UPC Barrandov TV HD Freq:770000 ONID:1 TSID:117 SID:1701 PMT:0xAB0 FTA:True LCN:10000 SymbolRate:6900 Modulation:Mod64Qam

    Grab starts:
    [2015-06-28 21:10:50,655] [Log ] [22 ] [INFO ] - Timeshifting epg grabber started.

    Grab completed:
    [2015-06-28 21:12:41,064] [EPG ] [21 ] [INFO ] - dvb:mhw ready MHW 0 titles found
    [2015-06-28 21:12:41,064] [EPG ] [21 ] [INFO ] - dvb:dvb ready.EPG 183 channels
    [2015-06-28 21:12:44,059] [EPG ] [21 ] [INFO ] - TimeshiftingEpgGrabber: OnEPGReceived got 183 channels

    Neither. It was during what happens between grabbing and storing.

    EPG and EPG grabbing is not simple, and the situation varies from provider to provider. Therefore I don't think you will ever find a simple document.
    It took me months or years to fully understand. If you want to understand more then my advice is to read the specifications. If you don't want to read specifications then perhaps you could look for books at your local library or something, because I cannot spend months or years explaining to you. :)
     
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