Ability to watch the TV stream directly without the timeshift buffer delay? | Page 3

Discussion in 'General Support' started by Chris Melville, January 14, 2018.

  1. regeszter
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    regeszter Retired Team Member

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    Hi,



    I tested the delay using the PIP function of my LCD TV. The same channel is showed on internal tuner of the TV (in small PIP window) and with Mediaportal (full screen). The delay was 1-2 second. I use multi seat configuration but the timeshift buffer is on ramdisk.
     
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  3. rlevis
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    rlevis MP Donator

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    In my case the TV Server is another computer in the house which has 4GB of the RAM as a RAM drive for time shifting. Starting a DVB-T channel in MP on another PC takes about 1.5 seconds, DVB-S (satellite) about 3 seconds, so the delay is no more than that here. First play after a reboot of any channel can be 4 or 5 seconds while codecs are loaded, etc, but after that it's very responsive.
     
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  4. Spaceboy

    Spaceboy Portal Member

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    Hi, this is a bit of an old thread but its most relevant to my question so i hope i can ask it here.

    i'm using mediaportal 1.19 as a "dumb tuner" for emby. i have created a m3u from each of the channel streaming urls and supplied that to emby which does all the streaming recording etc. This works brilliantly except channel load times are a little slower than i would like so i thought i'd investigate. the first thing i noticed when looking at the MP Extended logs is that it does take a consistent 6 seconds between the starting timeshifting and timeshifting succeeded steps. This seems consistent with the OP's observations on his channel start up times. But most respondents here suggested it might be other things in the chain between, for me, the satellite dish and the stream opening in any player. Well it might, but doesnt the log absolutely confirm that it is a build up of a buffer for timeshifting that is causing it?

    I hope i havent been too controversial as this seems a sensitive topic but obviously the main reason i'm here is i wanted to ask if there is anything i can do to minimise this startup time even if i can't disable timeshifting? this does seem to be a universal position, the only tv server software i've found that discusses disabling timeshifting is tvheadend, but i like MP.

    cheers
     
  5. Hazza06

    Hazza06 Portal Member

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    Show System Specs
    I've found that when streaming live tv from server to client via rtsp/rtp, the initial playback on the 1st channel selection does take a number of seconds for the MP client to actually send the RTSP describe/setup and play messages to the MP TV server, however, subsequent channel changes as initiated from client from live tv are substantially quicker, like less than a second. My MP TV server runs nothing but SATA 3 SSD's, and timeshift buffer runs in 12GB RAM DISK, so IOPS is really good with very very very low latency.

    As with any RTP or multimedia digital packetizied transmission, capture and playback, there must be a timeshift buffer, which mostly serves the purpose of de-jitter and sequence re-ordering of the packetized media payload. Without this de-jitter buffer, the playout of the RTP media payload would introduce nasty frame slips, which are definitely more annoying than a small delay in media playout. And in a multipath IP network, where packets can easily arrive out of sequence, really messes up media decoding and playback.

    VOIP RTP SDP end points have the similar de-jitter buffers, which introduce a small amount of latency in media playout.

    You might want to have a read of ITU-T G.1021, which are standardized and recognized industry recommendations W.R.T Multimedia Quality of Service and performance – Generic and user-related for Buffer models for development of client performance metrics

    https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.1021-201207-I!!PDF-E&type=items

    Also if your using MP as the client, make sure you've set the zap delay to 0 seconds as below;

    MP_zap_delay.png
     
    Last edited: March 14, 2019
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