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Thread: DVR playback starts at the current live program

  1. #1
    Join Date
    Oct 2011
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    Default DVR playback starts at the current live program

    I have been able to successfully install the nDVR module, and i have been able to playback the file correctly. What i have found with all the players i have tried is that when i start the dvr stream, the player will always go to the current live posistion. What i would like the system to do is start the video file at the beginning of the dvr stream and playback from that point.

    Is that possible?

    I have tried the included OSMF player in the examples directory and i have even tried the strobe 1.6 and 1.5 players.

  2. #2
    Join Date
    Dec 2007
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    Default

    I don't think this is possible at present.

    Richard

  3. #3
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    Oct 2011
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    I think i might have found two solutions to the problem.

    If i use an older version of the OSMF player found here http://www.osmf.org/developers.html
    and use the OSMF Sample Player for HTTP Dynamic Streaming, it works as I would like.

    Also if I use the latest version of OSMF player and change the dvrSnapToLiveClockOffset: 1000000 it will also start the dvr stream to the very begining of the file.

  4. #4

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    Jeff,

    Why did you choose dvrSnapToLiveClockOffset: 1000000? I cannot find any decent documentation on this apram, but it seems the default value is 4 or 5.

    Scott

  5. #5
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    Oct 2011
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    This is what i understood to be happening:

    According to the OSMF 1.6 documentation
    http://sourceforge.net/apps/mediawik...ynamic_streams

    This feature of going to the current live point is called "Snap to Live" and is the default behavior of the current version of the player.

    The option dvrSnapToLiveClockOffset is how many seconds before live should the player start playing at. Since I never know at what point i would need the player to start playing, i had to pick a value that would encompass all my recordings. It seems that if i pick a big enough value, it just defaults to the begining of the file.

    1000000 seconds works out to 27 hours or so. Some of my recordings are three hours in length right now, so i could cut that value down to 250000 and i should be safe.

    I mainly just picked a million seconds since it would give me the most headroom for my player.

    But right now i am still testing, so if i come across anything else i will let you know.

  6. #6

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    Jeff,

    I'm curious how you are passing dvrSnapToLiveClockOffset into the OSMFplayer. Are you adding it as a param in the StrobeMediaPlayback.html shipped with Wowza?
    I've been playing with this setting and nDVR, but setting it to a large value does not start the playback at time=0 for me.

    Scott

  7. #7
    Join Date
    Oct 2011
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    Default

    Here are the params i am sending to the clientStrobe player included with Wowza examples.

    var parameters = {
    src: "http://10.1.84.89:1935/dvr/live/manifest.f4m?DVR",
    streamType: "dvr",
    autoPlay: "false",
    dvrSnapToLiveClockOffset: 1000000,
    verbose: true,
    controlBarAutoHide: "false",
    controlBarPosition: "bottom",
    poster: "images/poster.png"
    };

    Everything else remains the same from the default.

  8. #8

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    It's good to hear (~read :-) ) that one can create a player that plays the stream with a specific time offset from the current live point. It's exactly what I need.

    I've a single incoming stream and I've to provide both a player for the current live point and a player that plays the stream one hour from the current live.
    As I understand, this can be achieved with the dvrSnapToLiveClockOffset parameter in case of the Strobe player.
    What about HTTP Live Streaming (cupertino)? Is there a way to tell an HTTP Live Streaming client to start the playback 1h from the current live point? :-o Or is there any way to tell Wowza to force this "time-shift" on the client?
    Since nDVR saves the stream to disk (and if I specify a large enough WindowDuration, ie. 1h), this should be "feasable", the video data is there.
    But as far as I know, this cannot be achieved on the HTTP Live Streaming clients, and not even in Wowza (so that the server already presents the "time-shifted" stream to the client).
    I guess I've to create a module for this from scratch.
    Can you point me to the right direction regarding customization of HTTP Live Streaming (integrated with nDVR AddOn's functionality)?
    Sounds to be quite a steep learning curve for a newbie (in Wowza customization/development), but if I've to, then that's what I'm going to do. :-)

  9. #9

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    Quote Originally Posted by zsoltm View Post
    It's good to hear (~read :-) ) that one can create a player that plays the stream with a specific time offset from the current live point. It's exactly what I need.

    I've a single incoming stream and I've to provide both a player for the current live point and a player that plays the stream one hour from the current live.
    As I understand, this can be achieved with the dvrSnapToLiveClockOffset parameter in case of the Strobe player.
    What about HTTP Live Streaming (cupertino)? Is there a way to tell an HTTP Live Streaming client to start the playback 1h from the current live point? :-o Or is there any way to tell Wowza to force this "time-shift" on the client?
    Since nDVR saves the stream to disk (and if I specify a large enough WindowDuration, ie. 1h), this should be "feasable", the video data is there.
    But as far as I know, this cannot be achieved on the HTTP Live Streaming clients, and not even in Wowza (so that the server already presents the "time-shifted" stream to the client).
    I guess I've to create a module for this from scratch.
    Can you point me to the right direction regarding customization of HTTP Live Streaming (integrated with nDVR AddOn's functionality)?
    Sounds to be quite a steep learning curve for a newbie (in Wowza customization/development), but if I've to, then that's what I'm going to do. :-)

    Within 2 weeks there will be some enhancements to nDVR by which one will be able to provide a delegate to provide the requested playlist start and end points.
    However, this does not address the play start time, only the beginning and end of the known DVR playlist.


    The seekStart within that playlist is a different issue, and is entirely dependent on functionality provided by the client players. The typical approach of the players is to start playing at the live point for currently recording streams, and to start playing at the earliest time for streams that are no longer being recorded. nDVR has recently enhanced to differentiate the 'actively recording' from the 'recorded' to support this play start time for San Jose and Cupertino streaming. Smooth Streaming is coming.

    For example, in the Strobe/OSMF player which you are concerned with does not provide a way to specify the seekStart time.

    For streamType=dvr, some folks have said they can use dvrSnapToLiveClockOffset to force the the player to start playing at time=0. I have not been able to get that to work, and looking through the strobe code, it's not clear to me if this would work in all cases as a seekTime. It seems doubtful as a general solution for seek time, as this is not its intent.

    So, actually, I think your customization for specifying start/seek time would be on the Strobe/OSMF side not in Wowza.
    This is open source, so any enhancements in this area would be greatly appreciated by the community.

  10. #10

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    Scott, I have been following this thread and been wondering if this enhancement will do the following:

    1) For a currently being recorded stream (say the stream records from 9 to 9:30, but it is only 9:15 at the moment). Can I ensure that if a particular user tries to playback the stream, it "snaps to" 9:10 (i.e. 10 minutes from the beginning of the stream OR a 5 minute offset from the current "live" point, which is 9:15). Besides, the user cannot rewind any earlier than 9:10.

    2) For a stream already recorded (say it is 9:30 now and the full stream has been recorded from 9 to 9:30) - can I ensure that when a user attempts to playback the stream it "snaps to" 9:10 (i.e. 10 minutes after the beginning of the stream)

    Thanks!
    Last edited by cnfcnf; 11-01-2011 at 08:23 AM.

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