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I know this had been hashed before but...

Discussion in 'TiVo Stream' started by PCurry57, Jun 29, 2014.

  1. JWhites

    JWhites New Member

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    May 14, 2013
    I still don't understand just how much better using MPEG-DASH is compared to whatever TiVo uses now. How much better will the picture and audio quality be and will this finally allow me to stream both inside and outside the home at full 1080i/p HD?
     
  2. Dan203

    Dan203 Super Moderator Staff Member TCF Club

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    Apr 17, 2000
    Nevada
    There will be no change in quality. They're basically just two ways of packaging the stream, neither has an effect on the audio/video quality. DASH is just an industry standard so it has better support across devices. HLS, which is what TiVo uses now, is an Apple standard that they opened up to the public but was not well documented. Plus Apple added features to HLS on their own devices that they did not release as part of the open document. That's why the industry decided to create DASH as an alternative.

    DASH is basically using the MP4 format. The major difference is that it forgoes the MOOV atom, which can only be generated once the entire file is encoded, in favor of an alternative atom that is inserted into every segment. This way the file can be encoded live and played back from an point in the stream without the need for it to be complete.

    HLS is based on Transport Streams which have a similar mechanism where they insert a PMT (aka program map) every few hundred milliseconds so that the stream can be encoded live and played from any point.

    The actual audio/video data inside both streams could be identical.
     
  3. moyekj

    moyekj Well-Known Member

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    Mission...
    The main advantage of that solution is that it's actually true streaming. To date HME based tools such as "streambaby" are basically just copying data back to the TiVo, and with a limited buffer size. Hence no HME streaming solution works with TiVo Mini, for example, which doesn't have any video storage. Obviously the Mini doesn't work with pyTivo either. PlexTiVo is using html5 and the built in TiVo Opera browser which can play both HLS and MPEG-DASH streams (as well as just straight mp4 and TS containers with H.264 video and AAC audio) and works fine with TiVo Mini and allows easy arbitrary seeking to any point in the video.

    The down side to the above solution is the TiVo Opera browser has very limited video and audio codec support, so if the source video isn't H.264 and/or the source audio is not AAC or MP3 then the source video needs to be transcoded on the fly to be played and thus be lower quality than the source. I don't know how smart the Plex transcoder is in terms of only re-encoding what is necessary and in some cases simply just re-muxing, but the client should have some control over defining that.
     
  4. Dan203

    Dan203 Super Moderator Staff Member TCF Club

    38,323
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    Apr 17, 2000
    Nevada
    I didn't realize you guys had made some much progress with that Plex app. I thought we had determined early on that the Opera browser did not support HLS or DASH on the TiVo. Did a recent update change that? Is there actually a way to launch the app on the TiVo? I thought they had closed that loop hole too?
     
  5. moyekj

    moyekj Well-Known Member

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    Mission...
    The RPC backdoor is still slammed shut by TiVo. However if you sign up as an Opera TV developer (pretty easy to do) then you can setup 1 or more of your TiVos to be a developer platform which gives you an official URL Launcher from which you can launch your own pages.
    See OperaTV Store Backdoor thread for details on that.

    The issue of how you can get other people to actually use the app once it's been finished is still up in the air. Probably the cleanest way is to submit as an official app to Opera TV, but that sounds like may be painful. In the PlexTivo thread we discussed other possibilities such as DNS spoofing to "steal" an existing launch point on the TiVo, but that's not a good long term solution. Anyway, for now the number of interested participants is limited, so signing up as an Opera TV developer is the easiest way to go.
     
  6. JWhites

    JWhites New Member

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    May 14, 2013
    Sounds awesome in theory but how likely is it that the atom or PMT could become "screwed up" causing "unknown error" messages to occur? What will the benefits be in being able to stream MPEG4 or H.264 programs such as those from cable providers that encode channels in that format?
     

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