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  1. Hey all,

    Just need some quick help understanding how bitrates in DTS audio tracks contribute to file size. I know the answer is right there beneath everything but my brain just can't uncover it right yet.

    Here's the info:
    - DTS (MA/Core), 1509Kbps, 8 channel/6 channel
    - 1h 53min length
    - file size: 4.47GiB (no video included, just audio track)
    - MediaInfo reported overall bit rate: 5642Kbps

    Basically, I want to know how all the bitrates contribute to the file size of 4.47GB.


    Thanks!
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  2. Member
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    Well as far as i know dts-hd master and truehd dolby are lossless . That's why the file size is so huge.

    So if you can decode DTS-HD MA , you get the overall bit rate of 5642kbps.
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  3. I'm wondering if someone can show me how to do the math (if it exists) to get from a lossless DTS-HD MA stream to 4.47GiB.
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    1509 Kbits/sec × 6780 sec = 10231020 Kbits = 1.191047485918 GiB. Dunno why the file is bigger if all it contains is DTS.
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  5. Where does the file size of 4.47GiB come in, then?
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    I don't know. The reported overall bitrate pencils out. Why don't you post the whole MediaInfo?
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    1509kbps is only the embedded core. it's MA: 5642kbps/ Core 1509kbps . so i guess the MA is 3.28 gb
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    Aha! So MediaInfo reports the size of the lossy core stream as "DTS" and leaves the size of the Master Audio residuals as an exercise.
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  9. You guys definitely just lost me. There are multiple "streams"?
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    yes DTS-HD MA contains an embedded core (regular dts at 1509) and the master audio.

    but for some reason i never get the MASTER bit rate with mediainfo

    BitRate/String : Unknown / 1 509 Kbps

    i dont know how you got your overall bit rate
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  11. Well, knowing there are multiple streams makes sense. I, too, get "Unknown/1509Kbps" for the bit rate.
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    The core is a fallback for decoders that don't understand Master Audio. Decoders that do MA use the residual data streams in combination with the core to reconstitute the lossless audio. That's what Wikipedia tells me, anyway.
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  13. Well that's interesting. Good to know. It sucks that MediaInfo won't report the bitrates.
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    Think of a train analogy: the DTS Core is like an Engine+TinderCar+Caboose, a small and simple train. Doesn't use up a lot of space. The DTS-MA is like the PassengerCars - it uses up much more space, but holds lots more people/baggage. Yet it cannot function without the Engine/Tinder/Caboose being connected to it. The Core, OTOH, will still operate alone as a train if the MA is "de-coupled".

    Mediainfo understands the Core part, just not the extended part. This is mainly due to more complex nature (it is VBR, while the Core is CBR) and more guarded IP of the MA segment. In time, I would assume MediaInfo will also be able to give stats for that as well. However, other than actual average bitrate (which can already still be calculated from existing info), there really isn't any NEW info the MA would provide. It still maintains the same length, # channels, samplerate & bitdepth (it has to in order to maintain compatibility with the Core).

    Scott
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  15. Thanks Scott, I understand. I can get the bitrate as well, but I'd have to disassemble every package to do so. MediaInfo also has a habit of not displaying the video bitrate in most MKVs; can't imagine why. If I remux without the audio, it shows up, but with the audio no luck (most of the time).
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  16. can't imagine why.
    Since not all headers contain the average video bit rate of the whole clip. And MediaInfo in most (nearly all) cases only reads the headers or a file.

    This is mainly due to more complex nature,....
    More due to the fact that the average bit rate of the extension isn't mentioned inside the headers.
    Wrote code to calculate the size of the extension part of raw dts-hd/ma streams some time back, since I was curious about it, and the size and the average bit rate of those extensions can really vary a lot.
    Calculating the dts extension size while the audio stream is still inside a container, requires a complete parsing of the container or an extraction of the dts-hd/ma stream, which both requires quite some time.

    Cu Selur
    users currently on my ignore list: deadrats, Stears555
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  17. Yes, I definitely could not have imagined that!
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