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Thread: chunk binary of the same file is always different in Apple HTTP Live Streaming?!!

  1. #1
    Join Date
    Mar 2012

    Question chunk binary of the same file is always different in Apple HTTP Live Streaming?!!


    I'm an iOS developer, entirely new to wowza server, developing a music streaming application communicating w/ wowza server.
    I learned that wowza server slices an mp3 file uniformly in 10 secs, and sends the mp3 chunks with m3u8 file containing urls of the chunks.

    The problem is that, every time my iOS app request mp3 file, wowza server slices differently and sends different chunk binaries for the same mp3 file.
    Let's say that the app requests Adele's Rolling in the Deep (let's call it "R" file) to wowza server.
    At the first request, the app downloaded 6 chunks R1.mp3 ~ R6.mp3 chunks (duration of each chunk is 10 secs)
    Then, at the second request, the app continued to download other chunks from R7.mp3 to R-last-chunk.mp3. (all chunks the app downloads are mp3 files)
    I found that there is noise when the app plays between R6.mp3 and R7.mp3. Almost time it happens in similar cases!!

    So, I suspected that wowza server slices R mp3 file every time it receives request. It means R1-for-the-first-call.mp3 is different from R1-for-the-second-call.mp3.
    I compared the same R mp3 file from two different devices, and found that cached chunk binaries are different from each other.

    THIS IS A BIG PROBLEM since the app caches chunk files. If it caches a part of entire chunks at the first time, and then caches other parts at the second request, it must have noise between chunks.

    DO YOU HAVE ANY IDEA about how the server slices chunks, and solution for the problem?
    I will appreciate for any comments.
    Last edited by ncsoftios; 03-13-2012 at 12:00 AM.

  2. #2


    What you are describing is correct. If yoiu request the chunks in order then there will be no overlap in the chunks. If you request the chunks out of order then there can be overlap. Wowza Media Server is not setup well to be a cache origin if you are not requesting the chunks in order.


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