in reply to Re^11: pack/unpack binary editing
in thread pack/unpack binary editing

OK, that piece of code worked perfect. However, now when I look at the file the first frame is on synce but the rest are off by a few bits. I believe this to be because when we remove the bits prior to the sync and then pack it up the frame is no longer on a byte boundary. This is the problem I've been dealing with. If I remove a couple bits from the beginning then when I pack it up the files being padded to place it back on a byte boundary. I'm starting to think I'm going to have to just suck it up and either deal with the slowness or get a C programmer to do it. Any thoughts??

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Re^13: pack/unpack binary editing
by BrowserUk (Patriarch) on Feb 10, 2005 at 18:05 UTC
    ... the rest are off by a few bits.

    The only way that can be true, is if

  • the sync mark itself is not meant to be on a byte boundary.

    Ie. If it is meant be a few bits into each frame?

    This is possible and easily dealt with.

  • Or the frames are themselves are "a few bits" longer than 960 bytes, which doesn't makes much sense.

    Could you unpack the first 3 or 4 frames of the (raw) file to binascii and post them on your scratchpad?

    Examine what is said, not who speaks.
    Silence betokens consent.
    Love the truth but pardon error.
[reply]
      Sorry, the company would frown upon that. I think my problem is that I'm reading in the equivalent of 2 frames but have to discard so many bits to get to the sync. afterwhich I no longer have a frame left that's on a byte boundary. This is why I am currently writting the ascii-ized binary out to a file then reopening and going though the file to pack it back. I forgot I had changed that part of the code.
[reply]

        If you are only discarding from the first (double) record, then if the original file is sync'd, the resultant file will be: 

        Read 
|------------|------------|------------|------------|---|
---------------------------------------------------------
....|s 7680 bits |s 7680 bits |s 7680 bits |s 7680 bits |
---------------------------------------------------------
write
<<<<|s-------|----s-------|----s-------|----s-------|---|
|s-------|----s-------|----s-------|----s-------|---|
-----------------------------------------------------
|s 7680 bits |s 7680 bits |s 7680 bits |s 7680 bits |
-----------------------------------------------------

        [download]

        Anyway, good luck.

        Examine what is said, not who speaks.
        Silence betokens consent.
        Love the truth but pardon error.
[reply]
[d/l]

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