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A
Anonymous
August 15, 2011
Question

Occasional 13 Byte Files

  • August 15, 2011
  • 3 replies
  • 1635 views

My company recently swapped from FMS 2.5 to 4.1. After the swap we have noticed about 1 - 4% of all videos recorded end up as a 13 byte file on our file system. If you view the file, you see the contents of it are the typical FLV header:

vim:

FLV^A^@^@^@^@   ^@^@^@^@

hexdump:

0000000 4c46 0156 0000 0000 0009 0000 0000   

000000d

Has anyone run into a similar issue and found a solution? Our initial guess was it was based on a FMS error related to metadata not being included in the first buffer flush, but we have made additions to prevent such an event.

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    3 replies

    A
    Anonymous
    August 17, 2011

    SOLUTION:

    To anyone who has been following this looking for a solution, or anyone who finds this in the future, this is caused entirely by concurrent traffic to your FMS server.

    In our case, we increased our SERVER.FLVCACHE_MAXSIZE and have watched our 13 byte files go from 5% to 0%. This is properly documented in the depths of the FMS literature: http://livedocs.adobe.com/flashmediaserver/3.0/docs/help.html?content=03_configtasks_12.html

    When the cache is full, the server removes unused segments, starting with the least recently used. After removing all unused segments, if there still isn't enough room for a new segment, the server notifies the client that the stream is not available and makes an entry in the core log file.

    Because the cache is utilized for publishing, the effect is FMS outputting only the flv header to the file system, and ignoring all incoming stream data. This is not presented well, if at all, client side. This is something you should be watching your core.##.log files lest you experience unfortunate data loss.

    A
    Anonymous
    August 16, 2011

    Adding some more information here:

    I have been looking at the FMS core.log's and noticed a (potentially coincidental) correlation between some 13 byte file recordings and the message:

    "The FLV segment cache is full. -"

    Continuing to investiate...

    calmchessplayer
    calmchessplayer
    Inspiring
    August 16, 2011

    simple u are'nt recording or you aren't closing the netstream ........I lean twords not recording.

    A
    Anonymous
    August 16, 2011

    It seems weird to me that I wouldn't be recording... this never once happened on FMS 2.x. Closing the netstreams is something I do my best at but it is, to an extent, relient on the user (if they quit their browser mid recording I have no ability to close a stream).

    I will need to test what happens when I try to record without any stream closing, but i know Flash is not buffering the entire video client side and sending it all to FMS when I close the stream. I still don't understand how this results in nothing but FLV headers on the file system.

    calmchessplayer
    calmchessplayer
    Inspiring
    August 16, 2011

    you can close a stream by using a javascript in the html that says just before the browser closes tell the client .swf to close its netstream and netconnection you will also avoid ghost connections by doing this. I still lean twords you not actually recording.

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