[libav-bugs] [Bug 334] New: libavformat. add dss demuxer

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Mon Jul 16 09:48:29 CEST 2012


http://bugzilla.libav.org/show_bug.cgi?id=334

           Summary: libavformat. add dss demuxer
           Product: Libav
           Version: git HEAD
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: Normal
         Component: libavformat
        AssignedTo: bugzilla at libav.org
        ReportedBy: bug-track at fisher-privat.net


This mysterious format (DSS) exist for some years now, and descriptions like
this make it sound even more mysterious:
http://wiki.multimedia.cx/index.php?title=Digital_Speech_Standard
http://en.wikipedia.org/wiki/Digital_Speech_Standard

I started intensive research on this codec for a month and got some interesting
results. I can describe most parts of container, and Kostya Shishkov (thanks a
lot!) helped to identify one of audio codecs used in this container.
This form use at least two modes: lp (long play) and sp (standard play?).
lp mode is g723.1. After demuxing the stream i was able to play it with
mplayer.
Currently we still didn't found the sp codec. It use 16bit/11kHz/mono stream.
It can be reworked variant of g729 or g723.1. And analysis of decoder.dll show
that functions for sp and lp are similar, except it passes bigger arguments
then same functions for lp mode. So may be it is  g723.1-11kHz variant.

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