Leaked source code of windows server 2003
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July 22, 1996 Release (IPFCS1RC3)=================================o moved cst_lbc.h into acm archive
o modified g723.c so that SID modes are disabled. This way broken applications (e.g., SoundRecorder) aren't affected.
July 18, 1996 Beta Release==========================
o Added 11025 Hz PCM format capabilities.
o Integrated Mike Keith's 8000-to-11000 Hz and 11000-to-8000 Hz sample rate conversion routines.
o Added code to acmdStreamConvert() (in g723.c ) to fudge from 11000 Hz to 11025 Hz sampling rate and vice versa.
o Made 11025 Hz the default format since it is the more widely supported by PC hardware and since this prevents certain applications from using low quality sample rate converters and introducing unnecessary distortion (see CAVEATS below).
o Made changes in acmdStreamConvert() so that speech and silence frames can both be encoded from the same driver buffer. This ensures that applications using large driver buffer sizes will still benefit from silence detection.
o Corrected the name of the speech coding algorithm in g723.rc. The name of the algorithm is "G.723.1" and not "G.723".
o Microsoft's "Sound Recorder" application that comes with Win95 has some problems that are exposed by the G.723.1 ACM driver. Sound Recorder always uses the default ACM driver format. Therefore, when asked to encode 8 KHz PCM using G.723.1, it first upsamples the data to 11025 KHz using a low quality sample rate converter (thereby introducing unnecessary distortion).
o Microsoft's "Sound Recorder" and "ACMAPP" applications both apparently ignore the cbSrcLengthUsed field of the LPACMDRVSTREAMHEADER structure. Consequently, the unused portion of a buffer of G.723.1 data is discarded instead of being moved to the start of the next driver buffer. The result is that subsequent frames of G.723.1 data are misaligned and are not properly decoded.
ANY APPLICATION THAT IGNORES THE cbSrcLengthUsed FIELD IN THIS WAY WILL FAIL RESULTING IN GARBLED AUDIO!!!
o As a result of the above problem the G.723.1 formats that use silence detection have not been fully tested in this release.
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