You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
51 lines
2.2 KiB
51 lines
2.2 KiB
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.
|
|
|