[speex-dev] delay issues in speex, integer API

Christian Buchner Christian.Buchner1 at epost.de
Sun Jun 22 16:42:19 PDT 2003



Hmm, the delay caused by the filters in the speex UWB mode seems to be 509
samples.
I used the GoldWave editor to determine the offset. I have always been
confused by
the SNR output in the testenc source code. It did not make sense because it
uses a
640 (=FRAME_SIZE) offset for its SNR calculations. After changing the
calculation
method, the SNR readings are much better.

I may decide to adjust my ACM codec to compensate for this delay. I'll
probably
scrap the initial x samples in the decoding process where x would be 509 for
the UWB mode (x is yet to be determined for all the other modes).

In the integer Speex version, I changed all public API function names in
libspeex
to begin with "sphinx_" instead of "speex_". I also prepended every table,
typedef
or function name with an underscore. That allows me to link against libspeex
and
libsphinx at the same time without conflict and compare the SNR values of
both
implementations.

Regarding the ACM, I received a bug report indicating that the beta ACM
codec
crashes when used in VirtualDub. I will also look into this. And I got some
EMail
correspondence regarding someone trying to use the ACM codec with Microsoft
Netmeeting. It appears they will be checking this out for us.

Christian

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'speex-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.



More information about the Speex-dev mailing list