03-26-2009 10:41 AM
I'm using the USC library with IPP 5.2, implementing code to decode a WAV file GSM-FR codec file to PCM-16, and also to encode PCM-16 to GSM-FR and store in an MS WAV file. The Decode function works if passed 33 byte GSM-FR packed frames, but will not handle the 65 byte packed double frames which MS uses. Similar problem when encoding -- I tried simply packing together the two 32.5 byte encoded frames into a 65 byte frame, but it is not that simple. Does anyone have experience using the library with the MS 65 byte format?
New Contributor II
04-06-2009 01:58 AM
IPP does not support Microsoft propriatary GSMWAVformat (MSGSM), instead IPP support GSM RTP format (see RFC3551).Each frame in RTPGSM format has 4 leadingextra bits which are not used for decompression, so can be be omitted.These bits must beremoved by left-shift of all bits while packing two RTP GSM frames intoMSGSM 65-bytes double frame and vice versa.
Best regards, Vyacheslav, IPP, speech codecs.