FreeCalypso > hg > gsm-codec-lib

view libgsmefr/cnst.h @ 581:e2d5cad04cbf

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
libgsmhr1 RxFE: store CN R0+LPC separately from speech In the original GSM 06.06 code the ECU for speech mode is entirely separate from the CN generator, maintaining separate state. (The main intertie between them is the speech vs CN state variable, distinguishing between speech and CN BFIs, in addition to the CN-specific function of distinguishing between initial and update SIDs.) In the present RxFE implementation I initially thought that we could use the same saved_frame buffer for both ECU and CN, overwriting just the first 4 params (R0 and LPC) when a valid SID comes in. However, I now realize it was a bad idea: the original code has a corner case (long sequence of speech-mode BFIs to put the ECU in state 6, then SID and CN-mode BFIs, then a good speech frame) that would be broken by that buffer reuse approach. We could eliminate this corner case by resetting the ECU state when passing through a CN insertion period, but doing so would needlessly increase the behavioral diffs between GSM 06.06 and our version. Solution: use a separate CN-specific buffer for CN R0+LPC parameters, and match the behavior of GSM 06.06 code in this regard.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 13 Feb 2025 10:02:45 +0000
parents f9c9dd458d55
children
line wrap: on
line source

/*--------------------------------------------------------------------------*
*       Codec constant parameters (coder, decoder, and postfilter)          *
*---------------------------------------------------------------------------*/

#define  L_TOTAL      320       /* Total size of speech buffer.             */
#define  L_WINDOW     240       /* Window size in LP analysis               */
#define  L_FRAME      160       /* Frame size                               */
#define  L_FRAME_BY2  80        /* Frame size divided by 2                  */
#define  L_SUBFR      40        /* Subframe size                            */
#define  M            10        /* Order of LP filter                       */
#define  MP1          (M+1)     /* Order of LP filter + 1                   */
#define  AZ_SIZE      (4*M+4)   /* Size of array of LP filters in 4 subfr.s */
#define  PIT_MIN      18        /* Minimum pitch lag                        */
#define  PIT_MAX      143       /* Maximum pitch lag                        */
#define  L_INTERPOL   (10+1)    /* Length of filter for interpolation       */

#define  PRM_SIZE     57        /* Size of vector of analysis parameters    */

#define  MU       26214         /* Factor for tilt compensation filter 0.8  */
#define  AGC_FAC  29491         /* Factor for automatic gain control 0.9    */

#define DTX_HANGOVER 7                /* Period when SP=1 although VAD=0.
                                         Used for comfort noise averaging */