shithub: opus

ref: 1e22a4b7e9fa23997b45d6b455051a3fa35900b2
dir: /silk/control_audio_bandwidth.c/

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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "main.h"
#include "tuning_parameters.h"

/* Control internal sampling rate */
opus_int silk_control_audio_bandwidth(
    silk_encoder_state      *psEncC             /* I/O  Pointer to Silk encoder state               */
)
{
    opus_int   fs_kHz;
    opus_int32 fs_Hz;

    fs_kHz = psEncC->fs_kHz;
    fs_Hz = silk_SMULBB( fs_kHz, 1000 );
    if( fs_Hz == 0 ) {
        /* Encoder has just been initialized */
        fs_Hz  = silk_min( psEncC->desiredInternal_fs_Hz, psEncC->API_fs_Hz );
        fs_kHz = silk_DIV32_16( fs_Hz, 1000 );
    } else if( fs_Hz > psEncC->API_fs_Hz || fs_Hz > psEncC->maxInternal_fs_Hz || fs_Hz < psEncC->minInternal_fs_Hz ) {
        /* Make sure internal rate is not higher than external rate or maximum allowed, or lower than minimum allowed */
        fs_Hz  = psEncC->API_fs_Hz;
        fs_Hz  = silk_min( fs_Hz, psEncC->maxInternal_fs_Hz );
        fs_Hz  = silk_max( fs_Hz, psEncC->minInternal_fs_Hz );
        fs_kHz = silk_DIV32_16( fs_Hz, 1000 );
    } else {
        /* State machine for the internal sampling rate switching */
        if( psEncC->sLP.transition_frame_no >= TRANSITION_FRAMES ) {
            /* Stop transition phase */
            psEncC->sLP.mode = 0;
        }
        if( psEncC->allow_bandwidth_switch ) {
            /* Check if we should switch down */
            if( silk_SMULBB( psEncC->fs_kHz, 1000 ) > psEncC->desiredInternal_fs_Hz )
            {
                /* Switch down */
                if( psEncC->sLP.mode == 0 ) {
                    /* New transition */
                    psEncC->sLP.transition_frame_no = TRANSITION_FRAMES;

                    /* Reset transition filter state */
                    silk_memset( psEncC->sLP.In_LP_State, 0, sizeof( psEncC->sLP.In_LP_State ) );
                }
                if( psEncC->sLP.transition_frame_no <= 0 ) {
                    /* Stop transition phase */
                    psEncC->sLP.mode = 0;

                    /* Switch to a lower sample frequency */
                    fs_kHz = psEncC->fs_kHz == 16 ? 12 : 8;
                } else {
                    /* Direction: down (at double speed) */
                    psEncC->sLP.mode = -2;
                }
            }
            else
            /* Check if we should switch up */
            if( silk_SMULBB( psEncC->fs_kHz, 1000 ) < psEncC->desiredInternal_fs_Hz )
            {
                /* Switch up */
                if( psEncC->sLP.mode == 0 ) {
                    /* Switch to a higher sample frequency */
                    fs_kHz = psEncC->fs_kHz == 8 ? 12 : 16;

                    /* New transition */
                    psEncC->sLP.transition_frame_no = 0;

                    /* Reset transition filter state */
                    silk_memset( psEncC->sLP.In_LP_State, 0, sizeof( psEncC->sLP.In_LP_State ) );
                }
                /* Direction: up */
                psEncC->sLP.mode = 1;
            }
        }
    }

#ifdef FORCE_INTERNAL_FS_KHZ
    fs_kHz = FORCE_INTERNAL_FS_KHZ;
#endif

    return fs_kHz;
}