shithub: opus

ref: 744836604644fbb94409592069238088852db599
dir: /silk/control_audio_bandwidth.c/

/***********************************************************************
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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are met:
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names of specific contributors, may be used to endorse or promote
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS”
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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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               */
    silk_EncControlStruct       *encControl                     /* I    Control structure                           */
)
{
    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 || encControl->opusCanSwitch ) {
            /* 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( encControl->opusCanSwitch ) {
                    /* Stop transition phase */
                    psEncC->sLP.mode = 0;

                    /* Switch to a lower sample frequency */
                    fs_kHz = psEncC->fs_kHz == 16 ? 12 : 8;
                } else {
                   if( psEncC->sLP.transition_frame_no <= 0 ) {
                       encControl->switchReady = 1;
                       /* Make room for redundancy */
                       encControl->maxBits -= encControl->maxBits * 5 / ( encControl->payloadSize_ms + 5 );
                   } 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( encControl->opusCanSwitch ) {
                    /* 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;
                } else {
                   if( psEncC->sLP.mode == 0 ) {
                       encControl->switchReady = 1;
                       /* Make room for redundancy */
                       encControl->maxBits -= encControl->maxBits * 5 / ( encControl->payloadSize_ms + 5 );
                   } else {
                       /* Direction: up */
                       psEncC->sLP.mode = 1;
                   }
                }
            }
        }
    }

    return fs_kHz;
}