ref: fcf95bac9330e8e6db1184496ae33007a7c7a9cf
dir: /src_common/SKP_Silk_control_audio_bandwidth.c/
/***********************************************************************
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are permitted provided that the following conditions are met:
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BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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***********************************************************************/
#include "SKP_Silk_main.h"
#include "SKP_Silk_tuning_parameters.h"
/* Control internal sampling rate */
SKP_int SKP_Silk_control_audio_bandwidth(
SKP_Silk_encoder_state *psEncC, /* I/O Pointer to Silk encoder state */
SKP_int32 TargetRate_bps /* I Target max bitrate (bps) */
)
{
SKP_int fs_kHz;
SKP_int32 fs_Hz;
/* Reduce bitrate for 10 ms modes in these calculations */
if( psEncC->nb_subfr == 2 ) {
TargetRate_bps -= REDUCE_BITRATE_10_MS_BPS;
}
fs_kHz = psEncC->fs_kHz;
fs_Hz = SKP_SMULBB( fs_kHz, 1000 );
if( fs_Hz == 0 ) {
/* Encoder has just been initialized */
if( TargetRate_bps >= WB2MB_BITRATE_BPS ) {
fs_Hz = 16000;
} else if( TargetRate_bps >= MB2NB_BITRATE_BPS ) {
fs_Hz = 12000;
} else {
fs_Hz = 8000;
}
/* Make sure internal rate is not higher than external rate or maximum allowed, or lower than minimum allowed */
fs_Hz = SKP_min( fs_Hz, psEncC->API_fs_Hz );
fs_Hz = SKP_min( fs_Hz, psEncC->maxInternal_fs_Hz );
fs_Hz = SKP_max( fs_Hz, psEncC->minInternal_fs_Hz );
fs_kHz = SKP_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 = SKP_min( fs_Hz, psEncC->maxInternal_fs_Hz );
fs_Hz = SKP_max( fs_Hz, psEncC->minInternal_fs_Hz );
fs_kHz = SKP_DIV32_16( fs_Hz, 1000 );
} else {
/* State machine for the internal sampling rate switching */
if( psEncC->API_fs_Hz > 8000 && psEncC->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) {
/* Check if we should switch down */
if( ( psEncC->fs_kHz == 12 && TargetRate_bps < MB2NB_BITRATE_BPS && psEncC->minInternal_fs_Hz <= 8000 ) ||
( psEncC->fs_kHz == 16 && TargetRate_bps < WB2MB_BITRATE_BPS && psEncC->minInternal_fs_Hz <= 12000 ) )
{
/* Switch down */
if( psEncC->sLP.mode == 0 ) {
/* New transition */
psEncC->sLP.transition_frame_no = TRANSITION_FRAMES;
/* Reset transition filter state */
SKP_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
if( ( psEncC->fs_kHz == 8 && TargetRate_bps > NB2MB_BITRATE_BPS && psEncC->maxInternal_fs_Hz >= 12000 && psEncC->API_fs_Hz >= 12000 ) ||
( psEncC->fs_kHz == 12 && TargetRate_bps > MB2WB_BITRATE_BPS && psEncC->maxInternal_fs_Hz >= 16000 && psEncC->API_fs_Hz >= 16000 ) )
{
/* 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;
}
if( psEncC->sLP.transition_frame_no >= TRANSITION_FRAMES ) {
/* Stop transition phase */
psEncC->sLP.mode = 0;
} else {
/* Direction: up */
psEncC->sLP.mode = 1;
}
}
}
}
#ifdef FORCE_INTERNAL_FS_KHZ
fs_kHz = FORCE_INTERNAL_FS_KHZ;
#endif
return fs_kHz;
}