ref: dcb285211683d7e6d7ee7f47a7c556239f91c231
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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***********************************************************************/
#include "SKP_Silk_main.h"
/* Control internal sampling rate */
SKP_int SKP_Silk_control_audio_bandwidth(
SKP_Silk_encoder_state *psEncC, /* I/O Pointer to Silk encoder state */
const SKP_int32 TargetRate_bps /* I Target max bitrate (bps) */
)
{
SKP_int fs_kHz;
fs_kHz = psEncC->fs_kHz;
if( fs_kHz == 0 ) {
/* Encoder has just been initialized */
if( TargetRate_bps >= SWB2WB_BITRATE_BPS ) {
fs_kHz = 24;
} else if( TargetRate_bps >= WB2MB_BITRATE_BPS ) {
fs_kHz = 16;
} else if( TargetRate_bps >= MB2NB_BITRATE_BPS ) {
fs_kHz = 12;
} else {
fs_kHz = 8;
}
/* Make sure internal rate is not higher than external rate or maximum allowed, or lower than minimum allowed */
fs_kHz = SKP_min( fs_kHz, SKP_DIV32_16( psEncC->API_fs_Hz, 1000 ) );
fs_kHz = SKP_min( fs_kHz, psEncC->maxInternal_fs_kHz );
fs_kHz = SKP_max( fs_kHz, psEncC->minInternal_fs_kHz );
} else if( SKP_SMULBB( fs_kHz, 1000 ) > psEncC->API_fs_Hz || fs_kHz > psEncC->maxInternal_fs_kHz || fs_kHz < psEncC->minInternal_fs_kHz ) {
/* Make sure internal rate is not higher than external rate or maximum allowed, or lower than minimum allowed */
fs_kHz = SKP_DIV32_16( psEncC->API_fs_Hz, 1000 );
fs_kHz = SKP_min( fs_kHz, psEncC->maxInternal_fs_kHz );
fs_kHz = SKP_max( fs_kHz, psEncC->minInternal_fs_kHz );
} else {
/* State machine for the internal sampling rate switching */
if( psEncC->API_fs_Hz > 8000 ) {
/* Accumulate the difference between the target rate and limit for switching down */
psEncC->bitrateDiff += SKP_MUL( psEncC->PacketSize_ms, psEncC->TargetRate_bps - psEncC->bitrate_threshold_down );
psEncC->bitrateDiff = SKP_min( psEncC->bitrateDiff, 0 );
if( psEncC->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) { /* Low speech activity */
/* Check if we should switch down */
#if SWITCH_TRANSITION_FILTERING
if( ( psEncC->sLP.transition_frame_no == 0 ) && /* Transition phase not active */
( psEncC->bitrateDiff <= -ACCUM_BITS_DIFF_THRESHOLD || /* Bitrate threshold is met */
( psEncC->sSWBdetect.WB_detected * psEncC->fs_kHz == 24 ) ) ) { /* Forced down-switching due to WB input */
psEncC->sLP.transition_frame_no = 1; /* Begin transition phase */
psEncC->sLP.mode = 0; /* Switch down */
} else if(
( psEncC->sLP.transition_frame_no >= TRANSITION_FRAMES_DOWN ) && /* Transition phase complete */
( psEncC->sLP.mode == 0 ) ) { /* Ready to switch down */
psEncC->sLP.transition_frame_no = 0; /* Ready for new transition phase */
#else
if( psEncC->bitrateDiff <= -ACCUM_BITS_DIFF_THRESHOLD ) { /* Bitrate threshold is met */
#endif
psEncC->bitrateDiff = 0;
/* Switch to a lower sample frequency */
if( psEncC->fs_kHz == 24 ) {
fs_kHz = 16;
} else if( psEncC->fs_kHz == 16 ) {
fs_kHz = 12;
} else {
SKP_assert( psEncC->fs_kHz == 12 );
fs_kHz = 8;
}
}
/* Check if we should switch up */
if( ( ( psEncC->fs_kHz * 1000 < psEncC->API_fs_Hz ) &&
( psEncC->TargetRate_bps >= psEncC->bitrate_threshold_up ) &&
( psEncC->sSWBdetect.WB_detected * psEncC->fs_kHz < 16 ) ) &&
( ( psEncC->fs_kHz == 16 ) && ( psEncC->maxInternal_fs_kHz >= 24 ) ||
( psEncC->fs_kHz == 12 ) && ( psEncC->maxInternal_fs_kHz >= 16 ) ||
( psEncC->fs_kHz == 8 ) && ( psEncC->maxInternal_fs_kHz >= 12 ) )
#if SWITCH_TRANSITION_FILTERING
&& ( psEncC->sLP.transition_frame_no == 0 ) ) /* No transition phase running, ready to switch */
{
psEncC->sLP.mode = 1; /* Switch up */
#else
) {
#endif
psEncC->bitrateDiff = 0;
/* Switch to a higher sample frequency */
if( psEncC->fs_kHz == 8 ) {
fs_kHz = 12;
} else if( psEncC->fs_kHz == 12 ) {
fs_kHz = 16;
} else {
SKP_assert( psEncC->fs_kHz == 16 );
fs_kHz = 24;
}
}
}
}
#if SWITCH_TRANSITION_FILTERING
/* After switching up, stop transition filter during speech inactivity */
if( ( psEncC->sLP.mode == 1 ) &&
( psEncC->sLP.transition_frame_no >= TRANSITION_FRAMES_UP ) &&
( psEncC->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) ) {
psEncC->sLP.transition_frame_no = 0;
/* Reset transition filter state */
SKP_memset( psEncC->sLP.In_LP_State, 0, 2 * sizeof( SKP_int32 ) );
}
#endif
}
#ifdef FORCE_INTERNAL_FS_KHZ
fs_kHz = FORCE_INTERNAL_FS_KHZ;
#endif
return fs_kHz;
}