/*********************************************************************** | |
Copyright (c) 2006-2011, Skype Limited. All rights reserved. | |
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are permitted provided that the following conditions are met: | |
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- Redistributions in binary form must reproduce the above copyright | |
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BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND | |
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BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 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; | |
fs_kHz = psEncC->fs_kHz; | |
/* Reduce bitrate for 10 ms modes in these calculations */ | |
if( psEncC->nb_subfr == 2 ) { | |
TargetRate_bps -= REDUCE_BITRATE_10_MS_BPS; | |
} | |
if( fs_kHz == 0 ) { | |
/* Encoder has just been initialized */ | |
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 && psEncC->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) { /* Low speech activity */ | |
/* Check if we should switch down */ | |
if( ( psEncC->fs_kHz == 12 && TargetRate_bps < MB2NB_BITRATE_BPS && psEncC->minInternal_fs_kHz <= 8 ) || | |
( psEncC->fs_kHz == 16 && TargetRate_bps < WB2MB_BITRATE_BPS && psEncC->minInternal_fs_kHz <= 12 ) ) | |
{ | |
/* Switch down */ | |
if( SWITCH_TRANSITION_FILTERING && 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_kHz >= 12 && psEncC->API_fs_Hz >= 12000 ) || | |
( psEncC->fs_kHz == 12 && TargetRate_bps > MB2WB_BITRATE_BPS && psEncC->maxInternal_fs_kHz >= 16 && psEncC->API_fs_Hz >= 16000 ) ) | |
{ | |
/* Switch up */ | |
if( SWITCH_TRANSITION_FILTERING && 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; | |
} |