virtualx-engine/thirdparty/opus/silk/control_SNR.c
Rémi Verschelde d9a291f641 ogg/vorbis/opus: Make them modules and unbundle thirdparty libs
Took the opportunity to undo the Godot changed made to the
opus source. The opus module should eventually be built in its
own environment to avoid polluting others with too many include
dirs and defines.

TODO: Fix the platform/ stuff for opus.
2016-10-15 11:50:40 +02:00

76 lines
3.4 KiB
C

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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "main.h"
#include "tuning_parameters.h"
/* Control SNR of redidual quantizer */
opus_int silk_control_SNR(
silk_encoder_state *psEncC, /* I/O Pointer to Silk encoder state */
opus_int32 TargetRate_bps /* I Target max bitrate (bps) */
)
{
opus_int k, ret = SILK_NO_ERROR;
opus_int32 frac_Q6;
const opus_int32 *rateTable;
/* Set bitrate/coding quality */
TargetRate_bps = silk_LIMIT( TargetRate_bps, MIN_TARGET_RATE_BPS, MAX_TARGET_RATE_BPS );
if( TargetRate_bps != psEncC->TargetRate_bps ) {
psEncC->TargetRate_bps = TargetRate_bps;
/* If new TargetRate_bps, translate to SNR_dB value */
if( psEncC->fs_kHz == 8 ) {
rateTable = silk_TargetRate_table_NB;
} else if( psEncC->fs_kHz == 12 ) {
rateTable = silk_TargetRate_table_MB;
} else {
rateTable = silk_TargetRate_table_WB;
}
/* Reduce bitrate for 10 ms modes in these calculations */
if( psEncC->nb_subfr == 2 ) {
TargetRate_bps -= REDUCE_BITRATE_10_MS_BPS;
}
/* Find bitrate interval in table and interpolate */
for( k = 1; k < TARGET_RATE_TAB_SZ; k++ ) {
if( TargetRate_bps <= rateTable[ k ] ) {
frac_Q6 = silk_DIV32( silk_LSHIFT( TargetRate_bps - rateTable[ k - 1 ], 6 ),
rateTable[ k ] - rateTable[ k - 1 ] );
psEncC->SNR_dB_Q7 = silk_LSHIFT( silk_SNR_table_Q1[ k - 1 ], 6 ) + silk_MUL( frac_Q6, silk_SNR_table_Q1[ k ] - silk_SNR_table_Q1[ k - 1 ] );
break;
}
}
}
return ret;
}