Commit 3499e78b authored by Koen Vos's avatar Koen Vos Committed by Jean-Marc Valin

Fix for flutter with FEC

The bug was caused by an improper feedback of the per-frame bitrate, causing
the bitrate to jump up and down from frame to frame, within a packet.
The patch avoids this, and also gives a slight improvement in general for
multi-frame packets, even without FEC.
Signed-off-by: Jean-Marc Valin's avatarJean-Marc Valin <jmvalin@jmvalin.ca>
parent 8adff0bb
......@@ -70,11 +70,6 @@ opus_int silk_control_SNR(
break;
}
}
/* Reduce coding quality whenever LBRR is enabled, to free up some bits */
if( psEncC->LBRR_enabled ) {
psEncC->SNR_dB_Q7 = silk_SMLABB( psEncC->SNR_dB_Q7, 12 - psEncC->LBRR_GainIncreases, SILK_FIX_CONST( -0.25, 7 ) );
}
}
return ret;
......
......@@ -397,9 +397,10 @@ static OPUS_INLINE opus_int silk_setup_LBRR(
const opus_int32 TargetRate_bps /* I */
)
{
opus_int ret = SILK_NO_ERROR;
opus_int LBRR_in_previous_packet, ret = SILK_NO_ERROR;
opus_int32 LBRR_rate_thres_bps;
LBRR_in_previous_packet = psEncC->LBRR_enabled;
psEncC->LBRR_enabled = 0;
if( psEncC->useInBandFEC && psEncC->PacketLoss_perc > 0 ) {
if( psEncC->fs_kHz == 8 ) {
......@@ -413,8 +414,13 @@ static OPUS_INLINE opus_int silk_setup_LBRR(
if( TargetRate_bps > LBRR_rate_thres_bps ) {
/* Set gain increase for coding LBRR excitation */
if( LBRR_in_previous_packet == 0 ) {
/* Previous packet did not have LBRR, and was therefore coded at a higher bitrate */
psEncC->LBRR_GainIncreases = 7;
} else {
psEncC->LBRR_GainIncreases = silk_max_int( 7 - silk_SMULWB( (opus_int32)psEncC->PacketLoss_perc, SILK_FIX_CONST( 0.4, 16 ) ), 2 );
}
psEncC->LBRR_enabled = 1;
psEncC->LBRR_GainIncreases = silk_max_int( 7 - silk_SMULWB( (opus_int32)psEncC->PacketLoss_perc, SILK_FIX_CONST( 0.4, 16 ) ), 2 );
}
}
......
......@@ -376,26 +376,33 @@ opus_int silk_Encode( /* O Returns error co
for( n = 0; n < encControl->nChannelsInternal; n++ ) {
silk_memset( psEnc->state_Fxx[ n ].sCmn.LBRR_flags, 0, sizeof( psEnc->state_Fxx[ n ].sCmn.LBRR_flags ) );
}
psEnc->nBitsUsedLBRR = ec_tell( psRangeEnc );
}
silk_HP_variable_cutoff( psEnc->state_Fxx );
/* Total target bits for packet */
nBits = silk_DIV32_16( silk_MUL( encControl->bitRate, encControl->payloadSize_ms ), 1000 );
/* Subtract half of the bits already used */
/* Subtract bits used for LBRR */
if( !prefillFlag ) {
nBits -= ec_tell( psRangeEnc ) >> 1;
nBits -= psEnc->nBitsUsedLBRR;
}
/* Divide by number of uncoded frames left in packet */
nBits = silk_DIV32_16( nBits, psEnc->state_Fxx[ 0 ].sCmn.nFramesPerPacket - psEnc->state_Fxx[ 0 ].sCmn.nFramesEncoded );
nBits = silk_DIV32_16( nBits, psEnc->state_Fxx[ 0 ].sCmn.nFramesPerPacket );
/* Convert to bits/second */
if( encControl->payloadSize_ms == 10 ) {
TargetRate_bps = silk_SMULBB( nBits, 100 );
} else {
TargetRate_bps = silk_SMULBB( nBits, 50 );
}
/* Subtract fraction of bits in excess of target in previous packets */
/* Subtract fraction of bits in excess of target in previous frames and packets */
TargetRate_bps -= silk_DIV32_16( silk_MUL( psEnc->nBitsExceeded, 1000 ), BITRESERVOIR_DECAY_TIME_MS );
if( !prefillFlag && psEnc->state_Fxx[ 0 ].sCmn.nFramesEncoded > 0 ) {
/* Compare actual vs target bits so far in this packet */
opus_int32 bitsBalance = ec_tell( psRangeEnc ) - psEnc->nBitsUsedLBRR - nBits * psEnc->state_Fxx[ 0 ].sCmn.nFramesEncoded;
TargetRate_bps -= silk_DIV32_16( silk_MUL( bitsBalance, 1000 ), BITRESERVOIR_DECAY_TIME_MS );
}
/* Never exceed input bitrate */
TargetRate_bps = silk_LIMIT( TargetRate_bps, encControl->bitRate, 5000 );
......
......@@ -116,6 +116,7 @@ typedef struct {
typedef struct {
silk_encoder_state_FIX state_Fxx[ ENCODER_NUM_CHANNELS ];
stereo_enc_state sStereo;
opus_int32 nBitsUsedLBRR;
opus_int32 nBitsExceeded;
opus_int nChannelsAPI;
opus_int nChannelsInternal;
......
......@@ -115,6 +115,7 @@ typedef struct {
typedef struct {
silk_encoder_state_FLP state_Fxx[ ENCODER_NUM_CHANNELS ];
stereo_enc_state sStereo;
opus_int32 nBitsUsedLBRR;
opus_int32 nBitsExceeded;
opus_int nChannelsAPI;
opus_int nChannelsInternal;
......
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