ref: 8ca161212b2d88d91467968a909ab42bbc7e7477
parent: c30f8ca6660438d2cb5d35f2ea63c6efae8a0948
author: Jean-Marc Valin <[email protected]>
date: Thu Jan 27 11:28:16 EST 2011
Reducing waste at high bit-rate We now encode the highest bitrate part of the split first and transfer any unused bits to the other part. We use a dead zone of three bits to prevent redistributing in cases of random fluctuation (or else we will statistically lower the allocation of higher frequencies at low-mid bitrates).
--- a/libcelt/bands.c
+++ b/libcelt/bands.c
@@ -956,6 +956,7 @@
celt_norm *next_lowband2=NULL;
celt_norm *next_lowband_out1=NULL;
int next_level=0;
+ int rebalance;
/* Give more bits to low-energy MDCTs than they would otherwise deserve */
if (B0>1 && !stereo)
@@ -981,16 +982,38 @@
else
next_level = level+1;
- /* In stereo mode, we do not apply a scaling to the mid because we need the normalized
- mid for folding later */
- cm = quant_band(encode, m, i, X, NULL, N, mbits, spread, B, intensity, tf_change,
- lowband, resynth, ec, remaining_bits, LM, next_lowband_out1,
- NULL, next_level, seed, stereo ? Q15ONE : MULT16_16_P15(gain,mid), lowband_scratch, fill);
- /* For a stereo split, the high bits of fill are always zero, so no
- folding will be done to the side. */
- cm |= quant_band(encode, m, i, Y, NULL, N, sbits, spread, B, intensity, tf_change,
- next_lowband2, resynth, ec, remaining_bits, LM, NULL,
- NULL, next_level, seed, MULT16_16_P15(gain,side), NULL, fill>>B)<<(B0>>1&stereo-1);
+ rebalance = *remaining_bits;
+ if (mbits >= sbits)
+ {+ /* In stereo mode, we do not apply a scaling to the mid because we need the normalized
+ mid for folding later */
+ cm = quant_band(encode, m, i, X, NULL, N, mbits, spread, B, intensity, tf_change,
+ lowband, resynth, ec, remaining_bits, LM, next_lowband_out1,
+ NULL, next_level, seed, stereo ? Q15ONE : MULT16_16_P15(gain,mid), lowband_scratch, fill);
+ rebalance = mbits - (rebalance-*remaining_bits);
+ if (rebalance > 3<<BITRES)
+ sbits += rebalance - (3<<BITRES);
+
+ /* For a stereo split, the high bits of fill are always zero, so no
+ folding will be done to the side. */
+ cm |= quant_band(encode, m, i, Y, NULL, N, sbits, spread, B, intensity, tf_change,
+ next_lowband2, resynth, ec, remaining_bits, LM, NULL,
+ NULL, next_level, seed, MULT16_16_P15(gain,side), NULL, fill>>B)<<(B0>>1&stereo-1);
+ } else {+ /* For a stereo split, the high bits of fill are always zero, so no
+ folding will be done to the side. */
+ cm = quant_band(encode, m, i, Y, NULL, N, sbits, spread, B, intensity, tf_change,
+ next_lowband2, resynth, ec, remaining_bits, LM, NULL,
+ NULL, next_level, seed, MULT16_16_P15(gain,side), NULL, fill>>B)<<(B0>>1&stereo-1);
+ rebalance = sbits - (rebalance-*remaining_bits);
+ if (rebalance > 3<<BITRES)
+ mbits += rebalance - (3<<BITRES);
+ /* In stereo mode, we do not apply a scaling to the mid because we need the normalized
+ mid for folding later */
+ cm |= quant_band(encode, m, i, X, NULL, N, mbits, spread, B, intensity, tf_change,
+ lowband, resynth, ec, remaining_bits, LM, next_lowband_out1,
+ NULL, next_level, seed, stereo ? Q15ONE : MULT16_16_P15(gain,mid), lowband_scratch, fill);
+ }
}
} else {