diff options
| author | Timothy B. Terriberry <tterribe@xiph.org> | 2011-02-01 12:55:01 +0300 |
|---|---|---|
| committer | Jean-Marc Valin <jean-marc.valin@usherbrooke.ca> | 2011-02-01 14:35:14 +0300 |
| commit | 411a84faeada5092e2e94d8116b8adba45808183 (patch) | |
| tree | ee132bb65182fc2f1c31b11bf79e20c1754bfb2c | |
| parent | 4499263b444645cba4b616e0d8cc85d280695933 (diff) | |
Add a seprate qtheta offset for two-phase stereo.
9b34bd83 caused serious regressions for 240-sample frame stereo,
because the previous qb limit was _always_ hit for two-phase
stereo.
Two-phase stereo really does operate with a different model (for
example, the single bit allocated to the side should really
probably be thought of as a sign bit for qtheta, but we don't
count it as part of qtheta's allocation).
The old code was equivalent to a separate two-phase offset of 12,
however Greg Maxwell's testing demonstrates that 16 performs
best.
| -rw-r--r-- | libcelt/bands.c | 2 | ||||
| -rw-r--r-- | libcelt/rate.c | 2 | ||||
| -rw-r--r-- | libcelt/rate.h | 2 |
3 files changed, 3 insertions, 3 deletions
diff --git a/libcelt/bands.c b/libcelt/bands.c index 2102dfd..64e53fd 100644 --- a/libcelt/bands.c +++ b/libcelt/bands.c @@ -769,7 +769,7 @@ static unsigned quant_band(int encode, const CELTMode *m, int i, celt_norm *X, c /* Decide on the resolution to give to the split parameter theta */ pulse_cap = m->logN[i]+(LM<<BITRES); - offset = (pulse_cap>>1) - (stereo ? QTHETA_OFFSET_STEREO : QTHETA_OFFSET); + offset = (pulse_cap>>1) - (stereo&&N==2 ? QTHETA_OFFSET_TWOPHASE : QTHETA_OFFSET); qn = compute_qn(N, b, offset, pulse_cap, stereo); if (stereo && i>=intensity) qn = 1; diff --git a/libcelt/rate.c b/libcelt/rate.c index 2235013..15f1a88 100644 --- a/libcelt/rate.c +++ b/libcelt/rate.c @@ -212,7 +212,7 @@ void compute_pulse_cache(CELTMode *m, int LM) if (C==2) { max_bits <<= 1; - offset = (m->logN[j]+(i<<BITRES)>>1)-QTHETA_OFFSET_STEREO; + offset = (m->logN[j]+(i<<BITRES)>>1)-(N==2?QTHETA_OFFSET_TWOPHASE:QTHETA_OFFSET); ndof = 2*N-1-(N==2); /* The average measured cost for theta with the step PDF is 0.95164 times qb, approximated here as 487/512. */ diff --git a/libcelt/rate.h b/libcelt/rate.h index eabba93..d5f188d 100644 --- a/libcelt/rate.h +++ b/libcelt/rate.h @@ -43,7 +43,7 @@ #define BITRES 3 #define FINE_OFFSET 21 #define QTHETA_OFFSET 4 -#define QTHETA_OFFSET_STEREO 4 +#define QTHETA_OFFSET_TWOPHASE 16 #define BITOVERFLOW 30000 |