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Replace imprecise 32 bits calculations by 64 bits calculations

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Change-Id: If1b0a2d6603ce24f5dd99855e8dfe459e7a2835a
This commit is contained in:
Guillaume Martres
2014-04-05 22:32:06 +02:00
parent ded9e19144
commit 0ec5919d42
2 changed files with 4 additions and 13 deletions
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13
vp9/encoder/vp9_ratectrl.c
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@@ -152,11 +152,7 @@ static int estimate_bits_at_q(int frame_kind, int q, int mbs,
double correction_factor) {
const int bpm = (int)(vp9_rc_bits_per_mb(frame_kind, q, correction_factor));
// Attempt to retain reasonable accuracy without overflow. The cutoff is
// chosen such that the maximum product of Bpm and MBs fits 31 bits. The
// largest Bpm takes 20 bits.
return (mbs > (1 << 11)) ? (bpm >> BPER_MB_NORMBITS) * mbs
: (bpm * mbs) >> BPER_MB_NORMBITS;
return ((uint64_t)bpm * mbs) >> BPER_MB_NORMBITS;
}
int vp9_rc_clamp_pframe_target_size(const VP9_COMP *const cpi, int target) {
@@ -368,11 +364,8 @@ int vp9_rc_regulate_q(const VP9_COMP *cpi, int target_bits_per_frame,
// Calculate required scaling factor based on target frame size and size of
// frame produced using previous Q.
if (target_bits_per_frame >= (INT_MAX >> BPER_MB_NORMBITS))
// Case where we would overflow int
target_bits_per_mb = (target_bits_per_frame / cm->MBs) << BPER_MB_NORMBITS;
else
target_bits_per_mb = (target_bits_per_frame << BPER_MB_NORMBITS) / cm->MBs;
target_bits_per_mb =
((uint64_t)target_bits_per_frame << BPER_MB_NORMBITS) / cm->MBs;
i = active_best_quality;