shithub: libvpx

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Replace imprecise 32 bits calculations by 64 bits calculations

Change-Id: If1b0a2d6603ce24f5dd99855e8dfe459e7a2835a

--- a/vp9/encoder/vp9_firstpass.c

+++ b/vp9/encoder/vp9_firstpass.c

@@ -917,9 +917,7 @@

     return rc->worst_quality;          // Highest value allowed

   target_norm_bits_per_mb =

-      section_target_bandwitdh < (1 << 20)

-      ? (section_target_bandwitdh << BPER_MB_NORMBITS) / num_mbs

-      : (section_target_bandwitdh / num_mbs) << BPER_MB_NORMBITS;

+      ((uint64_t)section_target_bandwitdh << BPER_MB_NORMBITS) / num_mbs;

   // Try and pick a max Q that will be high enough to encode the

   // content at the given rate.

--- a/vp9/encoder/vp9_ratectrl.c

+++ b/vp9/encoder/vp9_ratectrl.c

@@ -152,11 +152,7 @@

                               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 @@

   // 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;