commit b0be6411db1fb52a8de7b12072a98e759d7b2c5d
author Alex Converse <aconverse@google.com> Wed Nov 30 15:51:50 2016 -0800
committer Alex Converse <aconverse@google.com> Mon Dec 12 21:28:43 2016 +0000
tree da2bcc03dd8f80db92489bdd05bdf12bd80306ae
parent b878d817ad8f5415ece20b73b37e7b7a203bfecc

ans: Use a fixed N-symbol window

Accept a small compression loss is in exchange for a fixed sized encoder
side buffering requirement.

subset1:
rans_base@2016-12-02T22:55:56.809Z -> rans_nsym@2016-12-02T22:58:19.859Z

    PSNR | PSNR Cb | PSNR Cr | PSNR HVS |   SSIM | MS SSIM | CIEDE 2000
  0.0304 |  0.0303 |  0.0305 |   0.0317 | 0.0312 |  0.0309 |     0.0301

Change-Id: I09dd143e4f1638b97dc9bba7023efa837a7d48c7

aom_dsp/buf_ans.c

diff --git a/aom_dsp/buf_ans.c b/aom_dsp/buf_ans.c
index 33db080..c4ac643 100644
--- a/aom_dsp/buf_ans.c
+++ b/aom_dsp/buf_ans.c
@@ -43,6 +43,10 @@
 
 void aom_buf_ans_flush(struct BufAnsCoder *const c) {
   int offset;
+#if ANS_MAX_SYMBOLS
+  if (c->offset == 0) return;
+#endif
+  assert(c->offset > 0);
   for (offset = c->offset - 1; offset >= 0; --offset) {
     if (c->buf[offset].method == ANS_METHOD_RANS) {
       struct rans_sym sym;