Stop adjusting the VBR drift during silent frames, this prevents overshoot after...

diff --git a/libcelt/celt.c b/libcelt/celt.c
index 6331553..d6c2b4d 100644 (file)
--- a/libcelt/celt.c
+++ b/libcelt/celt.c
@@ -1425,17 +1425,23 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, i
      nbAvailableBytes = IMAX(min_allowed,nbAvailableBytes);
      nbAvailableBytes = IMIN(nbCompressedBytes,nbAvailableBytes+nbFilledBytes) - nbFilledBytes;
 
+     /* By how much did we "miss" the target on that frame */
+     delta = target - vbr_rate;
+
+     target=nbAvailableBytes<<(BITRES+3);
+
+     /*If the frame is silent we don't adjust our drift, otherwise
+       the encoder will shoot to very high rates after hitting a
+       span of silence, but we do allow the bitres to refill.
+       This means that we'll undershoot our target in CVBR/VBR modes
+       on files with lots of silence. */
      if(silence)
      {
        nbAvailableBytes = 2;
        target = 2*8<<BITRES;
+       delta = 0;
      }
 
-     /* By how much did we "miss" the target on that frame */
-     delta = target - vbr_rate;
-
-     target=nbAvailableBytes<<(BITRES+3);
-
      if (st->vbr_count < 970)
      {
         st->vbr_count++;