From 98e34e71c06251531aaab668a870ec44c648de6e Mon Sep 17 00:00:00 2001
From: Justin Ruggles <justin.ruggles@gmail.com>
Date: Fri, 17 Dec 2010 15:02:12 +0000
Subject: [PATCH] Simplify bit allocation search by using a loop for the SNR
 offset increment.

Originally committed as revision 26044 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/ac3enc.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index 3495db0ad5..da9293b867 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -1055,7 +1055,7 @@ static int cbr_bit_allocation(AC3EncodeContext *s)
 {
     int ch;
     int bits_left;
-    int snr_offset;
+    int snr_offset, snr_incr;
 
     bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
 
@@ -1069,25 +1069,12 @@ static int cbr_bit_allocation(AC3EncodeContext *s)
         return AVERROR(EINVAL);
 
     FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
+    for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
     while (snr_offset + 64 <= 1023 &&
-           bit_alloc(s, snr_offset + 64) <= bits_left) {
-        snr_offset += 64;
+           bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
+        snr_offset += snr_incr;
         FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
     }
-    while (snr_offset + 16 <= 1023 &&
-           bit_alloc(s, snr_offset + 16) <= bits_left) {
-        snr_offset += 16;
-        FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
-    }
-    while (snr_offset + 4 <= 1023 &&
-           bit_alloc(s, snr_offset + 4) <= bits_left) {
-        snr_offset += 4;
-        FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
-    }
-    while (snr_offset + 1 <= 1023 &&
-           bit_alloc(s, snr_offset + 1) <= bits_left) {
-        snr_offset++;
-        FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
     }
     FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
     reset_block_bap(s);