[SCM] libav/experimental: Decode fully coded superblocks in the same manner as partial superblocks and qpi

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit 855c720c8637b959e4b98e3ebb70ec8b60f18e2c
Author: David Conrad <lessen42 at gmail.com>
Date:   Sun Feb 21 00:10:54 2010 +0000

    Decode fully coded superblocks in the same manner as partial superblocks and qpi
    
    No speed difference, but it will simplify the special 4129 case.
    
    Originally committed as revision 21929 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index e669332..5f871bc 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -452,8 +452,7 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
     int bit = 0;
     int current_superblock = 0;
     int current_run = 0;
-    int decode_fully_flags = 0;
-    int decode_partial_blocks = 0;
+    int num_partial_superblocks = 0;
     int first_c_fragment_seen;
 
     int i, j;
@@ -480,52 +479,46 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
             memset(s->superblock_coding + current_superblock, bit, current_run);
 
             current_superblock += current_run;
-
-                /* if any of the superblocks are not partially coded, flag
-                 * a boolean to decode the list of fully-coded superblocks */
-                if (bit == 0) {
-                    decode_fully_flags = 1;
-                } else {
-
-                    /* make a note of the fact that there are partially coded
-                     * superblocks */
-                    decode_partial_blocks = 1;
-                }
+            if (bit)
+                num_partial_superblocks += current_run;
 
                 bit ^= 1;
         }
 
         /* unpack the list of fully coded superblocks if any of the blocks were
          * not marked as partially coded in the previous step */
-        if (decode_fully_flags) {
+        if (num_partial_superblocks < s->superblock_count) {
+            int superblocks_decoded = 0;
 
             current_superblock = 0;
-            current_run = 0;
             bit = get_bits1(gb);
-            /* toggle the bit because as soon as the first run length is
-             * fetched the bit will be toggled again */
-            bit ^= 1;
-            while (current_superblock < s->superblock_count) {
-
-                /* skip any superblocks already marked as partially coded */
-                if (s->superblock_coding[current_superblock] == SB_NOT_CODED) {
-
-                    if (current_run-- == 0) {
-                        bit ^= 1;
+            while (superblocks_decoded < s->superblock_count - num_partial_superblocks) {
                         current_run = get_vlc2(gb,
-                            s->superblock_run_length_vlc.table, 6, 2);
-                        if (current_run == 33)
+                            s->superblock_run_length_vlc.table, 6, 2) + 1;
+                        if (current_run == 34)
                             current_run += get_bits(gb, 12);
+
+                for (j = 0; j < current_run; current_superblock++) {
+                    if (current_superblock >= s->superblock_count) {
+                        av_log(s->avctx, AV_LOG_ERROR, "Invalid fully coded superblock run length\n");
+                        return -1;
                     }
+
+                /* skip any superblocks already marked as partially coded */
+                if (s->superblock_coding[current_superblock] == SB_NOT_CODED) {
                     s->superblock_coding[current_superblock] = 2*bit;
+                    j++;
                 }
-                current_superblock++;
+                }
+                superblocks_decoded += current_run;
+
+                    bit ^= 1;
             }
         }
 
         /* if there were partial blocks, initialize bitstream for
          * unpacking fragment codings */
-        if (decode_partial_blocks) {
+        if (num_partial_superblocks) {
 
             current_run = 0;
             bit = get_bits1(gb);

-- 
Libav/FFmpeg packaging