[FFmpeg-devel] [PATCH 211/217] avcodec/bink: Don't waste space for VLC table

[Andreas Rheinhardt]

The Bink video decoder uses VLCs; the longest codes of these VLCs have
different lengths, yet they are all so small that each VLC is read in
one go, so that the number of elements in the VLC table actually used by
each table is 1 << nb_bits, where nb_bits is the length of the longest
code. Yet when determining the size of the VLC table nb_bits has been
overestimated as the number of bits of the longest code in all VLCs,
making said table unnecessary big (2048 vs 976 elements).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
---
 libavcodec/bink.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libavcodec/bink.c b/libavcodec/bink.c
index f1fa9c0071..04c104be48 100644
--- a/libavcodec/bink.c
+++ b/libavcodec/bink.c
@@ -1311,11 +1311,12 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
 
 static av_cold void bink_init_vlcs(void)
 {
-    for (int i = 0; i < 16; i++) {
-        static VLC_TYPE table[16 * 128][2];
+    for (int i = 0, offset = 0; i < 16; i++) {
+        static VLC_TYPE table[976][2];
         const int maxbits = bink_tree_lens[i][15];
-        bink_trees[i].table = table + i*128;
+        bink_trees[i].table           = table + offset;
         bink_trees[i].table_allocated = 1 << maxbits;
+        offset                       += bink_trees[i].table_allocated;
         init_vlc(&bink_trees[i], maxbits, 16,
                  bink_tree_lens[i], 1, 1,
                  bink_tree_bits[i], 1, 1, INIT_VLC_USE_NEW_STATIC | INIT_VLC_LE);
-- 
2.25.1