[FFmpeg-cvslog] h264: correct implicit weight table computation for long ref pics

[Jeff Downs]

ffmpeg | branch: release/0.6 | Jeff Downs <heydowns at somuchpressure.net> | Wed Jul  6 11:54:36 2011 -0400| [01b9a6e447d8a3abd86498be26b1aef3479a1cc9] | committer: Reinhard Tartler

h264: correct implicit weight table computation for long ref pics

Correct computation of implicit weight tables when referencing pictures
that are marked for long reference.

Signed-off-by: Diego Biurrun <diego at biurrun.de>
(cherry picked from commit 87cf70eb237e7586cc7399627dafa1b980ec0b7d)

Signed-off-by: Anton Khirnov <anton at khirnov.net>
Signed-off-by: Reinhard Tartler <siretart at tauware.de>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=01b9a6e447d8a3abd86498be26b1aef3479a1cc9
---

 libavcodec/h264.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 1f045a8..06ded4d 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -1448,15 +1448,17 @@ static void implicit_weight_table(H264Context *h, int field){
     for(ref0=ref_start; ref0 < ref_count0; ref0++){
         int poc0 = h->ref_list[0][ref0].poc;
         for(ref1=ref_start; ref1 < ref_count1; ref1++){
-            int poc1 = h->ref_list[1][ref1].poc;
-            int td = av_clip(poc1 - poc0, -128, 127);
-            int w= 32;
-            if(td){
-                int tb = av_clip(cur_poc - poc0, -128, 127);
-                int tx = (16384 + (FFABS(td) >> 1)) / td;
-                int dist_scale_factor = (tb*tx + 32) >> 8;
-                if(dist_scale_factor >= -64 && dist_scale_factor <= 128)
-                    w = 64 - dist_scale_factor;
+            int w = 32;
+            if (!h->ref_list[0][ref0].long_ref && !h->ref_list[1][ref1].long_ref) {
+                int poc1 = h->ref_list[1][ref1].poc;
+                int td = av_clip(poc1 - poc0, -128, 127);
+                if(td){
+                    int tb = av_clip(cur_poc - poc0, -128, 127);
+                    int tx = (16384 + (FFABS(td) >> 1)) / td;
+                    int dist_scale_factor = (tb*tx + 32) >> 8;
+                    if(dist_scale_factor >= -64 && dist_scale_factor <= 128)
+                        w = 64 - dist_scale_factor;
+                }
             }
             if(field<0){
                 h->implicit_weight[ref0][ref1][0]=