[FFmpeg-cvslog] avcodec/hqxvlc: Include implicit +1 run in RL VLC tables

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Thu Mar 13 20:04:16 2025 +0100| [09411fef3d0819e3a15ec25a0debeff848f5d365] | committer: Andreas Rheinhardt

avcodec/hqxvlc: Include implicit +1 run in RL VLC tables

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=09411fef3d0819e3a15ec25a0debeff848f5d365
---

 libavcodec/hqx.c    | 8 ++++----
 libavcodec/hqxvlc.c | 3 ++-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/libavcodec/hqx.c b/libavcodec/hqx.c
index b31c35bbcc..32acca79ac 100644
--- a/libavcodec/hqx.c
+++ b/libavcodec/hqx.c
@@ -115,7 +115,7 @@ static int decode_block(GetBitContext *gb, VLC *vlc,
 {
     int q, dc;
     int ac_idx;
-    int run, lev, pos = 1;
+    int run, lev, pos = 0;
 
     memset(block, 0, 64 * sizeof(*block));
     dc = get_vlc2(gb, vlc->table, HQX_DC_VLC_BITS, 2);
@@ -140,10 +140,10 @@ static int decode_block(GetBitContext *gb, VLC *vlc,
     do {
         hqx_get_ac(gb, &ff_hqx_ac[ac_idx], &run, &lev);
         pos += run;
-        if (pos >= 64)
+        if (pos > 63)
             break;
-        block[ff_zigzag_direct[pos++]] = lev * q;
-    } while (pos < 64);
+        block[ff_zigzag_direct[pos]] = lev * q;
+    } while (pos < 63);
 
     return 0;
 }
diff --git a/libavcodec/hqxvlc.c b/libavcodec/hqxvlc.c
index 94ab21724c..63ca5cc33c 100644
--- a/libavcodec/hqxvlc.c
+++ b/libavcodec/hqxvlc.c
@@ -726,7 +726,8 @@ HQXAC ff_hqx_ac[NUM_HQX_AC] = {
 };
 
 // level is in -255..255 range, run 0..64, so it fits into 16 bits.
-#define E(level, run) ((level * 128) | run)
+// We offset run by 1 in order to include the implicit run of 1.
+#define E(level, run) ((level * 128) | (run + 1))
 
 static const int16_t hqx_ac_run_level[] = {
     // AC table Q0 - 815 elements