avcodec/h261dec: Use VLC symbol table

This is possible now that MB_TYPE_CBP and MB_TYPE_QUANT
fit into an int16_t; only MB_TYPE_H261_FIL needs to
be remapped to MB_TYPE_CODEC_SPECIFIC.

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

libavcodec/h261.h

@@ -28,6 +28,7 @@
 #ifndef AVCODEC_H261_H
 #define AVCODEC_H261_H
 
+#include "mpegutils.h"
 #include "mpegvideo.h"
 #include "rl.h"
 
@@ -38,13 +39,13 @@ typedef struct H261Context {
     int mtype;
 } H261Context;
 
-#define MB_TYPE_H261_FIL 0x800000
+#define MB_TYPE_H261_FIL MB_TYPE_CODEC_SPECIFIC
 
 extern const uint8_t ff_h261_mba_code[35];
 extern const uint8_t ff_h261_mba_bits[35];
 extern const uint8_t ff_h261_mtype_code[10];
 extern const uint8_t ff_h261_mtype_bits[10];
-extern const int     ff_h261_mtype_map[10];
+extern const uint16_t ff_h261_mtype_map[10];
 extern const uint8_t ff_h261_mv_tab[17][2];
 extern const uint8_t ff_h261_cbp_tab[63][2];
 extern RLTable ff_h261_rl_tcoeff;

libavcodec/h261data.c

@@ -72,7 +72,7 @@ const uint8_t ff_h261_mtype_bits[10] = {
     2, 6
 };
 
-const int ff_h261_mtype_map[10] = {
+const uint16_t ff_h261_mtype_map[10] = {
     MB_TYPE_INTRA4x4,
     MB_TYPE_INTRA4x4 | MB_TYPE_QUANT,
     MB_TYPE_CBP,

libavcodec/h261dec.c

@@ -67,9 +67,10 @@ static av_cold void h261_decode_init_static(void)
     VLC_INIT_STATIC_TABLE(h261_mba_vlc, H261_MBA_VLC_BITS, 35,
                           ff_h261_mba_bits, 1, 1,
                           ff_h261_mba_code, 1, 1, 0);
-    VLC_INIT_STATIC_TABLE(h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
-                          ff_h261_mtype_bits, 1, 1,
-                          ff_h261_mtype_code, 1, 1, 0);
+    VLC_INIT_STATIC_SPARSE_TABLE(h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
+                                 ff_h261_mtype_bits, 1, 1,
+                                 ff_h261_mtype_code, 1, 1,
+                                 ff_h261_mtype_map,  2, 2, 0);
     VLC_INIT_STATIC_TABLE(h261_mv_vlc, H261_MV_VLC_BITS, 17,
                           &ff_h261_mv_tab[0][1], 2, 1,
                           &ff_h261_mv_tab[0][0], 2, 1, 0);
@@ -418,8 +419,6 @@ static int h261_decode_mb(H261DecContext *h)
                com->mtype);
         return SLICE_ERROR;
     }
-    av_assert0(com->mtype < FF_ARRAY_ELEMS(ff_h261_mtype_map));
-    com->mtype = ff_h261_mtype_map[com->mtype];
 
     // Read mquant
     if (IS_QUANT(com->mtype))