bitstream.c: improve init_vlc error messages.

Makes it far easier to spot the issue if e.g.
caused by a typo in the code table.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavcodec/bitstream.c

@@ -317,7 +317,7 @@ int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,
         }                                                                   \
         GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);            \
         if (buf[j].code >= (1LL<<buf[j].bits)) {                            \
-            av_log(NULL, AV_LOG_ERROR, "Invalid code in init_vlc\n");       \
+            av_log(NULL, AV_LOG_ERROR, "Invalid code %x for %d in init_vlc\n", buf[j].code, i);\
             if (!(flags & INIT_VLC_USE_NEW_STATIC))                         \
                 av_free(buf);                                               \
             return -1;                                                      \