avcodec/intrax8: Stop setting write-only block_last_index

These values are only used by the mpegvideo unquantize functions,
yet these are not active when intrax is in use. Furthermore,
given that ff_intrax8_decode_picture() decodes multiple
macroblocks in a given call, it makes no sense to return
any value (that was in practice the maximum of the indices
of all the macroblocks decoded).

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

libavcodec/intrax8.c

@@ -480,24 +480,18 @@ static void x8_ac_compensation(IntraX8Context *const w, const int direction,
 
         t        = T(1084); // g
         B(1, 1) += t;
-
-        w->block_last_index[0] = FFMAX(w->block_last_index[0], 7 * 8);
         break;
     case 1:
         B(0, 1) -= T(6269);
         B(0, 3) -= T(708);
         B(0, 5) -= T(172);
         B(0, 7) -= T(73);
-
-        w->block_last_index[0] = FFMAX(w->block_last_index[0], 7 * 8);
         break;
     case 2:
         B(1, 0) -= T(6269);
         B(3, 0) -= T(708);
         B(5, 0) -= T(172);
         B(7, 0) -= T(73);
-
-        w->block_last_index[0] = FFMAX(w->block_last_index[0], 7);
         break;
     }
 #undef B
@@ -599,10 +593,7 @@ static int x8_decode_intra_mb(IntraX8Context *const w, const int chroma)
 
             w->block[0][scantable[pos]] = level;
         } while (!final);
-
-        w->block_last_index[0] = pos;
     } else { // DC only
-        w->block_last_index[0] = 0;
         if (w->flat_dc && ((unsigned) (dc_level + 1)) < 3) { // [-1; 1]
             int32_t divide_quant = !chroma ? w->divide_quant_dc_luma
                                            : w->divide_quant_dc_chroma;
@@ -633,7 +624,6 @@ static int x8_decode_intra_mb(IntraX8Context *const w, const int chroma)
          * -> 01'10' 10'10' 00'00' 00'01' 01'11' 11'00 => 0x6A017C */
         direction = (0x6A017C >> (w->orient * 2)) & 3;
         if (direction != 3) {
-            // modify block_last[]
             x8_ac_compensation(w, direction, w->block[0][0]);
         }
     }
@@ -689,7 +679,6 @@ static void x8_init_block_index(IntraX8Context *w, AVFrame *frame)
 av_cold int ff_intrax8_common_init(AVCodecContext *avctx,
                                    IntraX8Context *w,
                                    int16_t (*block)[64],
-                                   int block_last_index[12],
                                    int mb_width, int mb_height)
 {
     static AVOnce init_static_once = AV_ONCE_INIT;
@@ -698,7 +687,6 @@ av_cold int ff_intrax8_common_init(AVCodecContext *avctx,
     w->mb_width  = mb_width;
     w->mb_height = mb_height;
     w->block = block;
-    w->block_last_index = block_last_index;
 
     // two rows, 2 blocks per cannon mb
     w->prediction_table = av_mallocz(w->mb_width * 2 * 2);

libavcodec/intrax8.h

@@ -38,7 +38,6 @@ typedef struct IntraX8Context {
     WMV2DSPContext wdsp;
     uint8_t idct_permutation[64];
     AVCodecContext *avctx;
-    int *block_last_index;  ///< last nonzero coefficient in block
     int16_t (*block)[64];
 
     // set by the caller codec
@@ -77,7 +76,6 @@ typedef struct IntraX8Context {
  * @param avctx pointer to AVCodecContext
  * @param w pointer to IntraX8Context
  * @param block pointer to block array
- * @param block_last_index pointer to index array
  * @param mb_width macroblock width
  * @param mb_height macroblock height
  * @return 0 on success, a negative AVERROR value on error
@@ -85,7 +83,6 @@ typedef struct IntraX8Context {
 int ff_intrax8_common_init(AVCodecContext *avctx,
                            IntraX8Context *w,
                            int16_t (*block)[64],
-                           int block_last_index[12],
                            int mb_width, int mb_height);
 
 /**

libavcodec/vc1dec.c

@@ -422,8 +422,7 @@ static av_cold int vc1_decode_init_alloc_tables(VC1Context *v)
                 return AVERROR(ENOMEM);
     }
 
-    ret = ff_intrax8_common_init(s->avctx, &v->x8,
+    ret = ff_intrax8_common_init(s->avctx, &v->x8, s->block,
-                                 s->block, s->block_last_index,
                                  s->mb_width, s->mb_height);
     if (ret < 0)
         return ret;

libavcodec/wmv2dec.c

@@ -575,8 +575,7 @@ static av_cold int wmv2_decode_init(AVCodecContext *avctx)
 
     decode_ext_header(w);
 
-    return ff_intrax8_common_init(avctx, &w->x8,
+    return ff_intrax8_common_init(avctx, &w->x8, w->s.block,
-                                  w->s.block, w->s.block_last_index,
                                   w->s.mb_width, w->s.mb_height);
 }