avcodec/vc1dec: Factor (re)initializing code out

This is in preparation for removing the msmpeg4 dependency
from VC-1.

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

libavcodec/mss2.c

@@ -29,7 +29,6 @@
 #include "error_resilience.h"
 #include "mpeg_er.h"
 #include "mpegvideodec.h"
-#include "msmpeg4dec.h"
 #include "qpeldsp.h"
 #include "vc1.h"
 #include "wmv2data.h"
@@ -852,8 +851,8 @@ static av_cold int wmv9_init(AVCodecContext *avctx)
 
     ff_vc1_init_transposed_scantables(v);
 
-    if ((ret = ff_msmpeg4_decode_init(avctx)) < 0 ||
-        (ret = ff_vc1_decode_init_alloc_tables(v)) < 0)
+    ret = ff_vc1_decode_init(avctx);
+    if (ret < 0)
         return ret;
 
     /* error concealment */

libavcodec/vc1.h

@@ -413,7 +413,7 @@ int ff_vc1_parse_frame_header    (VC1Context *v, GetBitContext *gb);
 int ff_vc1_parse_frame_header_adv(VC1Context *v, GetBitContext *gb);
 void ff_vc1_init_common(VC1Context *v);
 
-int  ff_vc1_decode_init_alloc_tables(VC1Context *v);
+int  ff_vc1_decode_init(AVCodecContext *avctx);
 void ff_vc1_init_transposed_scantables(VC1Context *v);
 int  ff_vc1_decode_end(AVCodecContext *avctx);
 void ff_vc1_decode_blocks(VC1Context *v);

libavcodec/vc1dec.c

@@ -329,7 +329,7 @@ static void vc1_sprite_flush(AVCodecContext *avctx)
 
 #endif
 
-av_cold int ff_vc1_decode_init_alloc_tables(VC1Context *v)
+static av_cold int vc1_decode_init_alloc_tables(VC1Context *v)
 {
     MpegEncContext *s = &v->s;
     int i, ret = AVERROR(ENOMEM);
@@ -404,10 +404,24 @@ av_cold int ff_vc1_decode_init_alloc_tables(VC1Context *v)
     return 0;
 
 error:
-    ff_vc1_decode_end(s->avctx);
     return ret;
 }
 
+av_cold int ff_vc1_decode_init(AVCodecContext *avctx)
+{
+    int ret = ff_msmpeg4_decode_init(avctx);
+    VC1Context *const v = avctx->priv_data;
+    if (ret < 0)
+        return ret;
+
+    ret = vc1_decode_init_alloc_tables(v);
+    if (ret < 0) {
+        ff_vc1_decode_end(avctx);
+        return ret;
+    }
+    return 0;
+}
+
 av_cold void ff_vc1_init_transposed_scantables(VC1Context *v)
 {
     int i;
@@ -947,12 +961,9 @@ static int vc1_decode_frame(AVCodecContext *avctx, AVFrame *pict,
     }
 
     if (!s->context_initialized) {
-        if ((ret = ff_msmpeg4_decode_init(avctx)) < 0)
-            goto err;
-        if ((ret = ff_vc1_decode_init_alloc_tables(v)) < 0) {
-            ff_mpv_common_end(s);
+        ret = ff_vc1_decode_init(avctx);
+        if (ret < 0)
             goto err;
-        }
 
         s->low_delay = !avctx->has_b_frames || v->res_sprite;