avcodec/mpegvideo: Move parent to MPVEncContext

This is more type-safe and avoids having parent contexts
when unnecessary.

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

libavcodec/mpegvideo.c

@@ -142,8 +142,6 @@ av_cold int ff_mpv_init_duplicate_contexts(MpegEncContext *s)
     int nb_slices = s->slice_context_count, ret;
     size_t slice_size = s->slice_ctx_size ? s->slice_ctx_size : sizeof(*s);
 
-    s->parent = s;
-
     /* We initialize the copies before the original so that
      * fields allocated in init_duplicate_context are NULL after
      * copying. This prevents double-frees upon allocation error. */

libavcodec/mpegvideo.h

@@ -80,10 +80,6 @@ typedef struct MpegEncContext {
     uint8_t permutated_intra_v_scantable[64];
 
     struct AVCodecContext *avctx;
-    union {
-        const struct MpegEncContext *parent;
-        const struct MPVMainEncContext *encparent;
-    };
     /* The following pointer is intended for codecs sharing code
      * between decoder and encoder and in need of a common context to do so. */
     void *private_ctx;

libavcodec/mpegvideo_enc.c

@@ -1024,6 +1024,7 @@ av_cold int ff_mpv_encode_init(AVCodecContext *avctx)
     /* ff_mpv_common_init() will copy (memdup) the contents of the main slice
      * to the slice contexts, so we initialize various fields of it
      * before calling ff_mpv_common_init(). */
+    s->parent = m;
     ff_mpv_idct_init(&s->c);
     init_unquantize(&s->c, avctx);
     ff_fdctdsp_init(&s->fdsp, avctx);

libavcodec/mpegvideoenc.h

@@ -69,6 +69,8 @@ typedef struct MPVEncContext {
      */
     AVFrame *new_pic;
 
+    struct MPVMainEncContext *parent;
+
     FDCTDSPContext fdsp;
     MpegvideoEncDSPContext mpvencdsp;
     PixblockDSPContext pdsp;
@@ -254,7 +256,7 @@ static inline const MPVMainEncContext *slice_to_mainenc(const MPVEncContext *s)
                !(s->c.avctx->codec->capabilities & AV_CODEC_CAP_SLICE_THREADS));
     return (const MPVMainEncContext*)s;
 #else
-    return s->c.encparent;
+    return s->parent;
 #endif
 }