avcodec/svq1dec: Make decoder init-threadsafe

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/svq1dec.c

@@ -33,6 +33,7 @@
  */
 
 #include "libavutil/crc.h"
+#include "libavutil/thread.h"
 
 #include "avcodec.h"
 #include "get_bits.h"
@@ -762,22 +763,8 @@ err:
     return result;
 }
 
-static av_cold int svq1_decode_init(AVCodecContext *avctx)
+static av_cold void svq1_static_init(void)
 {
-    SVQ1Context *s = avctx->priv_data;
-    int i;
-    int offset = 0;
-
-    s->prev = av_frame_alloc();
-    if (!s->prev)
-        return AVERROR(ENOMEM);
-
-    s->width            = avctx->width  + 3 & ~3;
-    s->height           = avctx->height + 3 & ~3;
-    avctx->pix_fmt      = AV_PIX_FMT_YUV410P;
-
-    ff_hpeldsp_init(&s->hdsp, avctx->flags);
-
     INIT_VLC_STATIC(&svq1_block_type, 2, 4,
                     &ff_svq1_block_type_vlc[0][1], 2, 1,
                     &ff_svq1_block_type_vlc[0][0], 2, 1, 6);
@@ -786,7 +773,7 @@ static av_cold int svq1_decode_init(AVCodecContext *avctx)
                     &ff_mvtab[0][1], 2, 1,
                     &ff_mvtab[0][0], 2, 1, 176);
 
-    for (i = 0; i < 6; i++) {
+    for (int i = 0, offset = 0; i < 6; i++) {
         static const uint8_t sizes[2][6] = { { 14, 10, 14, 18, 16, 18 },
                                              { 10, 10, 14, 14, 14, 16 } };
         static VLC_TYPE table[168][2];
@@ -813,6 +800,24 @@ static av_cold int svq1_decode_init(AVCodecContext *avctx)
     INIT_VLC_STATIC(&svq1_inter_mean, 9, 512,
                     &ff_svq1_inter_mean_vlc[0][1], 4, 2,
                     &ff_svq1_inter_mean_vlc[0][0], 4, 2, 1434);
+}
+
+static av_cold int svq1_decode_init(AVCodecContext *avctx)
+{
+    static AVOnce init_static_once = AV_ONCE_INIT;
+    SVQ1Context *s = avctx->priv_data;
+
+    s->prev = av_frame_alloc();
+    if (!s->prev)
+        return AVERROR(ENOMEM);
+
+    s->width            = avctx->width  + 3 & ~3;
+    s->height           = avctx->height + 3 & ~3;
+    avctx->pix_fmt      = AV_PIX_FMT_YUV410P;
+
+    ff_hpeldsp_init(&s->hdsp, avctx->flags);
+
+    ff_thread_once(&init_static_once, svq1_static_init);
 
     return 0;
 }
@@ -848,4 +853,5 @@ AVCodec ff_svq1_decoder = {
     .flush          = svq1_flush,
     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV410P,
                                                      AV_PIX_FMT_NONE },
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };