[FFmpeg-devel] [PATCH] libavcodec/vp8dec: fix the multi-thread HWAccel decode error

[Jun Zhao]

the root cause is update_dimentions call get_pixel_format will
trigger the hwaccel_uninit/hwaccel_init , in current context,
there are 3 situations in the update_dimentions():
1. First time calling. No matter single thread or multithread,
   get_pixel_format() should be called after dimentions were
   set;
2. Dimention changed at the runtime. Dimention need to be
   updated when macroblocks_base is already allocated,
   get_pixel_format() should be called to recreate new frames
   according to updated dimention;
3. Multithread first time calling. After decoder init, the
   other threads will call update_dimentions() at first time
   to allocate macroblocks_base and set dimentions.
   But get_pixel_format() is shouldn't be called due to low
   level frames and context are already created.
In this fix, we only call update_dimentions as need.

Signed-off-by: Wang, Shaofei <shaofei.wang at intel.com>
Reviewed-by: Jun, Zhao <jun.zhao at intel.com>
---
 libavcodec/vp8.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavcodec/vp8.c b/libavcodec/vp8.c
index 3adfeac..18d1ada 100644
--- a/libavcodec/vp8.c
+++ b/libavcodec/vp8.c
@@ -187,7 +187,7 @@ static av_always_inline
 int update_dimensions(VP8Context *s, int width, int height, int is_vp7)
 {
     AVCodecContext *avctx = s->avctx;
-    int i, ret;
+    int i, ret, dim_reset = 0;
 
     if (width  != s->avctx->width || ((width+15)/16 != s->mb_width || (height+15)/16 != s->mb_height) && s->macroblocks_base ||
         height != s->avctx->height) {
@@ -196,9 +196,12 @@ int update_dimensions(VP8Context *s, int width, int height, int is_vp7)
         ret = ff_set_dimensions(s->avctx, width, height);
         if (ret < 0)
             return ret;
+
+        dim_reset = (s->macroblocks_base != NULL);
     }
 
-    if (!s->actually_webp && !is_vp7) {
+    if ((s->pix_fmt == AV_PIX_FMT_NONE || dim_reset) &&
+         !s->actually_webp && !is_vp7) {
         s->pix_fmt = get_pixel_format(s);
         if (s->pix_fmt < 0)
             return AVERROR(EINVAL);
-- 
1.7.1