lavc: Add hwaccel_flags field to AVCodecContext

This "reuses" the flags introduced for the av_vdpau_bind_context() API
function, and makes them available to all hwaccels. This does not affect
the current vdpau API, as av_vdpau_bind_context() should obviously
override the AVCodecContext.hwaccel_flags flags for the sake of
compatibility.

doc/APIchanges

@@ -13,6 +13,10 @@ libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2017-03-xx - xxxxxxx - lavc 57.37.0 - avcodec.h
+  Add AVCodecContext.hwaccel_flags field. This will control some hwaccels at
+  a later point.
+
 2017-03-xx - xxxxxxx - lavu 55.35.0 - hwcontext.h
   Add AV_HWDEVICE_TYPE_NONE, av_hwdevice_find_type_by_name(),
   av_hwdevice_get_type_name() and av_hwdevice_iterate_types().

libavcodec/avcodec.h

@@ -3186,6 +3186,15 @@ typedef struct AVCodecContext {
      * contexts used must be created on the same device.
      */
     AVBufferRef *hw_device_ctx;
+
+    /**
+     * Bit set of AV_HWACCEL_FLAG_* flags, which affect hardware accelerated
+     * decoding (if active).
+     * - encoding: unused
+     * - decoding: Set by user (either before avcodec_open2(), or in the
+     *             AVCodecContext.get_format callback)
+     */
+    int hwaccel_flags;
 } AVCodecContext;
 
 /**

libavcodec/pthread_frame.c

@@ -270,6 +270,8 @@ FF_ENABLE_DEPRECATION_WARNINGS
                     return AVERROR(ENOMEM);
             }
         }
+
+        dst->hwaccel_flags = src->hwaccel_flags;
     }
 
     if (for_user) {

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 57
-#define LIBAVCODEC_VERSION_MINOR 36
+#define LIBAVCODEC_VERSION_MINOR 37
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \