video: have a generic context struct for hwdec backends

Before this commit, each hw backend had their own specific struct types
for context, and some, like VDA, had none at all. Add a context struct
(mp_hwdec_ctx) that provides a somewhat generic way to pass the hwdec
context around. Some things get slightly better, some slightly more
verbose.

mp_hwdec_info is still around; it's still needed, but is reduced to its
role of handling delayed loading of the hwdec backend.

1 files changed, 15 insertions, 3 deletions

diff --git a/video/hwdec.h b/video/hwdec.h
index ca18340ae1..149cd81bae 100644
--- a/video/hwdec.h
+++ b/video/hwdec.h
@@ -1,14 +1,26 @@
 #ifndef MP_HWDEC_H_
 #define MP_HWDEC_H_
 
+struct mp_image_pool;
+
+struct mp_hwdec_ctx {
+    void *priv; // for free use by hwdec implementation
+
+    // API-specific, not needed by all backends.
+    struct mp_vdpau_ctx *vdpau_ctx;
+    struct mp_vaapi_ctx *vaapi_ctx;
+};
+
 // Used to communicate hardware decoder API handles from VO to video decoder.
 // The VO can set the context pointer for supported APIs.
 struct mp_hwdec_info {
-    struct mp_vdpau_ctx *vdpau_ctx;
-    struct mp_vaapi_ctx *vaapi_ctx;
+    // (Since currently only 1 hwdec API is loaded at a time, this pointer
+    // simply maps to the loaded one.)
+    struct mp_hwdec_ctx *hwctx;
+
     // Can be used to lazily load a requested API.
     // api_name is e.g. "vdpau" (like the fields above, without "_ctx")
-    // Can be NULL, is idempotent, caller checks _ctx fields for success/access.
+    // Can be NULL, is idempotent, caller checks hwctx fields for success/access.
     // Due to threading, the callback is the only code that is allowed to
     // change fields in this struct after initialization.
     void (*load_api)(struct mp_hwdec_info *info, const char *api_name);