vdpau: add av_vdpau_bind_context()

This function provides an explicit VDPAU device and VDPAU driver to
libavcodec, so that the application is relieved from codec specifics
and VdpDevice life cycle management.

A stub flags parameter is added for future extension. For instance, it
could be used to ignore codec level capabilities (if someone feels
dangerous).
Signed-off-by: Anton Khirnov <anton@khirnov.net>

doc/APIchanges

@@ -13,6 +13,10 @@ libavutil:     2014-08-09
 
 API changes, most recent first:
 
+2014-09-xx - xxxxxxx - lavc 56.2.0 - vdpau.h
+  Add av_vdpau_bind_context(). This function should now be used for creating
+  (or resetting) a AVVDPAUContext instead of av_vdpau_alloc_context().
+
 2014-08-xx - xxxxxxx - lavc 56.1.0 - avcodec.h
   Add AV_PKT_DATA_STEREO3D to export container-level stereo3d information.
 

libavcodec/vdpau.c

@@ -78,6 +78,7 @@ int ff_vdpau_common_init(AVCodecContext *avctx, VdpDecoderProfile profile,
 
     vdctx->width            = UINT32_MAX;
     vdctx->height           = UINT32_MAX;
+    hwctx->reset            = 0;
 
     if (hwctx->context.decoder != VDP_INVALID_HANDLE) {
         vdctx->decoder = hwctx->context.decoder;
@@ -138,12 +139,13 @@ int ff_vdpau_common_uninit(AVCodecContext *avctx)
 
 static int ff_vdpau_common_reinit(AVCodecContext *avctx)
 {
+    VDPAUHWContext *hwctx = avctx->hwaccel_context;
     VDPAUContext *vdctx = avctx->internal->hwaccel_priv_data;
 
     if (vdctx->device == VDP_INVALID_HANDLE)
         return 0; /* Decoder created by user */
     if (avctx->coded_width == vdctx->width &&
-        avctx->coded_height == vdctx->height)
+        avctx->coded_height == vdctx->height && !hwctx->reset)
         return 0;
 
     avctx->hwaccel->uninit(avctx);
@@ -266,4 +268,22 @@ AVVDPAUContext *av_vdpau_alloc_context(void)
     return av_mallocz(sizeof(AVVDPAUContext));
 }
 
+int av_vdpau_bind_context(AVCodecContext *avctx, VdpDevice device,
+                          VdpGetProcAddress *get_proc, unsigned flags)
+{
+    VDPAUHWContext *hwctx;
+
+    if (av_reallocp(&avctx->hwaccel_context, sizeof(*hwctx)))
+        return AVERROR(ENOMEM);
+
+    hwctx = avctx->hwaccel_context;
+
+    memset(hwctx, 0, sizeof(*hwctx));
+    hwctx->context.decoder  = VDP_INVALID_HANDLE;
+    hwctx->device           = device;
+    hwctx->get_proc_address = get_proc;
+    hwctx->reset            = 1;
+    return 0;
+}
+
 /* @}*/

libavcodec/vdpau.h

@@ -130,6 +130,26 @@ typedef struct AVVDPAUContext {
 #endif
 } AVVDPAUContext;
 
+/**
+ * Associate a VDPAU device with a codec context for hardware acceleration.
+ * This function is meant to be called from the get_format() codec callback,
+ * or earlier. It can also be called after avcodec_flush_buffers() to change
+ * the underlying VDPAU device mid-stream (e.g. to recover from non-transparent
+ * display preemption).
+ *
+ * @note get_format() must return AV_PIX_FMT_VDPAU if this function completes
+ * succesfully.
+ *
+ * @param avctx decoding context whose get_format() callback is invoked
+ * @param device VDPAU device handle to use for hardware acceleration
+ * @param get_proc_address VDPAU device driver
+ * @param flags for future use, must be zero
+ *
+ * @return 0 on success, an AVERROR code on failure.
+ */
+int av_vdpau_bind_context(AVCodecContext *avctx, VdpDevice device,
+                          VdpGetProcAddress *get_proc_address, unsigned flags);
+
 /**
  * Allocate an AVVDPAUContext.
  *

libavcodec/vdpau_internal.h

@@ -52,6 +52,7 @@ typedef struct VDPAUHWContext {
     AVVDPAUContext context;
     VdpDevice device;
     VdpGetProcAddress *get_proc_address;
+    char reset;
 } VDPAUHWContext;
 
 typedef struct VDPAUContext {

libavcodec/version.h

@@ -29,7 +29,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 56
-#define LIBAVCODEC_VERSION_MINOR  1
+#define LIBAVCODEC_VERSION_MINOR  2
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \