From a853a5d294c3847fccc22ba0655335f64f13ce16 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Thu, 19 May 2016 15:59:25 +0200
Subject: hwcontext: add a function for opening devices

---
 doc/APIchanges                 |  3 +++
 libavutil/hwcontext.c          | 36 ++++++++++++++++++++++++++++++++++++
 libavutil/hwcontext.h          | 28 ++++++++++++++++++++++++++++
 libavutil/hwcontext_internal.h |  3 +++
 libavutil/version.h            |  2 +-
 5 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index 8f6cdca467..a69899fa0d 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -13,6 +13,9 @@ libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2016-xx-xx - xxxxxxx - lavu 55.13.0 - hwcontext.h
+  Add av_hwdevice_ctx_create().
+
 2016-xx-xx - xxxxxxx - lavf 57.7.0 - avio.h
   Add AVIODataMarkerType, write_data_type, ignore_boundary_point and
   avio_write_marker.
diff --git a/libavutil/hwcontext.c b/libavutil/hwcontext.c
index 2ddae90f10..3028b67a6c 100644
--- a/libavutil/hwcontext.c
+++ b/libavutil/hwcontext.c
@@ -452,3 +452,39 @@ void av_hwframe_constraints_free(AVHWFramesConstraints **constraints)
     }
     av_freep(constraints);
 }
+
+int av_hwdevice_ctx_create(AVBufferRef **pdevice_ref, enum AVHWDeviceType type,
+                           const char *device, AVDictionary *opts, int flags)
+{
+    AVBufferRef *device_ref = NULL;
+    AVHWDeviceContext *device_ctx;
+    int ret = 0;
+
+    device_ref = av_hwdevice_ctx_alloc(type);
+    if (!device_ref) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    device_ctx = (AVHWDeviceContext*)device_ref->data;
+
+    if (!device_ctx->internal->hw_type->device_create) {
+        ret = AVERROR(ENOSYS);
+        goto fail;
+    }
+
+    ret = device_ctx->internal->hw_type->device_create(device_ctx, device,
+                                                       opts, flags);
+    if (ret < 0)
+        goto fail;
+
+    ret = av_hwdevice_ctx_init(device_ref);
+    if (ret < 0)
+        goto fail;
+
+    *pdevice_ref = device_ref;
+    return 0;
+fail:
+    av_buffer_unref(&device_ref);
+    *pdevice_ref = NULL;
+    return ret;
+}
diff --git a/libavutil/hwcontext.h b/libavutil/hwcontext.h
index 505b1748be..d8e7c3f090 100644
--- a/libavutil/hwcontext.h
+++ b/libavutil/hwcontext.h
@@ -241,6 +241,34 @@ AVBufferRef *av_hwdevice_ctx_alloc(enum AVHWDeviceType type);
  */
 int av_hwdevice_ctx_init(AVBufferRef *ref);
 
+/**
+ * Open a device of the specified type and create an AVHWDeviceContext for it.
+ *
+ * This is a convenience function intended to cover the simple cases. Callers
+ * who need to fine-tune device creation/management should open the device
+ * manually and then wrap it in an AVHWDeviceContext using
+ * av_hwdevice_ctx_alloc()/av_hwdevice_ctx_init().
+ *
+ * The returned context is already initialized and ready for use, the caller
+ * should not call av_hwdevice_ctx_init() on it. The user_opaque/free fields of
+ * the created AVHWDeviceContext are set by this function and should not be
+ * touched by the caller.
+ *
+ * @param device_ctx On success, a reference to the newly-created device context
+ *                   will be written here. The reference is owned by the caller
+ *                   and must be released with av_buffer_unref() when no longer
+ *                   needed. On failure, NULL will be written to this pointer.
+ * @param type The type of the device to create.
+ * @param device A type-specific string identifying the device to open.
+ * @param opts A dictionary of additional (type-specific) options to use in
+ *             opening the device. The dictionary remains owned by the caller.
+ * @param flags currently unused
+ *
+ * @return 0 on success, a negative AVERROR code on failure.
+ */
+int av_hwdevice_ctx_create(AVBufferRef **device_ctx, enum AVHWDeviceType type,
+                           const char *device, AVDictionary *opts, int flags);
+
 /**
  * Allocate an AVHWFramesContext tied to a given device context.
  *
diff --git a/libavutil/hwcontext_internal.h b/libavutil/hwcontext_internal.h
index 281eae892b..2e1daaeeeb 100644
--- a/libavutil/hwcontext_internal.h
+++ b/libavutil/hwcontext_internal.h
@@ -64,6 +64,9 @@ typedef struct HWContextType {
      */
     size_t             frames_priv_size;
 
+    int              (*device_create)(AVHWDeviceContext *ctx, const char *device,
+                                      AVDictionary *opts, int flags);
+
     int              (*device_init)(AVHWDeviceContext *ctx);
     void             (*device_uninit)(AVHWDeviceContext *ctx);
 
diff --git a/libavutil/version.h b/libavutil/version.h
index 4cee2b0ba1..48a5878325 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -54,7 +54,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 55
-#define LIBAVUTIL_VERSION_MINOR 12
+#define LIBAVUTIL_VERSION_MINOR 13
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
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