vulkan: add a ff_vk_init function

This function sets the class correctly, and calls functions
that all users have to call anyway.

libavutil/vulkan.c

@@ -22,6 +22,7 @@
 #include "mem.h"
 
 #include "vulkan.h"
+#include "libavutil/vulkan_loader.h"
 
 const VkComponentMapping ff_comp_identity_map = {
     .r = VK_COMPONENT_SWIZZLE_IDENTITY,
@@ -816,7 +817,7 @@ int ff_vk_alloc_mem(FFVulkanContext *s, VkMemoryRequirements *req,
     }
 
     if (index < 0) {
-        av_log(s->device, AV_LOG_ERROR, "No memory type found for flags 0x%x\n",
+        av_log(s, AV_LOG_ERROR, "No memory type found for flags 0x%x\n",
                req_flags);
         return AVERROR(EINVAL);
     }
@@ -1868,5 +1869,59 @@ void ff_vk_uninit(FFVulkanContext *s)
     av_freep(&s->video_props);
     av_freep(&s->coop_mat_props);
 
+    av_buffer_unref(&s->device_ref);
     av_buffer_unref(&s->frames_ref);
 }
+
+int ff_vk_init(FFVulkanContext *s, void *log_parent,
+               AVBufferRef *device_ref, AVBufferRef *frames_ref)
+{
+    int err;
+
+    static const AVClass vulkan_context_class = {
+        .class_name       = "vk",
+        .version          = LIBAVUTIL_VERSION_INT,
+        .parent_log_context_offset = offsetof(FFVulkanContext, log_parent),
+    };
+
+    memset(s, 0, sizeof(*s));
+    s->log_parent = log_parent;
+    s->class      = &vulkan_context_class;
+
+    if (frames_ref) {
+        s->frames_ref = av_buffer_ref(frames_ref);
+        if (!s->frames_ref)
+            return AVERROR(ENOMEM);
+
+        s->frames = (AVHWFramesContext *)s->frames_ref->data;
+        s->hwfc = s->frames->hwctx;
+
+        device_ref = s->frames->device_ref;
+    }
+
+    s->device_ref = av_buffer_ref(device_ref);
+    if (!s->device_ref) {
+        ff_vk_uninit(s);
+        return AVERROR(ENOMEM);
+    }
+
+    s->device = (AVHWDeviceContext *)s->device_ref->data;
+    s->hwctx = s->device->hwctx;
+
+    s->extensions = ff_vk_extensions_to_mask(s->hwctx->enabled_dev_extensions,
+                                             s->hwctx->nb_enabled_dev_extensions);
+
+    err = ff_vk_load_functions(s->device, &s->vkfn, s->extensions, 1, 1);
+    if (err < 0) {
+        ff_vk_uninit(s);
+        return err;
+    }
+
+    err = ff_vk_load_props(s);
+    if (err < 0) {
+        ff_vk_uninit(s);
+        return err;
+    }
+
+    return 0;
+}

libavutil/vulkan.h

@@ -227,7 +227,8 @@ typedef struct FFVkExecPool {
 } FFVkExecPool;
 
 typedef struct FFVulkanContext {
-    const AVClass *class; /* Filters and encoders use this */
+    const AVClass *class;
+    void *log_parent;
 
     FFVulkanFunctions     vkfn;
     FFVulkanExtensions    extensions;
@@ -251,6 +252,7 @@ typedef struct FFVulkanContext {
     VkPhysicalDeviceVulkan12Features feats_12;
     VkPhysicalDeviceFeatures2 feats;
 
+    AVBufferRef           *device_ref;
     AVHWDeviceContext     *device;
     AVVulkanDeviceContext *hwctx;
 
@@ -303,6 +305,14 @@ static inline void ff_vk_link_struct(void *chain, const void *in)
 /* Identity mapping - r = r, b = b, g = g, a = a */
 extern const VkComponentMapping ff_comp_identity_map;
 
+/**
+ * Initializes the AVClass, in case this context is not used
+ * as the main user's context.
+ * May use either a frames context reference, or a device context reference.
+ */
+int ff_vk_init(FFVulkanContext *s, void *log_parent,
+               AVBufferRef *device_ref, AVBufferRef *frames_ref);
+
 /**
  * Converts Vulkan return values to strings
  */