vkdownload: implement decide_allocation virtual method

In the case of caps change such as frame size, a new buffer pool should be
created according to this new caps via the decide_allocation() vmethod.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8931>

subprojects/gst-plugins-bad/ext/vulkan/vkdownload.c

@@ -83,7 +83,6 @@ struct ImageToRawDownload
   GstVideoInfo out_info;
 
   GstBufferPool *pool;
-  gboolean pool_active;
 
   GstVulkanOperation *exec;
 };
@@ -138,6 +137,61 @@ _image_to_raw_propose_allocation (gpointer impl, GstQuery * decide_query,
   /* FIXME: implement */
 }
 
+static gboolean
+_image_to_raw_decide_allocation (gpointer impl, GstQuery * query)
+{
+  struct ImageToRawDownload *raw = impl;
+  GstStructure *config;
+  guint min = 1, max = 0, size = 1;
+  GstCaps *caps;
+  gboolean update_pool = FALSE;
+  GstBufferPool *pool = NULL;
+
+  gst_query_parse_allocation (query, &caps, NULL);
+  if (!caps)
+    return FALSE;
+
+  if (gst_query_get_n_allocation_pools (query) > 0) {
+    gst_query_parse_nth_allocation_pool (query, 0, &pool, &size, &min, &max);
+    if (GST_IS_VULKAN_BUFFER_POOL (pool)) {
+      update_pool = TRUE;
+    } else {
+      gst_clear_object (&pool);
+    }
+  }
+
+  /* let's null current pool */
+  gst_clear_object (&raw->pool);
+
+  if (!pool) {
+    pool = gst_vulkan_buffer_pool_new (raw->download->device);
+  }
+
+  config = gst_buffer_pool_get_config (pool);
+
+  gst_buffer_pool_config_set_params (config, raw->download->out_caps, size,
+      min, max);
+  if (gst_query_find_allocation_meta (query, GST_VIDEO_META_API_TYPE, NULL)) {
+    gst_buffer_pool_config_add_option (config,
+        GST_BUFFER_POOL_OPTION_VIDEO_META);
+  }
+
+  if (!gst_buffer_pool_set_config (pool, config)) {
+    gst_clear_object (&pool);
+    GST_ERROR_OBJECT (raw->download, "Failed to set buffer pool config");
+    return FALSE;
+  }
+
+  if (update_pool)
+    gst_query_set_nth_allocation_pool (query, 0, pool, size, min, max);
+  else
+    gst_query_add_allocation_pool (query, pool, size, min, max);
+
+  raw->pool = pool;
+
+  return TRUE;
+}
+
 static GstFlowReturn
 _image_to_raw_perform (gpointer impl, GstBuffer * inbuf, GstBuffer ** outbuf)
 {
@@ -161,22 +215,13 @@ _image_to_raw_perform (gpointer impl, GstBuffer * inbuf, GstBuffer ** outbuf)
   }
 
   if (!raw->pool) {
-    GstStructure *config;
-    guint min = 0, max = 0;
-    gsize size = 1;
-
-    raw->pool = gst_vulkan_buffer_pool_new (raw->download->device);
-    config = gst_buffer_pool_get_config (raw->pool);
-    gst_buffer_pool_config_set_params (config, raw->download->out_caps, size,
-        min, max);
-    if (!gst_buffer_pool_set_config (raw->pool, config)) {
-      gst_clear_object (&raw->pool);
-      return GST_FLOW_ERROR;
-    }
+    GST_ERROR_OBJECT (raw->download, "No pool found.");
+    goto error;
   }
-  if (!raw->pool_active) {
-    gst_buffer_pool_set_active (raw->pool, TRUE);
-    raw->pool_active = TRUE;
+
+  if (!gst_buffer_pool_set_active (raw->pool, TRUE)) {
+    GST_ERROR_OBJECT (raw->download, "Couldn't activate pool.");
+    goto error;
   }
 
   if ((ret =
@@ -321,10 +366,7 @@ _image_to_raw_free (gpointer impl)
   struct ImageToRawDownload *raw = impl;
 
   if (raw->pool) {
-    if (raw->pool_active) {
-      gst_buffer_pool_set_active (raw->pool, FALSE);
-    }
-    raw->pool_active = FALSE;
+    gst_buffer_pool_set_active (raw->pool, FALSE);
     gst_object_unref (raw->pool);
     raw->pool = NULL;
   }
@@ -346,6 +388,7 @@ static const struct DownloadMethod image_to_raw_download = {
   _image_to_raw_transform_caps,
   _image_to_raw_set_caps,
   _image_to_raw_propose_allocation,
+  _image_to_raw_decide_allocation,
   _image_to_raw_perform,
   _image_to_raw_free,
 };
@@ -756,7 +799,40 @@ gst_vulkan_download_propose_allocation (GstBaseTransform * bt,
 static gboolean
 gst_vulkan_download_decide_allocation (GstBaseTransform * bt, GstQuery * query)
 {
-  return TRUE;
+  GstVulkanDownload *vk_download = GST_VULKAN_DOWNLOAD (bt);
+  guint i;
+  gboolean ret = TRUE;
+
+  for (i = 0; i < G_N_ELEMENTS (download_methods); i++) {
+    GstCaps *templ;
+    gboolean res;
+
+    templ = gst_static_caps_get (download_methods[i]->in_template);
+    if (!gst_caps_can_intersect (vk_download->in_caps, templ)) {
+      gst_caps_unref (templ);
+      continue;
+    }
+    gst_caps_unref (templ);
+
+    templ = gst_static_caps_get (download_methods[i]->out_template);
+    if (!gst_caps_can_intersect (vk_download->out_caps, templ)) {
+      gst_caps_unref (templ);
+      continue;
+    }
+    gst_caps_unref (templ);
+
+    res =
+        download_methods[i]->decide_allocation (vk_download->download_impls[i],
+        query);
+
+    /* if all methods fail, function fails */
+    if (i == 0)
+      ret = res;
+    else
+      ret |= res;
+  }
+
+  return ret;
 }
 
 static gboolean

subprojects/gst-plugins-bad/ext/vulkan/vkdownload.h

@@ -53,6 +53,8 @@ struct DownloadMethod
   void              (*propose_allocation)       (gpointer impl,
                                                  GstQuery * decide_query,
                                                  GstQuery * query);
+  gboolean          (*decide_allocation)        (gpointer impl,
+                                                 GstQuery * decide_query);
   GstFlowReturn     (*perform)                  (gpointer impl,
                                                  GstBuffer * buffer,
                                                  GstBuffer ** outbuf);