From a45d30a67579f00926525ffd23c7a6b5470d77a0 Mon Sep 17 00:00:00 2001
From: Niklas Haas <git@haasn.dev>
Date: Wed, 20 Aug 2025 16:56:22 +0200
Subject: [PATCH] avutil/hwcontext_vulkan: always enable baseline usage flags

The documentation states that this field is for enabling "extra" usage
flags. This conflicts with the implementation, and the rest of the comment,
though.

In resolving this ambiguity, I think it's better to lean towards the first
sentence and treat this field purely as specifying *extra* usage flags to
enable. Otherwise, this may break vulkan encoding or subsequent hwdownload
if the upstream filter did not specifically advertise this.

Change the default behavior and update the documentation slightly to more
clearly document the semantics.
---
 libavutil/hwcontext_vulkan.c | 24 +++++++++++-------------
 libavutil/hwcontext_vulkan.h |  3 ++-
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/libavutil/hwcontext_vulkan.c b/libavutil/hwcontext_vulkan.c
index 286e13c509..ae4b07c698 100644
--- a/libavutil/hwcontext_vulkan.c
+++ b/libavutil/hwcontext_vulkan.c
@@ -2901,21 +2901,19 @@ static int vulkan_frames_init(AVHWFramesContext *hwfc)
         supported_usage &= ~VK_IMAGE_USAGE_HOST_TRANSFER_BIT_EXT;
 
     /* Image usage flags */
-    if (!hwctx->usage) {
-        hwctx->usage = supported_usage & (VK_IMAGE_USAGE_TRANSFER_DST_BIT |
-                                          VK_IMAGE_USAGE_TRANSFER_SRC_BIT |
-                                          VK_IMAGE_USAGE_STORAGE_BIT      |
-                                          VK_IMAGE_USAGE_SAMPLED_BIT);
+    hwctx->usage |= supported_usage & (VK_IMAGE_USAGE_TRANSFER_DST_BIT |
+                                       VK_IMAGE_USAGE_TRANSFER_SRC_BIT |
+                                       VK_IMAGE_USAGE_STORAGE_BIT      |
+                                       VK_IMAGE_USAGE_SAMPLED_BIT);
 
-        if ((p->vkctx.extensions & FF_VK_EXT_HOST_IMAGE_COPY) && !p->disable_host_transfer)
-            hwctx->usage |= supported_usage & VK_IMAGE_USAGE_HOST_TRANSFER_BIT_EXT;
+    if ((p->vkctx.extensions & FF_VK_EXT_HOST_IMAGE_COPY) && !p->disable_host_transfer)
+        hwctx->usage |= supported_usage & VK_IMAGE_USAGE_HOST_TRANSFER_BIT_EXT;
 
-        /* Enables encoding of images, if supported by format and extensions */
-        if ((supported_usage & VK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHR) &&
-            (p->vkctx.extensions & (FF_VK_EXT_VIDEO_ENCODE_QUEUE |
-                                   FF_VK_EXT_VIDEO_MAINTENANCE_1)))
-            hwctx->usage |= VK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHR;
-    }
+    /* Enables encoding of images, if supported by format and extensions */
+    if ((supported_usage & VK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHR) &&
+        (p->vkctx.extensions & (FF_VK_EXT_VIDEO_ENCODE_QUEUE |
+                                FF_VK_EXT_VIDEO_MAINTENANCE_1)))
+        hwctx->usage |= VK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHR;
 
     /* Image creation flags.
      * Only fill them in automatically if the image is not going to be used as
diff --git a/libavutil/hwcontext_vulkan.h b/libavutil/hwcontext_vulkan.h
index 15cf515668..0bb536ab3f 100644
--- a/libavutil/hwcontext_vulkan.h
+++ b/libavutil/hwcontext_vulkan.h
@@ -218,7 +218,8 @@ typedef struct AVVulkanFramesContext {
 
     /**
      * Defines extra usage of output frames. If non-zero, all flags MUST be
-     * supported by the VkFormat. Otherwise, will use supported flags amongst:
+     * supported by the VkFormat. Regardless, frames will always have the
+     * following usage flags enabled, if supported by the format:
      * - VK_IMAGE_USAGE_SAMPLED_BIT
      * - VK_IMAGE_USAGE_STORAGE_BIT
      * - VK_IMAGE_USAGE_TRANSFER_SRC_BIT