hwcontext_vulkan: convert to general layout and transfer queue when exporting

The specs note that images should be in the GENERAL layout when exporting
for maximum compatibility.
CUDA exported images are handled differently, and the queue is the same,
so we don't need to do that there.

libavutil/hwcontext_vulkan.c

@@ -1225,12 +1225,14 @@ static int alloc_bind_mem(AVHWFramesContext *hwfc, AVVkFrame *f,
 enum PrepMode {
     PREP_MODE_WRITE,
     PREP_MODE_RO_SHADER,
+    PREP_MODE_EXTERNAL_EXPORT,
 };
 
 static int prepare_frame(AVHWFramesContext *hwfc, VulkanExecCtx *ectx,
                          AVVkFrame *frame, enum PrepMode pmode)
 {
     VkResult ret;
+    uint32_t dst_qf;
     VkImageLayout new_layout;
     VkAccessFlags new_access;
     AVHWDeviceContext *ctx = hwfc->device_ctx;
@@ -1244,6 +1246,8 @@ static int prepare_frame(AVHWFramesContext *hwfc, VulkanExecCtx *ectx,
         .flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT,
     };
 
+    VkPipelineStageFlagBits wait_st = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
+
     VkSubmitInfo s_info = {
         .sType                = VK_STRUCTURE_TYPE_SUBMIT_INFO,
         .commandBufferCount   = 1,
@@ -1257,10 +1261,20 @@ static int prepare_frame(AVHWFramesContext *hwfc, VulkanExecCtx *ectx,
     case PREP_MODE_WRITE:
         new_layout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
         new_access = VK_ACCESS_TRANSFER_WRITE_BIT;
+        dst_qf     = VK_QUEUE_FAMILY_IGNORED;
         break;
     case PREP_MODE_RO_SHADER:
         new_layout = VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL;
         new_access = VK_ACCESS_TRANSFER_READ_BIT;
+        dst_qf     = VK_QUEUE_FAMILY_IGNORED;
+        break;
+    case PREP_MODE_EXTERNAL_EXPORT:
+        new_layout = VK_IMAGE_LAYOUT_GENERAL;
+        new_access = VK_ACCESS_MEMORY_READ_BIT | VK_ACCESS_MEMORY_WRITE_BIT;
+        dst_qf     = VK_QUEUE_FAMILY_EXTERNAL_KHR;
+        s_info.pWaitSemaphores = &frame->sem;
+        s_info.pWaitDstStageMask = &wait_st;
+        s_info.waitSemaphoreCount = 1;
         break;
     }
 
@@ -1278,7 +1292,7 @@ static int prepare_frame(AVHWFramesContext *hwfc, VulkanExecCtx *ectx,
         img_bar[i].oldLayout = frame->layout[i];
         img_bar[i].newLayout = new_layout;
         img_bar[i].srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
-        img_bar[i].dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
+        img_bar[i].dstQueueFamilyIndex = dst_qf;
         img_bar[i].image = frame->img[i];
         img_bar[i].subresourceRange.levelCount = 1;
         img_bar[i].subresourceRange.layerCount = 1;
@@ -2288,6 +2302,10 @@ static int vulkan_map_to_drm(AVHWFramesContext *hwfc, AVFrame *dst,
     if (!drm_desc)
         return AVERROR(ENOMEM);
 
+    err = prepare_frame(hwfc, &p->cmd, f, PREP_MODE_EXTERNAL_EXPORT);
+    if (err < 0)
+        goto end;
+
     err = ff_hwframe_map_create(src->hw_frames_ctx, dst, src, &vulkan_unmap_to_drm, drm_desc);
     if (err < 0)
         goto end;