[FFmpeg-devel] [PATCH] lavu/hwcontext_vulkan: Support write on drm frame

[Lynne]

On 11/06/2024 06:55, Xiang, Haihao wrote:
> From: Haihao Xiang <haihao.xiang at intel.com>
> 
> Otherwise nothing is written into the destination when a write mapping
> is requested.
> 
> For example, a vulkan frame mapped from a drm frame (which is wrapped as
> a vaapi frame in the example) is used as the output of scale_vulkan
> filter, it always gets a green screen without this patch.
> 
> ffmpeg -init_hw_device vaapi=va -init_hw_device vulkan=vulkan at va
> -filter_hw_device vulkan -f lavfi -i testsrc=size=352x288,format=nv12
> -vf
> "hwupload,scale_vulkan,hwmap=derive_device=vaapi:reverse=1,format=vaapi,hwdownload,format=nv12"
> -f nut - | ffplay -
> 
> Signed-off-by: Haihao Xiang <haihao.xiang at intel.com>
> ---
>   libavutil/hwcontext_vulkan.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/libavutil/hwcontext_vulkan.c b/libavutil/hwcontext_vulkan.c
> index e2f92af227..675ead0ba6 100644
> --- a/libavutil/hwcontext_vulkan.c
> +++ b/libavutil/hwcontext_vulkan.c
> @@ -2511,7 +2511,7 @@ static inline VkFormat drm_to_vulkan_fmt(uint32_t drm_fourcc)
>   }
>   
>   static int vulkan_map_from_drm_frame_desc(AVHWFramesContext *hwfc, AVVkFrame **frame,
> -                                          const AVFrame *src)
> +                                          const AVFrame *src, int flags)
>   {
>       int err = 0;
>       VkResult ret;
> @@ -2569,6 +2569,14 @@ static int vulkan_map_from_drm_frame_desc(AVHWFramesContext *hwfc, AVVkFrame **f
>               .pNext       = &ext_img_mod_spec,
>               .handleTypes = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
>           };
> +        int usage = (((flags & (AV_HWFRAME_MAP_READ | AV_HWFRAME_MAP_WRITE)) == (AV_HWFRAME_MAP_READ | AV_HWFRAME_MAP_WRITE)) ?
> +                      (VK_IMAGE_USAGE_SAMPLED_BIT |
> +                       VK_IMAGE_USAGE_TRANSFER_SRC_BIT |
> +                       VK_IMAGE_USAGE_TRANSFER_DST_BIT |
> +                       VK_IMAGE_USAGE_STORAGE_BIT) :
> +                     ((flags & AV_HWFRAME_MAP_WRITE) ?
> +                      (VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_STORAGE_BIT) :
> +                      (VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT)));

Changed to a more readable:
 > +        if (flags & AV_HWFRAME_MAP_READ)
 > +            create_info.usage |= VK_IMAGE_USAGE_SAMPLED_BIT |
 > +                                 VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
 > +        if (flags & AV_HWFRAME_MAP_WRITE)
 > +            create_info.usage |= VK_IMAGE_USAGE_STORAGE_BIT |
 > +                                 VK_IMAGE_USAGE_TRANSFER_DST_BIT;

By filling it down below.

>           VkImageCreateInfo create_info = {
>               .sType                 = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
>               .pNext                 = &ext_img_spec,
> @@ -2580,8 +2588,7 @@ static int vulkan_map_from_drm_frame_desc(AVHWFramesContext *hwfc, AVVkFrame **f
>               .flags                 = 0x0,
>               .tiling                = VK_IMAGE_TILING_DRM_FORMAT_MODIFIER_EXT,
>               .initialLayout         = VK_IMAGE_LAYOUT_UNDEFINED, /* specs say so */
> -            .usage                 = VK_IMAGE_USAGE_SAMPLED_BIT |
> -                                     VK_IMAGE_USAGE_TRANSFER_SRC_BIT,
> +            .usage                 = usage,
>               .samples               = VK_SAMPLE_COUNT_1_BIT,
>               .pQueueFamilyIndices   = p->img_qfs,
>               .queueFamilyIndexCount = p->nb_img_qfs,
> @@ -2788,7 +2795,7 @@ static int vulkan_map_from_drm(AVHWFramesContext *hwfc, AVFrame *dst,
>       int err = 0;
>       AVVkFrame *f;
>   
> -    if ((err = vulkan_map_from_drm_frame_desc(hwfc, &f, src)))
> +    if ((err = vulkan_map_from_drm_frame_desc(hwfc, &f, src, flags)))
>           return err;
>   
>       /* The unmapping function will free this */

Pushed, thanks.

Glad to know writing to DRM frames works, this was not tested, and it 
was for a long time unsupported, due to missing modifier support.

Once Vulkan encode is added, this should be updated with ENCODE_SRC, but 
hopefully I'll remember to take care of that.
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