[FFmpeg-devel] [PATCH v2] hwcontext_vulkan: fix exporting multi-plane DRM modifiers

[russellgreene8-at-gmail.com@ffmpeg.org]

From: Russell Greene <russellgreene8@gmail.com>

Previously, it was assumed that `drmFormatModifierPlaneCount` was one
for all modifiers when exporting, which is not always the case, in
particular for AMD GPUs and maybe others.

Fetch the number of memory planes and fill the structs appropriately in this situation.

The encoded stream is still bad in the case whre modifers are involved,
but I think this patch still stands on its own and I suspect that may be a driver bug.

A potential improvement that could be make is to cache the format
information, so we can avoid the two GetPhysicalDeviceFormatProperties2
calls for each export, as well as the allocation. I doubt this is very
expensive, but seemed worth noting.

v2 changes: query the format properties with the test image created in
`vulkan_frames_init` to avoid allocating space for the query during
export

Signed-off-by: Russell Greene <russellgreene8@gmail.com>
---
 libavutil/hwcontext_vulkan.c | 104 +++++++++++++++++++++++++++++++----
 1 file changed, 94 insertions(+), 10 deletions(-)

diff --git a/libavutil/hwcontext_vulkan.c b/libavutil/hwcontext_vulkan.c
index edff89af26..c51c66ba63 100644
--- a/libavutil/hwcontext_vulkan.c
+++ b/libavutil/hwcontext_vulkan.c
@@ -169,6 +169,9 @@ typedef struct VulkanFramesPriv {
 
     /* Modifier info list to free at uninit */
     VkImageDrmFormatModifierListCreateInfoEXT *modifier_info;
+
+    /* Properties for DRM modifier for each plane in the image */
+    VkDrmFormatModifierPropertiesEXT drm_format_modifier_properties[5];
 } VulkanFramesPriv;
 
 typedef struct AVVkFrameInternal {
@@ -2772,7 +2775,9 @@ static int vulkan_frames_init(AVHWFramesContext *hwfc)
     VulkanFramesPriv *fp = hwfc->hwctx;
     AVVulkanFramesContext *hwctx = &fp->p;
     VulkanDevicePriv *p = hwfc->device_ctx->hwctx;
+    AVVulkanDeviceContext *dev_hwctx = &p->p;
     VkImageUsageFlagBits supported_usage;
+    FFVulkanFunctions *vk = &p->vkctx.vkfn;
     const struct FFVkFormatEntry *fmt;
     int disable_multiplane = p->disable_multiplane ||
                              (hwctx->flags & AV_VK_FRAME_FLAG_DISABLE_MULTIPLANE);
@@ -2912,6 +2917,63 @@ static int vulkan_frames_init(AVHWFramesContext *hwfc)
     if (err)
         return err;
 
+    /* Collect `VkDrmFormatModifierPropertiesEXT` for each plane. Required for DRM export. */
+    if (p->vkctx.extensions & FF_VK_EXT_DRM_MODIFIER_FLAGS && hwctx->tiling == VK_IMAGE_TILING_DRM_FORMAT_MODIFIER_EXT) {
+        VkImageDrmFormatModifierPropertiesEXT drm_mod = {
+            .sType = VK_STRUCTURE_TYPE_IMAGE_DRM_FORMAT_MODIFIER_PROPERTIES_EXT,
+        };
+        err = vk->GetImageDrmFormatModifierPropertiesEXT(dev_hwctx->act_dev, f->img[0],
+                                                        &drm_mod);
+        if (err != VK_SUCCESS) {
+            av_log(hwfc, AV_LOG_ERROR, "Failed to get image DRM format modifier properties");
+            vulkan_frame_free(hwfc, f);
+            return AVERROR_EXTERNAL;
+        }
+        for (int i = 0; i < fmt->vk_planes; ++i) {
+            VkDrmFormatModifierPropertiesListEXT modp;
+            VkFormatProperties2 fmtp;
+            VkDrmFormatModifierPropertiesEXT *mod_props = NULL;
+
+            modp = (VkDrmFormatModifierPropertiesListEXT) {
+                .sType = VK_STRUCTURE_TYPE_DRM_FORMAT_MODIFIER_PROPERTIES_LIST_EXT,
+            };
+            fmtp = (VkFormatProperties2) {
+                .sType = VK_STRUCTURE_TYPE_FORMAT_PROPERTIES_2,
+                .pNext = &modp,
+            };
+
+            /* query drmFormatModifierCount by keeping pDrmFormatModifierProperties NULL */
+            vk->GetPhysicalDeviceFormatProperties2(dev_hwctx->phys_dev, fmt->fallback[i], &fmtp);
+
+            modp.pDrmFormatModifierProperties =
+                av_calloc(modp.drmFormatModifierCount, sizeof(*modp.pDrmFormatModifierProperties));
+            if (!modp.pDrmFormatModifierProperties) {
+                vulkan_frame_free(hwfc, f);
+                return AVERROR(ENOMEM);
+            }
+            vk->GetPhysicalDeviceFormatProperties2(dev_hwctx->phys_dev, fmt->fallback[i], &fmtp);
+
+            for (uint32_t i = 0; i < modp.drmFormatModifierCount; ++i) {
+                VkDrmFormatModifierPropertiesEXT *m = &modp.pDrmFormatModifierProperties[i];
+                if (m->drmFormatModifier == drm_mod.drmFormatModifier) {
+                    mod_props = m;
+                    break;
+                }
+            }
+
+            if (mod_props == NULL) {
+                av_log(hwfc, AV_LOG_ERROR, "No DRM format modifier properties found for modifier 0x%016lx\n",
+                          drm_mod.drmFormatModifier);
+                av_free(modp.pDrmFormatModifierProperties);
+                vulkan_frame_free(hwfc, f);
+                return AVERROR_EXTERNAL;
+            }
+
+            fp->drm_format_modifier_properties[i] = *mod_props;
+            av_free(modp.pDrmFormatModifierProperties);
+        }
+    }
+
     vulkan_frame_free(hwfc, f);
 
     /* If user did not specify a pool, hwfc->pool will be set to the internal one
@@ -3842,6 +3904,17 @@ static inline uint32_t vulkan_fmt_to_drm(VkFormat vkfmt)
     return DRM_FORMAT_INVALID;
 }
 
+#define MAX_MEMORY_PLANES 4
+static VkImageAspectFlags plane_index_to_aspect(int plane) {
+    if (plane == 0) return VK_IMAGE_ASPECT_MEMORY_PLANE_0_BIT_EXT;
+    if (plane == 1) return VK_IMAGE_ASPECT_MEMORY_PLANE_1_BIT_EXT;
+    if (plane == 2) return VK_IMAGE_ASPECT_MEMORY_PLANE_2_BIT_EXT;
+    if (plane == 3) return VK_IMAGE_ASPECT_MEMORY_PLANE_3_BIT_EXT;
+
+    av_assert2 (false && "Invalid plane index");
+    return VK_IMAGE_ASPECT_MEMORY_PLANE_0_BIT_EXT;
+}
+
 static int vulkan_map_to_drm(AVHWFramesContext *hwfc, AVFrame *dst,
                              const AVFrame *src, int flags)
 {
@@ -3910,14 +3983,29 @@ static int vulkan_map_to_drm(AVHWFramesContext *hwfc, AVFrame *dst,
 
     drm_desc->nb_layers = planes;
     for (int i = 0; i < drm_desc->nb_layers; i++) {
-        VkSubresourceLayout layout;
-        VkImageSubresource sub = {
-            .aspectMask = VK_IMAGE_ASPECT_MEMORY_PLANE_0_BIT_EXT,
-        };
         VkFormat plane_vkfmt = av_vkfmt_from_pixfmt(hwfc->sw_format)[i];
 
-        drm_desc->layers[i].format    = vulkan_fmt_to_drm(plane_vkfmt);
-        drm_desc->layers[i].nb_planes = 1;
+        drm_desc->layers[i].format = vulkan_fmt_to_drm(plane_vkfmt);
+        drm_desc->layers[i].nb_planes = fp->drm_format_modifier_properties[i].drmFormatModifierPlaneCount;
+
+        if (drm_desc->layers[i].nb_planes > MAX_MEMORY_PLANES) {
+            av_log(hwfc, AV_LOG_ERROR, "Too many memory planes for DRM format!\n");
+            err = AVERROR_EXTERNAL;
+            goto end;
+        }
+
+        for (int j = 0; j < drm_desc->layers[i].nb_planes; j++) {
+            VkSubresourceLayout layout;
+            VkImageSubresource sub = {
+                .aspectMask = plane_index_to_aspect(j),
+            };
+
+            drm_desc->layers[i].planes[j].object_index = FFMIN(i, drm_desc->nb_objects - 1);
+
+            vk->GetImageSubresourceLayout(hwctx->act_dev, f->img[i], &sub, &layout);
+            drm_desc->layers[i].planes[j].offset = layout.offset;
+            drm_desc->layers[i].planes[j].pitch  = layout.rowPitch;
+        }
 
         if (drm_desc->layers[i].format == DRM_FORMAT_INVALID) {
             av_log(hwfc, AV_LOG_ERROR, "Cannot map to DRM layer, unsupported!\n");
@@ -3925,14 +4013,10 @@ static int vulkan_map_to_drm(AVHWFramesContext *hwfc, AVFrame *dst,
             goto end;
         }
 
-        drm_desc->layers[i].planes[0].object_index = FFMIN(i, drm_desc->nb_objects - 1);
 
         if (f->tiling == VK_IMAGE_TILING_OPTIMAL)
             continue;
 
-        vk->GetImageSubresourceLayout(hwctx->act_dev, f->img[i], &sub, &layout);
-        drm_desc->layers[i].planes[0].offset = layout.offset;
-        drm_desc->layers[i].planes[0].pitch  = layout.rowPitch;
     }
 
     dst->width   = src->width;
-- 
2.50.0

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