wlvideobufferpool: Add DRM Dumb buffer support

This allow the wayland buffer pool to use a GstDRMDumbAllocator
if it has been configured to do so.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3801>

subprojects/gst-plugins-bad/gst-libs/gst/wayland/gstwlvideobufferpool.c

@@ -24,8 +24,198 @@
 
 #include "gstwlvideobufferpool.h"
 
-G_DEFINE_TYPE (GstWlVideoBufferPool, gst_wl_video_buffer_pool,
-    GST_TYPE_VIDEO_BUFFER_POOL);
+#include <gst/allocators/allocators.h>
+#include <drm_fourcc.h>
+
+GST_DEBUG_CATEGORY (gst_wl_videobufferpool_debug);
+#define GST_CAT_DEFAULT gst_wl_videobufferpool_debug
+
+struct _GstWlVideoBufferPool
+{
+  GstVideoBufferPool parent;
+  GstAllocator *allocator;
+  GstVideoInfo vinfo;
+};
+
+#define gst_wl_video_buffer_pool_parent_class parent_class
+G_DEFINE_TYPE_WITH_CODE (GstWlVideoBufferPool, gst_wl_video_buffer_pool,
+    GST_TYPE_VIDEO_BUFFER_POOL,
+    GST_DEBUG_CATEGORY_INIT (gst_wl_videobufferpool_debug,
+        "wl_videobufferpool", 0, "wl_dmabuf library"));
+
+static void
+gst_wl_update_video_info_from_pitch (GstVideoInfo * vinfo, gint n_planes,
+    guint32 pitch)
+{
+  gint i;
+  gsize offs = 0;
+  guint32 height = GST_VIDEO_INFO_HEIGHT (vinfo);
+
+  if (!pitch)
+    return;
+
+  for (i = 0; i < n_planes; i++) {
+    guint32 plane_pitch;
+
+    /* Overwrite the video info's stride and offset using the pitch calculcated
+     * by the kms driver. */
+    plane_pitch = gst_video_format_info_extrapolate_stride (vinfo->finfo, i,
+        pitch);
+    GST_VIDEO_INFO_PLANE_STRIDE (vinfo, i) = plane_pitch;
+    GST_VIDEO_INFO_PLANE_OFFSET (vinfo, i) = offs;
+
+    /* Note that we cannot negotiate special padding betweem each planes,
+     * hence using the display height here. */
+    offs += plane_pitch
+        * GST_VIDEO_FORMAT_INFO_SCALE_HEIGHT (vinfo->finfo, i, height);
+
+    GST_DEBUG ("Updated plane %i with stride %i and "
+        "offset %" G_GSIZE_FORMAT "(from pitch %u)", i,
+        GST_VIDEO_INFO_PLANE_STRIDE (vinfo, i),
+        GST_VIDEO_INFO_PLANE_OFFSET (vinfo, i), pitch);
+  }
+
+  /* Update with the size use for display, excluding any padding at the end */
+  GST_VIDEO_INFO_SIZE (vinfo) = offs;
+}
+
+static gboolean
+gst_wl_video_buffer_pool_start (GstBufferPool * pool)
+{
+  GstWlVideoBufferPool *self = GST_WL_VIDEO_BUFFER_POOL (pool);
+  GstStructure *config = gst_buffer_pool_get_config (pool);
+  GstCaps *caps;
+  GstAllocator *allocator;
+  gboolean ret = FALSE;
+  GstVideoFormat format;
+
+  if (!gst_buffer_pool_config_get_params (config, &caps, NULL, NULL, NULL))
+    goto wrong_config;
+
+  if (!gst_buffer_pool_config_get_allocator (config, &allocator, NULL))
+    goto wrong_config;
+
+  /* now parse the caps from the config */
+  if (!gst_video_info_from_caps (&self->vinfo, caps))
+    goto wrong_caps;
+
+  format = GST_VIDEO_INFO_FORMAT (&self->vinfo);
+  if (!gst_video_format_to_wl_dmabuf_format (format))
+    goto unsupported_pixel_format;
+
+  if (GST_IS_DRM_DUMB_ALLOCATOR (allocator)) {
+    if (!gst_drm_dumb_allocator_has_prime_export (allocator))
+      goto no_prime_export;
+
+    self->allocator = gst_object_ref (allocator);
+  }
+
+  /* all good */
+  ret = GST_BUFFER_POOL_CLASS (parent_class)->start (pool);
+
+done:
+  gst_structure_free (config);
+  return ret;
+
+wrong_config:
+  {
+    GST_WARNING_OBJECT (pool, "invalid config");
+    goto done;
+  }
+wrong_caps:
+  {
+    GST_WARNING_OBJECT (pool,
+        "failed getting geometry from caps %" GST_PTR_FORMAT, caps);
+    goto done;
+  }
+unsupported_pixel_format:
+  {
+    GST_WARNING_OBJECT (pool, "no support for %s pixel format",
+        gst_video_format_to_string (format));
+    goto done;
+  }
+no_prime_export:
+  {
+    GST_WARNING_OBJECT (self,
+        "not using DRM Dumb allocator as it can't export DMABuf.");
+    goto done;
+  }
+}
+
+static gboolean
+gst_wl_video_buffer_pool_stop (GstBufferPool * pool)
+{
+  GstWlVideoBufferPool *self = GST_WL_VIDEO_BUFFER_POOL (pool);
+  gst_clear_object (&self->allocator);
+  gst_video_info_init (&self->vinfo);
+  return GST_BUFFER_POOL_CLASS (parent_class)->stop (pool);
+}
+
+static GstFlowReturn
+gst_wl_video_buffer_pool_alloc_buffer (GstBufferPool * pool,
+    GstBuffer ** buffer, GstBufferPoolAcquireParams * params)
+{
+  GstWlVideoBufferPool *self = GST_WL_VIDEO_BUFFER_POOL (pool);
+  guint32 pitch;
+  GstBuffer *buf;
+  GstMemory *drm_mem, *dma_mem;
+  gsize dumbbuf_size;
+  GstVideoFormat format = GST_VIDEO_INFO_FORMAT (&self->vinfo);
+  guint32 drm_fourcc = gst_video_format_to_wl_dmabuf_format (format);
+
+  if (!self->allocator)
+    return GST_BUFFER_POOL_CLASS (parent_class)->alloc_buffer (pool, buffer,
+        params);
+
+  drm_mem = gst_drm_dumb_allocator_alloc (self->allocator,
+      drm_fourcc, GST_VIDEO_INFO_WIDTH (&self->vinfo),
+      GST_VIDEO_INFO_HEIGHT (&self->vinfo), &pitch);
+  if (!drm_mem)
+    goto alloc_failed;
+
+  dma_mem = gst_drm_dumb_memory_export_dmabuf (drm_mem);
+
+  gst_memory_unref (drm_mem);
+  drm_mem = NULL;
+
+  gst_wl_update_video_info_from_pitch (&self->vinfo,
+      GST_VIDEO_INFO_N_PLANES (&self->vinfo), pitch);
+
+  gst_memory_get_sizes (dma_mem, NULL, &dumbbuf_size);
+  if (dumbbuf_size < GST_VIDEO_INFO_SIZE (&self->vinfo)) {
+    GST_ERROR_OBJECT (self,
+        "DUMB buffer has a size of %" G_GSIZE_FORMAT
+        " but we require at least %" G_GSIZE_FORMAT " to hold a frame",
+        dumbbuf_size, GST_VIDEO_INFO_SIZE (&self->vinfo));
+    goto buffer_too_small;
+  }
+
+  gst_memory_resize (dma_mem, 0, GST_VIDEO_INFO_SIZE (&self->vinfo));
+
+  buf = gst_buffer_new ();
+  gst_buffer_append_memory (buf, dma_mem);
+  gst_buffer_add_video_meta_full (buf, GST_VIDEO_FRAME_FLAG_NONE,
+      GST_VIDEO_INFO_FORMAT (&self->vinfo), GST_VIDEO_INFO_WIDTH (&self->vinfo),
+      GST_VIDEO_INFO_HEIGHT (&self->vinfo),
+      GST_VIDEO_INFO_N_PLANES (&self->vinfo),
+      self->vinfo.offset, self->vinfo.stride);
+
+  *buffer = buf;
+
+  return GST_FLOW_OK;
+
+  /* ERRORS */
+alloc_failed:
+  {
+    GST_ERROR_OBJECT (self, "failed to allocate DRM Dumb buffer.");
+    return GST_FLOW_ERROR;
+  }
+buffer_too_small:
+  {
+    GST_ERROR_OBJECT (self, "dumb buffer too small to store an image.");
+    return GST_FLOW_ERROR;
+  }
+}
 
 static const gchar **
 gst_wl_video_buffer_pool_get_options (GstBufferPool * pool)
@@ -39,11 +229,15 @@ gst_wl_video_buffer_pool_class_init (GstWlVideoBufferPoolClass * klass)
 {
   GstBufferPoolClass *pool_class = GST_BUFFER_POOL_CLASS (klass);
   pool_class->get_options = gst_wl_video_buffer_pool_get_options;
+  pool_class->start = gst_wl_video_buffer_pool_start;
+  pool_class->stop = gst_wl_video_buffer_pool_stop;
+  pool_class->alloc_buffer = gst_wl_video_buffer_pool_alloc_buffer;
 }
 
 static void
-gst_wl_video_buffer_pool_init (GstWlVideoBufferPool * pool)
+gst_wl_video_buffer_pool_init (GstWlVideoBufferPool * self)
 {
+  gst_video_info_init (&self->vinfo);
 }
 
 GstBufferPool *

subprojects/gst-plugins-bad/gst-libs/gst/wayland/gstwlvideobufferpool.h

@@ -26,22 +26,18 @@
 
 G_BEGIN_DECLS
 
-/* A tiny GstVideoBufferPool subclass that modify the options to remove
+/* A GstVideoBufferPool subclass that modify the options to remove
  * VideoAlignment. To support VideoAlignment we would need to pass the padded
  * width/height + stride and use the viewporter interface to crop, a bit like
  * we use to do with XV. It would still be quite limited. It's a bit retro,
- * hopefully there will be a better Wayland interface in the future. */
+ * hopefully there will be a better Wayland interface in the future. This buffer
+ * pool also support GstDRMDumbAllocator. */
 
 #define GST_TYPE_WL_VIDEO_BUFFER_POOL (gst_wl_video_buffer_pool_get_type ())
 
 GST_WL_API
 G_DECLARE_FINAL_TYPE (GstWlVideoBufferPool, gst_wl_video_buffer_pool, GST, WL_VIDEO_BUFFER_POOL, GstVideoBufferPool);
 
-struct _GstWlVideoBufferPool
-{
-  GstVideoBufferPool parent;
-};
-
 GST_WL_API
 GstBufferPool * gst_wl_video_buffer_pool_new (void);