gldownload: enumerate emulated video formats

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6792>

girs/GstGL-1.0.gir

@@ -3507,6 +3507,9 @@ extension.</doc>
       <member name="linear_only" value="2" c:identifier="GST_GL_DRM_FORMAT_LINEAR_ONLY" version="1.26" glib:nick="linear-only" glib:name="GST_GL_DRM_FORMAT_LINEAR_ONLY">
         <doc xml:space="preserve" filename="../subprojects/gst-plugins-base/gst-libs/gst/gl/gstglutils.h">only include formats with linear modifier</doc>
       </member>
+      <member name="include_emulated" value="4" c:identifier="GST_GL_DRM_FORMAT_INCLUDE_EMULATED" version="1.26" glib:nick="include-emulated" glib:name="GST_GL_DRM_FORMAT_INCLUDE_EMULATED">
+        <doc xml:space="preserve" filename="../subprojects/gst-plugins-base/gst-libs/gst/gl/gstglutils.h">include emulated formats</doc>
+      </member>
     </bitfield>
     <class name="GLFilter" c:symbol-prefix="gl_filter" c:type="GstGLFilter" parent="GLBaseFilter" glib:type-name="GstGLFilter" glib:get-type="gst_gl_filter_get_type" glib:type-struct="GLFilterClass">
       <doc xml:space="preserve" filename="../subprojects/gst-plugins-base/gst-libs/gst/gl/gstglfilter.c">#GstGLFilter helps to implement simple OpenGL filter elements taking a

subprojects/gst-plugins-base/ext/gl/gstgldownloadelement.c

@@ -958,7 +958,7 @@ _convert_dma_drm (GstGLContext * context, GstStructure * s)
     GValue newfmtval = G_VALUE_INIT;
 
     if (context && gst_gl_dma_buf_transform_drm_formats_to_gst_formats (context,
-        drmval, 0, &newfmtval)) {
+            drmval, GST_GL_DRM_FORMAT_INCLUDE_EMULATED, &newfmtval)) {
       gst_structure_set_value (s, "format", &newfmtval);
       gst_structure_remove_field (s, "drm-format");
       g_value_unset (&newfmtval);

subprojects/gst-plugins-base/gst-libs/gst/gl/egl/gsteglimage.c

@@ -489,10 +489,9 @@ gst_egl_image_from_texture (GstGLContext * context, GstGLMemory * gl_mem,
  * target.
  */
 static int
-_drm_rgba_fourcc_from_info (const GstVideoInfo * info, int plane,
+_drm_rgba_fourcc_from_format (GstVideoFormat format, int plane,
     GstGLFormat * out_format)
 {
-  GstVideoFormat format = GST_VIDEO_INFO_FORMAT (info);
 #if G_BYTE_ORDER == G_LITTLE_ENDIAN
   const gint rgba_fourcc = DRM_FORMAT_ABGR8888;
   const gint rgb_fourcc = DRM_FORMAT_BGR888;
@@ -657,7 +656,8 @@ gst_egl_image_from_dmabuf (GstGLContext * context,
   gboolean with_modifiers;
 
   gst_video_format_info_component (in_info->finfo, plane, comp);
-  fourcc = _drm_rgba_fourcc_from_info (in_info, plane, &format);
+  fourcc = _drm_rgba_fourcc_from_format (GST_VIDEO_INFO_FORMAT (in_info), plane,
+      &format);
   GST_DEBUG ("fourcc %.4s (%d) plane %d (%dx%d)",
       (char *) &fourcc, fourcc, plane,
       GST_VIDEO_INFO_COMP_WIDTH (in_info, comp[0]),
@@ -1096,4 +1096,69 @@ gst_egl_image_export_dmabuf (GstEGLImage * image, int *fd, gint * stride,
   return TRUE;
 }
 
+/**
+ * gst_egl_image_can_emulate:
+ * @context: a #GstGLContext (must be an EGL context)
+ * @format: a #GstVideoFormat
+ *
+ * Checks if the given @context can emulate @format using a limited subset of
+ * RGB texture formats. Such @format is then suitable for importing using
+ * gst_egl_image_from_dmabuf() even when GL supports the video format as
+ * external-only or not at all.
+ *
+ * Returns: #TRUE if @format can be emulated
+ */
+gboolean
+gst_egl_image_can_emulate (GstGLContext * context, GstVideoFormat format)
+{
+  const GstVideoFormatInfo *info;
+  guint i;
+  GstGLFormat out_format;
+
+  info = gst_video_format_get_info (format);
+
+  for (i = 0; i != GST_VIDEO_FORMAT_INFO_N_PLANES (info); ++i) {
+    int fourcc;
+
+    fourcc = _drm_rgba_fourcc_from_format (format, i, &out_format);
+    if (fourcc == -1) {
+      return FALSE;
+    }
+
+    if (GST_VIDEO_FORMAT_INFO_IS_YUV (info)) {
+      /* For YUV formats we only support linear modifier. */
+      if (!gst_gl_context_egl_format_supports_modifier (context, fourcc,
+              DRM_FORMAT_MOD_LINEAR, FALSE)) {
+        return FALSE;
+      }
+    } else if (GST_VIDEO_FORMAT_INFO_IS_RGB (info)) {
+      /* For RGB formats any DMA format that is not external-only will do. */
+      const GArray *dma_modifiers;
+      guint j;
+
+      if (!gst_gl_context_egl_get_format_modifiers (context, fourcc,
+              &dma_modifiers)) {
+        return FALSE;
+      }
+
+      for (j = 0; j < dma_modifiers->len; ++j) {
+        GstGLDmaModifier *mod =
+            &g_array_index (dma_modifiers, GstGLDmaModifier, j);
+
+        if (!mod->external_only) {
+          break;
+        }
+      }
+
+      if (j == dma_modifiers->len) {
+        return FALSE;
+      }
+    } else {
+      return FALSE;
+    }
+  }
+
+  return TRUE;
+}
+
 #endif /* GST_GL_HAVE_DMABUF */

subprojects/gst-plugins-base/gst-libs/gst/gl/egl/gsteglimage.h

@@ -111,6 +111,10 @@ GstEGLImage *           gst_egl_image_from_dmabuf_direct_target_with_dma_drm
                                                                  GstGLTextureTarget target);
 GST_GL_API
 gboolean                gst_egl_image_export_dmabuf             (GstEGLImage *image, int *fd, gint *stride, gsize *offset);
+
+GST_GL_API
+gboolean                gst_egl_image_can_emulate               (GstGLContext * context,
+                                                                 GstVideoFormat format);
 #endif
 
 /**

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglutils.c

@@ -47,13 +47,13 @@
 
 #if GST_GL_HAVE_PLATFORM_EGL
 #include "egl/gstglcontext_egl.h"
-#endif
-
+#include "egl/gsteglimage.h"
 #if GST_GL_HAVE_DMABUF
 #ifdef HAVE_LIBDRM
 #include <drm_fourcc.h>
 #endif
 #endif
+#endif
 
 #define USING_OPENGL(context) (gst_gl_context_check_gl_version (context, GST_GL_API_OPENGL, 1, 0))
 #define USING_OPENGL3(context) (gst_gl_context_check_gl_version (context, GST_GL_API_OPENGL3, 3, 1))
@@ -934,6 +934,7 @@ _append_drm_formats_from_video_format (GstGLContext * context,
     GstVideoFormat format, GstGLDrmFormatFlags flags, GPtrArray * drm_formats)
 {
   gint32 i, fourcc;
+  gint32 num_added = 0;
   const GArray *dma_modifiers = NULL;
   char *drm_format;
 
@@ -964,6 +965,14 @@ _append_drm_formats_from_video_format (GstGLContext * context,
 
     drm_format = gst_video_dma_drm_fourcc_to_string (fourcc, mod->modifier);
     g_ptr_array_add (drm_formats, drm_format);
+    ++num_added;
+  }
+
+  if (num_added == 0 && (flags & GST_GL_DRM_FORMAT_INCLUDE_EMULATED) &&
+      gst_egl_image_can_emulate (context, format)) {
+    drm_format =
+        gst_video_dma_drm_fourcc_to_string (fourcc, DRM_FORMAT_MOD_LINEAR);
+    g_ptr_array_add (drm_formats, drm_format);
   }
 }
 #endif
@@ -1071,7 +1080,9 @@ _get_video_format_from_drm_format (GstGLContext * context,
     return GST_VIDEO_FORMAT_UNKNOWN;
 
   if (!gst_gl_context_egl_format_supports_modifier (context, fourcc, modifier,
-      flags & GST_GL_DRM_FORMAT_INCLUDE_EXTERNAL))
+          flags & GST_GL_DRM_FORMAT_INCLUDE_EXTERNAL) &&
+      !(flags & GST_GL_DRM_FORMAT_INCLUDE_EMULATED &&
+          gst_egl_image_can_emulate (context, gst_format)))
     return GST_VIDEO_FORMAT_UNKNOWN;
 
   return gst_format;

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglutils.h

@@ -71,6 +71,7 @@ void gst_gl_multiply_matrix4 (const gfloat * a, const gfloat * b, gfloat * resul
  * GstGLDrmFormatFlags:
  * @GST_GL_DRM_FORMAT_INCLUDE_EXTERNAL: include external-only formats (Since: 1.26)
  * @GST_GL_DRM_FORMAT_LINEAR_ONLY: only include formats with linear modifier (Since: 1.26)
+ * @GST_GL_DRM_FORMAT_INCLUDE_EMULATED: include emulated formats (Since: 1.26)
  *
  * Since: 1.26
  */
@@ -92,6 +93,14 @@ typedef enum
   * Since: 1.26
   */
   GST_GL_DRM_FORMAT_LINEAR_ONLY = 1 << 1,
+  /**
+   * GST_GL_DRM_FORMAT_INCLUDE_EMULATED:
+   *
+   * include emulated formats
+   *
+   * Since: 1.26
+   */
+  GST_GL_DRM_FORMAT_INCLUDE_EMULATED = 1 << 2,
 } GstGLDrmFormatFlags;
 
 GST_GL_API