gl/download: add support for output memory:NVMM buffers

Currently RGBA-only.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1071>

3 files changed, 917 insertions, 6 deletions

diff --git a/ext/gl/gstgldownloadelement.c b/ext/gl/gstgldownloadelement.c
index 2b6508898..4e16d1f98 100644
--- a/ext/gl/gstgldownloadelement.c
+++ b/ext/gl/gstgldownloadelement.c
@@ -34,6 +34,742 @@
 GST_DEBUG_CATEGORY_STATIC (gst_gl_download_element_debug);
 #define GST_CAT_DEFAULT gst_gl_download_element_debug
 
+#if GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM)
+#include <gst/gl/egl/gstgldisplay_egl.h>
+#include <gst/gl/egl/gstglmemoryegl.h>
+
+#include "nvbuf_utils.h"
+
+static const char *
+nv_buffer_payload_type_to_string (NvBufferPayloadType ptype)
+{
+  switch (ptype) {
+    case NvBufferPayload_SurfArray:
+      return "SurfArray";
+    case NvBufferPayload_MemHandle:
+      return "MemHandle";
+    default:
+      return "<unknown>";
+  }
+}
+
+static const char *
+nv_buffer_pixel_format_to_string (NvBufferColorFormat fmt)
+{
+  switch (fmt) {
+    case NvBufferColorFormat_YUV420:
+      return "YUV420";
+    case NvBufferColorFormat_YVU420:
+      return "YVU420";
+    case NvBufferColorFormat_YUV422:
+      return "YUV422";
+    case NvBufferColorFormat_YUV420_ER:
+      return "YUV420_ER";
+    case NvBufferColorFormat_YVU420_ER:
+      return "YVU420_ER";
+    case NvBufferColorFormat_NV12:
+      return "NV12";
+    case NvBufferColorFormat_NV12_ER:
+      return "NV12_ER";
+    case NvBufferColorFormat_NV21:
+      return "NV21";
+    case NvBufferColorFormat_NV21_ER:
+      return "NV21_ER";
+    case NvBufferColorFormat_UYVY:
+      return "UYVY";
+    case NvBufferColorFormat_UYVY_ER:
+      return "UYVY_ER";
+    case NvBufferColorFormat_VYUY:
+      return "VYUY";
+    case NvBufferColorFormat_VYUY_ER:
+      return "VYUY_ER";
+    case NvBufferColorFormat_YUYV:
+      return "YUYV";
+    case NvBufferColorFormat_YUYV_ER:
+      return "YUYV_ER";
+    case NvBufferColorFormat_YVYU:
+      return "YVYU";
+    case NvBufferColorFormat_YVYU_ER:
+      return "YVYU_ER";
+    case NvBufferColorFormat_ABGR32:
+      return "ABGR32";
+    case NvBufferColorFormat_XRGB32:
+      return "XRGB32";
+    case NvBufferColorFormat_ARGB32:
+      return "ARGB32";
+    case NvBufferColorFormat_NV12_10LE:
+      return "NV12_10LE";
+    case NvBufferColorFormat_NV12_10LE_709:
+      return "NV12_10LE_709";
+    case NvBufferColorFormat_NV12_10LE_709_ER:
+      return "NV12_10LE_709_ER";
+    case NvBufferColorFormat_NV12_10LE_2020:
+      return "NV12_2020";
+    case NvBufferColorFormat_NV21_10LE:
+      return "NV21_10LE";
+    case NvBufferColorFormat_NV12_12LE:
+      return "NV12_12LE";
+    case NvBufferColorFormat_NV12_12LE_2020:
+      return "NV12_12LE_2020";
+    case NvBufferColorFormat_NV21_12LE:
+      return "NV21_12LE";
+    case NvBufferColorFormat_YUV420_709:
+      return "YUV420_709";
+    case NvBufferColorFormat_YUV420_709_ER:
+      return "YUV420_709_ER";
+    case NvBufferColorFormat_NV12_709:
+      return "NV12_709";
+    case NvBufferColorFormat_NV12_709_ER:
+      return "NV12_709_ER";
+    case NvBufferColorFormat_YUV420_2020:
+      return "YUV420_2020";
+    case NvBufferColorFormat_NV12_2020:
+      return "NV12_2020";
+    case NvBufferColorFormat_SignedR16G16:
+      return "SignedR16G16";
+    case NvBufferColorFormat_A32:
+      return "A32";
+    case NvBufferColorFormat_YUV444:
+      return "YUV444";
+    case NvBufferColorFormat_GRAY8:
+      return "GRAY8";
+    case NvBufferColorFormat_NV16:
+      return "NV16";
+    case NvBufferColorFormat_NV16_10LE:
+      return "NV16_10LE";
+    case NvBufferColorFormat_NV24:
+      return "NV24";
+    case NvBufferColorFormat_NV16_ER:
+      return "NV16_ER";
+    case NvBufferColorFormat_NV24_ER:
+      return "NV24_ER";
+    case NvBufferColorFormat_NV16_709:
+      return "NV16_709";
+    case NvBufferColorFormat_NV24_709:
+      return "NV24_709";
+    case NvBufferColorFormat_NV16_709_ER:
+      return "NV16_709_ER";
+    case NvBufferColorFormat_NV24_709_ER:
+      return "NV24_709_ER";
+    case NvBufferColorFormat_NV24_10LE_709:
+      return "NV24_10LE_709";
+    case NvBufferColorFormat_NV24_10LE_709_ER:
+      return "NV24_10LE_709_ER";
+    case NvBufferColorFormat_NV24_10LE_2020:
+      return "NV24_10LE_2020";
+    case NvBufferColorFormat_NV24_12LE_2020:
+      return "NV24_12LE_2020";
+    case NvBufferColorFormat_RGBA_10_10_10_2_709:
+      return "RGBA_10_10_10_2_709";
+    case NvBufferColorFormat_RGBA_10_10_10_2_2020:
+      return "RGBA_10_10_10_2_2020";
+    case NvBufferColorFormat_BGRA_10_10_10_2_709:
+      return "BGRA_10_10_10_2_709";
+    case NvBufferColorFormat_BGRA_10_10_10_2_2020:
+      return "BGRA_10_10_10_2_2020";
+    case NvBufferColorFormat_Invalid:
+      return "Invalid";
+    default:
+      return "<unknown>";
+  }
+}
+
+static void
+nv_buffer_dump_params (GstObject * debug_object, NvBufferParamsEx * params)
+{
+  GST_DEBUG_OBJECT (debug_object, "nvbuffer fd: %u size %i nv_buffer: %p of "
+      "size %u, payload: (0x%x) %s, pixel format: (0x%x) %s, n_planes: %u, "
+      "plane 0 { wxh: %ux%u, pitch: %u, offset: %u, psize: %u, layout: %u } "
+      "plane 1 { wxh: %ux%u, pitch: %u, offset: %u, psize: %u, layout: %u } "
+      "plane 2 { wxh: %ux%u, pitch: %u, offset: %u, psize: %u, layout: %u }",
+      params->params.dmabuf_fd, params->params.memsize,
+      params->params.nv_buffer, params->params.nv_buffer_size,
+      params->params.payloadType,
+      nv_buffer_payload_type_to_string (params->params.payloadType),
+      params->params.pixel_format,
+      nv_buffer_pixel_format_to_string (params->params.pixel_format),
+      params->params.num_planes, params->params.width[0],
+      params->params.height[0], params->params.pitch[0],
+      params->params.offset[0], params->params.psize[0],
+      params->params.offset[0], params->params.width[1],
+      params->params.height[1], params->params.pitch[1],
+      params->params.offset[1], params->params.psize[1],
+      params->params.offset[1], params->params.width[2],
+      params->params.height[2], params->params.pitch[2],
+      params->params.offset[2], params->params.psize[2],
+      params->params.offset[2]);
+}
+
+struct _GstMemoryNVMM
+{
+  GstMemory parent;
+
+  int dmabuf_fd;
+  NvBufferParamsEx params;
+};
+
+typedef struct _GstMemoryNVMM GstMemoryNVMM;
+
+struct _GstAllocatorNVMM
+{
+  GstAllocator parent;
+};
+
+typedef struct _GstAllocatorNVMM GstAllocatorNVMM;
+
+struct _GstAllocatorNVMMClass
+{
+  GstAllocatorClass parent_class;
+};
+
+typedef struct _GstAllocatorNVMMClass GstAllocatorNVMMClass;
+
+GType gst_allocator_nvmm_get_type (void);
+G_DEFINE_TYPE (GstAllocatorNVMM, gst_allocator_nvmm, GST_TYPE_ALLOCATOR);
+
+static gboolean
+gst_memory_nvmm_init (GstMemoryNVMM * nvmm, GstMemoryFlags flags,
+    GstAllocator * allocator, GstMemory * parent, const GstVideoInfo * vinfo)
+{
+  gsize size = NvBufferGetSize ();
+  NvBufferCreateParams create_params = {
+    .width = GST_VIDEO_INFO_WIDTH (vinfo),
+    .height = GST_VIDEO_INFO_HEIGHT (vinfo),
+    .payloadType = NvBufferPayload_SurfArray,
+    .memsize = GST_VIDEO_INFO_SIZE (vinfo),
+    .layout = NvBufferLayout_BlockLinear,
+    .colorFormat = NvBufferColorFormat_ABGR32,
+    .nvbuf_tag = NvBufferTag_NONE,
+  };
+
+  nvmm->dmabuf_fd = -1;
+
+  if (NvBufferCreateEx (&nvmm->dmabuf_fd, &create_params)) {
+    GST_WARNING_OBJECT (allocator, "Failed to create NvBuffer");
+    return FALSE;
+  }
+
+  if (NvBufferGetParamsEx (nvmm->dmabuf_fd, &nvmm->params)) {
+    GST_WARNING_OBJECT (allocator, "Failed to get NvBuffer params");
+    NvReleaseFd (nvmm->dmabuf_fd);
+    nvmm->dmabuf_fd = -1;
+    return FALSE;
+  }
+  nv_buffer_dump_params ((GstObject *) allocator, &nvmm->params);
+
+  gst_memory_init (&nvmm->parent, flags, allocator, parent, size, 0, 0, size);
+
+  return TRUE;
+}
+
+static gpointer
+gst_memory_nvmm_map_full (GstMemory * mem, GstMapInfo * info, gsize size)
+{
+  GstMemoryNVMM *nvmm = (GstMemoryNVMM *) mem;
+
+  GST_TRACE ("%p fd:%i map", mem, nvmm->dmabuf_fd);
+
+  // This is what the Nvidia elements do so...
+  return nvmm->params.params.nv_buffer;
+}
+
+static void
+gst_memory_nvmm_unmap_full (GstMemory * mem, GstMapInfo * info)
+{
+  GstMemoryNVMM *nvmm = (GstMemoryNVMM *) mem;
+
+  GST_TRACE ("%p fd:%i unmap", mem, nvmm->dmabuf_fd);
+}
+
+static GstMemory *
+gst_memory_nvmm_copy (GstMemory * mem, gssize offset, gssize size)
+{
+  return NULL;
+}
+
+static GstMemory *
+gst_memory_nvmm_share (GstMemory * mem, gssize offset, gssize size)
+{
+  return NULL;
+}
+
+static gboolean
+gst_memory_nvmm_is_span (GstMemory * mem, GstMemory * mem2, gsize * offset)
+{
+  return FALSE;
+}
+
+static gboolean
+gst_is_memory_nvmm (GstMemory * mem)
+{
+  return mem && mem->allocator
+      && g_type_is_a (G_OBJECT_TYPE (mem->allocator),
+      gst_allocator_nvmm_get_type ());
+}
+
+static GstAllocator *_nvmm_allocator;
+
+static void
+init_nvmm_allocator (void)
+{
+  static gsize _init = 0;
+
+  if (g_once_init_enter (&_init)) {
+    _nvmm_allocator = g_object_new (gst_allocator_nvmm_get_type (), NULL);
+/*    gst_allocator_register ("NvBuffer", _nvmm_allocator); */
+    GST_OBJECT_FLAG_SET (_nvmm_allocator, GST_OBJECT_FLAG_MAY_BE_LEAKED);
+    g_once_init_leave (&_init, 1);
+  }
+}
+
+static GstMemory *
+gst_allocator_nvmm_alloc (const GstVideoInfo * info)
+{
+  GstMemoryNVMM *nvmm = g_new0 (GstMemoryNVMM, 1);
+
+  init_nvmm_allocator ();
+
+  if (!gst_memory_nvmm_init (nvmm, 0, _nvmm_allocator, NULL, info)) {
+    g_free (nvmm);
+    return NULL;
+  }
+
+  return (GstMemory *) nvmm;
+}
+
+static GstMemory *
+_gst_allocator_nvmm_alloc (GstAllocator * alloc, gsize size,
+    GstAllocationParams * params)
+{
+  g_warning
+      ("Can't allocate using gst_allocator_alloc().  Use gst_allocator_nvmm_alloc() instead");
+
+  return NULL;
+}
+
+static void
+_gst_allocator_nvmm_free (GstAllocator * alloc, GstMemory * mem)
+{
+  GstMemoryNVMM *nvmm = (GstMemoryNVMM *) mem;
+
+  if (nvmm->dmabuf_fd > 0)
+    NvReleaseFd (nvmm->dmabuf_fd);
+  nvmm->dmabuf_fd = -1;
+
+  g_free (nvmm);
+}
+
+static void
+gst_allocator_nvmm_class_init (GstAllocatorNVMMClass * klass)
+{
+  GstAllocatorClass *alloc_class = (GstAllocatorClass *) klass;
+
+  alloc_class->alloc = _gst_allocator_nvmm_alloc;
+  alloc_class->free = _gst_allocator_nvmm_free;
+}
+
+static void
+gst_allocator_nvmm_init (GstAllocatorNVMM * nvmm)
+{
+  GstAllocator *alloc = (GstAllocator *) nvmm;
+
+  alloc->mem_map_full = gst_memory_nvmm_map_full;
+  alloc->mem_unmap_full = gst_memory_nvmm_unmap_full;
+  alloc->mem_copy = gst_memory_nvmm_copy;
+  alloc->mem_share = gst_memory_nvmm_share;
+  alloc->mem_is_span = gst_memory_nvmm_is_span;
+}
+
+GType gst_nvmm_parent_meta_api_get_type (void);
+#define GST_NVMM_PARENT_META_API_TYPE (gst_nvmm_parent_meta_api_get_type())
+
+#define gst_buffer_get_nvmm_parent_meta(b) \
+  ((GstNVMMParentMeta*)gst_buffer_get_meta((b),GST_NVMM_PARENT_META_API_TYPE))
+
+const GstMetaInfo *gst_nvmm_parent_meta_get_info (void);
+#define GST_NVMM_PARENT_META_INFO (gst_nvmm_parent_meta_get_info())
+
+/* GstParentBufferMeta but supporting NULL and no copying to avoid accidentally
+ * introducing a circular reference when copying GstMeta's */
+struct _GstNVMMParentMeta
+{
+  GstMeta parent;
+
+  GstBuffer *buffer;
+};
+typedef struct _GstNVMMParentMeta GstNVMMParentMeta;
+
+static GstNVMMParentMeta *
+gst_buffer_add_nvmm_parent_meta (GstBuffer * buffer, GstBuffer * ref)
+{
+  GstNVMMParentMeta *meta;
+
+  g_return_val_if_fail (GST_IS_BUFFER (ref), NULL);
+
+  meta =
+      (GstNVMMParentMeta *) gst_buffer_add_meta (buffer,
+      GST_NVMM_PARENT_META_INFO, NULL);
+
+  if (!meta)
+    return NULL;
+
+  if (ref)
+    meta->buffer = gst_buffer_ref (ref);
+
+  return meta;
+}
+
+static gboolean
+_gst_nvmm_parent_meta_transform (GstBuffer * dest, GstMeta * meta,
+    GstBuffer * buffer, GQuark type, gpointer data)
+{
+  return FALSE;
+}
+
+static void
+_gst_nvmm_parent_meta_free (GstNVMMParentMeta * parent_meta, GstBuffer * buffer)
+{
+  GST_DEBUG ("Dropping reference on buffer %p", parent_meta->buffer);
+  gst_clear_buffer (&parent_meta->buffer);
+}
+
+static gboolean
+_gst_nvmm_parent_meta_init (GstNVMMParentMeta * parent_meta,
+    gpointer params, GstBuffer * buffer)
+{
+  parent_meta->buffer = NULL;
+
+  return TRUE;
+}
+
+GType
+gst_nvmm_parent_meta_api_get_type (void)
+{
+  static GType type = 0;
+  static const gchar *tags[] = { GST_META_TAG_MEMORY_STR, NULL };
+
+  if (g_once_init_enter (&type)) {
+    GType _type = gst_meta_api_type_register ("GstNVMMParentMetaAPI", tags);
+    g_once_init_leave (&type, _type);
+  }
+
+  return type;
+}
+
+const GstMetaInfo *
+gst_nvmm_parent_meta_get_info (void)
+{
+  static const GstMetaInfo *meta_info = NULL;
+
+  if (g_once_init_enter ((GstMetaInfo **) & meta_info)) {
+    const GstMetaInfo *meta =
+        gst_meta_register (gst_nvmm_parent_meta_api_get_type (),
+        "GstNVMMParentMeta",
+        sizeof (GstNVMMParentMeta),
+        (GstMetaInitFunction) _gst_nvmm_parent_meta_init,
+        (GstMetaFreeFunction) _gst_nvmm_parent_meta_free,
+        _gst_nvmm_parent_meta_transform);
+    g_once_init_leave ((GstMetaInfo **) & meta_info, (GstMetaInfo *) meta);
+  }
+
+  return meta_info;
+}
+
+static GstMiniObjectDisposeFunction parent_gst_buffer_dispose = NULL;
+
+static gboolean
+gst_buffer_nvmm_dispose (GstMiniObject * obj)
+{
+  GstBuffer *buf = (GstBuffer *) obj;
+  GstNVMMParentMeta *nv_buf_meta = gst_buffer_get_nvmm_parent_meta (buf);
+
+  GST_TRACE ("nvmm buffer dispose %p, parent_buf_meta %p", obj, nv_buf_meta);
+  if (nv_buf_meta && nv_buf_meta->buffer) {
+    GstNVMMParentMeta *gl_buf_meta;
+
+    gl_buf_meta = gst_buffer_get_nvmm_parent_meta (nv_buf_meta->buffer);
+    if (gl_buf_meta && !gl_buf_meta->buffer) {
+      // reattache the NVMM buffer to the parent buffer
+      GST_LOG ("readding nvmm buffer %p %i, to glmemory buffer %p %i", buf,
+          GST_MINI_OBJECT_REFCOUNT_VALUE (buf), nv_buf_meta->buffer,
+          GST_MINI_OBJECT_REFCOUNT_VALUE (nv_buf_meta->buffer));
+      gl_buf_meta->buffer = gst_buffer_ref (buf);
+      gst_clear_buffer (&nv_buf_meta->buffer);
+      return FALSE;
+    }
+  }
+
+  return parent_gst_buffer_dispose (obj);
+}
+
+struct _GstGLBufferPoolNVMMPrivate
+{
+  GstGLVideoAllocationParams *gl_params;
+};
+typedef struct _GstGLBufferPoolNVMMPrivate GstGLBufferPoolNVMMPrivate;
+
+struct _GstGLBufferPoolNVMM
+{
+  GstGLBufferPool parent;
+};
+
+#define NVMM_POOL_GET_PRIV(obj) gst_gl_buffer_pool_nvmm_get_instance_private((GstGLBufferPoolNVMM *)(obj));
+
+G_DECLARE_FINAL_TYPE (GstGLBufferPoolNVMM, gst_gl_buffer_pool_nvmm, GST,
+    GL_BUFFER_POOL_NVMM, GstGLBufferPool);
+G_DEFINE_TYPE_WITH_CODE (GstGLBufferPoolNVMM, gst_gl_buffer_pool_nvmm,
+    GST_TYPE_GL_BUFFER_POOL, G_ADD_PRIVATE (GstGLBufferPoolNVMM));
+
+static gboolean
+gst_gl_buffer_pool_nvmm_set_config (GstBufferPool * pool, GstStructure * config)
+{
+  GstGLBufferPoolNVMMPrivate *priv;
+  GstGLBufferPool *glpool = GST_GL_BUFFER_POOL (pool);
+  GstGLVideoAllocationParams *parent_gl_params;
+  GstCaps *caps = NULL;
+  GstVideoInfo vinfo;
+  GstAllocationParams alloc_params;
+
+  priv = NVMM_POOL_GET_PRIV (pool);
+
+  if (!gst_buffer_pool_config_get_allocator (config, NULL, &alloc_params))
+    goto wrong_config;
+
+  if (!gst_buffer_pool_config_get_params (config, &caps, NULL, NULL, NULL))
+    goto wrong_config;
+
+  if (caps == NULL)
+    goto no_caps;
+
+  /* now parse the caps from the config */
+  if (!gst_video_info_from_caps (&vinfo, caps))
+    goto wrong_caps;
+
+  // TODO: fallback to regular GLMemory PBO/GetTexImage downloads?
+  if (GST_VIDEO_INFO_FORMAT (&vinfo) != GST_VIDEO_FORMAT_RGBA)
+    goto wrong_vformat;
+
+  if (!GST_BUFFER_POOL_CLASS (gst_gl_buffer_pool_nvmm_parent_class)->set_config
+      (pool, config))
+    return FALSE;
+
+  parent_gl_params = (GstGLVideoAllocationParams *)
+      gst_gl_buffer_pool_get_gl_allocation_params (glpool);
+
+  if (priv->gl_params)
+    gst_gl_allocation_params_free ((GstGLAllocationParams *) priv->gl_params);
+  priv->gl_params =
+      gst_gl_video_allocation_params_new_wrapped_gl_handle
+      (parent_gl_params->parent.context, parent_gl_params->parent.alloc_params,
+      parent_gl_params->v_info, 0, parent_gl_params->valign,
+      parent_gl_params->target, parent_gl_params->tex_format, NULL, NULL, NULL);
+
+  gst_buffer_pool_config_set_gl_allocation_params (config,
+      (GstGLAllocationParams *) priv->gl_params);
+  gst_gl_allocation_params_free ((GstGLAllocationParams *) parent_gl_params);
+
+  if (!GST_BUFFER_POOL_CLASS (gst_gl_buffer_pool_nvmm_parent_class)->set_config
+      (pool, config))
+    return FALSE;
+
+  return TRUE;
+
+wrong_config:
+  {
+    GST_WARNING_OBJECT (pool, "invalid config");
+    return FALSE;
+  }
+no_caps:
+  {
+    GST_WARNING_OBJECT (pool, "no caps in config");
+    return FALSE;
+  }
+wrong_caps:
+  {
+    GST_WARNING_OBJECT (pool,
+        "failed getting geometry from caps %" GST_PTR_FORMAT, caps);
+    return FALSE;
+  }
+wrong_vformat:
+  {
+    GST_WARNING_OBJECT (pool, "This pool only deals with RGBA textures");
+    return FALSE;
+  }
+}
+
+static void
+nv_buffer_egl_image_mem_unref (GstEGLImage * image, GstMemory * mem)
+{
+  GstGLDisplayEGL *egl_display = NULL;
+  EGLDisplay display;
+
+  egl_display = gst_gl_display_egl_from_gl_display (image->context->display);
+  if (!egl_display) {
+    GST_ERROR ("Could not retrieve GstGLDisplayEGL from GstGLDisplay");
+    return;
+  }
+  display =
+      (EGLDisplay) gst_gl_display_get_handle (GST_GL_DISPLAY (egl_display));
+
+  if (NvDestroyEGLImage (display, image->image)) {
+    GST_ERROR ("Failed to destroy EGLImage %p from NvBuffer", image->image);
+  } else {
+    GST_DEBUG ("destroyed EGLImage %p from NvBuffer", image->image);
+  }
+
+  gst_memory_unref (mem);
+  gst_object_unref (egl_display);
+}
+
+static GstFlowReturn
+gst_gl_buffer_pool_nvmm_alloc (GstBufferPool * pool, GstBuffer ** outbuf,
+    GstBufferPoolAcquireParams * acquire_params)
+{
+  GstGLBufferPool *gl_pool = GST_GL_BUFFER_POOL (pool);
+  GstGLBufferPoolNVMMPrivate *priv;
+  GstFlowReturn ret = GST_FLOW_ERROR;
+  GstBuffer *downstream_buf = NULL;
+  GstMapInfo in_map_info = GST_MAP_INFO_INIT;
+  GstGLDisplayEGL *egl_display = NULL;
+  GstEGLImage *eglimage = NULL;
+  EGLDisplay display = EGL_NO_DISPLAY;
+  EGLImageKHR image = EGL_NO_IMAGE;
+  GstGLMemoryAllocator *allocator = NULL;
+  GstMemory *nvmm_mem = NULL;
+  int in_dmabuf_fd;
+
+  priv = NVMM_POOL_GET_PRIV (pool);
+
+  *outbuf = NULL;
+  downstream_buf = gst_buffer_new ();
+  if (!parent_gst_buffer_dispose)
+    parent_gst_buffer_dispose = ((GstMiniObject *) downstream_buf)->dispose;
+  ((GstMiniObject *) downstream_buf)->dispose = gst_buffer_nvmm_dispose;
+
+  nvmm_mem = gst_allocator_nvmm_alloc (priv->gl_params->v_info);
+  if (!nvmm_mem) {
+    GST_WARNING_OBJECT (pool, "Failed to create NVMM GstMemory");
+    return GST_FLOW_ERROR;
+  }
+  gst_buffer_append_memory (downstream_buf, nvmm_mem);
+  in_dmabuf_fd = ((GstMemoryNVMM *) nvmm_mem)->dmabuf_fd;
+
+  egl_display = gst_gl_display_egl_from_gl_display (gl_pool->context->display);
+  if (!egl_display) {
+    GST_WARNING ("Failed to retrieve GstGLDisplayEGL from GstGLDisplay");
+    goto done;
+  }
+  display =
+      (EGLDisplay) gst_gl_display_get_handle (GST_GL_DISPLAY (egl_display));
+
+  image = NvEGLImageFromFd (display, in_dmabuf_fd);
+  if (!image) {
+    GST_DEBUG_OBJECT (pool, "Failed construct EGLImage "
+        "from NvBuffer fd %i", in_dmabuf_fd);
+    goto done;
+  }
+  GST_DEBUG_OBJECT (pool, "constructed EGLImage %p "
+      "from NvBuffer fd %i", image, in_dmabuf_fd);
+
+  eglimage = gst_egl_image_new_wrapped (gl_pool->context, image,
+      GST_GL_RGBA, gst_memory_ref (nvmm_mem),
+      (GstEGLImageDestroyNotify) nv_buffer_egl_image_mem_unref);
+  if (!eglimage) {
+    GST_WARNING_OBJECT (pool, "Failed to wrap constructed "
+        "EGLImage from NvBuffer");
+    goto done;
+  }
+
+  gst_buffer_unmap (downstream_buf, &in_map_info);
+  in_map_info = (GstMapInfo) GST_MAP_INFO_INIT;
+
+  allocator =
+      GST_GL_MEMORY_ALLOCATOR (gst_allocator_find
+      (GST_GL_MEMORY_EGL_ALLOCATOR_NAME));
+
+  /* TODO: buffer pool */
+  *outbuf = gst_buffer_new ();
+  if (!gst_gl_memory_setup_buffer (allocator, *outbuf, priv->gl_params,
+          NULL, (gpointer *) & eglimage, 1)) {
+    GST_WARNING_OBJECT (pool, "Failed to setup NVMM -> EGLImage buffer");
+    goto done;
+  }
+
+  gst_egl_image_unref (eglimage);
+
+  /* TODO: NvBuffer has some sync functions that may be more useful here */
+  {
+    GstGLSyncMeta *sync_meta;
+
+    sync_meta = gst_buffer_add_gl_sync_meta (gl_pool->context, *outbuf);
+    if (sync_meta) {
+      gst_gl_sync_meta_set_sync_point (sync_meta, gl_pool->context);
+    }
+  }
+
+  // possible circular reference here
+  gst_buffer_add_nvmm_parent_meta (*outbuf, downstream_buf);
+  gst_buffer_unref (downstream_buf);
+
+  ret = GST_FLOW_OK;
+
+done:
+  if (in_map_info.memory)
+    gst_buffer_unmap (downstream_buf, &in_map_info);
+
+  gst_clear_object (&egl_display);
+  gst_clear_object (&allocator);
+
+  return ret;
+}
+
+static void
+gst_gl_buffer_pool_nvmm_finalize (GObject * object)
+{
+  GstGLBufferPoolNVMMPrivate *priv = NVMM_POOL_GET_PRIV (object);
+
+  if (priv->gl_params)
+    gst_gl_allocation_params_free ((GstGLAllocationParams *) priv->gl_params);
+  priv->gl_params = NULL;
+
+  G_OBJECT_CLASS (gst_gl_buffer_pool_nvmm_parent_class)->finalize (object);
+}
+
+static void
+gst_gl_buffer_pool_nvmm_init (GstGLBufferPoolNVMM * pool)
+{
+}
+
+static void
+gst_gl_buffer_pool_nvmm_class_init (GstGLBufferPoolNVMMClass * klass)
+{
+  GstBufferPoolClass *pool_class = (GstBufferPoolClass *) klass;
+  GObjectClass *gobject_class = (GObjectClass *) klass;
+
+  pool_class->set_config = gst_gl_buffer_pool_nvmm_set_config;
+  pool_class->alloc_buffer = gst_gl_buffer_pool_nvmm_alloc;
+
+  gobject_class->finalize = gst_gl_buffer_pool_nvmm_finalize;
+}
+
+static GstBufferPool *
+gst_gl_buffer_pool_nvmm_new (GstGLContext * context)
+{
+  GstGLBufferPoolNVMM *pool;
+  GstGLBufferPool *gl_pool;
+
+  pool = g_object_new (gst_gl_buffer_pool_nvmm_get_type (), NULL);
+  gst_object_ref_sink (pool);
+  gl_pool = GST_GL_BUFFER_POOL (pool);
+  gl_pool->context = gst_object_ref (context);
+
+  GST_LOG_OBJECT (pool, "new NVMM GL buffer pool for context %" GST_PTR_FORMAT,
+      context);
+
+  return GST_BUFFER_POOL_CAST (pool);
+}
+#endif /* GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM) */
+
 #define gst_gl_download_element_parent_class parent_class
 G_DEFINE_TYPE_WITH_CODE (GstGLDownloadElement, gst_gl_download_element,
     GST_TYPE_GL_BASE_FILTER,
@@ -57,25 +793,37 @@ gst_gl_download_element_prepare_output_buffer (GstBaseTransform * bt,
     GstBuffer * buffer, GstBuffer ** outbuf);
 static GstFlowReturn gst_gl_download_element_transform (GstBaseTransform * bt,
     GstBuffer * buffer, GstBuffer * outbuf);
+static gboolean gst_gl_download_element_transform_meta (GstBaseTransform * bt,
+    GstBuffer * outbuf, GstMeta * meta, GstBuffer * inbuf);
 static gboolean gst_gl_download_element_decide_allocation (GstBaseTransform *
     trans, GstQuery * query);
 static gboolean gst_gl_download_element_sink_event (GstBaseTransform * bt,
     GstEvent * event);
 static gboolean gst_gl_download_element_src_event (GstBaseTransform * bt,
     GstEvent * event);
+static gboolean gst_gl_download_element_propose_allocation (GstBaseTransform *
+    bt, GstQuery * decide_query, GstQuery * query);
 static void gst_gl_download_element_finalize (GObject * object);
 
+#define GST_CAPS_FEATURE_MEMORY_NVMM "memory:NVMM"
+
+#if GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM)
+#define EXTRA_CAPS_TEMPLATE1 "video/x-raw(" GST_CAPS_FEATURE_MEMORY_NVMM "), format=(string)RGBA; "
+#else
+#define EXTRA_CAPS_TEMPLATE1
+#endif
+
 #if GST_GL_HAVE_PLATFORM_EGL && GST_GL_HAVE_DMABUF
-#define EXTRA_CAPS_TEMPLATE "video/x-raw(" GST_CAPS_FEATURE_MEMORY_DMABUF "); "
+#define EXTRA_CAPS_TEMPLATE2 "video/x-raw(" GST_CAPS_FEATURE_MEMORY_DMABUF "); "
 #else
-#define EXTRA_CAPS_TEMPLATE
+#define EXTRA_CAPS_TEMPLATE2
 #endif
 
 static GstStaticPadTemplate gst_gl_download_element_src_pad_template =
     GST_STATIC_PAD_TEMPLATE ("src",
     GST_PAD_SRC,
     GST_PAD_ALWAYS,
-    GST_STATIC_CAPS (EXTRA_CAPS_TEMPLATE
+    GST_STATIC_CAPS (EXTRA_CAPS_TEMPLATE1 EXTRA_CAPS_TEMPLATE2
         "video/x-raw; video/x-raw(memory:GLMemory)"));
 
 static GstStaticPadTemplate gst_gl_download_element_sink_pad_template =
@@ -103,6 +851,8 @@ gst_gl_download_element_class_init (GstGLDownloadElementClass * klass)
   bt_class->decide_allocation = gst_gl_download_element_decide_allocation;
   bt_class->sink_event = gst_gl_download_element_sink_event;
   bt_class->src_event = gst_gl_download_element_src_event;
+  bt_class->propose_allocation = gst_gl_download_element_propose_allocation;
+  bt_class->transform_meta = gst_gl_download_element_transform_meta;
 
   bt_class->passthrough_on_same_caps = TRUE;
 
@@ -166,14 +916,23 @@ gst_gl_download_element_set_caps (GstBaseTransform * bt, GstCaps * in_caps,
 
   if (gst_caps_features_contains (features, GST_CAPS_FEATURE_MEMORY_GL_MEMORY)) {
     dl->mode = GST_GL_DOWNLOAD_MODE_PASSTHROUGH;
+    GST_INFO_OBJECT (dl, "caps signal passthrough");
+#if GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM)
+  } else if (gst_caps_features_contains (features,
+          GST_CAPS_FEATURE_MEMORY_NVMM)) {
+    dl->mode = GST_GL_DOWNLOAD_MODE_NVMM;
+    GST_INFO_OBJECT (dl, "caps signal NVMM");
+#endif
 #if GST_GL_HAVE_PLATFORM_EGL && GST_GL_HAVE_DMABUF
   } else if (g_atomic_int_get (&dl->try_dmabuf_exports) &&
       gst_caps_features_contains (features, GST_CAPS_FEATURE_MEMORY_DMABUF)) {
     dl->mode = GST_GL_DOWNLOAD_MODE_DMABUF_EXPORTS;
+    GST_INFO_OBJECT (dl, "caps signal dma-buf export");
 #endif
   } else {
     /* System Memory */
     dl->mode = GST_GL_DOWNLOAD_MODE_PBO_TRANSFERS;
+    GST_INFO_OBJECT (dl, "caps signal sysmem download");
   }
 
   return TRUE;
@@ -221,6 +980,13 @@ gst_gl_download_element_transform_caps (GstBaseTransform * bt,
     GstCaps *newcaps;
     tmp = gst_caps_ref (caps);
 
+#if GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM)
+    newcaps = _set_caps_features (caps, GST_CAPS_FEATURE_MEMORY_NVMM);
+    _remove_field (newcaps, "texture-target");
+    // FIXME: RGBA-only?
+    tmp = gst_caps_merge (tmp, newcaps);
+#endif
+
 #if GST_GL_HAVE_PLATFORM_EGL && GST_GL_HAVE_DMABUF
     newcaps = _set_caps_features (caps, GST_CAPS_FEATURE_MEMORY_DMABUF);
     _remove_field (newcaps, "texture-target");
@@ -461,10 +1227,57 @@ gst_gl_download_element_prepare_output_buffer (GstBaseTransform * bt,
     GstBuffer * inbuf, GstBuffer ** outbuf)
 {
   GstGLDownloadElement *dl = GST_GL_DOWNLOAD_ELEMENT (bt);
+  GstBaseTransformClass *bclass = GST_BASE_TRANSFORM_GET_CLASS (bt);
   gint i, n;
 
   *outbuf = inbuf;
 
+  (void) bclass;
+
+#if GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM)
+  if (dl->mode == GST_GL_DOWNLOAD_MODE_NVMM) {
+    GstNVMMParentMeta *buf_meta = gst_buffer_get_nvmm_parent_meta (inbuf);
+    GstMemory *mem;
+    GstMemoryNVMM *nvmm_mem;
+
+    if (!buf_meta || !buf_meta->buffer) {
+      // TODO: remove this restriction with an e.g. copy...
+      GST_ERROR_OBJECT (dl,
+          "Cannot push upstream created buffer when outputting NVMM");
+      return GST_FLOW_ERROR;
+    }
+
+    if (!(mem = gst_buffer_peek_memory (buf_meta->buffer, 0))) {
+      GST_ERROR_OBJECT (dl, "No memory in buffer?");
+      return GST_FLOW_ERROR;
+    }
+
+    if (!gst_is_memory_nvmm (mem)) {
+      GST_ERROR_OBJECT (dl,
+          "Upstream buffer does not contain an attached NVMM GstMemory");
+      return GST_FLOW_ERROR;
+    }
+    nvmm_mem = (GstMemoryNVMM *) mem;
+
+    /* switch up the parent buffer references so that when the NVMM buffer is
+     * released, the associated EGLImage/OpenGL texture is as well
+     */
+    GST_DEBUG_OBJECT (dl, "NVMM buffer fd:%i passed through %" GST_PTR_FORMAT,
+        nvmm_mem->dmabuf_fd, buf_meta->buffer);
+    *outbuf = buf_meta->buffer;
+    bclass->copy_metadata (bt, inbuf, *outbuf);
+    buf_meta->buffer = NULL;
+    buf_meta = gst_buffer_get_nvmm_parent_meta (*outbuf);
+    if (!buf_meta) {
+      buf_meta = gst_buffer_add_nvmm_parent_meta (*outbuf, inbuf);
+    } else {
+      gst_clear_buffer (&buf_meta->buffer);
+      buf_meta->buffer = gst_buffer_ref (inbuf);
+    }
+
+    return GST_FLOW_OK;
+  }
+#endif
 #if GST_GL_HAVE_PLATFORM_EGL && GST_GL_HAVE_DMABUF
   if (dl->mode == GST_GL_DOWNLOAD_MODE_DMABUF_EXPORTS) {
     GstBuffer *buffer = _try_export_dmabuf (dl, inbuf);
@@ -530,6 +1343,19 @@ gst_gl_download_element_transform (GstBaseTransform * bt,
 }
 
 static gboolean
+gst_gl_download_element_transform_meta (GstBaseTransform * bt,
+    GstBuffer * outbuf, GstMeta * meta, GstBuffer * inbuf)
+{
+  if (g_type_is_a (meta->info->api, GST_GL_SYNC_META_API_TYPE)) {
+    GST_LOG_OBJECT (bt, "not copying GstGLSyncMeta onto output buffer");
+    return FALSE;
+  }
+
+  return GST_BASE_TRANSFORM_CLASS (parent_class)->transform_meta (bt, outbuf,
+      meta, inbuf);
+}
+
+static gboolean
 gst_gl_download_element_decide_allocation (GstBaseTransform * trans,
     GstQuery * query)
 {
@@ -569,6 +1395,83 @@ gst_gl_download_element_src_event (GstBaseTransform * bt, GstEvent * event)
   return GST_BASE_TRANSFORM_CLASS (parent_class)->src_event (bt, event);
 }
 
+static gboolean
+gst_gl_download_element_propose_allocation (GstBaseTransform * bt,
+    GstQuery * decide_query, GstQuery * query)
+{
+  GstBufferPool *pool = NULL;
+  GstCaps *caps;
+  GstGLContext *context;
+  GstStructure *config;
+  GstVideoInfo info;
+  gsize size;
+
+  if (!GST_BASE_TRANSFORM_CLASS (parent_class)->propose_allocation (bt,
+          decide_query, query))
+    return FALSE;
+
+  gst_query_parse_allocation (query, &caps, NULL);
+  if (caps == NULL)
+    goto invalid_caps;
+
+  context = GST_GL_BASE_FILTER (bt)->context;
+  if (!context) {
+    GST_ERROR_OBJECT (context, "got no GLContext");
+    return FALSE;
+  }
+
+  if (!gst_video_info_from_caps (&info, caps))
+    goto invalid_caps;
+
+#if GST_GL_HAVE_PLATFORM_EGL && defined(HAVE_NVMM)
+  if (!pool && decide_query) {
+    GstCaps *decide_caps;
+
+    gst_query_parse_allocation (decide_query, &decide_caps, NULL);
+    if (decide_caps && gst_caps_get_size (decide_caps) > 0) {
+      GstCapsFeatures *features = gst_caps_get_features (decide_caps, 0);
+
+      if (gst_caps_features_contains (features, GST_CAPS_FEATURE_MEMORY_NVMM)) {
+        pool = gst_gl_buffer_pool_nvmm_new (context);
+        GST_INFO_OBJECT (bt, "have NVMM downstream, proposing NVMM "
+            "pool %" GST_PTR_FORMAT, pool);
+      }
+    }
+  }
+#endif
+  if (!pool) {
+    pool = gst_gl_buffer_pool_new (context);
+  }
+  config = gst_buffer_pool_get_config (pool);
+
+  /* the normal size of a frame */
+  size = info.size;
+  gst_buffer_pool_config_set_params (config, caps, size, 0, 0);
+  gst_buffer_pool_config_add_option (config,
+      GST_BUFFER_POOL_OPTION_GL_SYNC_META);
+
+  if (!gst_buffer_pool_set_config (pool, config)) {
+    gst_object_unref (pool);
+    goto config_failed;
+  }
+  gst_query_add_allocation_pool (query, pool, size, 1, 0);
+
+  gst_object_unref (pool);
+  return TRUE;
+
+invalid_caps:
+  {
+    GST_ERROR_OBJECT (bt, "Invalid Caps specified");
+    return FALSE;
+  }
+config_failed:
+  {
+    GST_ERROR_OBJECT (bt, "failed setting config");
+    return FALSE;
+  }
+}
+
+
 static void
 gst_gl_download_element_finalize (GObject * object)
 {
diff --git a/ext/gl/gstgldownloadelement.h b/ext/gl/gstgldownloadelement.h
index 93bfd50c7..7ae7c44ec 100644
--- a/ext/gl/gstgldownloadelement.h
+++ b/ext/gl/gstgldownloadelement.h
@@ -43,7 +43,8 @@ typedef enum
 {
   GST_GL_DOWNLOAD_MODE_PASSTHROUGH,
   GST_GL_DOWNLOAD_MODE_PBO_TRANSFERS,
-  GST_GL_DOWNLOAD_MODE_DMABUF_EXPORTS
+  GST_GL_DOWNLOAD_MODE_DMABUF_EXPORTS,
+  GST_GL_DOWNLOAD_MODE_NVMM,
 } GstGlDownloadMode;
 
 struct _GstGLDownloadElement
diff --git a/ext/gl/meson.build b/ext/gl/meson.build
index a0012147b..7175f0f59 100644
--- a/ext/gl/meson.build
+++ b/ext/gl/meson.build
@@ -133,10 +133,17 @@ if ['darwin', 'ios'].contains(host_system)
   gl_objc_args += ['-fobjc-arc']
 endif
 
+extra_c_args = []
+# gl_nvmm and nvbuf_utils_dep are set in gst-libs/gst/gl/meson.build
+if gl_nvmm
+  extra_c_args += ['-DHAVE_NVMM']
+  optional_deps += [nvbuf_utils_dep]
+endif
+
 gstopengl = library('gstopengl',
   opengl_sources,
-  c_args : gst_plugins_base_args,
-  objc_args : gst_plugins_base_args + gl_objc_args,
+  c_args : gst_plugins_base_args + extra_c_args,
+  objc_args : gst_plugins_base_args + gl_objc_args + extra_c_args,
   link_args : noseh_link_args,
   include_directories : [configinc],
   dependencies : [gstgl_dep, video_dep,