gstvideometa

## gstvideometa gstvideometa |

## Synopsis

    #include <>gst/video/gstvideometa.h>

    struct              GstVideoMeta;
    gboolean            gst_video_meta_map                  (GstVideoMeta *meta,
                                                             guint plane,
                                                             GstMapInfo *info,
                                                             gpointer *data,
                                                             gint *stride,
                                                             GstMapFlags flags);
    gboolean            gst_video_meta_unmap                (GstVideoMeta *meta,
                                                             guint plane,
                                                             GstMapInfo *info);
    const GstMetaInfo * gst_video_meta_get_info             (void);
    GstVideoMeta *      gst_buffer_add_video_meta           (GstBuffer *buffer,
                                                             GstVideoFrameFlags flags,
                                                             GstVideoFormat format,
                                                             guint width,
                                                             guint height);
    GstVideoMeta *      gst_buffer_add_video_meta_full      (GstBuffer *buffer,
                                                             GstVideoFrameFlags flags,
                                                             GstVideoFormat format,
                                                             guint width,
                                                             guint height,
                                                             guint n_planes,
                                                             gsize offset[GST_VIDEO_MAX_PLANES],
                                                             gint stride[GST_VIDEO_MAX_PLANES]);
    #define             gst_buffer_get_video_meta           (b)
    GstVideoMeta *      gst_buffer_get_video_meta_id        (GstBuffer *buffer,
                                                             gint id);
    struct              GstVideoCropMeta;
    #define             gst_buffer_add_video_crop_meta      (b)
    #define             gst_buffer_get_video_crop_meta      (b)

## Description

## Details

### struct GstVideoMeta

    struct GstVideoMeta {
      GstMeta            meta;

      GstBuffer         *buffer;

      GstVideoFrameFlags flags;
      GstVideoFormat     format;
      gint               id;
      guint              width;
      guint              height;

      guint              n_planes;
      gsize              offset[GST_VIDEO_MAX_PLANES];
      gint               stride[GST_VIDEO_MAX_PLANES];

      gboolean (*map)    (GstVideoMeta *meta, guint plane, GstMapInfo *info,
                          gpointer *data, gint * stride, GstMapFlags flags);
      gboolean (*unmap)  (GstVideoMeta *meta, guint plane, GstMapInfo *info);
    };

Extra buffer metadata describing image properties

GstMeta `meta`; | parent GstMeta
GstBuffer *`buffer`; | the buffer this metadata belongs to
GstVideoFrameFlags `flags`; | additional video flags
GstVideoFormat `format`; | the video format
gint `id`; | identifier of the frame
guint `width`; | the video width
guint `height`; | the video height
guint `n_planes`; | the number of planes in the image
gsize `offset`[GST_VIDEO_MAX_PLANES]; | array of offsets for the planes. This field might not always be valid, it is used by the default implementation of `map`.
gint `stride`[GST_VIDEO_MAX_PLANES]; | array of strides for the planes. This field might not always be valid, it is used by the default implementation of `map`.
`map` () | map the memory of a plane
`unmap` () | unmap the memory of a plane

### gst_video_meta_map ()

    gboolean            gst_video_meta_map                  (GstVideoMeta *meta,
                                                             guint plane,
                                                             GstMapInfo *info,
                                                             gpointer *data,
                                                             gint *stride,
                                                             GstMapFlags flags);

Map the video plane with index `plane` in `meta` and return a pointer to the first byte of the plane and the stride of the plane.

`meta` : | a GstVideoMeta
`plane` : | a plane
`info` : | a GstMapInfo
`data` : | the data of `plane`
`stride` : | the stride of `plane`
`flags` : | `GstMapFlags`
Returns : | TRUE if the map operation was successful.

### gst_video_meta_unmap ()

    gboolean            gst_video_meta_unmap                (GstVideoMeta *meta,
                                                             guint plane,
                                                             GstMapInfo *info);

Unmap a previously mapped plane with `gst_video_meta_map()`.

`meta` : | a GstVideoMeta
`plane` : | a plane
`info` : | a GstMapInfo
Returns : | TRUE if the memory was successfully unmapped.

### gst_video_meta_get_info ()

    const GstMetaInfo * gst_video_meta_get_info             (void);

### gst_buffer_add_video_meta ()

    GstVideoMeta *      gst_buffer_add_video_meta           (GstBuffer *buffer,
                                                             GstVideoFrameFlags flags,
                                                             GstVideoFormat format,
                                                             guint width,
                                                             guint height);

Attaches GstVideoMeta metadata to `buffer` with the given parameters and the default offsets and strides for `format` and `width` x `height`.

This function calculates the default offsets and strides and then calls `gst_buffer_add_video_meta_full()` with them.

`buffer` : | a GstBuffer
`flags` : | GstVideoFrameFlags
`format` : | a GstVideoFormat
`width` : | the width
`height` : | the height
Returns : | the GstVideoMeta on `buffer`.

### gst_buffer_add_video_meta_full ()

    GstVideoMeta *      gst_buffer_add_video_meta_full      (GstBuffer *buffer,
                                                             GstVideoFrameFlags flags,
                                                             GstVideoFormat format,
                                                             guint width,
                                                             guint height,
                                                             guint n_planes,
                                                             gsize offset[GST_VIDEO_MAX_PLANES],
                                                             gint stride[GST_VIDEO_MAX_PLANES]);

Attaches GstVideoMeta metadata to `buffer` with the given parameters.

`buffer` : | a GstBuffer
`flags` : | GstVideoFrameFlags
`format` : | a GstVideoFormat
`width` : | the width
`height` : | the height
`n_planes` : | number of planes
`offset` : | offset of each plane
`stride` : | stride of each plane
Returns : | the GstVideoMeta on `buffer`.

### gst_buffer_get_video_meta()

    #define gst_buffer_get_video_meta(b) ((GstVideoMeta*)gst_buffer_get_meta((b),GST_VIDEO_META_API_TYPE))

### gst_buffer_get_video_meta_id ()

    GstVideoMeta *      gst_buffer_get_video_meta_id        (GstBuffer *buffer,
                                                             gint id);

Find the GstVideoMeta on `buffer` with the given `id`.

Buffers can contain multiple GstVideoMeta metadata items when dealing with multiview buffers.

`buffer` : | a GstBuffer
`id` : | a metadata id
Returns : | the GstVideoMeta with `id` or `NULL` when there is no such metadata on `buffer`.

### struct GstVideoCropMeta

    struct GstVideoCropMeta {
      GstMeta       meta;

      guint         x;
      guint         y;
      guint         width;
      guint         height;
    };

Extra buffer metadata describing image cropping.

GstMeta `meta`; | parent GstMeta
guint `x`; | the horizontal offset
guint `y`; | the vertical offset
guint `width`; | the cropped width
guint `height`; | the cropped height

### gst_buffer_add_video_crop_meta()

    #define gst_buffer_add_video_crop_meta(b) ((GstVideoCropMeta*)gst_buffer_add_meta((b),GST_VIDEO_CROP_META_INFO, NULL))

### gst_buffer_get_video_crop_meta()

    #define gst_buffer_get_video_crop_meta(b) ((GstVideoCropMeta*)gst_buffer_get_meta((b),GST_VIDEO_CROP_META_API_TYPE))