diff --git a/gst-libs/gst/video/gstvideometa.h b/gst-libs/gst/video/gstvideometa.h index 3519a54d8d..4abf173617 100644 --- a/gst-libs/gst/video/gstvideometa.h +++ b/gst-libs/gst/video/gstvideometa.h @@ -59,6 +59,21 @@ typedef struct _GstVideoCropMeta GstVideoCropMeta; * to no padding and no alignment. Since: 1.18 * * Extra buffer metadata describing image properties + * + * This meta can also be used by downstream elements to specifiy their + * buffer layout requirements for upstream. Upstream should try to + * fit those requirements, if possible, in order to prevent buffer copies. + * + * This is done by passing a custom #GstStructure to + * gst_query_add_allocation_meta() when handling the ALLOCATION query. + * This structure should be named 'video-meta' and can have the following + * fields: + * - padding-top (uint): extra pixels on the top + * - padding-bottom (uint): extra pixels on the bottom + * - padding-left (uint): extra pixels on the left side + * - padding-right (uint): extra pixels on the right side + * The padding fields have the same semantic as #GstVideoMeta.alignment + * and so represent the paddings requested on produced video buffers. */ struct _GstVideoMeta { GstMeta meta;