iMX8 Gstreamer, pointer to access to overlay rectangle, GstBuffer data

Keith_RL — Thu, 07 Jul 2022 09:29:49 GMT

Using an iMX8MPLUS-BB, Yocto honister,

Gstreamer plugin that can write initially static data (RGBA) that is overlaid on video. Similar to what is described in

Basic tutorial 8: Short-cutting the pipeline (gstreamer.freedesktop.org)

The overlay on video will be a gst_video_overlay_rectangle

Gst_video_overlay_rectangle_new_raw(
                GstBuffer * pixels,
                gint render_x, render_y
                gint render_width, render_height
GstVideoOVerlayFormatFlags flags)

In old Gstreamer 0.10 the GstBuffer structure was as follows and contained a pointer to the actual data, *data. And a Macro for access the pointer. Looks like what I need. But is old gstreamer

struct _GstBuffer {
GstMiniObject mini_object;
/*< public >*/ /* with COW */
/* pointer to data and its size */

guint8 *data;
guint size;

/* timestamp */
GstClockTime timestamp;
GstClockTime duration;

/* the media type of this buffer */
GstCaps *caps;

/* media specific offset */
guint64                offset;
guint64                offset_end;
guint8                *malloc_data;

/* ABI Added */
GFreeFunc free_func;
GstBuffer *parent;

/*< private >*/
gpointer _gst_reserved[GST_PADDING - 2];
};

GST_BUFFER_DATA (buffer)

The iMX8 used GStreamer Core Library version 1.18.5, where the structure of GstBuffer is a follows

struct _GstBuffer {
GstMiniObject mini_object;
/*< public >*/ /* with COW */
GstBufferPool *pool;

/* timestamp */
GstClockTime           pts;
GstClockTime           dts;
GstClockTime           duration;

/* media specific offset */
guint64 offset;
guint64 offset_end;
};

It no longer provides the data pointer and uses GstBufferPool, I have investigated the GstBufferPool but have not found an obvious method to get the memory address, so is there a mechanism for obtaining a pointer to the memory address from the GstBufferPool ?

Re: iMX8 Gstreamer, pointer to access to overlay rectangle, GstBuffer data

Keith_RL — Fri, 08 Jul 2022 13:28:10 GMT

Found the answer to my question in the gstreamer 0.10 to 1.0 porting guide

docs/random/porting-to-1.0.txt · master · GStreamer / gstreamer · GitLab

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iMX8 Gstreamer, pointer to access to overlay rectangle, GstBuffer data

Re: iMX8 Gstreamer, pointer to access to overlay rectangle, GstBuffer data