gstreamer向appsrc發送幀畫面的代碼

這個代碼可以正常運作，黑白畫面交替：

#include <gst/gst.h>
 
#define VIDEO_WIDTH   384
#define VIDEO_HEIGHT  288
#define VIDEO_FORMAT  "RGB16"
#define PIXEL_SIZE    2
 
static void cb_need_data (GstElement *appsrc, guint       unused_size, gpointer    user_data)
{
    static gboolean white = FALSE;
    static GstClockTime timestamp = 0;
    GstBuffer *buffer;
    guint size;
    GstFlowReturn ret;
 
    size = VIDEO_WIDTH * VIDEO_HEIGHT * PIXEL_SIZE;
    buffer = gst_buffer_new_allocate (NULL, size, NULL);
 
    /* this makes the image black/white */
    gst_buffer_memset (buffer, 0, white ? 0xFF : 0x00, size);
 
    white = !white;
 
    GST_BUFFER_PTS (buffer) = timestamp;
    GST_BUFFER_DURATION (buffer) = gst_util_uint64_scale_int (1, GST_SECOND, 2);
 
    timestamp += GST_BUFFER_DURATION (buffer);
 
    g_signal_emit_by_name (appsrc, "push-buffer", buffer, &ret);
    gst_buffer_unref (buffer);
 
    if (ret != GST_FLOW_OK)
    {
        /* something wrong, stop pushing */
        g_main_loop_quit (loop);
    }
}
 
gint main (gint   argc, gchar *argv[])
{
    GstElement *pipeline, *appsrc, *conv, *videosink;
    GMainLoop *loop;
 
    /* init GStreamer */
    gst_init (NULL, NULL);
    loop = g_main_loop_new (NULL, FALSE);
 
    /* setup pipeline */
    pipeline  = gst_pipeline_new ("pipeline");
    appsrc    = gst_element_factory_make ("appsrc",       "source");
    conv      = gst_element_factory_make ("videoconvert", "conv");
    videosink = gst_element_factory_make ("xvimagesink",  "videosink");
 
    /* setup */
    g_object_set (G_OBJECT (appsrc), "caps",
        gst_caps_new_simple ("video/x-raw",
                     "format",    G_TYPE_STRING,     VIDEO_FORMAT,
                     "width",     G_TYPE_INT,        VIDEO_WIDTH,
                     "height",    G_TYPE_INT,        VIDEO_HEIGHT,
                     "framerate", GST_TYPE_FRACTION, 0, 1,
                     NULL), NULL);
    gst_bin_add_many (GST_BIN (pipeline), appsrc, conv, videosink, NULL);
    gst_element_link_many (appsrc, conv, videosink, NULL);
 
    /* setup appsrc */
    g_object_set (G_OBJECT (appsrc),
        "stream-type", 0,
        "format", GST_FORMAT_TIME, NULL);
    g_signal_connect (appsrc, "need-data", G_CALLBACK (cb_need_data), NULL);
 
    /* play */
    gst_element_set_state (pipeline, GST_STATE_PLAYING);
    g_main_loop_run (loop);
 
    /* clean up */
    gst_element_set_state (pipeline, GST_STATE_NULL);
    gst_object_unref (GST_OBJECT (pipeline));
    g_main_loop_unref (loop);
 
    return 0;
}