这个代码可以正常运行，黑白画面交替：
#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;
}
