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gst-appsrc.c
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gst-appsrc.c
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// example appsrc for gstreamer 1.0 with own mainloop & external buffers. based on example from gstreamer docs.
// public domain, 2015 by Florian Echtler <floe@butterbrot.org>. compile with:
// gcc --std=c99 -Wall $(pkg-config --cflags gstreamer-1.0) -o gst-appsrc gst-appsrc.c $(pkg-config --libs gstreamer-1.0) -lgstapp-1.0
#include <gst/gst.h>
#include <gst/app/gstappsrc.h>
#include <stdio.h>
#include <stdint.h>
#define WHITE ((uint16_t) 0xFFFF)
#define RED ((uint16_t) 0x00F00F)
#define BLUE ((uint16_t) 0x0F00F0)
#define GREEN ((uint16_t) 0xF00F00)
#define BLACK ((uint16_t) 0x0)
static void
cb_need_data (GstElement *appsrc, guint unused_size, gpointer arr)
{
// If needed, buffers would be prepared in a different thread and allowed
// to be pushed by this func.
static GstClockTime timestamp = 0;
GstBuffer *buffer;
guint size;
GstFlowReturn ret;
// Notice our array takes two bytes each position. This matches sizeof(arr))
size = 384 * 288 * 2;
buffer = gst_buffer_new_wrapped_full(0, (gpointer)arr, size, 0, size, NULL, NULL);
// Define presentation time, duration (fraction) and add for PTS of next buf
GST_BUFFER_PTS (buffer) = timestamp;
GST_BUFFER_DURATION (buffer) = gst_util_uint64_scale_int (1, GST_SECOND, 5);
timestamp += GST_BUFFER_DURATION (buffer);
ret = gst_app_src_push_buffer((GstAppSrc*) appsrc, buffer);
if (ret != GST_FLOW_OK) {
/* something wrong, stop pushing */
// g_main_loop_quit (loop);
}
}
static void
print_caps (GstElement* ele)
{
GstCaps* caps;
gchar* cap_str;
g_object_get (G_OBJECT (ele), "caps", &caps, NULL);
cap_str = gst_caps_to_string (caps);
printf("Element caps: %s\n", cap_str);
}
gint
main (gint argc, gchar *argv[])
{
GstElement *pipeline, *appsrc;
GError *error = NULL;
uint16_t arr[384*288];
// Tune array to display a line
for (int x=0; x<288 ; x++) {
for (int y=0; y<384; y++) {
if (y == 1 * x + 0) {
arr[x*384 + y] = WHITE;
}
else if (y == -1 * x + 200) {
arr[x*384 + y] = GREEN;
}
else if (y == 200) {
arr[x*384 + y] = BLUE;
}
else if (y == x + 200) {
arr[x*384 + y] = RED;
}
else {
arr[x*384 + y] = BLACK;
}
}
}
/* init GStreamer */
gst_init (&argc, &argv);
gchar* desc =
" appsrc stream-type=0 format=time is-live=true name=source "
" caps=video/x-raw,format=RGB16,width=384,height=288,framerate=0/1 "
" ! videoconvert ! timeoverlay ! xvimagesink ";
pipeline = gst_parse_launch (desc, &error);
if (error) {
g_printerr ("pipeline parsing error: %s\n", error->message);
g_error_free (error);
return 1;
}
// Plug callbacks into appsrc
appsrc = gst_bin_get_by_name (GST_BIN (pipeline), "source");
g_assert (appsrc != NULL);
g_signal_connect(appsrc, "need-data", G_CALLBACK(cb_need_data), (gpointer) arr);
gst_element_set_state (pipeline, GST_STATE_PLAYING);
printf("Image size in bytes %ld\n", sizeof(arr));
print_caps(appsrc);
// why not g mainloop
while (1) {
g_main_context_iteration(g_main_context_default(), FALSE);
}
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (GST_OBJECT (pipeline));
return 0;
}