I am trying to learn gstreamer appsrc plugin to play AV from a transport stream demultiplexer that I wrote (I know plugins are already available, I wanted to do it myself to learn). I have extracted audio and video elementary streams from the MPEG transport stream; now I have to push it to the appsrc plugin and play it using a gst pipeline (this part is not yet clear to me: as to which plugins to use - any tips will be highly appreciated).
I found a sample code on using appsrc, but when I run that, there is no output. I verified that start_feed
and read_data
functions are indeed invoked. In read_data
function, there is a timer check to decide whether to push data or not:
ms = g_timer_elapsed(app->timer, NULL);
printf("ms %f\n", ms);
if (ms > 1.0/20.0) {
I don't know what this timer is for, but the value of ms
is always around 0.035 and data is never pushed into the appsrc. So I changed the if condition to if(ms > 0.03)
but then I got an internal data flow error:
ms 0.033747
ms 0.000010
ERROR from element mysource: Internal data flow error.
Debugging info: gstbasesrc.c(2582): gst_base_src_loop (): /GstPipeline:pipeline0/GstAppSrc:mysource:
streaming task paused, reason not-negotiated (-4)
Can someone tell me how to tweak this to see the video? The code from the linked website is given below.
#include <gst/gst.h>
#include <gst/app/gstappsrc.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <gdk-pixbuf/gdk-pixbuf.h>
GST_DEBUG_CATEGORY (appsrc_pipeline_debug);
#define GST_CAT_DEFAULT appsrc_pipeline_debug
typedef struct _App App;
struct _App
{
GstElement *pipeline;
GstElement *appsrc;
GMainLoop *loop;
guint sourceid;
GTimer *timer;
};
App s_app;
static gboolean
read_data (App * app)
{
guint len;
GstFlowReturn ret;
gdouble ms;
ms = g_timer_elapsed(app->timer, NULL);
printf("ms %f\n", ms);
if (ms > 1.0/20.0) {
GstBuffer *buffer;
GdkPixbuf *pb;
gboolean ok = TRUE;
buffer = gst_buffer_new();
pb = gdk_pixbuf_new(GDK_COLORSPACE_RGB, FALSE, 8, 640, 480);
gdk_pixbuf_fill(pb, 0xffffffff);
GST_BUFFER_DATA (buffer) = gdk_pixbuf_get_pixels(pb);
GST_BUFFER_SIZE (buffer) = 640*480*3*sizeof(guchar);
GST_DEBUG ("feed buffer");
g_signal_emit_by_name (app->appsrc, "push-buffer", buffer, &ret);
gst_buffer_unref (buffer);
if (ret != GST_FLOW_OK) {
/* some error, stop sending data */
GST_DEBUG ("some error");
ok = FALSE;
}
g_timer_start(app->timer);
return ok;
}
// g_signal_emit_by_name (app->appsrc, "end-of-stream", &ret);
return FALSE;
}
/* This signal callback is called when appsrc needs data, we add an idle handler
* to the mainloop to start pushing data into the appsrc */
static void
start_feed (GstElement * pipeline, guint size, App * app)
{
if (app->sourceid == 0) {
GST_DEBUG ("start feeding");
app->sourceid = g_idle_add ((GSourceFunc) read_data, app);
}
}
/* This callback is called when appsrc has enough data and we can stop sending.
* We remove the idle handler from the mainloop */
static void
stop_feed (GstElement * pipeline, App * app)
{
if (app->sourceid != 0) {
GST_DEBUG ("stop feeding");
g_source_remove (app->sourceid);
app->sourceid = 0;
}
}
static gboolean
bus_message (GstBus * bus, GstMessage * message, App * app)
{
GST_DEBUG ("got message %s",
gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
switch (GST_MESSAGE_TYPE (message)) {
case GST_MESSAGE_ERROR: {
GError *err = NULL;
gchar *dbg_info = NULL;
gst_message_parse_error (message, &err, &dbg_info);
g_printerr ("ERROR from element %s: %s\n",
GST_OBJECT_NAME (message->src), err->message);
g_printerr ("Debugging info: %s\n", (dbg_info) ? dbg_info : "none");
g_error_free (err);
g_free (dbg_info);
g_main_loop_quit (app->loop);
break;
}
case GST_MESSAGE_EOS:
g_main_loop_quit (app->loop);
break;
default:
break;
}
return TRUE;
}
int
main (int argc, char *argv[])
{
App *app = &s_app;
GError *error = NULL;
GstBus *bus;
GstCaps *caps;
gst_init (&argc, &argv);
GST_DEBUG_CATEGORY_INIT (appsrc_pipeline_debug, "appsrc-pipeline", 0,
"appsrc pipeline example");
/* create a mainloop to get messages and to handle the idle handler that will
* feed data to appsrc. */
app->loop = g_main_loop_new (NULL, TRUE);
app->timer = g_timer_new();
app->pipeline = gst_parse_launch("appsrc name=mysource ! video/x-raw-rgb,width=640,height=480,bpp=24,depth=24 ! ffmpegcolorspace ! videoscale method=1 ! theoraenc bitrate=150 ! udpsink host=127.0.0.1 port=1234", NULL);
g_assert (app->pipeline);
bus = gst_pipeline_get_bus (GST_PIPELINE (app->pipeline));
g_assert(bus);
/* add watch for messages */
gst_bus_add_watch (bus, (GstBusFunc) bus_message, app);
/* get the appsrc */
app->appsrc = gst_bin_get_by_name (GST_BIN(app->pipeline), "mysource");
g_assert(app->appsrc);
g_assert(GST_IS_APP_SRC(app->appsrc));
g_signal_connect (app->appsrc, "need-data", G_CALLBACK (start_feed), app);
g_signal_connect (app->appsrc, "enough-data", G_CALLBACK (stop_feed), app);
/* set the caps on the source */
caps = gst_caps_new_simple ("video/x-raw-rgb",
"bpp",G_TYPE_INT,24,
"depth",G_TYPE_INT,24,
"width", G_TYPE_INT, 640,
"height", G_TYPE_INT, 480,
NULL);
gst_app_src_set_caps(GST_APP_SRC(app->appsrc), caps);
/* go to playing and wait in a mainloop. */
gst_element_set_state (app->pipeline, GST_STATE_PLAYING);
/* this mainloop is stopped when we receive an error or EOS */
g_main_loop_run (app->loop);
GST_DEBUG ("stopping");
gst_element_set_state (app->pipeline, GST_STATE_NULL);
gst_object_unref (bus);
g_main_loop_unref (app->loop);
return 0;
}
Update: I tried replacing udpsink with normal xvimagesink and it didn't help
Since no one has bothered to answer, I will post a working test code for appsrc plugin - although this doesn't answer why the code in the question doesn't work, this will help people landing here from Google when they search for appsrc test code.
#include <stdio.h>
#include <gst/gst.h>
#include <gst/app/gstappsrc.h>
typedef struct {
GstPipeline *pipeline;
GstAppSrc *src;
GstElement *sink;
GstElement *decoder;
GstElement *ffmpeg;
GstElement *xvimagesink;
GMainLoop *loop;
guint sourceid;
FILE *file;
}gst_app_t;
static gst_app_t gst_app;
#define BUFF_SIZE (1024)
static gboolean read_data(gst_app_t *app)
{
GstBuffer *buffer;
guint8 *ptr;
gint size;
GstFlowReturn ret;
ptr = g_malloc(BUFF_SIZE);
g_assert(ptr);
size = fread(ptr, 1, BUFF_SIZE, app->file);
if(size == 0){
ret = gst_app_src_end_of_stream(app->src);
g_debug("eos returned %d at %d\n", ret, __LINE__);
return FALSE;
}
buffer = gst_buffer_new();
GST_BUFFER_MALLOCDATA(buffer) = ptr;
GST_BUFFER_SIZE(buffer) = size;
GST_BUFFER_DATA(buffer) = GST_BUFFER_MALLOCDATA(buffer);
ret = gst_app_src_push_buffer(app->src, buffer);
if(ret != GST_FLOW_OK){
g_debug("push buffer returned %d for %d bytes \n", ret, size);
return FALSE;
}
if(size != BUFF_SIZE){
ret = gst_app_src_end_of_stream(app->src);
g_debug("eos returned %d at %d\n", ret, __LINE__);
return FALSE;
}
return TRUE;
}
static void start_feed (GstElement * pipeline, guint size, gst_app_t *app)
{
if (app->sourceid == 0) {
GST_DEBUG ("start feeding");
app->sourceid = g_idle_add ((GSourceFunc) read_data, app);
}
}
static void stop_feed (GstElement * pipeline, gst_app_t *app)
{
if (app->sourceid != 0) {
GST_DEBUG ("stop feeding");
g_source_remove (app->sourceid);
app->sourceid = 0;
}
}
static void on_pad_added(GstElement *element, GstPad *pad)
{
GstCaps *caps;
GstStructure *str;
gchar *name;
GstPad *ffmpegsink;
GstPadLinkReturn ret;
g_debug("pad added");
caps = gst_pad_get_caps(pad);
str = gst_caps_get_structure(caps, 0);
g_assert(str);
name = (gchar*)gst_structure_get_name(str);
g_debug("pad name %s", name);
if(g_strrstr(name, "video")){
ffmpegsink = gst_element_get_pad(gst_app.ffmpeg, "sink");
g_assert(ffmpegsink);
ret = gst_pad_link(pad, ffmpegsink);
g_debug("pad_link returned %d\n", ret);
gst_object_unref(ffmpegsink);
}
gst_caps_unref(caps);
}
static gboolean bus_callback(GstBus *bus, GstMessage *message, gpointer *ptr)
{
gst_app_t *app = (gst_app_t*)ptr;
switch(GST_MESSAGE_TYPE(message)){
case GST_MESSAGE_ERROR:{
gchar *debug;
GError *err;
gst_message_parse_error(message, &err, &debug);
g_print("Error %s\n", err->message);
g_error_free(err);
g_free(debug);
g_main_loop_quit(app->loop);
}
break;
case GST_MESSAGE_EOS:
g_print("End of stream\n");
g_main_loop_quit(app->loop);
break;
default:
g_print("got message %s\n", \
gst_message_type_get_name (GST_MESSAGE_TYPE (message)));
break;
}
return TRUE;
}
int main(int argc, char *argv[])
{
gst_app_t *app = &gst_app;
GstBus *bus;
GstStateChangeReturn state_ret;
if(argc != 2){
printf("File name not specified\n");
return 1;
}
app->file = fopen(argv[1], "r");
g_assert(app->file);
gst_init(NULL, NULL);
app->pipeline = (GstPipeline*)gst_pipeline_new("mypipeline");
bus = gst_pipeline_get_bus(app->pipeline);
gst_bus_add_watch(bus, (GstBusFunc)bus_callback, app);
gst_object_unref(bus);
app->src = (GstAppSrc*)gst_element_factory_make("appsrc", "mysrc");
app->decoder = gst_element_factory_make("decodebin", "mydecoder");
app->ffmpeg = gst_element_factory_make("ffmpegcolorspace", "myffmpeg");
app->xvimagesink = gst_element_factory_make("xvimagesink", "myvsink");
g_assert(app->src);
g_assert(app->decoder);
g_assert(app->ffmpeg);
g_assert(app->xvimagesink);
g_signal_connect(app->src, "need-data", G_CALLBACK(start_feed), app);
g_signal_connect(app->src, "enough-data", G_CALLBACK(stop_feed), app);
g_signal_connect(app->decoder, "pad-added", G_CALLBACK(on_pad_added), app->decoder);
gst_bin_add_many(GST_BIN(app->pipeline), (GstElement*)app->src, app->decoder, app->ffmpeg, app->xvimagesink, NULL);
if(!gst_element_link((GstElement*)app->src, app->decoder)){
g_warning("failed to link src anbd decoder");
}
if(!gst_element_link(app->ffmpeg, app->xvimagesink)){
g_warning("failed to link ffmpeg and xvsink");
}
state_ret = gst_element_set_state((GstElement*)app->pipeline, GST_STATE_PLAYING);
g_warning("set state returned %d\n", state_ret);
app->loop = g_main_loop_new(NULL, FALSE);
printf("Running main loop\n");
g_main_loop_run(app->loop);
state_ret = gst_element_set_state((GstElement*)app->pipeline, GST_STATE_NULL);
g_warning("set state null returned %d\n", state_ret);
return 0;
}