I am new to gstremaer. I have written a code for playing avi file using gstreamer. But on executing the code it just hangs after a while, I am unable to debug whats the problem, Can someone help me please. The code and the output is as below:
Code:
#include<stdio.h>
#include<gst/gst.h>
#include<glib.h>
//Function to process message on bus of pipeline
gboolean process_message(GstBus *bus, GstMessage *msg,gpointer data);
//Function to add pad dynamically for ogg demux
void dynamic_addpad(GstElement *element, GstPad *pad, gpointer data);
void dynamic_decodepad (GstElement* object, GstPad* arg0, gboolean arg1,gpointer user_data);
GstElement *source, *demuxer, *audio_decoder, *video_decoder, *audio_convertor,*video_convertor, *audio_sink,*video_sink,*audioqueue,*videoqueue;//*audio_demuxer, *video_demuxer,
int main(int argc,char* argv[])
{
GstPipeline *pipeline;
GstBin *Bin;
GstBus *bus;
GMainLoop *Mainloop;
gst_init (&argc,&argv);
Mainloop = g_main_loop_new(NULL,FALSE);//NULL to use the current context and False to tell its not in running state
pipeline = gst_pipeline_new("PIPELINE");
Bin = GST_BIN(pipeline);
bus = gst_pipeline_get_bus(pipeline);
source = gst_element_factory_make("filesrc","file-source");
g_object_set(G_OBJECT(source),"location",argv[1],NULL);
demuxer = gst_element_factory_make("avidemux","avi-demuxer");
audioqueue = gst_element_factory_make("queue","Queue for audio");
videoqueue = gst_element_factory_make("queue","Queue for video");
video_decoder = gst_element_factory_make("decodebin","decoderbin");//"Vorbis audio decoder","vorbis");
audio_convertor = gst_element_factory_make("audioconvert","audio convertor");//"Audio converter","audioconvert");
video_convertor = gst_element_factory_make("videoscale","video convertor");//"Audio converter","audioconvert");
audio_sink = gst_element_factory_make("autoaudiosink","Auto audio sink");
video_sink = gst_element_factory_make("xvimagesink","XV video sink ");
if(!source || !demuxer || !audioqueue || !videoqueue || !video_decoder ||!audio_convertor || !video_convertor || !audio_sink || !video_sink )
{ g_print("Could not not create element\n");
return 0;
}
gst_bin_add(Bin,source);
gst_bin_add_many(Bin,demuxer,audioqueue,videoqueue,audio_convertor,video_decoder,video_convertor,audio_sink,video_sink,NULL);
gst_element_link(source,demuxer);
gst_element_link_many(audioqueue,video_decoder,audio_convertor,audio_sink,NULL);
gst_element_link_many(videoqueue,video_decoder,video_convertor,video_sink,NULL);
g_signal_connect(demuxer,"pad-added",G_CALLBACK(dynamic_addpad),NULL);//demuxer and decoder are passed as instance and data as pads of both the elements are linked in dynamic_addpad
g_signal_connect(video_decoder,"new-decoded-pad",G_CALLBACK(dynamic_decodepad),NULL);//demuxer and decoder are passed as instance and data as pads of both the elements are linked in dynamic_addpad
gst_bus_add_watch(bus,process_message,Mainloop); //Mainloop is passed as user data as in the process_message actions are taken on the loop
g_object_unref(bus);
g_print("In playing state\n");
gst_element_set_state(pipeline,GST_STATE_PLAYING);//Pipeline is also a bin and bin is also an element at abstract level and hence gst_element_set_state call is used to set state of pipeline.
g_main_loop_run(Mainloop);
g_print("In playing state2\n");
gst_element_set_state(pipeline,GST_STATE_NULL);
g_object_unref(G_OBJECT(pipeline));
}
//Function to process message on bus of pipeline
gboolean process_message(GstBus *bus, GstMessage *msg,gpointer data)
{
GError *error;
gchar *debug;
GMainLoop *loop = (GMainLoop *)data;
g_print(" In process message msg->type : %d\n",GST_MESSAGE_TYPE(msg));
switch(GST_MESSAGE_TYPE(msg))
{
case GST_MESSAGE_UNKNOWN :
g_print("GST_MESSAGE_UNKNOWN \n");
break;
case GST_MESSAGE_EOS :
g_print("GST_MESSAGE_EOS \n");
g_main_loop_quit(loop);
break;
case GST_MESSAGE_ERROR :
g_print("GST_MESSAGE_ERROR \n");
gst_message_parse_error (msg, &error, &debug);
g_free(debug);
//if(!error)
{
g_print("GST_MESSAGE_ERROR message : %s \n",error->message);
}
g_main_loop_quit(loop);
break;
case GST_MESSAGE_WARNING :
g_print("GST_MESSAGE_WARNING \n");
break;
case GST_MESSAGE_INFO :
g_print("GST_MESSAGE_INFO \n");
break;
case GST_MESSAGE_TAG :
g_print("GST_MESSAGE_TAG \n");
break;
case GST_MESSAGE_BUFFERING:
g_print("GST_MESSAGE_BUFFERING \n");
break;
case GST_MESSAGE_STATE_CHANGED:
g_print("GST_MESSAGE_STATE_CHANGED \n");
break;
default :
g_print("default \n");
break;
}
return TRUE; //returns true always as it has to be always registered returning false will deregister the function
}
//Function to add pad dynamically for ogg demux
void dynamic_addpad(GstElement *element, GstPad *pad, gpointer data)
{
GstPad *audiodemuxsink;
GstPad *videodemuxsink;
GstElement *decoder = (GstElement *)data;
g_print(" In dynamic ADDING PAD\n");
audiodemuxsink = gst_element_get_static_pad(audioqueue,"sink");
gst_pad_link(pad,audiodemuxsink );
videodemuxsink = gst_element_get_static_pad(videoqueue,"sink");
gst_pad_link(pad,videodemuxsink );
g_print(" In dynamic ADDING PAD2\n");
}
void dynamic_decodepad (GstElement* object, GstPad* pad, gboolean arg1,gpointer user_data)
{
GstPad *videoconvertsink;
GstPad *audioconvertsink ;
g_print(" In dynamic_decodepad ADDING PAD\n");
videoconvertsink = gst_element_get_static_pad(video_convertor,"sink");
gst_pad_link(pad,videoconvertsink);
audioconvertsink = gst_element_get_static_pad(audio_convertor,"sink");
gst_pad_link(pad,audioconvertsink );
g_print(" In dynamic_decodepad ADDING PAD2\n");
}
Output:
In playing state
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 8192
default
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 8192
default
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 8192
default
In process message msg->type : 8192
default
In dynamic ADDING PAD
In dynamic ADDING PAD2
In dynamic ADDING PAD
In dynamic ADDING PAD2
In process message msg->type : 16
GST_MESSAGE_TAG
In process message msg->type : 16
GST_MESSAGE_TAG
In process message msg->type : 16
GST_MESSAGE_TAG
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In dynamic_decodepad ADDING PAD
In dynamic_decodepad ADDING PAD2
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
In process message msg->type : 64
GST_MESSAGE_STATE_CHANGED
It hangs at this point. Any help is appreciated. Thanks in advance.
Your code is wrong in several ways, that is why my answer is so long.
First of all, gst_pipeline_new returns GstElement* not GstPipeline*:
- pipeline = gst_pipeline_new("PIPELINE");
+ GstElement *pipeline = gst_pipeline_new("PIPELINE");
Bin = GST_BIN(pipeline);
- bus = gst_pipeline_get_bus(pipeline);
+ bus = gst_pipeline_get_bus(GST_PIPELINE(pipeline));
Then, your pipeline is wrong: you trying to decode both streams (audio and video) with one decodebin but you need two. Create it and don't forget to add it to the bin:
videoqueue = gst_element_factory_make("queue","Queue for video");
+ audio_decoder = gst_element_factory_make("decodebin","a_decodebin");
video_decoder = gst_element_factory_make("decodebin","decoderbin");//"Vorbis audio decoder","vorbis");
- gst_bin_add_many(Bin,demuxer,audioqueue,videoqueue,audio_convertor,video_decoder,video_convertor,audio_sink,video_sink,NULL);
+ gst_bin_add_many(
+ Bin,
+ demuxer,
+ audioqueue,videoqueue,
+ audio_decoder,audio_convertor,
+ video_decoder,video_convertor,
+ audio_sink,video_sink,
+ NULL);
And, by the way, it's better to use decodebin2 as decodebin is deprecated.
Then you linking some elements dynamically: demuxer to queue and decodebin to convertors. Hence you should not create link between decodebin and convertors with gst_element_link_many:
gst_element_link(source,demuxer);
- gst_element_link_many(audioqueue,video_decoder,audio_convertor,audio_sink,NULL);
- gst_element_link_many(videoqueue,video_decoder,video_convertor,video_sink,NULL);
+ gst_element_link_many(audioqueue,audio_decoder,NULL);
+ gst_element_link_many(audio_convertor,audio_sink,NULL);
+ gst_element_link_many(videoqueue,video_decoder,NULL);
+ gst_element_link_many(video_convertor,video_sink,NULL);
And of course, as we added audio_decoder decodebin, we need to handle it's pad creation signal:
+ g_signal_connect(audio_decoder,"new-decoded-pad",G_CALLBACK(dynamic_decodepad),NULL);
g_signal_connect(video_decoder,"new-decoded-pad",G_CALLBACK(dynamic_decodepad),NULL);
And now we are at the most interesting part.
void dynamic_addpad(GstElement *element, GstPad *pad, gpointer data)
{
GstPad *audiodemuxsink;
GstPad *videodemuxsink;
GstElement *decoder = (GstElement *)data;
g_print(" In dynamic ADDING PAD\n");
audiodemuxsink = gst_element_get_static_pad(audioqueue,"sink");
gst_pad_link(pad,audiodemuxsink );
videodemuxsink = gst_element_get_static_pad(videoqueue,"sink");
gst_pad_link(pad,videodemuxsink );
g_print(" In dynamic ADDING PAD2\n");
}
This is completely wrong! dynamic_addpad is called on each pad creation. avidemux commonly creates two pads (one for each data stream): "audio_00" and "video_00". So, dynamic_addpad will be called twice and we need to distinguish what to link depending on pad name:
void dynamic_addpad(GstElement *element, GstPad *pad, gpointer data)
{
char* pad_name = gst_pad_get_name(pad);
g_print(" In dynamic ADDING PAD %s\n", pad_name);
if (g_str_has_prefix(pad_name,"audio")) {
GstPad *audiodemuxsink = gst_element_get_static_pad(audioqueue,"sink");
gst_pad_link(pad,audiodemuxsink );
}
else if (g_str_has_prefix(pad_name,"video")) {
GstPad *videodemuxsink = gst_element_get_static_pad(videoqueue,"sink");
gst_pad_link(pad,videodemuxsink );
}
g_free (pad_name);
}
Almost the same is for dynamic_decodepad. As it's only one src pad is created by decodebin, it will be easier to create separate handlers for video_decoder and audio_decoder.
But for pedagogical reasons I will do it in one function. Now we can distinguish which element to connect to pad by it's caps.
void dynamic_decodepad (GstElement* object, GstPad* pad, gboolean arg1,gpointer user_data)
{
GstPad* videoconvertsink = gst_element_get_static_pad(video_convertor,"sink");
if (gst_pad_can_link(pad,videoconvertsink)) {
gst_pad_link(pad,videoconvertsink);
}
GstPad* audioconvertsink = gst_element_get_static_pad(audio_convertor,"sink");
if (gst_pad_can_link(pad,audioconvertsink)) {
gst_pad_link(pad,audioconvertsink);
}
}
gst_pad_can_link will not work in dynamic_addpath because it's possible to connect query element both to "audio_00" and "video_00".
That's it. Don't hesitate to ask if you have other questions.
来源：https://stackoverflow.com/questions/8396127/gstreamer-code-for-playing-avi-file-is-hanging