GStreamer pwg ch 11

 

11.     Building a Test Application

 

plugin test 방법

    Ÿ   plugin이 GStreamer가 search 하는 directory에 설치된 경우

        n  gst-launch-1.0

    Ÿ   설치 안 된 경우

        n  GST_PLUGIN_PATH에 plugin directory를 설정

        n  혹은 --gst-plugin-path를 사용해서 설정

    Ÿ   plugin인gst-plugin template 기반으로 만들어진 경우

        n  gst-launch-1.0 --gst-plugin-path=$HOME/gst-template/gst-plugin/src/.libs TESTPIPELINE

    Ÿ   더 많은 feature를 test 하고자 하는 경우

        n  ex. seeking, event, interactivity 등

        n  test app 작성이 필요함

 

 

*   gst_init()

    n  처음에 gst_init을 호출하여 GStreamer core library를 초기화 해야함

    n  혹은 gst_init_get_option_group을 호출

        s   GOptionGroup의 pointer를 리턴

        s   GOption을 사용해서 초기화 수행

 

*   gst_element_factory_make()

    n  element type과 free-form name을 입력

    n  ex.

        s   identity element

            -       data-to-application transmitter로 동작

            -       data의 점검에 사용됨

        s   fakesink element

            -       data를 stdout으로 dump

        s   valgrind

            -       memory error check

 

*   linking

    n  linking 시 filtered caps을 사용

        s   특정 data type이 element로 in/out 되도록 함

 

*   running

    n  message를 listen 해야 함 (from pipeline to app)

        s   error라던가, eos를 listen

        s   이들에 대한 event들을 pipeline에 추가하여 correct 해야 함

 

*   cleanup

    n  NULL state로 가게되면, element는 할당한 memory와 cache들을 clean up 해야 함

    n  unref()을 수행

 

 

#include <gst/gst.h>   static gboolean bus_call (GstBus     *bus,       GstMessage *msg,       gpointer    data) {   GMainLoop *loop = data;     switch (GST_MESSAGE_TYPE (msg)) {     case GST_MESSAGE_EOS:       g_print ("End-of-stream\n");       g_main_loop_quit (loop);       break;     case GST_MESSAGE_ERROR: {       gchar *debug = NULL;       GError *err = NULL;         gst_message_parse_error (msg, &err, &debug);         g_print ("Error: %s\n", err->message);       g_error_free (err);         if (debug) {         g_print ("Debug details: %s\n", debug);         g_free (debug);       }         g_main_loop_quit (loop);       break;     }     default:       break;   }     return TRUE; }   gint main (gint   argc,       gchar *argv[]) {   GstStateChangeReturn ret;   GstElement *pipeline, *filesrc, *decoder, *filter, *sink;   GstElement *convert1, *convert2, *resample;   GMainLoop *loop;   GstBus *bus;   guint watch_id;     /* initialization */   gst_init (&argc, &argv);   loop = g_main_loop_new (NULL, FALSE);   if (argc != 2) {     g_print ("Usage: %s <mp3 filename>\n", argv[0]);     return 01;   }     /* create elements */   pipeline = gst_pipeline_new ("my_pipeline");     /* watch for messages on the pipeline's bus (note that this will only    * work like this when a GLib main loop is running) */   bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));   watch_id = gst_bus_add_watch (bus, bus_call, loop);   gst_object_unref (bus);     filesrc  = gst_element_factory_make ("filesrc", "my_filesource");   decoder  = gst_element_factory_make ("mad", "my_decoder");     /* putting an audioconvert element here to convert the output of the    * decoder into a format that my_filter can handle (we are assuming it    * will handle any sample rate here though) */   convert1 = gst_element_factory_make ("audioconvert", "audioconvert1");     /* use "identity" here for a filter that does nothing */   filter   = gst_element_factory_make ("my_filter", "my_filter");     /* there should always be audioconvert and audioresample elements before    * the audio sink, since the capabilities of the audio sink usually vary    * depending on the environment (output used, sound card, driver etc.) */   convert2 = gst_element_factory_make ("audioconvert", "audioconvert2");   resample = gst_element_factory_make ("audioresample", "audioresample");   sink     = gst_element_factory_make ("pulsesink", "audiosink");     if (!sink || !decoder) {     g_print ("Decoder or output could not be found - check your install\n");     return -1;   } else if (!convert1 || !convert2 || !resample) {     g_print ("Could not create audioconvert or audioresample element, "              "check your installation\n");     return -1;   } else if (!filter) {     g_print ("Your self-written filter could not be found. Make sure it "              "is installed correctly in $(libdir)/gstreamer-1.0/ or "              "~/.gstreamer-1.0/plugins/ and that gst-inspect-1.0 lists it. "              "If it doesn't, check with 'GST_DEBUG=*:2 gst-inspect-1.0' for "              "the reason why it is not being loaded.");     return -1;   }     g_object_set (G_OBJECT (filesrc), "location", argv[1], NULL);     gst_bin_add_many (GST_BIN (pipeline), filesrc, decoder, convert1, filter,                     convert2, resample, sink, NULL);     /* link everything together */   if (!gst_element_link_many (filesrc, decoder, convert1, filter, convert2,                               resample, sink, NULL)) {     g_print ("Failed to link one or more elements!\n");     return -1;   }     /* run */   ret = gst_element_set_state (pipeline, GST_STATE_PLAYING);   if (ret == GST_STATE_CHANGE_FAILURE) {     GstMessage *msg;       g_print ("Failed to start up pipeline!\n");       /* check if there is an error message with details on the bus */     msg = gst_bus_poll (bus, GST_MESSAGE_ERROR, 0);     if (msg) {       GError *err = NULL;         gst_message_parse_error (msg, &err, NULL);       g_print ("ERROR: %s\n", err->message);       g_error_free (err);       gst_message_unref (msg);     }     return -1;   }     g_main_loop_run (loop);     /* clean up */   gst_element_set_state (pipeline, GST_STATE_NULL);   gst_object_unref (pipeline);   g_source_remove (watch_id);   g_main_loop_unref (loop);     return 0; }