No Video

[Ian Davidson]

If I use the following command, I can record Audio and Video into an AVI 
File.

gst-launch-1.0 -e v4l2src norm=PAL ! videorate ! 
'video/x-raw,format=(string)I420,width=320,height=240,framerate=(fraction)25/1' 
! queue ! mux. alsasrc ! audioconvert ! 
'audio/x-raw,rate=44100,channels=2' ! queue ! mux. avimux name=mux ! 
filesink location=script-test.avi

I would like to replicate that in a program and my program is below.  
However, the video does not make it through - the Audio plays OK when I 
play the avi file.

It had been suggested that videorate and audiorate might be beneficial 
for me.  In my program, if I included audiorate (as indicated by the 
commented out lines), I just heard a brief burst of sound at the 
beginning of the clip, whereas without audiorate, I heard the full 
audio.  Including/excluding videorate does not seem to make any 
difference at the moment.

I tried to set a value for "norm" on the v4l2src as PAL, but the 
compiler did not recognise the ENUM value.  The only way I could set it 
was to use the value indicated by gst-inspect.

I assume that I have done something stupid again, but I cannot see what 
it is.

Thanks for your help.

Ian

#include <gst/gst.h>
#include <glib.h>


static gboolean
bus_call (GstBus     *bus,
           GstMessage *msg,
           gpointer    data)
{
   GMainLoop *loop = (GMainLoop *) 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;
       GError *error;

       gst_message_parse_error (msg, &error, &debug);
       g_free (debug);

       g_printerr ("Error: %s\n", error->message);
       g_error_free (error);

       g_main_loop_quit (loop);
       break;
     }
     default:
       break;
   }

   return TRUE;
}


static void
on_pad_added (GstElement *element,
               GstPad     *pad,
               gpointer    data)
{
   GstPad *sinkpad;
   GstElement *decoder = (GstElement *) data;

   /* We can now link this pad with the vorbis-decoder sink pad */
   g_print ("Dynamic pad created, linking demuxer/decoder\n");

   sinkpad = gst_element_get_static_pad (decoder, "sink");

   gst_pad_link (pad, sinkpad);

   gst_object_unref (sinkpad);
}



int
main (int   argc,
       char *argv[])
{
   GMainLoop *loop;

   GstElement *pipeline, *vsource, *vcapsfilter, *vidrate, *queue1;
   GstElement *asource, *aconv, *audrate, *acapsfilter, *queue2;
   GstElement *mux, *sink;
   GstBus *bus;
   guint bus_watch_id;

   GstCaps *caps;

   /* Initialisation */
   gst_init (&argc, &argv);

   loop = g_main_loop_new (NULL, FALSE);


   /* Check input arguments */
   if (argc != 2) {
     g_printerr ("Usage: %s <AVI filename>\n", argv[0]);
     return -1;
   }


   /* Create gstreamer elements */
   pipeline     = gst_pipeline_new ("av-recorder");
   vsource      = gst_element_factory_make ("v4l2src", "vid-source");
   vcapsfilter  = gst_element_factory_make ("capsfilter", "vid-caps");
   vidrate      = gst_element_factory_make ("videorate", "vidrate");
   queue1       = gst_element_factory_make ("queue", "queue1");
   asource      = gst_element_factory_make ("alsasrc", "alsa-source");
   aconv        = gst_element_factory_make ("audioconvert", "audio-conv");
   acapsfilter  = gst_element_factory_make ("capsfilter", "audio-caps");
   audrate      = gst_element_factory_make ("audiorate", "audrate");
   queue2       = gst_element_factory_make ("queue", "queue2");
   mux          = gst_element_factory_make ("avimux", "avi-mux");
   sink         = gst_element_factory_make ("filesink", "file-output");

   if (!pipeline || !vsource || !vcapsfilter || !vidrate || !queue1 || 
!asource || !aconv || !audrate || !acapsfilter || !queue2 || !mux || 
!sink) {
     g_printerr ("One element could not be created. Exiting.\n");
     return -1;
   }

   /* Set up the pipeline */

   /* we set the output filename to the sink element */
   g_object_set (G_OBJECT (sink), "location", argv[1], NULL);

   /* we set the video capabilities on the vidcaps element */
   caps = 
gst_caps_from_string("video/x-raw,format=(string)I420,width=320,height=240,framerate=(fraction)25/1");
   g_object_set (G_OBJECT (vcapsfilter), "caps", caps, NULL);
   gst_caps_unref (caps);

   /* we set the audio capabilities on the audiocaps element */
   caps = gst_caps_from_string("audio/x-raw,rate=44100,channels=2");
   g_object_set (G_OBJECT (acapsfilter), "caps", caps, NULL);
   gst_caps_unref (caps);

   g_object_set (G_OBJECT (vsource), "norm", 255, NULL);

   /* we add a message handler */
   bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
   bus_watch_id = gst_bus_add_watch (bus, bus_call, loop);
   gst_object_unref (bus);

   /* we add all elements into the pipeline */
   /*      vsource, vcapsfilter, vidrate, queue1,
           asource, aconv, acapsfilter, queue2,
           mux, sink */
   gst_bin_add_many (GST_BIN (pipeline),
                         vsource,  vcapsfilter, queue1,
/*                        vsource, vidrate, vcapsfilter, queue1,*/
                         asource, aconv,  acapsfilter, queue2,
/*                        asource, aconv, audrate, acapsfilter, queue2,*/
                         mux, sink, NULL);

   /* we link the elements together */
   /*      vsource -> vcapsfilter -> vidrate -> queue1 -> avimux
           asource -> aconv -> acapsfilter -> queue2 -> avimux
           mux -> sink */
   gst_element_link_many (vsource, vcapsfilter,  queue1, mux, NULL);
/*  gst_element_link_many (vsource, vcapsfilter, vidrate, queue1, mux, 
NULL);*/
   gst_element_link_many (asource, aconv,  acapsfilter, queue2, mux, NULL);
/*  gst_element_link_many (asource, aconv, audrate, acapsfilter, queue2, 
mux, NULL);*/
   gst_element_link_many (mux, sink, NULL);


   /* Set the pipeline to "playing" state*/
   g_print ("Now recording: %s\n", argv[1]);
   gst_element_set_state (pipeline, GST_STATE_PLAYING);


   /* Iterate */
   g_print ("Recording (or not!)...\n");
   g_main_loop_run (loop);


   /* Out of the main loop, clean up nicely */
   g_print ("Returned, stopping recording\n");
   gst_element_set_state (pipeline, GST_STATE_NULL);

   g_print ("Deleting pipeline\n");
   gst_object_unref (GST_OBJECT (pipeline));
   g_source_remove (bus_watch_id);
   g_main_loop_unref (loop);

   return 0;
}
-- 
--
Ian Davidson
--
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