[gst-devel] Converting a gst-launch pipeline to C code
Alan Carvalho de Assis
acassis at gmail.com
Thu Oct 2 11:48:02 CEST 2008
Hi there,
I got it working and I am posting the code here for future references:
#include <gst/gst.h>
#include <glib.h>
#include <string.h>
static GstElement *source, *demuxer, *vdqueue, *adqueue, *vdsink,
*adsink, *decvd, *decad;
void on_pad_added (GstElement *element, GstPad *pad)
{
g_debug ("Signal: pad-added");
GstCaps *caps;
GstStructure *str;
caps = gst_pad_get_caps (pad);
g_assert (caps != NULL);
str = gst_caps_get_structure (caps, 0);
g_assert (str != NULL);
if (g_strrstr (gst_structure_get_name (str), "video")) {
g_debug ("Linking video pad to dec_vd");
// Link it actually
GstPad *targetsink = gst_element_get_pad (decvd, "sink");
g_assert (targetsink != NULL);
gst_pad_link (pad, targetsink);
gst_object_unref (targetsink);
}
if (g_strrstr (gst_structure_get_name (str), "audio")) {
g_debug ("Linking audio pad to dec_ad");
// Link it actually
GstPad *targetsink = gst_element_get_pad (decad, "sink");
g_assert (targetsink != NULL);
gst_pad_link (pad, targetsink);
gst_object_unref (targetsink);
}
gst_caps_unref (caps);
}
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;
}
int
main (int argc,
char *argv[])
{
GMainLoop *loop;
GstElement *pipeline;
GstBus *bus;
/* Initialisation */
gst_init (&argc, &argv);
loop = g_main_loop_new (NULL, FALSE);
/* Check input arguments */
if (argc != 2) {
g_printerr ("Usage: %s <AVI (h264+mp3) filename>\n", argv[0]);
return -1;
}
/* Create gstreamer elements */
pipeline = gst_pipeline_new ("media-player");
source = gst_element_factory_make ("filesrc", "file-source");
demuxer = gst_element_factory_make ("avidemux", "avi-demuxer");
decvd = gst_element_factory_make ("ffdec_h264", "h264-decoder");
decad = gst_element_factory_make ("mad", "mp3-decoder");
vdsink = gst_element_factory_make ("autovideosink", "video-sink");
vdqueue = gst_element_factory_make ("queue", "video-queue");
adqueue = gst_element_factory_make ("queue", "audio-queue");
adsink = gst_element_factory_make ("alsasink", "audio-sink");
if (!pipeline || !source || !demuxer || !decvd || !decad || !vdsink
|| !vdqueue || !adqueue || !adsink) {
g_printerr ("One element could not be created. Exiting.\n");
return -1;
}
/* Set up the pipeline */
/* we set the input filename to the source element */
g_object_set (G_OBJECT (source), "location", argv[1], NULL);
/* we add a message handler */
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
gst_bus_add_watch (bus, bus_call, loop);
gst_object_unref (bus);
/* we add all elements into the pipeline */
/* file-source | ogg-demuxer | vorbis-decoder | converter | alsa-output */
gst_bin_add_many (GST_BIN (pipeline),
source, demuxer, decvd, decad, adqueue, vdqueue,
vdsink, adsink, NULL);
//gst_bin_add_many (GST_BIN (pipeline),
// source, demuxer, decvd, vdqueue, vdsink, NULL);
/* we link the elements together */
/* file-source -> demuxer ~> {video-decoder -> video-output} ~>
{audio-decoder -> alsa-output} */
gst_element_link (source, demuxer);
gst_element_link (decvd, vdqueue);
gst_element_link (vdqueue, vdsink);
gst_element_link (decad, adqueue);
gst_element_link (adqueue, adsink);
g_signal_connect (demuxer, "pad-added", G_CALLBACK (on_pad_added), NULL);
/* note that the demuxer will be linked to the decoder dynamically.
The reason is that Media may contain various streams (for example
audio and video). The source pad(s) will be created at run time,
by the demuxer when it detects the amount and nature of streams.
Therefore we connect a callback function which will be executed
when the "pad-added" is emitted.*/
/* Set the pipeline to "playing" state*/
g_print ("Now playing: %s\n", argv[1]);
gst_element_set_state (pipeline, GST_STATE_PLAYING);
/* Iterate */
g_print ("Running...\n");
g_main_loop_run (loop);
/* Out of the main loop, clean up nicely */
g_print ("Returned, stopping playback\n");
gst_element_set_state (pipeline, GST_STATE_NULL);
g_print ("Deleting pipeline\n");
gst_object_unref (GST_OBJECT (pipeline));
return 0;
}
Best Regards,
Alan
2008/9/29 Thijs Vermeir <thijsvermeir at gmail.com>:
> Hi,
>
> On Mon, Sep 29, 2008 at 7:57 PM, Alan Carvalho de Assis
> <acassis at gmail.com> wrote:
>> Hi,
>>
>> I am converting a gst-launch command to C code but it is not working.
>>
>> This is the line I am trying to convert (this is working fine):
>> gst-launch-0.10 -v filesrc location=potter.avi ! avidemux name=demux
>> demux.video_00 ! {queue ! ffdec_h264 ! xvimagesink} demux.audio_00 !
>> {queue ! mad ! alsasink}
>>
>> I am basing on manual Ogg playback example, but I can't get video and
>> audio working at the same time. When I try to do that I see a window
>> stopped at first video frame and no audio is played.
>
> Avidemux is adding 2 pads so it calls on_pad_added twice, so you should
> check if the new pad is a audio/video pad and connect to the correct
> decoder element.
>
> Gr,
> Thijs
>
>> Please find below my video/audio player. Notice I don't want to use
>> playbin, I really want to fix this code to understand what I am doing
>> wrong.
>>
>> Best Regards,
>>
>> Alan
>>
>>
>>
>>
>> #include <gst/gst.h>
>> #include <glib.h>
>> #include <string.h>
>>
>> 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);
>> }
>>
>> 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;
>> }
>>
>> int
>> main (int argc,
>> char *argv[])
>> {
>> GMainLoop *loop;
>>
>> GstElement *pipeline, *source, *demuxer, *decvd, *decad, *vdqueue,
>> *adqueue, *vdsink, *adsink;
>> GstBus *bus;
>>
>> /* Initialisation */
>> gst_init (&argc, &argv);
>>
>> loop = g_main_loop_new (NULL, FALSE);
>>
>>
>> /* Check input arguments */
>> if (argc != 2) {
>> g_printerr ("Usage: %s <Ogg/Vorbis filename>\n", argv[0]);
>> return -1;
>> }
>>
>>
>> /* Create gstreamer elements */
>> pipeline = gst_pipeline_new ("media-player");
>> source = gst_element_factory_make ("filesrc", "file-source");
>> demuxer = gst_element_factory_make ("avidemux", "avi-demuxer");
>> decvd = gst_element_factory_make ("ffdec_h264", "h264-decoder");
>> decad = gst_element_factory_make ("mad", "mp3-decoder");
>> vdsink = gst_element_factory_make ("autovideosink", "video-sink");
>> vdqueue = gst_element_factory_make ("queue", "video-queue");
>> adqueue = gst_element_factory_make ("queue", "audio-queue");
>> adsink = gst_element_factory_make ("alsasink", "audio-sink");
>>
>> if (!pipeline || !source || !demuxer || !decvd || !decad || !vdsink
>> || !vdqueue || !adqueue || !adsink) {
>> g_printerr ("One element could not be created. Exiting.\n");
>> return -1;
>> }
>>
>> /* Set up the pipeline */
>>
>> /* we set the input filename to the source element */
>> g_object_set (G_OBJECT (source), "location", argv[1], NULL);
>>
>> /* we add a message handler */
>> bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
>> gst_bus_add_watch (bus, bus_call, loop);
>> gst_object_unref (bus);
>>
>> /* we add all elements into the pipeline */
>> /* file-source | ogg-demuxer | vorbis-decoder | converter | alsa-output */
>> gst_bin_add_many (GST_BIN (pipeline),
>> source, demuxer, decvd, decad, vdsink, vdqueue,
>> adqueue, adsink, NULL);
>> //gst_bin_add_many (GST_BIN (pipeline),
>> // source, demuxer, decvd, vdqueue, vdsink, NULL);
>>
>> /* we link the elements together */
>> /* file-source -> ogg-demuxer ~> vorbis-decoder -> converter -> alsa-output */
>> gst_element_link (source, demuxer);
>> gst_element_link (decvd, vdqueue);
>> gst_element_link (vdqueue, vdsink);
>> gst_element_link (decad, adqueue);
>> gst_element_link (adqueue, adsink);
>> //gst_element_link_many (decvd, vdqueue, vdsink, NULL);
>>
>> g_signal_connect (demuxer, "pad-added", G_CALLBACK (on_pad_added), decvd);
>>
>> /* note that the demuxer will be linked to the decoder dynamically.
>> The reason is that Ogg may contain various streams (for example
>> audio and video). The source pad(s) will be created at run time,
>> by the demuxer when it detects the amount and nature of streams.
>> Therefore we connect a callback function which will be executed
>> when the "pad-added" is emitted.*/
>>
>> /* Set the pipeline to "playing" state*/
>> g_print ("Now playing: %s\n", argv[1]);
>> gst_element_set_state (pipeline, GST_STATE_PLAYING);
>>
>>
>> /* Iterate */
>> g_print ("Running...\n");
>> g_main_loop_run (loop);
>>
>>
>> /* Out of the main loop, clean up nicely */
>> g_print ("Returned, stopping playback\n");
>> gst_element_set_state (pipeline, GST_STATE_NULL);
>>
>> g_print ("Deleting pipeline\n");
>> gst_object_unref (GST_OBJECT (pipeline));
>>
>> return 0;
>> }
>>
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