Clicking images in the gstreamer path

Question

After playing with some toy apps, documentation, and searching the Internet (including the mailing list archives), I am still puzzled that I think the use case is quite common.

I have existing code that generates images (in memory), and I would like to push these images into the gstreamer pipeline (to create flv video at the end).

I could not find an "obvious way to do this." My best guess would be in the source code of GstMultiFileSrc and its parent GstPushSrc to figure this out.

Can any of you point me to the "obvious way" of this? Is there any related piece of documentation / tutorial / example?

As soon as I have input right, the rest is a piece of cake, thanks to Gstreamer awesomeness! (something like "my magic input -> ffmpegcolorspace! ffenc_flv! flvmux! filesink location = desktop.flv")

Thank you for your responses.

Answer 1

GStreamer uses plugins to do everything. Plugins that create data or take it from an external source are called src plugins.

The common src plugin for entering data created by the application into the pipeline is called appsrc . The API provided by appsrc is documented as part of the Application Library .

Here is one example that demonstrates how appsrc feeds generated images: gdk-gstappsrc-stream.c . It seems to be derived from some test code in the GStreamer source tree: here .

Another approach is to create your own src plugin. Take a look at the goom music visualization plugin for an example that seems to work similar to what you specified.

Answer 2

I found a solution (maybe) for this (I get images with OpenCV) ... but I have a pipeline error: ERROR from the mysource element: Error en el flujo de datos interno. Debug info: gstbasesrc.c (2574): gst_base_src_loop (): / GstPipeline: pipe0 / GstAppSrc: mysource: thread task is suspended, reason is not consistent (-4)

this is the code:

typedef struct _App App; struct _App{ GstElement *pipeline; GstElement *appsrc; GMainLoop *loop; guint sourceid; GTimer *timer; }; App s_app; CvCapture *capture; static gboolean read_data(App *app){ GstFlowReturn ret; GstBuffer *buffer = gst_buffer_new(); IplImage* frame = cvQueryFrame(capture); GST_BUFFER_DATA(buffer) = (uchar*)frame->imageData; GST_BUFFER_SIZE(buffer) = frame->width*frame->height*sizeof(uchar*); g_signal_emit_by_name(app->appsrc,"push-buffer",buffer,&ret); gst_buffer_unref(buffer); if(ret != GST_FLOW_OK){ GST_DEBUG("Error al alimentar buffer"); return FALSE; } return TRUE; } static void start_feed(GstElement* pipeline,guint size, App* app){ if(app->sourceid == 0){ GST_DEBUG("Alimentando"); app->sourceid = g_idle_add((GSourceFunc) read_data, app); } } 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; capture = cvCaptureFromCAM(0); gst_init(&argc,&argv); /* 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 ! tcpserversink host=127.0.0.1 port=5000", 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); cvReleaseCapture(&capture); return 0; } 

Any idea ???

Answer 3

You can try hacking imagefreeze to do what you want. appsrc can also do this.