[gst-devel] source plugin blocked in PAUSE state

[René Stadler]

Am Donnerstag, den 28.06.2007, 13:09 +0200 schrieb Riccardo Corona:
> Hi,
> I'm writing a source plugin, I'm started from GstPluginTemplate to
> make a simple plugin that generate only B&W frames...
> The problem is that with this pipeline:
> 
I strongly suggest deriving from GstBaseSrc instead.


> mysrc ! ffmpegcolorspace ! directdrawsink 
> 
> the pipeline is blocked on PREROLLING and in debug mode I can see that
> the last state of my plugin is PAUSED.
> Here the snipped of code in which I set the buffer:
> 
> 
> 
> /* get_range function
>  * makes it a source of a stream 
>  */
> static gboolean gst_plugin_template_get_range (GstPad *pad, guint64
> offset, guint lenght, GstBuffer **buf)
> {
>     static  gboolean white=1;
>     
>     GstPluginTemplate *plug= GST_PLUGIN_TEMPLATE (GST_OBJECT_PARENT
> (pad) ); 
> 
>      GstBuffer *buffer;
>       gint size, width, height, bpp;
>       width = 320; height = 240; bpp = 16;
>       size = width * height * bpp;
>       buffer = gst_buffer_new();
>       GST_BUFFER_SIZE (buffer) = size; 
> 
>     if (white)GST_BUFFER_MALLOCDATA (buffer) =  g_memdup (0xff,size);
>         else GST_BUFFER_MALLOCDATA (buffer) =  g_memdup (0x0,size);
> 
>     white=!white;
> 
>       GST_BUFFER_DATA (buffer) = GST_BUFFER_MALLOCDATA (buffer); 
>     
> 
>     ts = gst_util_uint64_scale_int (frame_num * GST_SECOND, FPS_DEN,
> FPS_NUM);
>     next_ts = gst_util_uint64_scale_int ((frame_num + 1) * GST_SECOND,
> FPS_DEN,  FPS_NUM);
>     
>     GST_BUFFER_TIMESTAMP (buffer) = ts; 
>     GST_BUFFER_DURATION (buffer) = next_ts-ts;
> 
>     frame_num++;
> 
> 
>     return gst_pad_push (plug->srcpad, buffer);
> 
> }
> 
This is completely wrong.  In a get_range function, you are supposed to
return the buffer to the supplied location!  Take a look at
gstreamer/docs/design/part-scheduling.txt [1] and other docs in that
directory to get some insight.

[1]:
http://webcvs.freedesktop.org/gstreamer/gstreamer/docs/design/part-scheduling.txt?view=markup
> 
> I thought that setting the timestamp is enough to have continuosly a
> stream of images but it seems that I'm wrong. 
> Do I must force the state of the plugin in PLAY mode?
> Or maybe I'm wrong with the buffer management?
> 
> Any help will be very appreciate becouse I'm new to plugin writing...
> 
> 
> Best Regards.
> 
> 
> 
> -- 
> Riccardo Corona 

-- 
Regards,
  René Stadler