Dynamic pipelines
Stirling Westrup
swestrup at gmail.com
Thu May 16 10:07:41 PDT 2013
I think you need to add bin to pipeline BEFORE linking it:
if( strncmp( name, "audio", 5 ) == 0 && audio_bin != NULL ) {
// Add audio bin to the pipeline.
gst_bin_add( GST_BIN(pipeline), audio_bin );
// Get the audio sink from the bin.
sinkpad = gst_element_get_pad( audio_bin, "audiosink" );
// Link demux src pad to audio sink pad of bin.
gst_pad_link( pad, sinkpad );
gst_object_unref( sinkpad );
//gst_element_set_state( audio_bin, GST_STATE_PLAYING );
}
On Tue, May 14, 2013 at 5:12 PM, Jorge Fernandez Monteagudo <
jorgefm at cirsa.com> wrote:
> Hi!
>
> I've follow your idea but I still have no sound. When I create the
> pipeline I create the audio bin where I add
> all the elements and I create a ghost pad to be linked on the pad-added
> signal. This is the code:
>
> // Create audio bin elements
> audio_bin = gst_bin_new( NULL );
> audio_queue = gst_element_factory_make( "queue", NULL );
> audio_decode = gst_element_factory_make( "faad", NULL );
> audio_sink = gst_element_factory_make( "alsasink", NULL );
>
> // Compose the audio bin.
> gst_bin_add_many( GST_BIN( audio_bin ),
> audio_queue, audio_decode, audio_sink, NULL );
>
> // Link all elements that can be automatically linked because they have
> "Always" pads.
> if( gst_element_link_many( audio_queue, audio_decode, audio_sink, NULL )
> != TRUE ) {
> gst_object_unref( audio_bin );
> gst_object_unref( pipeline );
> return;
> }
>
> // Create ghost pad on the bin and link to audio queue.
> GstPad *sinkpad = gst_element_get_static_pad( audio_queue, "sink" );
> gst_element_add_pad( audio_bin, gst_ghost_pad_new( "audiosink", sinkpad
> ) );
> gst_object_unref( sinkpad );
>
>
> Then on the pad-added signal from the demux element I have:
>
> static void on_pad_demux_added( GstElement *element, GstPad *pad, gpointer
> data )
> {
> gchar *name;
> GstCaps *caps;
> GstPad *sinkpad;
>
> // Retrieve negotiated caps (or acceptable caps if negotiation is not
> finished yet).
> caps = gst_pad_get_negotiated_caps( pad );
> if( !caps )
> caps = gst_pad_get_caps_reffed( pad );
>
> // Get the pad name and link the next element when audio sink is
> detected.
> name = gst_pad_get_name( pad );
>
> if( strncmp( name, "audio", 5 ) == 0 && audio_bin != NULL ) {
>
> // Get the audio sink from the bin.
> sinkpad = gst_element_get_pad( audio_bin, "audiosink" );
>
> // Link demux src pad to audio sink pad of bin.
> gst_pad_link( pad, sinkpad );
> gst_object_unref( sinkpad );
>
> // Add audio bin to the pipeline.
> gst_bin_add( GST_BIN(pipeline), audio_bin );
>
> //gst_element_set_state( audio_bin, GST_STATE_PLAYING );
> }
>
> gst_caps_unref( caps );
> g_free( caps_str );
> g_free( name );
> }
>
>
> Then when I run the app I can see the video but I get no audio. Am I
> missing something?
> Maybe some state change, like the commented line? Any hint is welcome!
>
> Thanks!
>
> ________________________________________
> From: gstreamer-devel-bounces+jorgefm=cirsa.com at lists.freedesktop.org[gstreamer-devel-bounces+jorgefm=
> cirsa.com at lists.freedesktop.org] On Behalf Of Stirling Westrup [
> swestrup at gmail.com]
> Sent: Tuesday, May 14, 2013 12:07 AM
> To: Discussion of the development of and with GStreamer
> Subject: Re: Dynamic pipelines
>
> The secret is to not add any elements to a pipeline that aren't going to
> be used by the pipeline. I have a very similar setup in my application and
> I ended up creating output bins for the audio and video outputs. Then on a
> pad-added signal I insert the needed bin and connect it to the pad.
>
> On EOS, after the pipeline is put into the ready state I pull the two bins
> back out of the pipeline in anticipation of the next file to play.
>
>
>
> On Mon, May 13, 2013 at 5:05 PM, Jorge Fernandez Monteagudo <
> jorgefm at cirsa.com<mailto:jorgefm at cirsa.com>> wrote:
> Hi all!
>
> I have implemented this pipeline by code:
>
> gst-launch-0.10 filesrc location=test.mp4 ! qtdemux name=demux \
> demux.video_00 ! queue max-size-buffers=2 max-size-time=0
> max-size-bytes=0 ! ffdec_h264 ! xvimagesink \
> demux.audio_00 ! queue max-size-buffers=8000 max-size-time=0
> max-size-bytes=0 ! faad ! alsasink
>
> When I try to play a 'test.mp4' without audio channel the pipeline is
> frozen. I use the qtdemux callback
> "pad-added" to link the demux with the queues. When no audio channel is
> present no link is made from
> demux and audio queue. The problem is that the elements has been added
> initially to the pipeline but
> they never has data, then they can change to ready or playing state
>
> // Compose the pipeline.
> gst_bin_add_many( GST_BIN( pipeline ), filesrc, demux,
> video_queue, video_decode, video_sink,
> audio_queue, audio_decode, audio_sink, NULL );
>
> // Link all elements that can be automatically linked because they have
> "Always" pads.
> if( gst_element_link_many( filesrc, demux, NULL ) != TRUE ||
> gst_element_link_many( video_queue, video_decode, NULL ) != TRUE ||
> gst_element_link_many( video_decode, video_sink, NULL ) != TRUE ||
> gst_element_link_many( audio_queue, audio_decode, NULL ) != TRUE ||
> gst_element_link_many( audio_decode, audio_sink, NULL ) != TRUE ) {
> TRACEMSG( "%s - One element could not be linked.\n", __FUNCTION__ );
> gst_object_unref( pipeline );
> return NULL;
> }
>
> I think its a begginer question but how can I solve this? Ideally I would
> like to know if it's
> possible to generate the correct pipeline at runtime? What's the correct
> way to implement this?
>
> Thanks!!
> Jorge
>
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>
> --
> Stirling Westrup
> Programmer, Entrepreneur.
> https://www.linkedin.com/e/fpf/77228
> http://www.linkedin.com/in/swestrup
> http://technaut.livejournal.com
> http://sourceforge.net/users/stirlingwestrup
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--
Stirling Westrup
Programmer, Entrepreneur.
https://www.linkedin.com/e/fpf/77228
http://www.linkedin.com/in/swestrup
http://technaut.livejournal.com
http://sourceforge.net/users/stirlingwestrup
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