[gst-devel] gst-launch v. c launching and flv v. mpeg2

[E. Westbrook]

That did it, thanks very much indeed.  Your response also helped me find the
example in the "decodebin" section of the developer documentation that
refers to this method of pad connection.

Connecting the 'new-decoded-pad' signal from the decoder to a callback,
which then links the decoder to the sink when a pad is ready, does the trick
quite nicely (and I presume, now, correctly).

Thanks again, and by the way thanks also to everyone helping out the newbs
like me on this list.  Sure, even the newbs around here still seem to
generally have some pretty good chops, but it's always nice to get a nudge
when you're stuck. :)

Thanks again and take care,
E. Westbrook

On Mon, Jul 20, 2009 at 12:10 AM, sudarshan bisht <bisht.sudarshan at gmail.com
> wrote:

> Hi
>
>    You can not link demuxer and decoder using gst_element_link_many(src,
> dmx, dec, sink, NULL) function . You need to link these two elements in
> callback function  because demuxer has to create these pads dynamically.
>
> On Mon, Jul 20, 2009 at 10:00 AM, E. Westbrook <gstreamer at westbrook.com>wrote:
>
>> Can someone please help me spot how I'm being stupid?
>>
>> I can play a FLV file using:
>>
>> $ gst-launch filesrc location=jerrydog.flv ! ffdemux_flv ! ffdec_flv !
>> xvimagesink
>>
>> But when I try to play the same file with the following code, it hangs
>> with no output.
>>
>> #include <unistd.h>
>> #include <stdio.h>
>> #include <stdlib.h>
>>
>> #include <gst/gst.h>
>>
>> int main(int argc, char** argv) {
>>   gst_init(&argc, &argv);
>>
>>   GMainLoop* loop = g_main_loop_new(NULL, FALSE);
>>
>>   GstPipeline* p = GST_PIPELINE(gst_pipeline_new("pipey"));
>>
>>   GstElement* src = gst_element_factory_make("filesrc", "filey");
>>   GstElement* dmx = gst_element_factory_make("ffdemux_flv", "demuxey");
>>   GstElement* dec = gst_element_factory_make("ffdec_flv", "decodey");
>>   GstElement* sink = gst_element_factory_make("xvimagesink", "sinky");
>>
>>   g_object_set(G_OBJECT(src), "location", "jerrydog.flv", NULL);
>>
>>   gst_bin_add_many(GST_BIN(p), src, dmx, dec, sink, NULL);
>>   gst_element_link_many(src, dmx, dec, sink, NULL);
>>
>>   gst_element_set_state(GST_ELEMENT(p), GST_STATE_PLAYING);
>>
>>   g_main_loop_run(loop);
>>
>>   return 0;
>> }
>>
>> The thing is, I've separately encoded the file to mpeg2, and I can also
>> play it using:
>>
>> $ gst-launch filesrc location=jerrydog.mp2 ! mpeg2dec ! xvimagesink
>>
>> and then, puzzlingly, unlike the FLV version, my C code plays the mpeg2
>> flavor just great:
>>
>> #include <unistd.h>
>> #include <stdio.h>
>> #include <stdlib.h>
>>
>> #include <gst/gst.h>
>>
>> int main(int argc, char** argv) {
>>   gst_init(&argc, &argv);
>>
>>   GMainLoop* loop = g_main_loop_new(NULL, FALSE);
>>
>>   GstPipeline* p = GST_PIPELINE(gst_pipeline_new("pipey"));
>>   GstElement* src = gst_element_factory_make("filesrc", "filey");
>>   GstElement* dec = gst_element_factory_make("mpeg2dec", "decodey");
>>   GstElement* sink = gst_element_factory_make("xvimagesink", "sinky");
>>
>>   g_object_set(G_OBJECT(src), "location", "jerrydog.mp2", NULL);
>>
>>   gst_bin_add_many(GST_BIN(p), src, dec, sink, NULL);
>>   gst_element_link_many(src, dec, sink, NULL);
>>
>>   gst_element_set_state(GST_ELEMENT(p), GST_STATE_PLAYING);
>>
>>   g_main_loop_run(loop);
>>
>>   return 0;
>> }
>>
>> So what's confusing me is, in the FLV case, how am I constructing the
>> pipeline wrongly in C, in the FLV case anyway, that differs from
>> gst-launch?  Or am I?  Is this as dumb a question as it seems to me it must
>> be?
>>
>> Thanks,
>> E. Westbrook
>>
>> PS - All test case source is here exactly as I'm compiling it.  My input
>> video files are available at:
>>
>> http://media.westbrook.com/media/jerrydog.flv
>> http://media.westbrook.com/media/jerrydog.mp2
>>
>>
>>
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>
>
> --
> Regards,
>
> Sudarshan Bisht
>
>
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