[gst-devel] need help about my first video test application
Favor Tang
tangher at gmail.com
Tue Jun 2 04:57:15 CEST 2009
hi.
does it work for you?
In my pc running ubuntu linux on vmware, I tested a ogg video file, I
don't get the video or the sound, even I don't get any error output.
I can't give you any help output infomation except the example code,
because I don't get any error.
code snippet:
/* link 'n play*/
GST_INFO ("Found video stream.\n");
g_print ("Found video stream.\n");
gst_pad_link (pad,newpad);
gst_element_link_many (videodec, colorspace, videosink, NULL);
gst_element_set_state (pipeline, GST_STATE_PLAYING);
/* link 'n play*/
GST_INFO ("Found audio stream.\n");
g_print ("Found audio stream.\n");
gst_pad_link (pad,newpad);
gst_element_link_many (decoder, conv, sink, NULL);
gst_element_set_state (pipeline, GST_STATE_PLAYING);
Except for in main function, I added gst_element_set_state to set
pipeline to PLAYING in the 'on_pad_added" callback after it found
audio or video respectively, so that it can be aware of the new pad
had been added. or, should I add this "gst_element_set_state
(pipeline, GST_STATE_PLAYING);" to the end of the callback function?
Could you test it again, and see if you can watch the video output or
hear the sound. or should you give me the example code which works on
your pc.
if it were you, how would you implement this example application? I
doubt it is an good example, though.
thanks.
On Mon, Jun 1, 2009 at 6:40 PM, Andoni Morales <ylatuya at gmail.com> wrote:
> 2009/6/1 Favor Tang <tangher at gmail.com>:
>> Hi, Andoni
>> It's taken me some time to understand you code, meanwhile,
>> according to your advice I changed my code to link to correct element
>> respectively In the 'on_pad_added' callback. In the callback function,
>> I add new elements to pipeline and link them according to if it's
>> audio or video. I think I still not get the right clue of this
>> example. I know some applications use playbin or decodebin, I'd prefer
>> to use it later on.
>>
> This is not the way a I would implement this, but as it's just an
> example... After linking all the element in the 'on_pad_added'
> callback, set the pipeline to PLAYING, because the new added elements
> are not aware of the previous change. I have tested it and it works
> for me.
>
> /* link 'n play*/
>
> GST_INFO ("Found video stream.\n");
>
> gst_pad_link (pad,newpad);
>
> gst_element_link_many (videodec, colorspace, videosink, NULL);
> gst_element_set_state (pipeline, GST_STATE_PLAYING);
>
> g_object_unref (newpad);
>
>
>
>
>>
>> I would highly appreciate your help.
>>
>> thanks
>>
>> On Mon, Jun 1, 2009 at 8:02 AM, Andoni Morales <ylatuya at gmail.com> wrote:
>>> 2009/5/31 Favor Tang <tangher at gmail.com>:
>>>> hi.
>>>>
>>>> sorry for this question of a newbie. I am a beginner into
>>>> gstreamer, and wanna write a application for video playing. I didn't
>>>> found a simple example about video.
>>>> I modified the audio play example. I can't get the video on screen,
>>>> what's the problem? I doubt if I create the pipeline correctly.
>>>
>>> You are linking both the audio stream and the video stream to the
>>> 'decoder' element wich is an audio decoder.
>>> In the 'on_pad_added' callback you need to read the caps of the new
>>> pad and link it to the correct element. If it's a video stream you
>>> will link it to the video decoder and if it's an audio stream you need
>>> to link it to the audio decoder. This example shows you how to check
>>> from the caps the media type and link the demuxer new pad to the
>>> appropiate element:
>>>
>>> GstCaps *caps=NULL;
>>> GstStructure *str =NULL;
>>> GstPad *newpad=NULL;
>>>
>>>
>>> /* check media type */
>>> caps = gst_pad_get_caps (pad);
>>> str = gst_caps_get_structure (caps, 0);
>>>
>>> if (g_strrstr (gst_structure_get_name (str), "video")){
>>>
>>> newpad = gst_element_get_compatible_pad (videodec, pad, NULL);
>>> /* only link once */
>>> if (GST_PAD_IS_LINKED (newpad)) {
>>> g_object_unref (newpad);
>>> gst_caps_unref (caps);
>>> return;
>>> }
>>>
>>> /* link 'n play*/
>>> GST_INFO ("Found video stream.");
>>> gst_pad_link (pad,newpad);
>>> g_object_unref (newpad);
>>> }
>>> if (g_strrstr (gst_structure_get_name (str), "audio")){
>>>
>>> newpad = gst_element_get_compatible_pad (decoder, pad, NULL);
>>> /* only link once */
>>> if (GST_PAD_IS_LINKED (newpad)) {
>>> g_object_unref (newpad);
>>> gst_caps_unref (caps);
>>> return;
>>> }
>>>
>>> /* link 'n play*/
>>> GST_INFO ("Found audio stream.");
>>> gst_pad_link (pad,newpad);
>>> g_object_unref (newpad);
>>> }
>>>
>>>
>>> BTW, you can also use the playbin element.
>>>
>>>
>>>>
>>>> I got error like below:
>>>>
>>>> Running....
>>>> Dynamic pad created, linking demuxer/decoder
>>>> Dynamic pad created, linking demuxer/decoder
>>>> Error: Internal data streame error.
>>>> Retured, stopping playback
>>>> deleting pipeline
>>>>
>>>> and I attached my source file, hope this can help you to figure out
>>>> what I am doing wrong.
>>>> besides, can you give me an example about how to write program for
>>>> video playing?
>>>>
>>>> any help is highly appreciated!
>>>>
>>>> thanks
>>>>
>>>> --
>>>> ~~~~~~~~~~~~~~~~~
>>>> /favor
>>>> ~~~~~~~~~~~~~~~~~
>>>>
>>>> ------------------------------------------------------------------------------
>>>> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>>>> is a gathering of tech-side developers & brand creativity professionals. Meet
>>>> the minds behind Google Creative Lab, Visual Complexity, Processing, &
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>>>> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>>>> _______________________________________________
>>>> gstreamer-devel mailing list
>>>> gstreamer-devel at lists.sourceforge.net
>>>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>>>>
>>>>
>>>
>>> ------------------------------------------------------------------------------
>>> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>>> is a gathering of tech-side developers & brand creativity professionals. Meet
>>> the minds behind Google Creative Lab, Visual Complexity, Processing, &
>>> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
>>> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>>> _______________________________________________
>>> gstreamer-devel mailing list
>>> gstreamer-devel at lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>>>
>>
>>
>>
>> --
>> ~~~~~~~~~~~~~~~~~
>> /favor
>> ~~~~~~~~~~~~~~~~~
>>
>> ------------------------------------------------------------------------------
>> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
>> is a gathering of tech-side developers & brand creativity professionals. Meet
>> the minds behind Google Creative Lab, Visual Complexity, Processing, &
>> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
>> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
>> _______________________________________________
>> gstreamer-devel mailing list
>> gstreamer-devel at lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>>
>>
>
> ------------------------------------------------------------------------------
> Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT
> is a gathering of tech-side developers & brand creativity professionals. Meet
> the minds behind Google Creative Lab, Visual Complexity, Processing, &
> iPhoneDevCamp as they present alongside digital heavyweights like Barbarian
> Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>
--
~~~~~~~~~~~~~~~~~
/favor
~~~~~~~~~~~~~~~~~
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