[gst-devel] need help about my first video test application
Andoni Morales
ylatuya at gmail.com
Tue Jun 2 12:15:51 CEST 2009
2009/6/2 Andoni Morales <ylatuya at gmail.com>:
> 2009/6/2 Favor Tang <tangher at gmail.com>:
>> 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.
>
> If you need to debug a GStreamer app you can enable the debug output by setting:
> # export GST_DEBUG=3.
>
> I attach the fix to your example.
I forgot to mention that on a virtual machine the xv output is not
always avalaible, You have to use the ximagesink element instead of
using the autovideosink which uses by default the xvimagesink element.
Andoni
>
>>
>> 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
>>>>>> ~~~~~~~~~~~~~~~~~
>>>>>>
>>>>>> ------------------------------------------------------------------------------
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>>>>>> _______________________________________________
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>>>>>>
>>>>>>
>>>>>
>>>>> ------------------------------------------------------------------------------
>>>>> 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
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>>>>> _______________________________________________
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>>>>> 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
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>>>>
>>>>
>>>
>>> ------------------------------------------------------------------------------
>>> 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
>>> _______________________________________________
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>>>
>>
>>
>>
>> --
>> ~~~~~~~~~~~~~~~~~
>> /favor
>> ~~~~~~~~~~~~~~~~~
>>
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>
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