gstreamer video playback , cannot play

David Röthlisberger david at rothlis.net
Tue Mar 12 07:26:12 PDT 2013


I'll repeat this just because it's the most important part of Ian's advice:

    Start by building a test pipeline using gst-launch. 


On 12 Mar 2013, at 09:53, Ian Davidson wrote:
> 
> There are sounds that we hear and things that we see. In order to be able to record these things, they need to be converted to some digital format – and there are many choices for these. For example, a sound could be stored as a WAV file, a WMA file, an OGG file (and many more). The sound could have been recorded at 44100 samples per second (quite typical) or perhaps 1100 samples per second (very poor quality).
> Many of the elements in a Gstreamer pipeline are used to manipulate the data from one format to another. A typical element will have a 'sink' (where you can 'pour in some data') and a 'src' (which will supply data to the next element in the sequence).
> Obviously, the data will need to come from somewhere – so if you are reading a file, you will have a 'filesrc' which will pick up the data from a file and pass it on to the next element; such an element will have a 'location' parameter to tell it where to find the file.
> At the other end of the pipeline you will want to do something with this data you have been manipulating, so you will choose a 'sink' such as 'alsasink' to play the sound.
> In between, you will need to manipulate the data that you read from disk such that it can be played – so if your input is a WAV file, you will need 'wavparse' to convert the data.
> It may be that 'wavparse' is not always ready to accept data when your source wants to give it, so it is a good idea to include a 'queue' between elements to handle such problems.
> I don't know exactly what you want to do. Go to http://gstreamer.freedesktop.org/documentation/ and follow the link to “Overview of all Plug-ins ” to see what plug-ins are available. Many of the descriptions give an example of how you might use them.
> Start by building a test pipeline using gst-launch. When you have got that working, then look to writing a program to replicate what you have tested using gst-launch.
> 
> On 12/03/2013 02:06, aero wrote:
>> 
>> in brief my question is what are the elements required to play an audio and
>> video. how to connect them.
>> if elements depends on format of the flie (ogg,mp3,avi etc)  how to know
>> what  to use for what type.
>> 
>> i just want to get some basic idea of properties of elements before i do any
>> programming.
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> --
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>> 
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