Internal Dataflow Error

[aft]

On Tue, Feb 4, 2014 at 3:35 AM, Tim Müller <tim at centricular.com> wrote:
> On Mon, 2014-02-03 at 17:53 +0600, aft wrote:
>
> Hi,
>
>> I'm Trying a simple pipeline which is not working :
>>
>> arif at dev:~/GS_samples/sample_media$gst-launch-0.10 filesrc
>> location="M1F1-Alaw-AFsp.wav" ! alawdec ! autoaudiosink
>
>> WARN <alawdec0> no input format set: not-negotiated
>> What i'm doing wrong? I want to understand it conceptually.
>

Hi,

Thanks for the reply.

> alawdec is a decoder element, and it needs to know what the input caps
> are in order to interpret and process the data properly. filesrc will
> not set any caps whatsoever on the buffers, it will just read them and
> push them downstream.
>

> If alaw was a typefindable format, you could just add a 'typefind'
> element between filesrc and alwadec, but it's not typefindable.
>

What is this "type findable format"? Which of the "elements" are type
findable and why?

> From the filename I would guess that the file is in fact a WAV file,
> which means you need to use a 'wavparse' element before the decoder, so
> try e.g.:
>
>  filesrc location=foo.wav ! wavparse ! alawdec ! audioconvert !
> autoaudiosink

Is the wav demuxer mandatory? I mean if put "caps" appropriate for
cpm-alaw explicitly would that work? Or i need a demuxer every time i
try to read a "container" media format?

>
> but you could also just use playbin2 or decodebin2:
>
>  playbin2 uri=file:///path/to/foo.wav
>
>  filesrc location=foo.wav ! decodebin2 ! audioconvert ! autoaudiosink
>

As i'm trying to understand it more well, i guess i should avoid
"built-in" pipelines.

>  Cheers
>   -Tim
>
> --
> Tim Müller, Centricular Ltd - http://www.centricular.com
>
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-- 
-Cheers
-Arif