Internal Dataflow Error
aftnix at gmail.com
Wed Feb 5 12:50:52 CET 2014
On Tue, Feb 4, 2014 at 8:25 PM, Sebastian Dröge
<sebastian at centricular.com> wrote:
> On Di, 2014-02-04 at 15:15 +0600, aft wrote:
>> > 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?
> alaw is not type-findable because there are no magic bytes or any known
> headers or really anything in there that distinguishes alaw from random
> All of the container formats (MP4, AVI, WAV, MKV, Ogg, ...) are
> type-findable, and some codecs like h264 too.
> For those GStreamer can guess the caps after reading some bytes of
>> > 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?
> wav demuxer is not mandatory, but any container format and the
> corresponding demuxer element will make your life much easier.
> Without you will have to a) set the caps and b) make sure that buffers
> are provided in appropriate sized chunks to the decoder.
Thanks for the explanation.
> Sebastian Dröge, Centricular Ltd - http://www.centricular.com
> Expertise, Straight from the Source
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> gstreamer-devel at lists.freedesktop.org
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