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Qt-interest Archive, April 2008
doubts about phonon


Message 1 in thread

i am using Qt 4.4 for devoleping mediaplayer[which should use H.264
video decoder and MP3 audio decoder with in AVI container format from
ffmpeg].

i am using gstreamer as phonon backend.there are musicplayer and
mediaplayer examples present in it and i am able to run those example
application.i am using fedora core 6 .the applications were done with
phonon API.

is it possible to make a mediaplayer or musicplayer to choose that
particular video decoder or audio decoder from ffmpeg , or it is
possible for me with phonon to make use of my own audio decoder or video
decoder for the musicplayer.

regards
madhan kumar.R


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Message 2 in thread

Hi,

Am Dienstag, 22. April 2008 schrieb madhan kumar:
> i am using Qt 4.4 for devoleping mediaplayer[which should use H.264
> video decoder and MP3 audio decoder with in AVI container format from
> ffmpeg].

I don't understand your point. You want to play different media-files in 
possibly different formates. But you want to tell phonon (or its backend) to 
just use one specific codec for playback? That will give you more files you 
can't play than files you can play.

And ffmpeg is probably not available on all the systems qt runs on.

And why do you even care about specific codecs? The reason of phonon is to 
keep your mind free of that and focus on the real features your player should 
have to distinguish your app from the various players out there (including 
the one in the examples).


If phonon (haven't yet looked at it) has an interface to send it binary data 
to play, you can use your own libs to decode audio and video and just send 
that to phonon. But that is certainly not the real purpose if phonon...

> The information contained in this electronic message and any attachments to
> this message are intended for the exclusive use of the addressee(s) and may
> contain proprietary, confidential or privileged information. If you are not
> the intended recipient, you should not disseminate, distribute or copy this
> e-mail. Please notify the sender immediately and destroy all copies of this
> message and any attachments contained in it.
> Contact your Administrator for further information.

Could you people please stop to add these meaningless "disclaimers"???
Email is like sending a postcard, everyone who has it in the hands (or on his 
computer) can read it. (And even modify it when its not signed!)

Sending email to such a list means sending a postcard to a _lot_ of people. 
Adding 7 lines explaining how to act if I am not the intended recipient is 
just plain senseless.

And it has probably no legal effect...

Have fun,

Arnold
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Message 3 in thread

Please reply to the list...

Am Dienstag, 22. April 2008 schrieben Sie:
> On Tue, 2008-04-22 at 09:31 +0200, Arnold Krille wrote:
> ok leave things about specific codecs, i want to use my own audio and
> video decoder in my application. is it possible with phonon?

If you want to use your own codecs, there is nothing that hinders you. But why 
do you want to use phonon then (except for easy sound-device-access)?
Phonon is a middle-layer that plugs between your "simple multimedia needs" and 
the complicated interfaces of the different soundsystems. When playing audio 
and video all you want (as a dev) to say "play that" and it plays. When you 
_really_ want to say "decode that with this specific codec" you should not 
try to hack phonon in some strange (and probably unportable way) but just 
decode it yourself before putting the decoded data into phonon.

So the question is not "can i use phonon with my specific codec" but more 
like:
 1) (possibly) check wether phonon can already play that media-format with its 
backends, if not
 2) use your own decoder to produce uncompressed binary data to send to 
phonon.

And I repeat you are probably far better off with letting phonon do the 
decoding because then you don't have to deal with that...

Have fun,

Arnold
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