RE: CN: www/2009/devdocs/XFP-SOD-CrossFadePlayer.doc

The context you get in RegisterContext is
the media platform. The media playback engine
(IHXClientEngine) is also a component plugin.
So from that context you receive in RegisterContext,
you can QI it for CCF and then use that CCF
to do a CreateInstance on CLSID_IHXClientEngine.

Eric

=======================================
Eric Hyche ([email protected])
Principal Engineer
RealNetworks, Inc.


>-----Original Message-----
>From: Nicholas Hart [mailto:[email protected]]
>Sent: Thursday, February 19, 2009 6:27 PM
>To: [email protected]
>Cc: [email protected]
>Subject: Re: [Helix-client-dev] CN: www/2009/devdocs/XFP-SOD-CrossFadePlayer.doc
>
>I have one more question about this.
>
>I've setup the plugin as described and the IHXCrossFadePlayer implements
>IHXContextUser.  Its RegisterContext() is called, but when I try to QI
>the IUnknown context for IHXClientEngine I get a "no interface" error.
>
>Is there something else I should do to get the client engine?  Or should
>I use a different mechanism to pass the client engine in to the
>crossfade player?
>
>thanks!
>
>
>
>Eric Hyche wrote:
>> Nick,
>>
>> Sorry for the delay in providing feedback. Here's mine:
>>
>> 1) I like client/xfadeplayer instead of client/xfadeplugin,
>>    although whatever you choose will be fine.
>>
>> 2) Inside of client/xfadeplayer, I would have two sub-Umakefil's:
>>    one that builds the IHXCrossFadePlayer into a static lib,
>>    and the other sub-Umakefil that builds an Atlas component
>>    plugin (and links in the static lib built in the other
>>    sub-Umakefil).
>>
>>    A component plugin is one that implements IHXComponentPlugin.
>>    This interface tells the media platform that this plugin
>>    can create certain CLSID_xxx's. It specifies how many CLSID_xxx's
>>    it can create via IHXComponentPlugin::GetNumComponents()
>>    and it provides the list of CLSID_xxx's via
>>    IHXComponentPlugin:: GetComponentInfoAtIndex().
>>
>>    The IHXCrossFadePlayer object should also implement IHXContextUser.
>>    That way, when the plugin handler creates it, it will automatically
>>    pass it the context via IHXContextUser::RegisterContext.
>>
>>    See client/netwksvc/hxnetwksvcpln.cpp, client\autoupgdmgr\autoupgdpln.cpp,
>>    client\downloadmgr\downloadpln.cpp, or client\core\hxmedengpln.cpp
>>    for examples of component plugins.
>>
>> 3) When an application uses an IHXPlayer, then it:
>>
>>     - loads the media platform
>>     - QI's the media platform for CCF
>>     - uses CCF to create IHXClientEngine
>>     - uses IHXClientEngine to create IHXPlayer
>>
>>    So for IHXCrossFadePlayer, it will:
>>
>>     - load the media platform
>>     - QI the media platform for CCF
>>     - use CCF to create IHXCrossFadePlayer. The plugin
>>       handler will make sure that the object gets a context
>>       via its IHXContextUser::RegisterContext() method.
>>       The context that it is passed will *be* the media
>>       platform.
>>
>>    There is no need to specifically have the application create
>>    a client engine and pass it to the IHXCrossFadePlayer object.
>>    The crossfade player object has a context, so it can create
>>    a client engine internally itself and then manage the
>>    lifetime of that client engine.
>>
>> 4) Under "Testing Provisions", I would suggest a command-line
>>    test app in client/xfadeplayer/test. You could use splay
>>    as a starting point for that, or better yet, use my dirt-simple
>>    SHAPE (Simplest Helix Audio Player Ever) player at
>>    clientapps\samples\shape as a starting point.
>>
>>
>> Eric
>>
>> =======================================
>> Eric Hyche ([email protected])
>> Principal Engineer
>> RealNetworks, Inc.
>>
>>
>>> -----Original Message-----
>>> From: [email protected] [mailto:helix-client-dev-
>[email protected]]
>>> On Behalf Of Nicholas Hart
>>> Sent: Wednesday, February 18, 2009 4:48 PM
>>> To: [email protected]
>>> Subject: Re: [Helix-client-dev] CN: www/2009/devdocs/XFP-SOD-CrossFadePlayer.doc
>>>
>>> there has been zero commentary on this proposal.
>>>
>>> I'm at a point where I'd like to start checking in some files.  The
>>> project is by no means finished, but I'd like the security of keeping my
>>> work in CVS in case my hard drive gets fried.
>>>
>>> Should I start submitting some code reviews to this alias?
>>>
>>> Thanks!
>>>
>>>
>>>
>>>
>>> Nicholas Hart wrote:
>>>> Modified by: [email protected]
>>>> Reviewed by:
>>>> Date: 2/11/09
>>>> Project: internal RealNetworks product
>>>>
>>>> Synopsis: SOD for client feature to enable cross-fade and gap-less
>>>> playback of audio clips
>>>>
>>>> Overview: I've committed a SOD for a new player object which uses the
>>>> client engine to perform a cross-fade between two audio clips.
>>>>
>>>> Files Added:
>>>> [File 1]
>>>> https://helixcommunity.org/viewcvs/helix-client/www/2009/devdocs/XFP-SOD-
>>> CrossFadePlayer.doc?view=log
>>>> - SOD for this feature
>>>>
>>>> Platforms and Profiles Affected:
>>>> none - SOD only
>>>>
>>>> Platforms and Profiles Functionality verified:
>>>> none - SOD only
>>>>
>>>> Branch:  HEAD
>>>>
>>>> Copyright assignment:
>>>>
>>>>    4.      I am a RealNetworks employee or contractor
>>>>
>>>>
>>>>
>>>> _______________________________________________
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>>>>
>>>>
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>>
>>
>>