[Gpephone-devel] functions of sound server

[Yu Yijun]

Hi, Dirk,
  It's good to know a different approach for the concurrent sound device access. However, I'm not very clear on your model. 
  Do you still need a sound server? if no, it's a pity that there is no sound mix functionality since some time we need to hear sound from different sources. e.g, we listen to a music and at the same time hear the alert sound of low battery signal. if yes, the model is a little bit complex, isn't it?  Moreover, if two apps open the sound device with different priorities, the lower priority app just keeps running but quitely. Some time it is not the expected behavior and a pause mechanism to the lower priority app should be provided.
  BTW, I'm curious that what is the concrete scenario that an application want to use sound device directly, bypassing sound server.
   
  Regards
  Yu Yijun
  

Dirk Sigurdson <dsigurdson at a-la-mobile.com> wrote:
  My company has had some experience with this issue in the Qtopia 
environment. Qtopia has a sound server that will mute applications 
(example, media players) when there's a call in place as long as your 
application is using the Qtopia sound API. Our problem has been that 
there are some applications that want to access the sound device 
directly, bypassing the Qtopia sound server. Rather than handling 
this problem at the application level we decided to handle it in the 
driver level. When the application opens the sound device it can 
indicate a priority. If it's a high priority app then when two 
applications are using the device the user would only hear the high 
priority audio.

As long as you're in control of all the applications that are in the 
device and can modify them to use a single sound API or to listen for 
the incoming call event, then that's probably the way to go. 
However, I just wanted to point out a different approach that might 
be able to handle a larger set of applications.

Dirk


On Feb 13, 2007, at 2:34 AM, YU Yijun RD-ILAB-PEK wrote:

>
>
>>>>
>>>> Thanks!
>>>> What happens when there comes a phone call,or user estiblish a call
> while
>> playing
>>>> music?
>>>> Normally, music playing will be paused( or just mute?).
>>>>
>>> Currently, sound server just mixes them up.
>>> We may use other mechanism to pause the music player. Say music 
>>> player
> will
>> register an incoming call event and once it receives this event, it
> will pause
>> itself.
>>>
>>> There is no such mechanism in the current edition and we welcome
> suggestions
>> & contributions.
>>>
>>> Regards
>>> Yu Yijun
>>
>> Two ways I think:
>> 1, pause music playing
>> sound server should send messages to all playing processes to pause.
> perhaps
>> it will cause a long delay, and make applications that want to play
> music more
>> complicated.
>>
>> 2, mute all music
>> it's application transparent. sound server should have a timer to
> process
>> audio buffers periodically. perhaps it wasts too much resources.
>>
>> Any better suggestions?
> Hi,
> In fact, I mean that once there is an incoming call, phone server will
> broadcast this event and any application can register it.e.g., diaer
> application, music player application, etc.
> When music application receives this event it can then pause itself.
> Unfortunately, in the current code, phone server sends incoming call
> event directly to dialer app and music app has no chance to receive 
> this
> event. Therefore, in the following version, I suggest we should revise
> phone server's ability.
>
>
>>
>> REGARDS
>> littertiger
>
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