xAP-Audio schema questions....

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

This is a posting of a couple of email exchanges now moved to this list
as it is of interest to all I feel.


Hi P - yes I can see why you've done that ...

In re-reading the schema I understand how certain .events are sent but I
am still unsure of some and I can't see a list of the 'modes' for
example and what should be sent if say a player is put into pause or FF
or whatever. I also see there is a refererence to allowing the .events
to be sent 'as needed'

It strikes me we could do with defining some additional time related
parameters for inclusion in the event reporting timeline including

Duration  <mandatory>
StartTime <mandatory>
EndTime <mandatory>
CurrentTime  <mandatory>
ElapsedTime   <optional ?>
RemainingTime  <optional ?>

.. and that these should be sent periodically at a frequency that is
configurable as different users might want tighter feedback. 10 secs
sounds a useful time for most implementations. Towards the end of the
current track it may be desireable to increase the frequency of events

Just to expand on the above time information I was considering what
would happen if a player was asked to play a track whose duration was
say 5 mins but starting at position 1min22secs and ending at 1min44secs
which I think our schema should/does support (the actual time being down
to 100'ths of a sec perhaps).The current 'Duration' is the length of the
whole track and the currentTime the exact current position relative to
that. The StartTime and EndTime are the actual markers for what section
is to be played. ElapsedTime and RemainingTime can be derived from the
other values but could be defined such that they can be inserted as
optional .

What does anyone think ? I think this is needed and I am keen to resolve
it whilst Malcolm is focussed on teh xAP aspects of TelCanto.  Edward
and Stuart I would particularly value your comments as you are the two
who have done this practically already...

Kevin


Patrick Lidstone wrote:

>I do an "elapsed time" event which includes current play
state for the
>Rio stuff (sent once every 10s or so, plus whenever a button causes a
>change). This is an integral part of the audio spec - I can dig out the
>exact message if no-one else chips in.
>
>P.
>
>
>
>>-----Original Message-----
>>From: Kevin Hawkins
>>Sent: 09 December 2004 13:44
>>
>>
>>xAP guys...
>>
>>    The newer audio schema isnt one I'm familiar with  so I'm just
>>coming up to speed on that as I provide feedback to Malcolm. What I
>>can't seem to see is how a player keeps people informed of its
state.
>>For example when it is paused by a press of the pause button on the
>>player or IR remote or FF'wded perhaps causing the track position
to
>>change (not the actual track just the time remaining).  How do we
>>indicate a player is in pause/play or whatever ?.    It strikes me
we
>>need a whole series of periodic event messages being generated by a
>>player that keep people updated about it current state eg 'time
>>remaining'.  ... and that such event messages should probably
>>be issued
>>quite frequently (configurable), particulalry towards the end
>>of a track
>>playing (eg track about to end /finished).  Additionally
>>anything that
>>causes the estimated time remaining to change should
>>immediately send an
>>update (eg a REW) This way monitoring apps can accurately
>>become synched
>>with a players status even if they are only turned on half
>>way through
>>a  track eg the xAP Desktop SliMP3 display...    I can see
>>some specific
>>SliMP3 bits that would help but not in the general schema and in
>>telCanto's case it could be driving lots of different clients.
>>
>> Or have I missed something ?
>>
>>Kevin
>>
>>
>>