Re: [Iaxclient-devel] iaxc_play_sound

[stevebvt <ste...@gm...>]

it's not a case of buffer overrun

what i was talking about was in the case of OutputBuffer full
it seemed that (since there was only 1 OutputBuffer) that sound N+1 would 
overwrite
sound N until the last sound was reached (which i considered problematic)

please explain the usefulness of the current functionality
(clearly i'm missing it)

if i want to play N sounds (for example dtmf tones) & there is no way to 
tell when a sound ends
how do i send N distinct tones?

steve


----- Original Message ----- 
From: "Peter Grayson" <jpg...@gm...>
To: "stevebvt" <ste...@gm...>
Cc: <iax...@li...>
Sent: Monday, April 14, 2008 10:01 AM
Subject: Re: [Iaxclient-devel] iaxc_play_sound


> Hi Steve,
>
> On Thu, Apr 10, 2008 at 11:24 AM, stevebvt <ste...@gm...> wrote:
>>
>>
>> i have a question regarding multiple calls to iaxc_play_sound
>> (without waiting for a prior call to complete
>>  by the way - is there a way to determine when a call to iaxc_play_sound 
>> has
>> completed?)
>
> There is nothing in the API to know when a sound has completed. The
> api would have to be extended somehow to have this functionality. As
> it stands, iaxc_play_sound() has a fire-and-forget semantic.
>
>> i would have expected it to work this way
>> (given the case of a call to iaxc_play_sound - where a prior call has not
>> completed)
>>
>> 1. the new iaxc_sound{} would be added to the end of the existing chain 
>> of
>> iaxc_sounds (fifo)
>>    using iaxc_sound.next
>> 2.when the current iaxc_sound completed the next iaxc_sound would become
>>    the head of the fifo queue & output
>>
>> what the code sees to do is
>> 1. the new iaxc_sound{} is added to the front of the existing chain of
>> iaxc_sounds (lifo)
>>     pa_play_sound () -
>>       sound->next = sounds;
>>       sounds = sound;
>> 2. if there is BUFFER OVERFLOW subsequent iaxc_sound{}  data seems to be
>> discarded
>>    pa_mix_sounds () -
>>      if ( *sp ) /* don't advance if we removed this member */
>>       sp = &((*sp)->next);
>>
>> what should happen in this case?
>
> The way iaxc_play_sound() works is to play each sound as soon as
> possible. If there are multiple sounds in the "sounds" list, then they
> are played at the same time and mixed together (see mix_slin()). This
> is why it doesn't matter whether the sounds are prepended or appended
> to the sounds list.
>
> I do not see any potential buffer overflows in pa_mix_sounds(), but I
> could be missing what you are seeing. Could you give a little more
> explanation of where a buffer may be overrun?
>
> Pete