[Asterisk-Dev] Formats for storing Audio archives.

[Adam Hart]

James Gardiner wrote:

> On the topic below..
> 
> 
>> On Thu, 2004-04-15 at 20:22, James Gardiner wrote:
>>
>>>Thanks Steve,
>>>Very helpful, really appreciated,
>>>
>>>But do you think that because I am joining the two voice channels into 
>>>one STEREO wav file, (One channel to the left, the other to the 
>>>right.)  is GSM still the best method.
>>
>>GSM is a monno only format. It is specialised for telephony. Stereo would
> 
> have to either be down mixed or stored in another format.
> 
>>>I did try ogg with default parameters, and it was only a few k more 
>>>then the GSM file.
>>>I'm ruff at this, so maybe I should try it some more and make sure, 
>>>clear I am comparing apples with peaches. ;)
>>
>>It all depends on how you want to access these files.
>>
>>BTW, it is important to keep these messages on list so it helps the
> 
> greatest number of people.
> 
> Well, for storing the audio from a call, it does sound like a good idea to
> keep each channel separate so a left/right (Caller/receiver) stereo mix
> sounds like a great idea, especially if you need to really analyse one of
> the channels audio for whatever reason.
> However, if going to this level, a good compression with least drop in audio
> quality is what your most likely looking for.
> 
> In terms of accessing the files, an archive would more likely be accessed
> via WEB interface.  So standard audio compressions like MPEG audio OGG or
> other free based hi quality methods would be ok.  Mainly as we want an audio
> format readily available on any PC without having to use special player. (Ie
> GSM is not supported out of the box from windows from my understanding.)
> 
> Considering all this, I was wondering if the list had any comments on this.
> 
> I wanted to discuss this application as I plan to implement all phone calls
> in my company being archived.  I have had considerable problems with loosed
> lipped employees and Intellectual property issues in our organisation with
> use of our facilities for employees own gain.
> 
> Thanks,
> James


I'd say the easist way would be to store in wav and (assuming wav causes 
storage issues), have a cron job to encode to mp3 every 5minutes (must 
remember to only encode completed calls - look at timestamp of file). 
You could even do this on another box if encoding of mp3 adds too much load.