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New Contributor
Posts: 2
Registered: ‎03-22-2010
My Device: simulator
My Carrier: simulator

format of PCM (audio/basic) recorded data?

Hi,

 

I am prorting a midlet to the Blackberry that records sound using RecordControl and analyses the frequency spectrum of the data. It records audio using:

 

Player p = Manager.createPlayer("capture://audio?encoding=pcm");

 

On Nokia and Sony-Ericsson phones the audio that I get is of type audio/x-wav including the standard header for audio/x-wav.

 

On Blackberry the data seems to be audio/basic (at least on the simulator) which is supposed to be the AU sound file format. However it does not contain the standard header of such a file,. Therefore I do not know the detailed format. Can somebody tell me:

 

-does it contain a header and if yes, where can I find the spec of the header?

-if no header where can I find information about the format, I need to know:

  -sampe rate ?

  - big endian or little endian ?

  - is the PCM linear encoded or µ-law encoded (logarithmic) ?

  - bits per sample ?

  - number of channels ?

 

I could not find this information anywhere in the docs, forum or web.

 

Best regards,

Ingo

 

 

Developer
Posts: 119
Registered: ‎03-10-2010
My Device: Bold 9000
My Carrier: Rogers

Re: format of PCM (audio/basic) recorded data?

Hi,

 

based on what I found here: http://www.rfc-editor.org/rfc/rfc2046.txt

 

I believe the audio/basic is uLaw - 8 bits - 8Khz - Mono without header.

 

 

 

 



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New Contributor
Posts: 2
Registered: ‎03-22-2010
My Device: simulator
My Carrier: simulator

Re: format of PCM (audio/basic) recorded data?

Hi, the initial AU file format from Sun was 8-bit µlaw big-endian. But now there are many different versions of the format: http://en.wikipedia.org/wiki/Au_file_format Newer files have a header, older ones do not. This Blackberry doc: http://www.blackberry.com/knowledgecenterpublic/livelink.exe/fetch/2000/348583/800332/1089414/How_To... says the audio is "8kHz mono-16-bit Pulse Code Modulation (PCM)". It is still unclear wheather it is little or big endian and linear or µlaw encoding. I read somewhere in here that someone thinks it is 16 bit, little-endian, 8KHz. Can someone confirm this? Is there somebody from Blackberry who can shine some light on this topic? Regards, Ingo