Decode G711(PCM u-law)

Please bear with me as my understanding of audio codec is limited. I have this audio source from a IPCAM (through a htto//... CGI interface). I am trying to write several client programs to play this audio source on Windows, MAC, as well as Android phone. The audio is encoded in G711 (PCM ulaw).

Do I need to decode the PCM aud开发者_JAVA百科io data to a raw audio data before I could pass it to the audio engine to play? If so, is there some sample code on how to decode it? I am confused as somehow I believe PCM is already RAW. Could I just feed it directly to the audio engine on Android for example?

thanks much in advance

It depends on what API you are using to play sound, but most require linear PCM and you have µ-law PCM, so unless your API supports µ-law playback you will need to convert the µ-law sample values to linear.

With G.711 the compressed µ-law samples are 8 bits and these will be converted to 14 bit linear values which you will store in a buffer as 2 bytes per sample. There is a brief description of the µ-law encoding on the G.711 Wikipedia page.

You may find this useful:

u-Law companding algorithm in C