System and method for merging multiple audio streams

A system for mixing multiple audio streams, said system comprising:

• an audio decoder for decoding a primary stream of audio data, said audio decoder producing a decoded primary stream of audio data;
• means for retrieving a secondary stream of audio data from system memory, said secondary stream comprising audio pulse code modulated (PCM) data;
• an audio playback device for formatting said secondary stream of audio data for mixing with said decoded primary stream of audio data;
• a mixer for mixing said decoded primary stream of audio data and said formatted secondary stream of audio data for output as a merged audio signal;
• and
• wherein said audio playback device further comprises a working buffer and a pending buffer coupled to receive in parallel portions of said audio PCM data, a buffer multiplexer receiving as input audio data read from said working buffer and said pending buffer, a serial shifter coupled to receive output from said buffer multiplexer and produce therefrom a serial PCM sample stream, a formatter coupled to receive said serial PCM sample stream from said serial shifter, said formatter converting said serial PCM sample stream to a digital, serial format, and a clock multiplexer for providing a clock to drive said formatter using one of a plurality of available clock signals.

A method for mixing multiple audio signals, said method comprising:

• decoding a primary stream of audio data and producing therefrom a decoded primary stream of audio data in digital, serial format, said decoding comprising employing a first audio digital playback device comprising an audio decoder;
• retrieving a secondary stream of audio data from system memory, said secondary stream comprising audio pulse code modulated (PCM) data;
• formatting said secondary stream of audio data in digital, serial format for mixing with said decoded primary stream of audio data in digital, serial format, said formatting employing a second audio digital playback device comprising an audio PCM playback macro;
• and
• mixing said decoded primary stream of audio data and said formatted secondary stream of audio data for output as a merged audio signal.

A method for mixing multiple audio signals, said method comprising:

• decoding a primary stream of audio data and producing therefrom a decoded primary stream of audio data;
• retrieving a secondary stream of audio data from system memory, said secondary stream comprising audio pulse code modulated (PCM) data;
• formatting said secondary stream of audio data for mixing with said decoded primary stream of audio data;
• mixing said decoded primary stream of audio data and said formatted secondary stream of audio data for output as a merged audio signal;
• and
• wherein said formatting comprises formatting said audio PCM data in digital, serial format, and wherein said decoding comprises outputting said decoded primary stream of audio data as audio PCM data in I2S format.

A method for mixing multiple audio signals, said method comprising:

• decoding a primary stream of audio data and producing therefrom a decoded primary stream of audio data;
• retrieving a secondary stream of audio data from system memory, said secondary stream comprising audio pulse code modulated (PCM) data;
• formatting said secondary stream of audio data for mixing with said decoded primary stream of audio data;
• mixing said decoded primary stream of audio data and said formatted secondary stream of audio data for output as a merged audio signal;
• and
• wherein said formatting comprises initially buffering in parallel portions of said audio PCM data, multiplexing the parallel buffered portions of said audio PCM data, serially shifting output of said multiplexing to produce a serial PCM sample stream, and converting the serial PCM sample stream to a digital, serial format, said converting employing one of a plurality of available clock signals.