3.2.5.1.6 Processing an Open PDU

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The structure and fields of the Open PDU are specified in section 2.2.2.3.

The server sends the Open PDU to indicate that it is ready to start receiving audio data. The Open PDU specifies two audio formats. The first format is specified by the InitialFormat field and is an index into the negotiated audio formats list. This format is the audio format that the client MUST use to encode audio data and send to the server.  The format is used to encode audio data that can be changed by a Format Change PDU later.

The second format is specified by the wFormatTag, nChannels, nSamplesPerSec, nAvgBytesPerSec, nBlockAlign, nBitsPerSample, cbSize, and ExtraFormatData fields. These fields specify the format that SHOULD be used to capture data from the actual audio input device.