| 1 |
Overview |
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======== |
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|
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The RDPSND protocol is a binary, packet based protocol that maps |
| 5 |
Microsoft's legacy wave API to a RDP channel. |
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|
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All values are in little endian ordering. |
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|
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Responses are sent with the same opcode as the request, and usually |
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also with the same packet structure. |
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|
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The basic structure of a packet is: |
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|
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0 1 2 3 |
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Opcode | Unknown | Payload size | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 19 |
| ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Opcode |
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|
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Command or response type. Known values: |
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|
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0x01 RDPSND_CLOSE |
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0x02 RDPSND_WRITE |
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0x03 RDPSND_SET_VOLUME |
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0x04 Unknown (4 bytes payload, no response) |
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0x05 RDPSND_COMPLETION |
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0x06 RDPSND_PING |
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0x07 RDPSND_NEGOTIATE |
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|
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Unknown |
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|
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Usage not known. Not valid when message comes from server |
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|
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Payload size |
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|
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Number of bytes following the header. |
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|
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Opcodes |
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======= |
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|
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Following is a list of all known opcodes and the contents in their |
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payloads. |
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|
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RDPSND_CLOSE |
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------------ |
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|
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Tells the client that all applications on the server have released |
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control of the sound system, allowing the client to free any local |
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resources. |
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|
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No payload and no response. |
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|
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RDPSND_WRITE |
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------------ |
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|
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Request to play a chunk of data. The client is expected to queue up |
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the data and send a RDPSND_COMPLETION when playback has finished. |
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|
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No response. |
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|
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0 1 2 3 |
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Tick | Format index | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Packet index | Pad | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Waveform data | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 74 |
| ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Tick |
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|
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Low 16 bits of clock tick count when packet was scheduled for |
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playback. |
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|
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Format index |
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|
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Waveform data format in the form of an index to the previously |
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negotiated format list. |
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|
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Packet index |
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|
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Index number of this packet. |
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|
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Pad |
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|
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Unused padding. |
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|
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Waveform data |
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|
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Binary waveform data in the format specified by the format index. |
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Size defined by the packet boundary. |
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|
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Because of a strange design in Microsoft's server, the length of |
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the packet will be 4 bytes short and bytes 12 to 15 (4 bytes) of |
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the payload should be removed. |
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|
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RDPSND_SET_VOLUME |
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----------------- |
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|
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Request from the server to the client to change the output volume. |
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No response. |
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|
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0 1 2 3 |
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Left channel | Right channel | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Left channel |
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|
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Volume of left channel in the range [0, 65535]. |
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|
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Right channel |
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|
| 122 |
Volume of right channel in the range [0, 65535]. |
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|
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RDPSND_COMPLETION |
| 125 |
----------------- |
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|
| 127 |
Sent by the client to the server when a packet, queued by |
| 128 |
RDPSND_WRITE, has finished playing. |
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|
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No response is sent by the server. |
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|
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0 1 2 3 |
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Tick | Packet index | Reserved | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Tick |
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|
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Clock tick count when packet finished playing on device. |
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|
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Packet index |
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|
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Index number of packet played. |
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|
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Reserved |
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|
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Reserved. Always 0. |
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|
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RDPSND_PING |
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----------- |
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|
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Sent by the server to the client to determine transport latency. |
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Response is identical to the request (including an unmodified tick). |
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|
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0 1 2 3 |
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Tick | Reserved | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Garbage | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Tick |
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|
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Clock tick count when sent from server. |
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|
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Reserved |
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|
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Reserved. Always 0. |
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|
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Garbage |
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|
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1016 optional bytes of random data. Purpose unknown. |
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Only sent from server. |
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|
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RDPSND_NEGOTIATE |
| 180 |
---------------- |
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|
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Initial packet sent by server when the client [re]connects. Allows |
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the server to determine the capabilities of the client. |
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|
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The client should reply with an identical packet, with the relevant |
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fields filled in, and a filtered list of formats (based on what the |
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client supports). |
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|
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0 1 2 3 |
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Flags | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Left channel | Right channel | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 196 |
| Pitch | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 198 |
| UDP port | Format count | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Pad1 | Version | Pad2 | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 202 |
| ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 204 |
| Format tag | Channels | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Frames per sec. | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Bytes per sec. | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 210 |
| Block align | Bits per sample | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 212 |
| Extra size | Extra data ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 214 |
| ... | |
| 215 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Flags |
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|
| 219 |
Flags for client capabilities. Data not valid when from server. |
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|
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0000 0001 Do UDP song and dance (details unknown). |
| 222 |
|
| 223 |
Left channel |
| 224 |
|
| 225 |
Initial volume for left channel. Data not valid when from server. |
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|
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Right channel |
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|
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Initial volume for right channel. Data not valid when from server. |
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|
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Pitch |
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|
| 233 |
Initial pitch of the sound device. Data not valid when from server. |
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|
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UDP port |
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|
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Port used for UDP transfers. Data not valid when from server. |
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|
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Format count |
| 240 |
|
| 241 |
Number of format structures following the header. |
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|
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Pad1 |
| 244 |
|
| 245 |
Usage not known. Offset 26 in secret protocol. Data not valid |
| 246 |
when from client. |
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|
| 248 |
Version |
| 249 |
|
| 250 |
Software version. Server (XP & 2K3) sets this to 5. |
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|
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Pad2 |
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|
| 254 |
Usage not known. Data not valid when from server, nor from |
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client. |
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|
| 257 |
Format tag |
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|
| 259 |
Audio format type as registered at Microsoft. |
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|
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Channels |
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|
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Number of channels per frame. |
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|
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Frames per sec. |
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|
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Frames per second in Hz. |
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|
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Bytes per sec. |
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|
| 271 |
Number of bytes per second. Should be the product of |
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"Frames per sec." and "Block align". |
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|
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Block align |
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|
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The size of each frame. Note that not all bytes may contain |
| 277 |
useful data. |
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|
| 279 |
Bits per sample |
| 280 |
|
| 281 |
Number of bits per sample. Commonly 8 or 16. |
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|
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Extra size |
| 284 |
|
| 285 |
Number of bytes of extra information following this format |
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description. |
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|
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Extra data |
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|
| 290 |
Optional extra format data. Contents specific to each format |
| 291 |
type. |
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