| 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 |
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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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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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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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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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|
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Volume of right channel in the range [0, 65535]. |
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|
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RDPSND_COMPLETION |
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----------------- |
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|
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Sent by the client to the server when a packet, queued by |
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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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The client must respond by echoing the first four bytes of this |
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packet. |
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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 |
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---------------- |
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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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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Pitch | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| UDP port | Format count | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Initial idx | Version | Padding | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 203 |
| ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| 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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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Block align | Bits per sample | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| Extra size | Extra data ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| ... | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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|
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Flags |
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|
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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). Must be |
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set for sound to work. |
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0000 0002 Volume control support. Indicates that volume |
| 225 |
fields are valid and that the client understands |
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RDPSND_SET_VOLUME. |
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0000 0004 Pitch field is valid. |
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|
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Left channel |
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|
| 231 |
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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|
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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. Sent in network (big endian) order. |
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Data not valid when from server. |
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|
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Format count |
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|
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Number of format structures following the header. |
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|
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Initial index |
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|
| 252 |
Initial packet index. The first RDPSND_WRITE will have a packet |
| 253 |
index one larger than this value. Data not valid when from client. |
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|
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Version |
| 256 |
|
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Software version. Server (XP & 2K3) sets this to 5. Client (XP) |
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also sets this to 5. |
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|
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Padding |
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|
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Unused. |
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|
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Format tag |
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|
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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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|
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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 |
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useful data. |
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|
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Bits per sample |
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|
| 288 |
Number of bits per sample. Commonly 8 or 16. |
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|
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Extra size |
| 291 |
|
| 292 |
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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|
| 297 |
Optional extra format data. Contents specific to each format |
| 298 |
type. |
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