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93 lines
3.4 KiB
Plaintext
93 lines
3.4 KiB
Plaintext
This documents the protocol used to pass data over fds between ipcpipelinesrc
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and ipcpipelinesink.
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The protocol is used in both directions. However, some combinations do
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not make sense (eg, a buffer going from ipcpipelinesrc to ipcpipelinesink).
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The protocol consists of an arbitrary number of variable sized chunks
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with a type. Each chunk has a request ID which can be used to match a
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request with its reply (ack / query result).
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Each chunk consists of:
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- a type (byte):
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1: ack
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2: query result
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3: buffer
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4: event
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5: sink message event
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6: query
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7: state change
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8: state lost
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9: message
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10: error/warning/info message
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- a request ID, 4 bytes, little endian
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- the payload size, 4 bytes, little endian
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- N bytes payload
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Depending on the type, the payload can contain:
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- 1: ack
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result: 4 bytes, little endian
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interpreted as GstFlowReturn for buffers, boolean for events and
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GstStateChangeReturn for state changes
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- 2: query result
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result boolean: 1 byte
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query type: 4 bytes, little endian
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returned query string representation, NUL terminated
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- 3: buffer:
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pts: 8 bytes, little endian
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dts: 8 bytes, little endian
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duration: 8 bytes, little endian
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offset: 8 bytes, little endian
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offset end: 8 bytes, little endian
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flags: 8 bytes, little endian
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buffer size: 4 bytes, little endian
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data: contents of the buffer data, size specified in "buffer size"
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number of GstMeta: 4 bytes, little endian
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For each GstMeta:
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bytes: 4 bytes, little endian
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this is the number of bytes before the string representation
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at the end of this block, including the 4 bytes of itself
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flags: 4 bytes, little endian
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length of the GstMetaInfo::api name: 4 bytes, little endian
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GstMetaInfo::api name: string, NUL terminated
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GstMetaInfo::size: 8 bytes, little endian
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length of the string representation: 4 bytes, little endian
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string representation, NUL terminated
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- 4: event
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event type: 4 bytes, little endian
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sequence number: 4 bytes, little endian
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direction: 1 byte
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whether the event is going upstream (1) or downstream (0)
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string representation, NUL terminated
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- 5: sink message event
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message type: 4 bytes, little endian
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event sequence number: 4 bytes, little endian
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message sequence number: 4 bytes, little endian
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length: 4 bytes, little endian
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event structure name: length bytes, NUL terminated
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message structure string representation: remaining bytes, NUL terminated
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- 6: query
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query type: 4 bytes, little endian
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direction: 1 byte
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whether the query is going upstream (1) or downstream (0)
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string representation, NUL terminated
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- 7: state change
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GstStateChange: 4 bytes, little endian
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- 8: state lost
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no payload
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- 9: message
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message type: 4 bytes, little endian
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string representation, NUL terminated
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- 10: error/warning/info message
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message type (2 = error, 1 = warning, 0 = info): 1 byte
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error domain string length: 4 bytes, little endian
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string representation of the error domain, NUL terminated
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error code: 4 bytes, little endian
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length: 4 bytes, little endian
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if zero: no error message
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if non zero: As many bytes as this length: the error message, NUL terminated
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length: 4 bytes, little endian
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if zero: no extra message
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if non zero: As many bytes as this length: the error extra debug message, NUL terminated
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