add log docs

old-commit-hash: 0f8c6f130b

selfdrive/loggerd/README.md

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+# loggerd
+
+openpilot records routes in one minute chunks called segments. A route starts on the rising edge of ignition and ends on the falling edge.
+
+Check out our [python library](https://github.com/commaai/openpilot/blob/master/tools/lib/logreader.py) for reading openpilot logs. Also checkout our [tools](https://github.com/commaai/openpilot/tree/master/tools) to replay and view your data. These are the same tools we use to debug and develop openpilot.
+
+## log types
+
+For each segment, openpilot records the following log types:
+
+## rlog.bz2
+
+rlogs contain all the messages passed amonsgt openpilot's processes. See [cereal/services.py](https://github.com/commaai/cereal/blob/master/services.py) for a list of all the logged services. They're a bzip2 archive of the serialized capnproto messages.
+
+## {f,e,d}camera.hevc
+
+Each camera stream is H.265 encoded and written to its respective file.
+* fcamera.hevc is the road camera
+* ecamera.hevc is the wide road camera
+* dcamera.hevc is the driver camera
+
+## qlog.bz2 & qcamera.ts
+
+qlogs are a decimated subset of the rlogs. Check out [cereal/services.py](https://github.com/commaai/cereal/blob/master/services.py) for the decimation.
+
+
+qcameras are H.264 encoded, lower res versions of the fcamera.hevc. The video shown in [comma connect](https://connect.comma.ai/) is from the qcameras.
+
+
+qlogs and qcameras are designed to be small enough to upload instantly on slow internet and store forever, yet useful enough for most analysis and debugging.