Serialize and deserialize protobufs through CLI? - protocol-buffers

Question

I am trying to deserialize a file saved as a protobuf through the CLI (seems like the easiest thing to do). I would prefer not to use protoc to compile, import it into a programming language and then read the result.
My use case: A TensorFlow lite tool has output some data in a protobuf format. I've found the protobuf message definition in the TensorFlow repo too. I just want to read the output quickly. Specifically, I am getting back a tflite::evaluation::EvaluationStageMetrics message from the inference_diff tool.

Answer 1

I assume that the tool outputs a protobuf message in binary format.
protoc can decode the message and output in text format. See this option:
--decode=MESSAGE_TYPE Read a binary message of the given type from
standard input and write it in text format
to standard output. The message type must
be defined in PROTO_FILES or their imports.

Answer 2

While Timo Stamms answer was instrumental, I still struggled with the paths to get protoc to work in a complex repo (e.g. TensorFlow).
In the end, this worked for me:
cat inference_diff.txt | \
protoc --proto_path="/Users/ben/butter/repos/tensorflow/" \
--decode tflite.evaluation.EvaluationStageMetrics \
$(pwd)/evaluation_config.proto
Here I pipe the binary contents of the file containing protobuf (inference_diff.txt in my case, generated by following this guide), and specify the fully qualified protobuf message (which I got by combining the package tflite.evaluation; and the message name, EvaluationStageMetrics), the absolute path of the project for the proto_path (which is the project root/ TensorFlow repo), and also the absolute path for the file which actually contains the message. proto_path is just used for resolving imports, where as the PROTO_FILE (in this case, evaluation_config.proto), is used to decode the file.
Example Output
num_runs: 50
process_metrics {
inference_profiler_metrics {
reference_latency {
last_us: 455818
max_us: 577312
min_us: 453121
sum_us: 72573828
avg_us: 483825.52
std_deviation_us: 37940
}
test_latency {
last_us: 59503
max_us: 66746
min_us: 57828
sum_us: 8992747
avg_us: 59951.646666666667
std_deviation_us: 1284
}
output_errors {
max_value: 122.371696
min_value: 83.0335922
avg_value: 100.17548828125
std_deviation: 8.16124535
}
}
}
If you just want to get the numbers in a rush and can't be bothered to fix the paths, you can do
cat inference_diff.txt | protoc --decode_raw
Example output
1: 50
2 {
5 {
1 {
1: 455818
2: 577312
3: 453121
4: 72573828
5: 0x411d87c6147ae148
6: 37940
}
2 {
1: 59503
2: 66746
3: 57828
4: 8992747
5: 0x40ed45f4b17e4b18
6: 1284
}
3 {
1: 0x42f4be4f
2: 0x42a61133
3: 0x40590b3b33333333
4: 0x41029476
}
}
}