decode/deserialize/parse bytes from mcap ros1msg in rust

[lucasw]

I think I need rosrust for this- or roslibrust?

[lucasw]

https://github.com/adnanademovic/serde_rosmsg

[lucasw]

Create simple test bag + mcap

rostopic pub /test marti_common_msgs/Float32Stamped  "header:
  seq: 3
  stamp:
    secs: 1
    nsecs: 7
  frame_id: 'test'
value: 1.0" -r 1

The test message is generated internally using the roslibrust message + serde_rosmsg to_vec()

test 28 - [18, 00, 00, 00, 03, 00, 00, 00, 01, 00, 00, 00, 07, 00, 00, 00, 04, 00, 00, 00, 74, 65, 73, 74, 00, 00, 80, 3f]
mcap 24 - [0a, 00, 00, 00, 01, 00, 00, 00, 07, 00, 00, 00, 04, 00, 00, 00, 74, 65, 73, 74, 00, 00, 80, 3f]

It has an extra 4 byte header over the mcap encoded message

-> #7 (comment)

https://github.com/adnanademovic/serde_rosmsg/blob/master/src/lib.rs#L13

[lucasw]

It would be nice if serde_rosmsg had from_slice option to not require the header bytes (unless it actually uses them, but it has an array/vector length already)

ros_one2z/mcap_to_rerun/src/main.rs

Lines 43 to 66 in e79615a

	// https://github.com/adnanademovic/serde_rosmsg/blob/master/src/lib.rs#L9
	let len_header = message.data.len() as u32;
	let mut msg_with_header = Vec::from(len_header.to_le_bytes());
	let mut message_data = Vec::from(message.data.clone());
	msg_with_header.append(&mut message_data);
	/*
	{
	let mut test_msg = marti_common_msgs::Float32Stamped::default();
	test_msg.header.seq = 3;
	test_msg.header.frame_id = "test".to_string();
	test_msg.header.stamp.secs = 1;
	test_msg.header.stamp.nsecs = 7;
	test_msg.value = 1.0;
	let test_data = serde_rosmsg::to_vec(&test_msg).unwrap();
	println!("test {} - {:02x?}", test_data.len(), &test_data[..]);
	println!("mcap {} - {:02x?}", msg_with_header_vec.len(), &msg_with_header_vec[..]);
	}
	*/
	// match serde_rosmsg::from_slice::<marti_common_msgs::Float32Stamped>(&msg_with_header) {
	match serde_rosmsg::from_slice::<nav_msgs::Odometry>(&msg_with_header) {
	Ok(odom_msg) => {
	println!("{:#?}", odom_msg);

use roslibrust_codegen_macro::find_and_generate_ros_messages;
find_and_generate_ros_messages!();

...

// https://github.com/adnanademovic/serde_rosmsg/blob/master/src/lib.rs#L9
let len_header = message.data.len() as u32;
let mut msg_with_header = Vec::from(len_header.to_le_bytes());
let mut message_data = Vec::from(message.data);
msg_with_header.append(&mut message_data);
match serde_rosmsg::from_slice::<nav_msgs::Odometry>(&msg_with_header) {
    Ok(odom_msg) => {
        println!("{:#?}", odom_msg);
...