英文:
extracting RGB image frames from the bag file: rosbag.bag.ROSBagException: unsupported compression type: lz4
问题
这段代码似乎无法正确读取消息。你在这里可能犯了一个错误。错误信息显示了它无法支持压缩类型lz4。
你可以尝试解决这个问题的方法是，确保你的代码支持lz4压缩类型。你可以查看rosbag库的文档，看看如何处理这种压缩类型。
如果你不确定如何处理，你也可以考虑尝试使用其他支持的压缩类型，例如bz2或者不使用压缩。
英文:
I have a piece of code that I want to extract the RGB frames from the bag file. Code is as follows:
import os
import argparse
import pdb
import cv2
import rosbag
from sensor_msgs.msg import Image
from cv_bridge import CvBridge
bag_file = './bag_files/20230707_152832.bag'
output_dir= './frames/rgb_bag_output'
# topic can be obtained by using the following command in terminal
# time rosbag info ./bag_files/20230707_152832.bag
image_topic = '/device_0/sensor_1/Color_0/image/data'
bag = rosbag.Bag(bag_file, "r")
bridge = CvBridge()
count = 0
for topic, msg, t in bag.read_messages(topics=[image_topic]):
cv_img = bridge.imgmsg_to_cv2(msg, desired_encoding= "rgb8")#"passthrough")
cv2.imwrite(os.path.join(output_dir, "frame%06i.png" % count), cv_img)
print("Wrote image %i" % count)
count += 1
bag.close()
But it seems it does not run the for loop at all. I ran the following command in terminal to get the topic info:
time rosbag info ./bag_files/20230707_152832.bag
path: ./bag_files/20230707_152832.bag
version: 2.0
duration: 12.6s
start: Jan 01 1970 07:30:00.00 (0.00)
end: Jan 01 1970 07:30:12.58 (12.58)
size: 410.0 MB
messages: 17874
compression: lz4 [757/757 chunks; 65.32%]
uncompressed: 627.0 MB @ 49.8 MB/s
compressed: 409.6 MB @ 32.5 MB/s (65.32%)
types: diagnostic_msgs/KeyValue [cf57fdc6617a881a88c16e768132149c]
geometry_msgs/Transform [ac9eff44abf714214112b05d54a3cf9b]
realsense_msgs/StreamInfo [311d7e24eac31bb87271d041bf70ff7d]
sensor_msgs/CameraInfo [c9a58c1b0b154e0e6da7578cb991d214]
sensor_msgs/Image [060021388200f6f0f447d0fcd9c64743]
std_msgs/Float32 [73fcbf46b49191e672908e50842a83d4]
std_msgs/String [992ce8a1687cec8c8bd883ec73ca41d1]
std_msgs/UInt32 [304a39449588c7f8ce2df6e8001c5fce]
topics: /device_0/info 13 msgs : diagnostic_msgs/KeyValue
/device_0/sensor_0/Depth_0/image/data 378 msgs : sensor_msgs/Image
/device_0/sensor_0/Depth_0/image/metadata 9072 msgs : diagnostic_msgs/KeyValue
/device_0/sensor_0/Depth_0/info 1 msg : realsense_msgs/StreamInfo
/device_0/sensor_0/Depth_0/info/camera_info 1 msg : sensor_msgs/CameraInfo
/device_0/sensor_0/Depth_0/tf/0 1 msg : geometry_msgs/Transform
/device_0/sensor_0/info 2 msgs : diagnostic_msgs/KeyValue
/device_0/sensor_0/option/Asic_Temperature/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Asic_Temperature/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Depth_Units/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Depth_Units/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Emitter_Always_On/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Emitter_Always_On/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Emitter_Enabled/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Emitter_Enabled/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Emitter_On_Off/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Emitter_On_Off/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Enable_Auto_Exposure/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Enable_Auto_Exposure/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Error_Polling_Enabled/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Error_Polling_Enabled/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Exposure/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Exposure/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Frames_Queue_Size/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Frames_Queue_Size/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Gain/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Gain/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Global_Time_Enabled/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Global_Time_Enabled/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Hdr_Enabled/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Hdr_Enabled/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Inter_Cam_Sync_Mode/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Inter_Cam_Sync_Mode/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Laser_Power/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Laser_Power/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Output_Trigger_Enabled/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Output_Trigger_Enabled/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Projector_Temperature/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Projector_Temperature/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Sequence_Id/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Sequence_Id/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Sequence_Name/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Sequence_Name/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Sequence_Size/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Sequence_Size/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Stereo_Baseline/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Stereo_Baseline/value 1 msg : std_msgs/Float32
/device_0/sensor_0/option/Visual_Preset/description 1 msg : std_msgs/String
/device_0/sensor_0/option/Visual_Preset/value 1 msg : std_msgs/Float32
/device_0/sensor_0/post_processing 9 msgs : std_msgs/String
/device_0/sensor_1/Color_0/image/data 378 msgs : sensor_msgs/Image
/device_0/sensor_1/Color_0/image/metadata 7938 msgs : diagnostic_msgs/KeyValue
/device_0/sensor_1/Color_0/info 1 msg : realsense_msgs/StreamInfo
/device_0/sensor_1/Color_0/info/camera_info 1 msg : sensor_msgs/CameraInfo
/device_0/sensor_1/Color_0/tf/0 1 msg : geometry_msgs/Transform
/device_0/sensor_1/info 2 msgs : diagnostic_msgs/KeyValue
/device_0/sensor_1/option/Auto_Exposure_Priority/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Auto_Exposure_Priority/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Backlight_Compensation/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Backlight_Compensation/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Brightness/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Brightness/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Contrast/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Contrast/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Enable_Auto_Exposure/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Enable_Auto_Exposure/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Enable_Auto_White_Balance/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Enable_Auto_White_Balance/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Exposure/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Exposure/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Frames_Queue_Size/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Frames_Queue_Size/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Gain/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Gain/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Gamma/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Gamma/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Global_Time_Enabled/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Global_Time_Enabled/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Hue/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Hue/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Power_Line_Frequency/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Power_Line_Frequency/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Saturation/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Saturation/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/Sharpness/description 1 msg : std_msgs/String
/device_0/sensor_1/option/Sharpness/value 1 msg : std_msgs/Float32
/device_0/sensor_1/option/White_Balance/description 1 msg : std_msgs/String
/device_0/sensor_1/option/White_Balance/value 1 msg : std_msgs/Float32
/device_0/sensor_1/post_processing 1 msg : std_msgs/String
/file_version 1 msg : std_msgs/UInt32
real 0m0.220s
user 0m0.096s
sys 0m0.016s
Where I am making mistake? It seems it does not read the messages at all. I tried to run the code in terminal, I get the following error:
Traceback (most recent call last):
File "grab_rgb_bag.py", line 51, in <module>
for topic, msg, t in bag.read_messages(topics=[image_topic]):
File "/home/es/anaconda3/envs/hsi-env/lib/python3.8/site-packages/rosbag/bag.py", line 2705, in read_messages
yield self.seek_and_read_message_data_record((entry.chunk_pos, entry.offset), raw, return_connection_header)
File "/home/es/anaconda3/envs/hsi-env/lib/python3.8/site-packages/rosbag/bag.py", line 2839, in seek_and_read_message_data_record
raise ROSBagException('unsupported compression type: %s' % chunk_header.compression)
rosbag.bag.ROSBagException: unsupported compression type: lz4
答案1
得分: 1
首先尝试安装 lz4 支持：
apt install ros-$ROS_DISTRO-roslz4
如果这不起作用，请尝试使用 rosbag decompress 命令解压缩包，看看是否能够解析解压后的 rosbag。
参考链接：
http://wiki.ros.org/rosbag/Commandline#decompress
英文:
First try installing lz4 support:
apt install ros-$ROS_DISTRO-roslz4
If that does not work, try decompressing the bag using the rosbag decompress command, see if you are able to parse the decompressed rosbag.
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