一、Python实现.mp4和.bag相互转化

1、.mp4转.bag

# -*- coding: utf-8 -*-
##import logging
##logging.basicConfig()
import time ,sys ,os
import rosbag
import roslib,rospy
from cv_bridge import CvBridge
import cv2
from sensor_msgs.msg import Image
 
TOPIC = 'camera/image_raw'
 
def my_resize(my_img,x,y):
    resized = cv2.resize(my_img,(  int(my_img.shape[1]*x),int(my_img.shape[0]*y) ))
    return resized
 
def CreateVideoBag(videopath, bagname):
    '''Creates a bag file with a video file'''
    print(videopath)
    print(bagname)
    bag = rosbag.Bag(bagname, 'w')
    cap = cv2.VideoCapture(videopath)
    cb = CvBridge()
    # prop_fps = cap.get(cv2.cv.CV_CAP_PROP_FPS)  # 源代码是这个,不能正常运行
    prop_fps = cap.get(cv2.CAP_PROP_FPS)  # 帧速率
    if prop_fps != prop_fps or prop_fps <= 1e-2:
        print ("Warning: can't get FPS. Assuming 24.")
        prop_fps = 24
 
    print(prop_fps)
    ret = True
    frame_id = 0
        
    while(ret):
        ret, frame = cap.read()
        if not ret:
            break
        frame = cv2.resize(frame,(  960,540 ))
        stamp = rospy.rostime.Time.from_sec(float(frame_id) / prop_fps)
        frame_id += 1
        image = cb.cv2_to_imgmsg(frame, encoding='bgr8')
        image.header.stamp = stamp
        image.header.frame_id = "camera"
        bag.write(TOPIC, image, stamp)
    cap.release()
    bag.close()
 
 
if __name__ == "__main__":
    CreateVideoBag('./123.mp4','./123.bag')
 
 
    
##if __name__ == "__main__":
##    if len( sys.argv ) == 3:
##        CreateVideoBag(*sys.argv[1:])
##    else:
##        print( "Usage: video2bag videofilename bagfilename")
 

运行方式： 修改话题名TOPIC、videopath、bagname后直接F5运行代码

或者

参考链接：https://stackoverflow.com/questions/31432870/how-do-i-convert-a-video-or-a-sequence-of-images-to-a-bag-file

import time, sys, os
from ros import rosbag
import roslib, rospy
roslib.load_manifest('sensor_msgs')
from sensor_msgs.msg import Image

from cv_bridge import CvBridge
import cv2

TOPIC = 'camera/image_raw'

def CreateVideoBag(videopath, bagname):
    '''Creates a bag file with a video file'''
    print videopath
    print bagname
    bag = rosbag.Bag(bagname, 'w')
    cap = cv2.VideoCapture(videopath)
    cb = CvBridge()
    # prop_fps = cap.get(cv2.cv.CV_CAP_PROP_FPS)  # 源代码是这个,不能正常运行
    prop_fps = cap.get(cv2.CAP_PROP_FPS)  # 我该成了这个
    if prop_fps != prop_fps or prop_fps <= 1e-2:
        print "Warning: can't get FPS. Assuming 24."
        prop_fps = 24
    prop_fps = 24 # 我手机拍摄的是29.78，我还是转成24的。
    print prop_fps
    ret = True
    frame_id = 0
    while(ret):
        ret, frame = cap.read()
        if not ret:
            break
        stamp = rospy.rostime.Time.from_sec(float(frame_id) / prop_fps)
        frame_id += 1
        image = cb.cv2_to_imgmsg(frame, encoding='bgr8')
        image.header.stamp = stamp
        image.header.frame_id = "camera"
        bag.write(TOPIC, image, stamp)
    cap.release()
    bag.close()

if __name__ == "__main__":
    if len( sys.argv ) == 3:
        CreateVideoBag(*sys.argv[1:])
    else:
        print( "Usage: video2bag videofilename bagfilename")

运行方式： python Video2ROSbag.py TLout.mp4 TLout.bag

验证是否转换成功：使用 rosplay

rosbag info TLout.bag  # 查看 bag 包信息
rosbag play -l TLout.bag camera/image_raw:=image_raw0   # 循环播放图片，并重命名成自己需要的话题名
rqt_image_view  # 显示播放的图片，能正常显示说明ros包制作成功。

2、.bag转.mp4

# -*- coding: utf-8 -*-
 
#!/usr/bin/env python2
 
import roslib
#roslib.load_manifest('rosbag')
import rospy
import rosbag
import sys, getopt
import os
from sensor_msgs.msg import CompressedImage  #压缩图片
from sensor_msgs.msg import Image
import cv2
 
import numpy as np
 
import shlex, subprocess  #读取命令行参数
#subprocess 是一个 python 标准类库，用于创建进程运行系统命令，并且可以连接进程的输入输出和
#错误管道，获取它们的返回，使用起来要优于 os.system，在这里我们使用这个库运行 hive 语句并获取返回结果。
 
#shlex 是一个 python 标准类库，使用这个类我们可以轻松的做出对 linux shell 的词法分析，在
#这里我们将格式化好的 hive 连接语句用 shlex 切分，配合 subprocess.run 使用。
MJPEG_VIDEO = 1
RAWIMAGE_VIDEO = 2
VIDEO_CONVERTER_TO_USE = "ffmpeg" # or you may want to use "avconv" #视频转换器
 
def print_help():
    print('rosbag2video.py [--fps 25] [--rate 1] [-o outputfile] [-v] [-s] [-t topic] bagfile1 [bagfile2] ...')
    print()
    print('Converts image sequence(s) in ros bag file(s) to video file(s) with fixed frame rate using',VIDEO_CONVERTER_TO_USE)
    print(VIDEO_CONVERTER_TO_USE,'needs to be installed!')
    print()
    print('--fps   Sets FPS value that is passed to',VIDEO_CONVERTER_TO_USE)
    print('        Default is 25.')
    print('-h      Displays this help.')
    print('--ofile (-o) sets output file name.')
    print('        If no output file name (-o) is given the filename \'<prefix><topic>.mp4\' is used and default output codec is h264.')
    print('        Multiple image topics are supported only when -o option is _not_ used.')
    print('        ',VIDEO_CONVERTER_TO_USE,' will guess the format according to given extension.')
    print('        Compressed and raw image messages are supported with mono8 and bgr8/rgb8/bggr8/rggb8 formats.')
    print('--rate  (-r) You may slow down or speed up the video.')
    print('        Default is 1.0, that keeps the original speed.')
    print('-s      Shows each and every image extracted from the rosbag file (cv_bride is needed).')
    print('--topic (-t) Only the images from topic "topic" are used for the video output.')
    print('-v      Verbose messages are displayed.')
    print('--prefix (-p) set a output file name prefix othervise \'bagfile1\' is used (if -o is not set).')
    print('--start Optional start time in seconds.')
    print('--end   Optional end time in seconds.')
 
 
 
class RosVideoWriter():
    def __init__(self, fps=25.0, rate=1.0, topic="", output_filename ="", display= False, verbose = False, start = rospy.Time(0), end = rospy.Time(sys.maxsize)):
        self.opt_topic = topic
        self.opt_out_file = output_filename
        self.opt_verbose = verbose
        self.opt_display_images = display
        self.opt_start = start
        self.opt_end = end
        self.rate = rate
        self.fps = fps
        self.opt_prefix= None
        self.t_first={}
        self.t_file={}
        self.t_video={}
        self.p_avconv = {}
        
    #语法分析Args
    def parseArgs(self, args):
        opts, opt_files = getopt.getopt(args,"hsvr:o:t:p:",["fps=","rate=","ofile=","topic=","start=","end=","prefix="])
        #getopt()
        for opt, arg in opts:
            if opt == '-h':
                print_help()
                sys.exit(0)
            elif opt == '-s':
                self.opt_display_images = True
            elif opt == '-v':
                self.opt_verbose = True
            elif opt in ("--fps"):
                self.fps = float(arg)
            elif opt in ("-r", "--rate"):
                self.rate = float(arg)
            elif opt in ("-o", "--ofile"):
                self.opt_out_file = arg
            elif opt in ("-t", "--topic"):
                self.opt_topic = arg
            elif opt in ("-p", "--prefix"):
                self.opt_prefix = arg
            elif opt in ("--start"):
                self.opt_start = rospy.Time(int(arg))
                if(self.opt_verbose):
                    print("starting at",self.opt_start.to_sec())
            elif opt in ("--end"):
                self.opt_end = rospy.Time(int(arg))
                if(self.opt_verbose):
                    print("ending at",self.opt_end.to_sec())
            else:
                print("opt:", opt,'arg:', arg)
 
        if (self.fps<=0):
            print("invalid fps", self.fps)
            self.fps = 1
 
        if (self.rate<=0):
            print("invalid rate", self.rate)
            self.rate = 1
 
        if(self.opt_verbose):
            print("using ",self.fps," FPS")
        return opt_files
 
 
    # filter messages using type or only the opic we whant from the 'topic' argument
    def filter_image_msgs(self, topic, datatype, md5sum, msg_def, header):
        if(datatype=="sensor_msgs/CompressedImage"):
            if (self.opt_topic != "" and self.opt_topic == topic) or self.opt_topic == "":
                print("############# COMPRESSED IMAGE  ######################")
                print(topic,' with datatype:', str(datatype))
                print()
                return True;
 
        if(datatype=="theora_image_transport/Packet"):
            if (self.opt_topic != "" and self.opt_topic == topic) or self.opt_topic == "":
                print(topic,' with datatype:', str(datatype))
                print('!!! theora is not supported, sorry !!!')
                return False;
 
        if(datatype=="sensor_msgs/Image"):
            if (self.opt_topic != "" and self.opt_topic == topic) or self.opt_topic == "":
                print("############# UNCOMPRESSED IMAGE ######################")
                print(topic,' with datatype:', str(datatype))
                print()
                return True;
 
        return False;
 
 
    def write_output_video(self, msg, topic, t, video_fmt, pix_fmt = ""):
        # no data in this topic
        if len(msg.data) == 0 :
            return
        # initiate data for this topic
        if not topic in self.t_first :
            self.t_first[topic] = t # timestamp of first image for this topic
            self.t_video[topic] = 0
            self.t_file[topic] = 0
        # if multiple streams of images will start at different times the resulting video files will not be in sync
        # current offset time we are in the bag file
        self.t_file[topic] = (t-self.t_first[topic]).to_sec()
        # fill video file up with images until we reache the current offset from the beginning of the bag file
        while self.t_video[topic] < self.t_file[topic]/self.rate :
            if not topic in self.p_avconv:
                # we have to start a new process for this topic
                if self.opt_verbose :
                    print("Initializing pipe for topic", topic, "at time", t.to_sec())
                if self.opt_out_file=="":
                    out_file = self.opt_prefix + str(topic).replace("/", "_")+".mp4"
                else:
                    out_file = self.opt_out_file
 
                if self.opt_verbose :
                    print("Using output file ", out_file, " for topic ", topic, ".")
 
                if video_fmt == MJPEG_VIDEO :
                    cmd = [VIDEO_CONVERTER_TO_USE, '-v', '1', '-stats', '-r',str(self.fps),'-c','mjpeg','-f','mjpeg','-i','-','-an',out_file]
                    self.p_avconv[topic] = subprocess.Popen(cmd, stdin=subprocess.PIPE)
                    if self.opt_verbose :
                        print("Using command line:")
                        print(cmd)
                elif video_fmt == RAWIMAGE_VIDEO :
                    size = str(msg.width)+"x"+str(msg.height)
                    cmd = [VIDEO_CONVERTER_TO_USE, '-v', '1', '-stats','-r',str(self.fps),'-f','rawvideo','-s',size,'-pix_fmt', pix_fmt,'-i','-','-an',out_file]
                    self.p_avconv[topic] = subprocess.Popen(cmd, stdin=subprocess.PIPE)
                    if self.opt_verbose :
                        print("Using command line:")
                        print(cmd)
 
                else :
                    print("Script error, unknown value for argument video_fmt in function write_output_video.")
                    exit(1)
            # send data to ffmpeg process pipe
            self.p_avconv[topic].stdin.write(msg.data)
            # next frame time
            self.t_video[topic] += 1.0/self.fps
 
    def addBag(self, filename):
        if self.opt_display_images:
            from cv_bridge import CvBridge, CvBridgeError
            bridge = CvBridge()
            cv_image = []
 
        if self.opt_verbose :
            print("Bagfile: {}".format(filename))
 
        if not self.opt_prefix:
            # create the output in the same folder and name as the bag file minu '.bag'
            self.opt_prefix = bagfile[:-4]
 
        #Go through the bag file
        bag = rosbag.Bag(filename)
        if self.opt_verbose :
            print("Bag opened.")
        # loop over all topics
        for topic, msg, t in bag.read_messages(connection_filter=self.filter_image_msgs, start_time=self.opt_start, end_time=self.opt_end):
            try:
                if msg.format.find("jpeg")!=-1 :
                    if msg.format.find("8")!=-1 and (msg.format.find("rgb")!=-1 or msg.format.find("bgr")!=-1 or msg.format.find("bgra")!=-1 ):
                        if self.opt_display_images:
                            np_arr = np.fromstring(msg.data, np.uint8)
                            cv_image = cv2.imdecode(np_arr, cv2.CV_LOAD_IMAGE_COLOR)
                        self.write_output_video( msg, topic, t, MJPEG_VIDEO )
                    elif msg.format.find("mono8")!=-1 :
                        if self.opt_display_images:
                            np_arr = np.fromstring(msg.data, np.uint8)
                            cv_image = cv2.imdecode(np_arr, cv2.CV_LOAD_IMAGE_COLOR)
                        self.write_output_video( msg, topic, t, MJPEG_VIDEO )
                    elif msg.format.find("16UC1")!=-1 :
                        if self.opt_display_images:
                            np_arr = np.fromstring(msg.data, np.uint16)
                            cv_image = cv2.imdecode(np_arr, cv2.CV_LOAD_IMAGE_COLOR)
                        self.write_output_video( msg, topic, t, MJPEG_VIDEO )
                    else:
                        print('unsupported jpeg format:', msg.format, '.', topic)
 
            # has no attribute 'format'
            except AttributeError:
                try:
                        pix_fmt=None
                        if msg.encoding.find("mono8")!=-1 or msg.encoding.find("8UC1")!=-1:
                            pix_fmt = "gray"
                            if self.opt_display_images:
                                cv_image = bridge.imgmsg_to_cv2(msg, "bgr8")
 
                        elif msg.encoding.find("bgra")!=-1 :
                            pix_fmt = "bgra"
                            if self.opt_display_images:
                                cv_image = bridge.imgmsg_to_cv2(msg, "bgr8")
 
                        elif msg.encoding.find("bgr8")!=-1 :
                            pix_fmt = "bgr24"
                            if self.opt_display_images:
                                cv_image = bridge.imgmsg_to_cv2(msg, "bgr8")
                        elif msg.encoding.find("bggr8")!=-1 :
                            pix_fmt = "bayer_bggr8"
                            if self.opt_display_images:
                                cv_image = bridge.imgmsg_to_cv2(msg, "bayer_bggr8")
                        elif msg.encoding.find("rggb8")!=-1 :
                            pix_fmt = "bayer_rggb8"
                            if self.opt_display_images:
                                cv_image = bridge.imgmsg_to_cv2(msg, "bayer_rggb8")
                        elif msg.encoding.find("rgb8")!=-1 :
                            pix_fmt = "rgb24"
                            if self.opt_display_images:
                                cv_image = bridge.imgmsg_to_cv2(msg, "bgr8")
                        elif msg.encoding.find("16UC1")!=-1 :
                            pix_fmt = "gray16le"
                        else:
                            print('unsupported encoding:', msg.encoding, topic)
                            #exit(1)
                        if pix_fmt:
                            self.write_output_video( msg, topic, t, RAWIMAGE_VIDEO, pix_fmt )
 
                except AttributeError:
                    # maybe theora packet
                    # theora not supported
                    if self.opt_verbose :
                        print("Could not handle this format. Maybe thoera packet? theora is not supported.")
                    pass
            if self.opt_display_images:
                cv2.imshow(topic, cv_image)
                key=cv2.waitKey(1)
                if key==1048603:
                    exit(1)
        if self.p_avconv == {}:
            print("No image topics found in bag:", filename)
        bag.close()
 
 
 
if __name__ == '__main__':
    #print()
    #print('rosbag2video, by Maximilian Laiacker 2020 and Abel Gabor 2019')
    #print()
 
    if len(sys.argv) < 2:
        print('Please specify ros bag file(s)!')
        print_help()
        sys.exit(1)
    else :
        videowriter = RosVideoWriter()
        try:
            opt_files = videowriter.parseArgs(sys.argv[1:])
        except getopt.GetoptError:
            print_help()
            sys.exit(2)
 
 
    # loop over all files
    for files in range(0,len(opt_files)):
        #First arg is the bag to look at
        bagfile = opt_files[files]
        videowriter.addBag(bagfile)
    print("finished")

使用方法：

$ python rosbag2video.py [-h] [-s] [-v] [-r] [-o outputfile] [-t topic] [-p prefix_name] [--fps 25] [--rate 1.0] [--ofile output_file_name] [--start start_time] [--end end_time] bagfile1 [bagfile2] ...

二、rviz 读取 *.bag 数据包并显示

1、查看bag数据包的基本信息

已有数据：test_room1.bag

查看.bag信息：rosbag info test_room1.bag

可以看出 topic：/mynteye/image_color
查看frame_id

//打开终端
roscore
//打开新终端 播放数据
rosbag play test_room1.bag
// 打开新终端 查看/velodyne_points的frame_id
rostopic echo /mynteye/image_color | grep frame_id

查看结果如下：frame_id=camera

若想更改frame_id，可以参考：改变ros bag 中消息的frame_id 和话题名

2、rviz 显示信息

执行以下命令：

roscore
//打开新终端
rosrun rviz rviz
//  打开rviz

rviz 设置：add->image
image 设置：Image Topic 设置为 /mynteye/image_color（上面info显示的topic）

播放bag包：rosbag play nsh_indoor_outdoor.bag

显示结果：

若需要显示的是点云，则需要设置pointcloud2

设置rviz：add->PointCloud2
设置：
fix-frame=camera
topic：/mynteye/image_color