OpenCV读写视频文件解析（二）

Parameters:

• propId –

Property identifier. It can be one of the following:

o   CV_CAP_PROP_POS_MSEC Current position of the video file in milliseconds.

o   CV_CAP_PROP_POS_FRAMES 0-based index of the frame to be decoded/captured next.

o   CV_CAP_PROP_POS_AVI_RATIO Relative position of the video file: 0 - start of the film, 1 - end of the film.

o   CV_CAP_PROP_FRAME_WIDTH Width of the frames in the video stream.

o   CV_CAP_PROP_FRAME_HEIGHT Height of the frames in the video stream.

o   CV_CAP_PROP_FPS Frame rate.

o   CV_CAP_PROP_FOURCC 4-character code of codec.

o   CV_CAP_PROP_FRAME_COUNT Number of frames in the video file.

o   CV_CAP_PROP_FORMAT Format of the Mat objects returned by retrieve() .

o   CV_CAP_PROP_MODE Backend-specific value indicating the current capture mode.

o   CV_CAP_PROP_BRIGHTNESS Brightness of the image (only for cameras).

o   CV_CAP_PROP_CONTRAST Contrast of the image (only for cameras).

o   CV_CAP_PROP_SATURATION Saturation of the image (only for cameras).

o   CV_CAP_PROP_HUE Hue of the image (only for cameras).

o   CV_CAP_PROP_GAIN Gain of the image (only for cameras).

o   CV_CAP_PROP_EXPOSURE Exposure (only for cameras).

o   CV_CAP_PROP_CONVERT_RGB Boolean flags indicating whether images should be converted to RGB.

o   CV_CAP_PROP_WHITE_BALANCE_U The U value of the whitebalance setting (note: only supported by DC1394 v 2.x backend currently)

o   CV_CAP_PROP_WHITE_BALANCE_V The V value of the whitebalance setting (note: only supported by DC1394 v 2.x backend currently)

o   CV_CAP_PROP_RECTIFICATION Rectification flag for stereo cameras (note: only supported by DC1394 v 2.x backend currently)

o   CV_CAP_PROP_ISO_SPEED The ISO speed of the camera (note: only supported by DC1394 v 2.x backend currently)

o   CV_CAP_PROP_BUFFERSIZE Amount of frames stored in internal buffer memory (note: only supported by DC1394 v 2.x backend currently)

• value – Value of the property.

Parameters:

• filename – Name of the output video file.
• fourcc – 4-character code of codec used to compress the frames. For example,
• CV_FOURCC('P','I','M','1') is a MPEG-1 codec,
• CV_FOURCC('M','J','P','G') is a motion-jpeg codec etc. List of codes can be obtained at Video Codecs by FOURCC page.
• fps – Framerate of the created video stream.
• frameSize – Size of the video frames.
• isColor – If it is not zero, the encoder will expect and encode color frames, otherwise it will work with grayscale frames (the flag is currently supported on Windows only).
• 参数：             
• file Name–输出视频文件的名称。             
• fourcc–用于压缩帧的编解码器的4字符代码。例如，CV_FOURCC（'P'，'I'，'M'，'1'）是MPEG-1编解码器，CV_FOURCC（'M'，'J'，'P'，'G'）是运动jpeg编解码器等。可通过FOURCC页面在视频编解码器处获得代码列表。             
• fps–创建的视频流的帧速率。             
• frameSize–视频帧的大小。             
• isColor–如果不为零，编码器将期望并编码彩色帧，否则将使用灰度帧（该标志当前仅在Windows上受支持）。
• 构造函数/函数初始化视频写入程序。在Linux上，FFMPEG用于编写视频；在Windows上，FFMPEG或VFW用于编写视频；在MacOSX上，QTKit用于编写视频。
• ReleaseVideoWriter
• 释放AVI writer。
• C:void cvReleaseVideoWriter(CvVideoWriter** writer)
• The function should be called after you finished using CvVideoWriter opened with CreateVideoWriter().
• 在使用完用CreateVideoWriter（）打开的CvVideoWriter之后，应该调用该函数。
• VideoWriter::open
• 初始化或重新初始化视频编写器。

C++:bool VideoWriter::open(const string& filename, int fourcc, double fps, Size frameSize, bool isColor=true)

Python:cv2.VideoWriter.open(filename, fourcc, fps, frameSize[, isColor]) → retval

• The method opens video writer. Parameters are the same as in the constructor
• VideoWriter::VideoWriter()
• 该方法打开视频编写器。参数与构造函数VideoWriter::VideoWriter（）中的参数相同。
• VideoWriter::isOpened
• 如果已成功初始化视频编写器，则返回true。

C++:bool VideoWriter::isOpened()

Python:cv2.VideoWriter.isOpened() → retval

VideoWriter::write

写入下一个视频帧

C++:VideoWriter& VideoWriter::operator<<(const Mat& image)

C++:void VideoWriter::write(const Mat& image)

Python:cv2.VideoWriter.write(image) → None

C:int cvWriteFrame(CvVideoWriter* writer, const IplImage* image)

Python:cv.WriteFrame(writer, image) → int

参数：             

writer—视频编写器结构（OpenCV 1.x API）             

image –写入帧

函数/方法将指定的图像写入视频文件。它的大小必须与打开视频编写器时指定的大小相同。