OpenCV读写视频文件解析（二）

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我是靠谱客的博主机灵画笔，最近开发中收集的这篇文章主要介绍OpenCV读写视频文件解析（二），觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

OpenCV读写视频文件解析（二）

VideoCapture::set

设置视频捕获中的属性。

C++: bool VideoCapture::set(int propId, double value)

Python: cv2.VideoCapture.set(propId, value) → retval

C: int cvSetCaptureProperty(CvCapture* capture, int property_id, double value)

Python: cv.SetCaptureProperty(capture, property_id, value) → retval

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.

参数：

propId -属性标识符。它可以是下列之一：

CV_CAP_PROP_POS_MSEC视频文件的当前位置（毫秒）。

CV_CAP_PROP_POS_FRAMES下一个要解码/捕获的帧的基于0的索引。
CV_CAP_PROP_POS_AVI_RATIO视频文件的相对位置：0-胶片开始，1-胶片结束。
CV_CAP_PROP_FRAME_WIDTH视频流中帧的宽度。

CV_CAP_PROP_FRAME_HEIGHT视频流中帧的高度。

CV_CAP_PROP_FPS帧速率。

CV_CAP_PROP_FOURCC编解码器的4个字符代码。

CV_CAP_PROP_FRAME_COUNT视频文件中的帧数。

CV_CAP_PROP_FORMAT retrieve（）返回的Mat对象格式。

CV_CAP_PROP_MODE后端特定值，指示当前捕获模式。

CV_CAP_PROP_BRIGHTNESS 图像亮度（仅适用于机）。

CV_CAP_PROP_CONTRAST图像的对比度（仅适用于机）。

CV_CAP_PROP_SATURATION图像饱和度（仅适用于相机）。

CV_CAP_PROP_HUE 图像的色调（仅适用于相机）。

CV_CAP_PROP_GAIN图像的增益（仅适用于相机）。

CV_CAP_PROP_EXPOSURE曝光（仅适用于相机）。

CV_CAP_PROP_CONVERT_RGB布尔标志，指示是否应将图像转换为RGB。

CV_CAP_PROP_WHITE_BALANCE_U设置白平衡的U值（注意：当前仅受DC1394v 2.x后端支持）

CV_CAP_PROP_WHITE_BALANCE_V设置白平衡的V值（注意：当前仅受DC1394V 2.x后端支持）

CV_CAP_PROP_RECTIFICATION立体摄像机的校正标志（注：目前仅受DC1394 v 2.x后端支持）

CV_CAP_PROP_ISO_SPEED相机的ISO速度（注意：当前仅受DC1394v 2.x后端支持）

CV_CAP_PROP_BUFFERSIZE存储在内部缓冲存储器中的帧数量（注意：当前仅受DC1394 v 2.x后端支持）

value–属性的值。

VideoWriter

class VideoWriter

Video writer class.

VideoWriter::VideoWriter

VideoWriter constructors构造

C++: VideoWriter::VideoWriter()

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

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

C: CvVideoWriter* cvCreateVideoWriter(const char* filename, int fourcc, double fps, CvSize frame_size, int is_color=1 )

Python: cv.CreateVideoWriter(filename, fourcc, fps, frame_size,
is_color=true) → CvVideoWriter

Python: cv2.VideoWriter.isOpened() → retval

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

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

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