Video writer class. More...
#include <opencv2/videoio.hpp>
Public Member Functions | |
VideoWriter () | |
Default constructors. More... | |
VideoWriter (const String &filename, int fourcc, double fps, Size frameSize, bool isColor=true) | |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More... | |
VideoWriter (const String &filename, int apiPreference, int fourcc, double fps, Size frameSize, bool isColor=true) | |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. The apiPreference parameter allows to specify API backends to use. More... | |
virtual | ~VideoWriter () |
Default destructor. More... | |
virtual double | get (int propId) const |
Returns the specified VideoWriter property. More... | |
String | getBackendName () const |
Returns used backend API name. More... | |
virtual bool | isOpened () const |
Returns true if video writer has been successfully initialized. More... | |
virtual bool | open (const String &filename, int fourcc, double fps, Size frameSize, bool isColor=true) |
Initializes or reinitializes video writer. More... | |
bool | open (const String &filename, int apiPreference, int fourcc, double fps, Size frameSize, bool isColor=true) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More... | |
virtual VideoWriter & | operator<< (const Mat &image) |
Stream operator to write the next video frame. More... | |
virtual VideoWriter & | operator<< (const UMat &image) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More... | |
virtual void | release () |
Closes the video writer. More... | |
virtual bool | set (int propId, double value) |
Sets a property in the VideoWriter. More... | |
virtual void | write (InputArray image) |
Writes the next video frame. More... | |
Static Public Member Functions | |
static int | fourcc (char c1, char c2, char c3, char c4) |
Concatenates 4 chars to a fourcc code. More... | |
Static Protected Member Functions | |
static Ptr< IVideoWriter > | create (const String &filename, int fourcc, double fps, Size frameSize, bool isColor=true) |
Protected Attributes | |
Ptr< IVideoWriter > | iwriter |
Ptr< CvVideoWriter > | writer |
Video writer class.
The class provides C++ API for writing video files or image sequences.
cv::VideoWriter::VideoWriter | ( | ) |
Default constructors.
The constructors/functions initialize video writers.
cv::VideoWriter::VideoWriter | ( | const String & | filename, |
int | fourcc, | ||
double | fps, | ||
Size | frameSize, | ||
bool | isColor = true |
||
) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
filename | Name of the output video file. |
fourcc | 4-character code of codec used to compress the frames. For example, VideoWriter::fourcc('P','I','M','1') is a MPEG-1 codec, VideoWriter::fourcc('M','J','P','G') is a motion-jpeg codec etc. List of codes can be obtained at Video Codecs by FOURCC page. FFMPEG backend with MP4 container natively uses other values as fourcc code: see ObjectType, so you may receive a warning message from OpenCV about fourcc code conversion. |
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). |
Tips:
fourcc=-1
pops up the codec selection dialog from the system.img_%02d.jpg
) and fourcc=0
OR fps=0
. Use uncompressed image format (eg. img_%02d.BMP
) to save raw frames.codec=0; fps=0;
you can create an uncompressed (raw) video file. cv::VideoWriter::VideoWriter | ( | const String & | filename, |
int | apiPreference, | ||
int | fourcc, | ||
double | fps, | ||
Size | frameSize, | ||
bool | isColor = true |
||
) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. The apiPreference
parameter allows to specify API backends to use.
Can be used to enforce a specific reader implementation if multiple are available: e.g. cv::CAP_FFMPEG or cv::CAP_GSTREAMER.
|
virtual |
Default destructor.
The method first calls VideoWriter::release to close the already opened file.
|
staticprotected |
|
static |
Concatenates 4 chars to a fourcc code.
This static method constructs the fourcc code of the codec to be used in the constructor VideoWriter::VideoWriter or VideoWriter::open.
|
virtual |
Returns the specified VideoWriter property.
propId | Property identifier from cv::VideoWriterProperties (eg. cv::VIDEOWRITER_PROP_QUALITY) or one of Additional flags for video I/O API backends |
String cv::VideoWriter::getBackendName | ( | ) | const |
Returns used backend API name.
|
virtual |
Returns true if video writer has been successfully initialized.
|
virtual |
Initializes or reinitializes video writer.
The method opens video writer. Parameters are the same as in the constructor VideoWriter::VideoWriter.
true
if video writer has been successfully initializedThe method first calls VideoWriter::release to close the already opened file.
bool cv::VideoWriter::open | ( | const String & | filename, |
int | apiPreference, | ||
int | fourcc, | ||
double | fps, | ||
Size | frameSize, | ||
bool | isColor = true |
||
) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
|
virtual |
Stream operator to write the next video frame.
|
virtual |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
|
virtual |
Closes the video writer.
The method is automatically called by subsequent VideoWriter::open and by the VideoWriter destructor.
|
virtual |
Sets a property in the VideoWriter.
propId | Property identifier from cv::VideoWriterProperties (eg. cv::VIDEOWRITER_PROP_QUALITY) or one of Additional flags for video I/O API backends |
value | Value of the property. |
true
if the property is supported by the backend used by the VideoWriter instance.
|
virtual |
Writes the next video frame.
image | The written frame. In general, color images are expected in BGR format. |
The function/method writes the specified image to video file. It must have the same size as has been specified when opening the video writer.
|
protected |
|
protected |