在 OpenCV FOURCC 编解码器中编写视频

Question

我正在尝试将YOLO 的结果保存到.avi 文件中。已经看过this post...（我什至在那里问了这个问题）我找不到任何解决方案。这是我试图保存.avi的代码。

{
    CvSize size;
    size.width = disp->width;
    size.height = disp->height;

    static CvVideoWriter* output_video = NULL;    // cv::VideoWriter output_video;
    if (output_video == NULL)
    {
        printf("\n SRC output_video = %p \n", output_video);
        const char* output_name = "test_dnn_out.avi";
        output_video = cvCreateVideoWriter(output_name, CV_FOURCC('D', 'I', 'V', 'X'), 25, size, 1);
        printf("\n cvCreateVideoWriter, DST output_video = %p  \n", output_video);
    }
    cvWriteFrame(output_video, disp);
}

尝试大量编解码器（更改 CV_FOURCC('D', 'I', 'V', 'X')）我收到以下错误：

**CODEC :-1**

**ERROR**

SRC output_video = (nil)  OpenCV: FFMPEG: tag 0xffffffff/'����' is not
found (format 'avi / AVI (Audio Video Interleaved)')' OpenCV Error:
Unsupported format or combination of formats (Gstreamer Opencv backend
does not support this codec.) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1522 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1522:
error: (-210) Gstreamer Opencv backend does not support this codec. in
function CvVideoWriter_GStreamer::open


**CODEC: CV_FOURCC('M', 'J', 'P', 'G')**

**ERROR**

SRC output_video = (nil)  OpenCV Error: Unspecified error (GStreamer:
cannot put pipeline to play ) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1690 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1690:
error: (-2) GStreamer: cannot put pipeline to play  in function
CvVideoWriter_GStreamer::open


**CODEC: CV_FOURCC('P','I','M','1')** SRC output_video = (nil) 

**ERROR**

** (Demo:6801): CRITICAL **: gst_ffmpeg_cfg_set_property: assertion 'qdata- 
size == sizeof (gint64)' failed OpenCV Error: Unspecified
error (GStreamer: cannot put pipeline to play ) in
CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1690 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1690:
error: (-2) GStreamer: cannot put pipeline to play  in function
CvVideoWriter_GStreamer::open



**CODEC:CV_FOURCC('M', 'P', '4', '2')**

**ERROR**

SRC output_video = (nil) 

** (Demo:7437): CRITICAL **: gst_ffmpeg_cfg_set_property: assertion 'qdata- 
size == sizeof (gint64)' failed OpenCV Error: Unspecified
error (GStreamer: cannot put pipeline to play ) in
CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1690 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1690:
error: (-2) GStreamer: cannot put pipeline to play  in function
CvVideoWriter_GStreamer::open


**CODEC::CV_FOURCC('D', 'I', 'V', '3')**

**ERROR** 

SRC output_video = (nil)  OpenCV Error: Unspecified error (GStreamer:
cannot put pipeline to play ) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1690 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1690:
error: (-2) GStreamer: cannot put pipeline to play  in function
CvVideoWriter_GStreamer::open


**CODEC:CV_FOURCC('D', 'I', 'V', 'X')**

**ERROR** 

SRC output_video = (nil)  OpenCV Error: Unspecified error (GStreamer:
cannot put pipeline to play ) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1690 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1690:
error: (-2) GStreamer: cannot put pipeline to play  in function
CvVideoWriter_GStreamer::open



**CODEC:CV_FOURCC('U', '2', '6', '3')**

**ERROR** 

OpenCV Error: Unspecified error (GStreamer: cannot put pipeline to
play ) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1690 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1690:
error: (-2) GStreamer: cannot put pipeline to play  in function
CvVideoWriter_GStreamer::open


cvCreateVideoWriter, DST output_video = (nil)  

SRC output_video = (nil)  Could not open codec 'h263': Unspecified
error

** (Demo:8342): CRITICAL **: gst_ffmpeg_cfg_set_property: assertion 'qdata- 
size == sizeof (gint64)' failed



**CODEC:CV_FOURCC('I', '2', '6', '3')**

**ERROR** 

SRC output_video = (nil)  Could not find encoder for codec id 21:
Encoder not found OpenCV Error: Unspecified error (GStreamer: cannot
link elements ) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1626 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1626:
error: (-2) GStreamer: cannot link elements  in function
CvVideoWriter_GStreamer::open


cvCreateVideoWriter, DST output_video = (nil)  


**CODEC:CV_FOURCC('F', 'L', 'V', '1')**

**ERROR** 

SRC output_video = (nil)  OpenCV Error: Unspecified error (GStreamer:
cannot link elements ) in CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1626 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1626:
error: (-2) GStreamer: cannot link elements  in function
CvVideoWriter_GStreamer::open


cvCreateVideoWriter, DST output_video = (nil)


**CODEC:CV_FOURCC('i','Y', 'U', 'V')**

**ERROR** 

SRC output_video = (nil)  OpenCV: FFMPEG: tag 0x56555969/'iYUV' is not
supported with codec id 14 and format 'avi / AVI (Audio Video
Interleaved)' OpenCV Error: Unsupported format or combination of
formats (Gstreamer Opencv backend does not support this codec.) in
CvVideoWriter_GStreamer::open, file
/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line
1522 VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps,
frameSize, is_color)): raised OpenCV exception:

/home/akde/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp:1522:
error: (-210) Gstreamer Opencv backend does not support this codec. in
function CvVideoWriter_GStreamer::open

这是我的设置

-ubuntu 16.04

-opencv 3.3.0

-ffmpeg version 2.8.14

在我看来，问题很可能与编解码器有关。因为人们通过使用不同的编解码器解决了同样的问题。即使我尝试了许多编解码器并正确安装了ffmepeg，我也找不到任何解决方案。所以我该怎么做？期待您的回复...

Answer 1

您没有使用 ffmpeg 创建视频，您应该首先检查，正如@zindarod 指出的那样，OpenCV 是否是使用 ffmpeg 构建的。为此，您可以在 C++ 中运行以下代码：

#include <opencv2/opencv.hpp>

int main(void)
{
  std::cout << cv::getBuildInformation() << std::endl;
}

另一件事除非必要，否则不要使用 C API。它已被弃用且不应使用，特别是如果您的代码是 C++ 中的代码，正如您问题的标签所建议的那样。

在 C++ API 中，您实际上可以选择不同的后端。看看documentation of VideoWriter。

cv::VideoWriter::VideoWriter ( const String & 文件名, int apiPreference, int Fourcc, double fps, Size frameSize, bool isColor = true )

这是一个重载的成员函数，是为了方便而提供的。它 与上述函数的不同之处仅在于它接受的参数。 apiPreference 参数允许指定要使用的 API 后端。能 如果有多个，则用于强制执行特定的读取器实现 可用：例如cv::CAP_FFMPEG 或 cv::CAP_GSTREAMER。

这意味着，如果两者都已安装并且 OpenCV 是在两者的支持下构建的，您可以根据自己的喜好切换它:)

GStreamer 不是一个不好用的后端，我实际上使用它，但我更多地使用它来打开视频而不是创建视频，但你需要安装插件以使其与更多编解码器一起使用......@ 987654322@建议这样安装：

apt-get install libgstreamer1.0-0 gstreamer1.0-plugins-base gstreamer1.0-plugins-good gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly gstreamer1.0-libav gstreamer1.0-doc gstreamer1.0-tools

1.0 可能会根据您已经使用的版本而改变。

我希望这能解决您的问题，如果不只是发表评论的话。