使用VideoWriter从OpenCV打开GStreamer管道 [英] Opening a GStreamer pipeline from OpenCV with VideoWriter
问题描述
我正在使用OpenCV捕获和处理视频帧，我想将它们编写为h265视频文件。我正在努力从OpenCV获得合适的Gstreamer管道来工作。
I am capturing and processing video frames with OpenCV, and I would like to write them as a h265 video file. I am struggling to get a proper Gstreamer pipeline to work from OpenCV.
Gstreamer本身可以正常工作。特别是，我能够运行此命令，该命令可以非常快速地对视频进行编码（由于GPU加速）并将其保存到mkv文件中：
Gstreamer works fine by itself. In particular, I am able to run this command, which encodes video very quickly (thanks to GPU acceleration) and saves it to a mkv file:
gst-launch-1.0 videotestsrc num-buffers=90 ! 'video/x-raw, format=(string)I420, width=(int)640, height=(int)480' ! omxh265enc ! matroskamux ! filesink location=test.mkv
现在，我想在OpenCV应用程序中执行相同的操作。我的代码是这样的：
Now I would like to do the same thing from within my OpenCV application. My code is something like:
Mat img_vid = Mat(1024, 1024, CV_8UC3);
VideoWriter video;
video.open("appsrc ! autovideoconvert ! omxh265enc ! matroskamux ! filesink location=test.mkv", 0, (double)25, cv::Size(1024, 1024), true);
if (!video.isOpened()) {
printf("can't create writer\n");
return -1;
}
while ( ... ) {
// Capture frame into img_vid => That works fine
video.write(img_vid);
...
}
似乎可以使用，但是它的作用是创建文件 named appsrc！autovideoconvert！omxh265enc！matroskamux！filesink location = test.mkv 并用未压缩的视频帧填充它，完全忽略了这是Gstreamer管道的事实。
At first sight, this seems to work, but what it does is it creates file named "appsrc ! autovideoconvert ! omxh265enc ! matroskamux ! filesink location=test.mkv" and fills it with uncompressed video frames, completely ignoring the fact that this is a Gstreamer pipeline.
我尝试了其他管道，但是它们导致了各种错误：
I have tried other pipelines, but they result in a variety of errors:
video.open("appsrc ! autovideoconvert ! omxh264enc ! 'video/x-h264, streamformat=(string)byte-stream' ! h264parse ! qtmux ! filesink location=test.mp4 -e", 0, (double)25, cv::Size(1024, 1024), true);
结果是：
（测试：5533）：GStreamer-CRITICAL **：gst_element_make_from_uri：
断言'gst_uri_is_valid（uri）'失败OpenCV错误：未指定
错误（GStreamer：在手动管道中找不到appsrc）在
CvVideoWriter_GStreamer :: open中，文件
/home/ubuntu/opencv/modules/videoio/src/cap_gstreamer.cpp，1363行
VIDEOIO（cvCreateVideoWriter_GStreamer（文件名，fourcc，fps，
frameSize，is_color））：引发OpenCV异常：
(Test:5533): GStreamer-CRITICAL **: gst_element_make_from_uri: assertion 'gst_uri_is_valid (uri)' failed OpenCV Error: Unspecified error (GStreamer: cannot find appsrc in manual pipeline ) in CvVideoWriter_GStreamer::open, file /home/ubuntu/opencv/modules/videoio/src/cap_gstreamer.cpp, line 1363 VIDEOIO(cvCreateVideoWriter_GStreamer(filename, fourcc, fps, frameSize, is_color)): raised OpenCV exception:
/home/ubuntu/opencv/modules/videoio/src/cap_gstreamer.cpp:1363：错误：
（-2）GStreamer：在函数
的手动管道中找不到appsrc CvVideoWriter_GStreamer :: open
/home/ubuntu/opencv/modules/videoio/src/cap_gstreamer.cpp:1363: error: (-2) GStreamer: cannot find appsrc in manual pipeline in function CvVideoWriter_GStreamer::open
我也尝试过简单：
video.open("appsrc ! autovideosink", 0, (double)25, cv::Size(1024, 1024), true);
这将产生：
GStreamer插件：嵌入式视频播放停止；模块appsrc0
报告：内部数据流错误。
GStreamer Plugin: Embedded video playback halted; module appsrc0 reported: Internal data flow error.
我正在使用支持Gstreamer的OpenCV 3.1。硬件是带有L4T 24.2.1的Jetson TX1。
I am using OpenCV 3.1 with Gstreamer support. The hardware is a Jetson TX1 with L4T 24.2.1.
推荐答案
我之前遇到过类似的问题。由于管道/文件名以 .mkv 结尾，因此OpenCV会将其解释为视频文件而不是管道。
I encountered a similar problem before. Since the pipe/file name ends with .mkv, OpenCV interprets it as a video file instead of a pipe.
您可以尝试在 mkv
video.open("appsrc ! autovideoconvert ! omxh265enc ! matroskamux ! filesink location=test.mkv ", 0, (double)25, cv::Size(1024, 1024), true);
或具有虚拟属性，如
video.open("appsrc ! autovideoconvert ! omxh265enc ! matroskamux ! filesink location=test.mkv sync=false", 0, (double)25, cv::Size(1024, 1024), true);
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