Hello, I am trying to use v4l2 example from API documentation: inhttp://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html . As a start, I wanted to first try uding it with vivid (virtual device driver). I found excelent vivid documentation in the kernel, which is very helpful: https://www.kernel.org/doc/Documentation/video4linux/vivid.txt But on trying to use the example as-is for capturing video frames into file, and playing the file, I encounter difficulties. I tried the example as-is, and then tried several resolution, pixelformat, different inputs, but it always result with video with a sync problems ( the test bars of the video are keep moving in the horizontal axis, or the text is changing its location for one frame to the next). I compiled the v4l2 API example AS-IS from: http://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html with minor modification in the --force part of the example (I also tried the example as is without modifications but it did not help), so that I choose hd input , and 1920x1080 resolution, V4L2_PIX_FMT_YUV420 (also tried V4L2_PIX_FMT_YUV422P) , progressive. if (force_format) { input = 3; // <<-- HD input device if (-1==xioctl(fd,VIDIOC_S_INPUT,&input)) { errno_exit("VIDIOC_S_INPUT"); } fmt.fmt.pix.width = 1920; fmt.fmt.pix.height = 1080; fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUV420; // <<- tried also V4L2_PIX_FMT_YUV422P fmt.fmt.pix.field = V4L2_FIELD_NONE; // <- trying to capture progressive if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt)) errno_exit("VIDIOC_S_FMT"); } else { I run the application with (the compiled code using pixelformat = V4L2_PIX_FMT_YUV420 trial ): ./v4l2_example -f -o -c 10 > cap_yuv420p.yuv And (the compiled code using pixelformat = V4L2_PIX_FMT_YUV422P trial ) ./v4l2_example -f -o -c 10 > cap_yuv422p.yuv I've tried to play them with: ffplay -f rawvideo -pixel_format yuv420p -video_size 1920x1080 -i cap_yuv420p.yuv And ffplay -f rawvideo -pixel_format yuv422p -video_size 1920x1080 -i cap_yuv422p.yuv These are the captured video files from my above trials: https://drive.google.com/folderview?id=0B22GsWueReZTUS1tSHBraTAyZ00&usp=sharing I probably am doing something wrong. Is there any idea what's wrong in my configurations or how I can debug it better ? Best Regards, Ran -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
