USB_Cam, Could not open MJPEG Decoder

asked 2011-07-09 06:06:20 -0500

davidcw
21 ●2 ●3 ●3

Whenever I run usb_cam with pixel_format:="mjpeg", I get the following error:

usb_cam video_device set to [/dev/video1]
...
usb_cam pixel_format set to [mjpeg]
[mjpeg @ 0x7fabe40f0160]codec type or id mismatches
Could not open MJPEG Decoder
Segmentation Fault

I'm using a Logitech Webcam Pro 9000, on Ubuntu 11.04, with the latest "usb_cam" downloaded from the bosch-ros-pkg repository. usb_cam works great when I set pixel_format to "yuyv", and I can see the image with image_view. However, the frame rates for "mjpeg" should be 4x higher than "yuyv" at this camera's native resolution (according to the list at http://www.quickcamteam.net/devices/l... ). I would ultimately like to use this webcam to track a 'fast' moving target, one that I should be able to catch at 30fps, but not reliably catch 5-7.5 fps.

I've installed ffmpeg and libavcodec-dev from Ubuntu's software center. I'd be happy to supply any additional information, but I'm not sure what to look for.

Thanks!

edit retag flag offensive close merge delete

Comments

The link below: https://code.ros.org/trac/opencv/tick... seems broken. Does anyone has an answer to this? Same problem here. I am using Indigo, usb_cam and Ubuntu 14.04.

cvcook ( 2015-07-09 20:46:22 -0500 )edit

add a comment

0

answered 2011-08-31 09:58:10 -0500

mgb
16

I fixed up CvCaptureCAM_DShow to allow MJPG and setting of all the webcam parameters. Fixes are against 2.3.0 see https://code.ros.org/trac/opencv/ticket/1281

edit flag offensive delete link

add a comment

0

answered 2011-09-05 20:52:09 -0500

rado0x54
191 ●8 ●11 ●18

updated 2011-09-05 20:56:32 -0500

Patch your usb_cam.cpp. This should fix the error.

--- usb_cam.cpp (revision 628)
+++ usb_cam.cpp (working copy)
@@ -296,6 +296,7 @@
   avpicture_alloc((AVPicture *)avframe_rgb, PIX_FMT_RGB24, image_width, image_height);

   avcodec_context->codec_id = CODEC_ID_MJPEG;
+  avcodec_context->codec_type = AVMEDIA_TYPE_VIDEO;
   avcodec_context->width = image_width;
   avcodec_context->height = image_height;

edit flag offensive delete link

add a comment

USB_Cam, Could not open MJPEG Decoder

Comments

2 Answers

Question Tools

Stats

Related questions

USB_Cam, Could not open MJPEG Decoder edit

Comments

2 Answers

Question Tools

Stats

Related questions

USB_Cam, Could not open MJPEG Decoder