[ros-users] compressed_image_transport and mjpeg webcams

[Christian Verbeek]

Dear all,

http://www.ros.org/wiki/compressed_image_transport

tells us at that the jpg output of webcams (e.g. many Logitech cams)
could be copied into a sensor_msgs/CompressedImage message.

At least the cams I own do not output real jpeg but mjpeg missing the
JPEG DHT segment for YCrCb. I had to patch the jpeg decoding inserting
the DHT segment manually.

For these cameras (and I guess there are many of them) the compressed
image does not make sense because the mjpeg from these cameras can not
be decoded with the standard tools. What I wonder about is if someone
knows a cheap way to insert the missing segment into the mjpeg making it
a full jpeg without the need of re-encoding.

Regards
Christian