Extraction of Kinect RGB and Depth Data from bag has a non-constant framerate

edit

Hi everybody,

I am recording using rosbag record data from kinect inside bag files. Then I replay them, in order to extract RGB images, as shown in this tutorial : Exporting images.

I modified the extractor in order to have the synchronized extractions of multiple topics (here two kinects RGB). However I saw a problem :

When I replay the bag, sometimes the rosbag slows down : the count of duration that rosbag shows in the terminal freeze, and in the extraction, I don't have the same framerate (namely, it skips a lot of frames, and only take one on few).

Is there another way of extraction images from bag than "extract_images" from the package "image_view", for images of type sensors_msgs::Image ?

[EDIT] : maybe by using the rosbag API, and making queries inside the bag, in order to avoid missing images ?

Thank you in advance,

Bests,

Stéphane

Ps : I am using Ubuntu 12.10, with ROS Groovy.

Ps 2 : if someone feel the necessity to see the code, I will edit my question to include it.