JPC-rr plays back slowly because JPC-rr is very slow.
dumpconvert is a command-line tool, and instructions to use it are given
here. It can convert your dump file to a video file (like AVI, MKV, MP4) and audio file (like WAV, OGG) for further mixing or encoding.
To make simple lossless video and audio files, run dumpconvert with the following parameters:
dumpconvert --video-width=((x)) --video-height=((y)) --video-framerate=((fps)) --output-wav=audio.wav --output-x264=video.avi,crf=0, ((dump))
where you replace "((x))" with the horizontal video resolution, "((y))" with the vertical video resolution, "((fps))" with the video frame rate, and "((dump))" with the name of your dump file. See also the examples for parameters given in the link above.
If you don't know how to use the command line, then look up 'how to use the command line' in Google.