Your interpretation seems correct to me. However, I'm not very familiar with video editing. It seems that the mp4 format is just a container, and the audio and video inside the container could be in just about any format. So, any parsing library that you find would have to support the audio and video codecs that are used in your files. Hopefully other monks that are more knowledgeable in this area will reply. I searched around but I did not find a perl library (I did find this Java library: http://github.com/sannies/mp4parser).