A media editing system for editing source material comprising digitizing apparatus for receiving and digitizing video and audio source material, the video source material including a sequence of images, each spanning both the horizontal and vertical display axes of the video source material. The editing system also includes computing apparatus including compression apparatus responsive to the digitizing apparatus. The compression apparatus compresses the images from the video source material. The computing apparatus determines if at least one of the compressed images occupies more than a target amount of storage and provides an indication if the at least one of the compressed images does occupy more than the target amount of storage. The compression apparatus is responsive to this indication to adjust its level of compression. The computing apparatus is also for manipulating the stored source material. The editing system further comprises a mass storage responsive to the computing apparatus to receive the compressed video source material and the audio source material, and output apparatus communicating with the computing apparatus to display the manipulated source material. In another general aspect, a data buffer that compensates for differences in data rates, between a storage device and an image compression processor, and a method and apparatus for the real time indexing of frames in a video data sequence.