Too good to be true?
Pazartesi, Nisan 14th, 2008
Is this too good to be true? Well, sort of: There is a catch. The video streams over FireWire using an MPEG-2-TS (or “Transport Stream”) format. This is a compressed format, which is incompatible with most DV editing software. MPEG compresses clusters of video frames (GOP or group of pictures) together into one stream for delivery. By taking advantage of the similarities between frames (after all, if the sky is blue in frame 1, what color is it likely to be in frame 2?) and compressing them together, MPEG is able to provide significant space saving. This also means that frame-accurate editing is difficult, to say the least. The computer must decompress each group of frames and then the whole thing re-compressed, even for simple timeline previews. MPEG, remember, is also a loss-y compression algorithm, so you can’t just keep compressing and decompressing it. Multiple rendering and re-rendering of the video will produce compression legacies that get worse and worse. MPEG also bundles (i.e. muxes) the audio into the compression stream. All this means is it’s difficult to edit with traditional editing tools.