movie sizes

[pumpinloins]

I am doing some experiments with different compression codecs....using Motion jpeg A gave me a QT movie size of 50mb for a 30 sec movie. By my reckoning this means that an hour long VJ set will use 6GB of my hard drive. Is this an acceptable size or should i be using a harsher compression codec. I do not want to restart all the debates about which compression codec to use :rolleyes: and I realise that the less i use of my hard drive the better but I would really value some answers along the lines of 'my set uses about 4GB and lasts about 1.5 hrs' benchmarks

[eXhale]

What is "Motion jpeg A"? If you mean MJPEG they come under many different formats. The PicVideo MJPEG (http://www.pegasusimaging.com/picvideomjpeg.htm) is pretty good for VJing but, on the other hand, the one outputted by Matrox capture cards is not compressed enough (I don't think any card can compress enough while capturing anyway, because it would not be able to capture all frames).

[holly]

MJPEG-A is excellent quality for archiving or keeping current clips at their cleanest while you re-use them in AfterEffects or other NLE apps for further processing, but you will quickly run out of harddrive space if you want to keep several full-length "sets" on your computer.

If you are not planning to re-edit your set, you might consider encoding it to a more storage-friendly codec like Sorenson3 or MPEG2. These codecs will not scratch or play backwards because each frame is dependant on information from the frame before. You may lose some quality (especially on graphics) and the can't go back and edit the footage, but your 6gig vj set will compress down to several hundred megs (I can't be more specific because the actual size will depend on the complexity of your video). You might also consider transfering your set to a reliable hardware device (like DVD or mini-DV) so you can free-up your computer for better use. A computer is an expensive alternative to a VCR, especially if it gets damaged or stolen.

Most laptop vjs prefer a codec that is processor friendly, so they will use hundreds of very short clips (10 seconds or less) compressed with Cinepak or Midivid for use in a vj app. These codecs look terrible, but they free-up the processor for realtime effects, layering, and fast cuts from clip to clip ? which is really what laptop vj-ing is all about.

Full size MJPEG is not practical for live effects because it will clog the processor with too much data, but it can be scratched, skipped through, or played backwards because each frame is independant from the next (no processing from frame to frame). This is why MJPEG files are so big. It's used more by video editors than vjs. Always set the "number of fields" to 1 under the OPTIONS menu for progressive frame with graphics or animations or if you plan to re-size the source. Captured video (like from a camera) stays at 2 fields for interlaced frames.

I hope this helps.

holly

[pumpinloins]

Yes...it definitely says motion jpegA and also motion jpegB as two of the quicktime save options in Snaps Pro X.... what the difference is between these two I'm not sure...maybe it is to do with the interlacing frames as in A interlaces and B does not....??.... So ...I am trying to control the number of frames per second using a midi clock therefore I cannot use a storage friendly codec as each frame has to be independent from each other but i had not thought about storing it on dv....if i can fit nearly 5 gb on this that should nearly be my 6gb set but that brings on another question.Do dvd's play at one speed? as in if i calculate my fps as 27 or whatever from a bpm of 183 for example, how can i tell the dvd to vary its playback speed accordingly.....or did you just mean store the actual data on the dvd and play it back through my laptop using firewire and the software to control the fps....
thanks for the help ...if it might free up my computer for something more interesting than outputting video :D....it sounds well cool :cool: :

[holly]

I think you might get better results buying a scan converter (http://www.vjcentral.com/show/62). Snapz is not going to be fast enough and you will drop frames and stutter once your buffer is used up.

With a scan converter you can record whatever is happening on your screen to a tapedeck or a camcorder.