A few visitors have recently reported some difficulty in using the Mac version of MPEG Streamclip to convert VOBs into DV. As you all know, MPEG Streamclip is a wonderful freeware title developed by Square 5.
DV (Digital Video) is a standard video compression for digital video camera. It is also used as an alternative codec when the original video is compressed in MPEG-2. That’s the case for Final Cut Pro, which no longer accepts MPEG-2 compression. Likewise, some people use DV compression so that they can use some clips from DVDs.
Many people believe that Apple’s iMovie only takes DV-compressed video. That’s actually not true. iMovie also accepts MPEG-4 compression like H.264, MP4…
More technically speaking, DV performs a discrete cosine transform (DCT) on intraframes (all I-frames) to compress video at a fixed rate of 25 Mbs. Although DV achieves high quality, its compression method is inefficient because of its fixed data rate. And the file size tends to be sufficiently large (about 13 GB for one-hour video). Another characteristic of DV is its color-sampling, which is 4:1:1 for NTSC.
Two variants of DV compression are DVCPRO (or DVCPRO25) and DVCPRO50. DVCPRO is developed by Panasonic and pretty much similar to DV. (DVCPRO also uses 4:1:1 color sub-sampling.) DVCPRO50 has a twice larger bitrate (50 Mbs) and improved color samples at 4:2:2.
Anyway, some people are concerned that video quality has worsen or will worsen when MPEG-2 is converted into DV and/or when DV video is eventually transformed into DVD. (DVD uses the 4:2:0 color space.) Either possibility is unlikely because DV is a lot better in video quality. (Again, DV uses all intraframes.) So what settings should we use when converting MPEG-2 or VOB into DV? Well, there aren’t many.
We have test-compressed a set of VOBs from a DVD into DV. We didn’t check any of the boxes as shown above. And comparing a still clip from DVD and DV, respectively, our eyes can’t tell any difference.
Tips
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The screenshot on the left is from DVD. The one on the right is from DV-compressed video. These screenshots are both compressed in JPG with 100% compression rate.
thanks for this info but for those of us who haven’t done any of this before, a step by step break down would be useful , although I realise that may not have been your intention here.
There are so many techy spec options on all this new software.
Our job is to maintain this website, deliver news and make video tutorials so that people can exchange ideas and information. I hope other visitors will help you although I doubt they will. People post comments only when they have questions or want to complain about how life is unfair in being unable to watch the video tuturial they want.