When I built MPressionist HDTV, I spent a great deal of time building a videophile reference decoder for showing compressed MPEG under ideal circumstances as well as building a fast/typical quality MPEG decoder for displaying your compressed MPEG footage under normal viewing circumstances. For the purposes of compression, it is actually quite handy to have both. So you can contrast and compare.

As it turns out, the high-quality videophile MPEG-2 decoder in MPressionist is also highly useful for transcoding from MPEG-2 source material into another form of MPEG compression. So we built a version of our videophile MPEG-2 decoder, which uses 32-bit floating point image processing, into MegaPEG HDTV as a frame reader. This allows you to transcode directly from raw HDV camera footage into another HD format (for instance 720p) or DVD.

To do this, you will need a program for capturing the raw MPEG-2 transport stream to your harddrive. I use Lumiere HD, myself. It turns out that the developers of Lumiere are users of MPressionist. I think they find it quite useful, in fact.

1. Hook up your HDV camera to your Macintosh.
2. Use Lumiere HD to capture video as a raw transport stream.
3. Take this transport stream into MegaPEG Pro HD or MegaPEG HDTV and open it. MegaPEG will start by demuxing the transport stream. Once demuxed, MegaPEG will also scan the stream. Depending on the length of your material you might want to get a coffee or something.
4. With MegaPEG you can look through the HDV MPEG-2 file. Because the origins of our analyzer are Macintosh G3, the features of MPressionist built into MegaPEG make it easy to wrangle HD frame sizes on a PowerBook. In fact, I regularly work with 1080i frames on my laptop. MegaPEG doesn't ever try to decode a frame unless you want it to. So the only time you'll see the hourglass is when it's doing something useful.
5. Now you can take the raw MPEG-2 video track (myMovie.m2v) and drop it directly onto a MegaPEG batch. Double click on the batch item to open the associated movie settings. For this example, I am transcoding from 1440x1080i to 352x480i (Half-D1 NTSC). However, MegaPEG can cross-convert from any time base and frame size, keeping the fields intact.
6. Now if you click over to the Process tab, you will see that the raw HDV MPEG-2 camera footage is available for scubbing and setting in&out points. Our encoder has no way of knowing this isn't an ordinary QuickTime file. But you will know the difference because there is quite a quality difference between our videophile decoder and the QuickTime MPEG-2 reader.
7. Save the settings and choose OK.
8. Now choose Make MPEG and let it run in the background. At any point you can hit "Pause & Review" to pause the encoder and bring up our analysis tools to inspect how the compression is coming along. I often use this feature to make quick adjustments to bitrate rather than waiting for encoding tests to complete.
9. Now you have a valid DVD compatible MPEG-2 file of the highest quality.

DETAIL: Notice that MegaPEG has downconverted the 1080i frame keeping the two fields perfectly intact in the 480i frame.