Technical Questions on DVDShrink and Instant Copy Difference

[rkr1958]

I've been reading some on MPEG2 encoding and transcoding. I was curious about the theory and have become somewhat familiar with Group of Pictures (GOP), I-frames, P-frames and B-frames and motion compenstation vector concepts.

I always wondered why the DVDShrink transcoder was much faster than Instant Copy's transcoder. I ran across a post on this site (I didn't keep the link to it) that briefly and at a high level discussed the theory behind DVDShrink and Instant Copy.

My understanding (and correct me if I wrong) is that DVDShrink first removes bits from the P-frames to reduce file size. After that it goes to the B-frames. It leaves the I-frames and motions compenstation vectors alone. Also, I understood that DVDShrink starts to "breakdown" at compressions 60% of original or so. Is this true?

What I read on Instant Copy (and this was really limited) is that IC uses a more sophisicated transcoder approach than DVDShrink. Is this true? If so, would IC do a better job than DVDShink on those videos that require significiant compression? Where might that breakpoint be? (e.g., 60%, 70% , 80 % of original)

I don't want to start some sort of flame war here, I'm really interested in responses that are based on sound theory and backed by technical understanding and facts.

[MackemX]

it probably was true at the time of writing but DVDShrink can give IC a good run for it's money now. There is no percentage break point as there are a few more factors than just a percentage to take into consideration

you could use the same percentage settings with both programs in 2 comparision tests with different DVD's. DVDShrink may give better results in the 1st test, yet the other test Instantcopy could be the best. Saying that, the 'best' for one person isn't necessarily the best for someone else due to the other factors

I've seen the explanation as to what IC does but can't recall it exactly. Basically IC rearranges the crap (which takes longer) insteading of just shrinking it . I'm sure some boffin will come along and explain in detail

[jimmalenko]

What I read on Instant Copy (and this was really limited) is that IC uses a more sophisicated transcoder approach than DVDShrink. Is this true? If so, would IC do a better job than DVDShink on those videos that require significiant compression?

I'm sure Jah_Rankin would testify to that


It might be interesting to bring in DVD2One also, as this is another popular transcoder with a different transcoding method again. I don't know much about the theory, but I m certainly looking forward to reading the repsonses here.

[MackemX]

so am I

the first numbskull who answers with _______(insert program) sucks/rocks will be shot to bits as I've seen enough of those threads to last a lifetime

try to keep this thread somewhat technical guys, or at least interesting 8)

[Jah_Rankin]

I'm sure Jah_Rankin would testify to that

[rkr1958]

It might be interesting to bring in DVD2One also, as this is another popular transcoder with a different transcoding method again.

I'm game to that. I'd like to learn the theories behind the various transcoders.

[MOVIEGEEK]

You might ask ddlooping or Dr.Shrink(aka dvdshrink) at www.dvdshrink.info