Why do multiple passes?

[-=MadDog=-]

What is actually the advantage of doing more than 2 passes when encoding a video-file?

[RB]

In theory, none.
http://forum.doom9.org/showthread.php?s=&threadid=83176#post551592

[RathO]

Right, i always do MPEG-2 (1-pass vbr), and i can't see any difference with 2 or more pass, so why would i waste my time? ;)

Regards

[influenza]

Well if you do more passes the program get's more info the distribute the bitrate. This should result in a better looking file.

However there's a limit to this of course. Most people would say doing 9 passes would not yield in a significant better output than doing let's say 4 passes.

[Arky]

This promo .pdf (http://www.cinemacraft.com/files/doc/ccx10j.pdf) for the new (high-end) CCE Xtream encoder has an interesting comparison between CCE-Pro 1-pass, and CCE-Pro 4-pass encodes. CCE-SP (which is an offline, software-only, encoder) uses essentially the same core software as the hardware-assisted, online encoding solution, CCE-Pro.

Although I have no intention of ever running more than 5 passes (at a stretch!), it is intriguing that Custom Technology elected to increase CCE-SP's multipass capability from 9max to 99max. Whether this was simply a marketing ploy (quite possibly), or whether they envisaged some peculiar, hypothetical, scenario which could, conceivably, benefit from so many passes, is something of a mystery. I suspect it was a case of allowing 99 passes simply because they could, and because it would 'look good on the spec sheet', since no other encoder on the planet can beat that number! Looking at the above .pdf, though, there is very clearly a difference between 1 and 4 passes, with the diminishing returns rule no doubt playing it's part with higher numbers of passes.


Arky ;o)

[influenza]

9max to 99max

LOL. Well it`s most certainly a marketing trick if you ask me. I never do more than 5 passes. Usually only 4 (including the first pass) if I have sufficient bitrate.

There seem to be a lot of people who think the higher the better so they will be quite happy })