What is difference between First Pass and First Pass(Fast)

[wdmalik]

What is difference between First Pass and First Pass (Fast),
what i got from the forum is that the first pass is the basis of the quality for second pass encoding .. so why two different first pass modes .. :confused:

[LoRd_MuldeR]

The first pass collects information and the second pass does the final encoding. With two passes the encoder can lower the data rate in the less complex scenes and give more data rate to the more complex scenes. This usually gives a better video quality at the same file size (compared to single-pass).

You can use First-Pass (Fast) instead of the "normal" First-Pass. Using the "Fast" mode does a less complex analysis during the first pass, which speeds up the process. With only 2 passes you will lose some quality when using First-Pass (Fast), but not too much. With more than 2 passes, you can use First-Pass (Fast) without losing any quality (at least you won't see any loss of quality ^^). IMO First-Pass (Fast) is fine :)

[Sirber]

:goodpost:

Good explanation of what fast first pass is :D

[LoRd_MuldeR]

:goodpost:

Good explanation of what fast first pass is :D

Don't laugh about me! I tried to explain as good as I can...

[Sirber]

I was serious... :(

People just can't take compliments... :p

[LoRd_MuldeR]

I was serious... :(

People just can't take compliments... :p

In that case, thanks :)

[Sirber]

In that case, you are welcome :D

[wdmalik]

Yea .. thnx man
u rock ... :)

[wdmalik]

Can u answer another question for me ...

Why do we get high compressibility values for low resolutions .. ?
and vice versa ...

[Sirber]

IMO, Blocks holds more datas and quantize more at the same time.

[Wilbert]

You can use First-Pass (Fast) instead of the "normal" First-Pass. Using the "Fast" mode does a less complex analysis during the first pass, which speeds up the process.
In what sense less complex?

[Sharktooth]

Well, most of the codec "heavy" routines can be disabled coz they are needed only for the final encode. Other options can be set to the lowest or fastest possible settings coz they're really not needed or they dont influence the analysis in a significant way during the first pass.

[Inventive Software]

As in the analysis is less complex. You know when you set the analysis complexity when you do the main encoding, Fast first pass does it a little less complexly.

[stephanV]

In what sense less complex?
Fast first pass uses faster motion search algorithms, and less block types IIRC.