any difference between 1 Pass and 2 Pass quality encoding ??

[lenti_75]

what's the difference between 1 Pass and 2 Pass quality encoding ???
does anyone knows, if there is any quality difference between these 2 options ?
I never used this before, but I guess that there is something if this option exists....

[FulciLives]

what's the difference between 1 Pass and 2 Pass quality encoding ???
does anyone knows, if there is any quality difference between these 2 options ?
I never used this before, but I guess that there is something if this option exists....

Would be helpfull if you told us what format you are talking about?

But basically a 2-pass or multipass encoding attempts to distribute the bits according to the scene. Some frames for instance only need a little bit whereas some (mostly due to fast motion) require more.

So if you do a single pass encode then every frame gets the same amount of bits. Some might have more than they really need while other's might not have enough ... and not having enough causes compression artifacts.

So the 2-pass or multipass mode attempts to lower the bitrate when it can (on low motion or static frames) while increasing it when it needs too (fast motion frames) ... thus attempting to avoid compression artifacts.

However even 2-pass mode can have compression artifacts if you use too low of a bitrate overall.

On the other hand single pass (often called CBR) can be artifact free if you pick a high enough bitrate.

- John "FulciLives" Coleman

[MpegEncoder]

But basically a 2-pass or multipass encoding attempts to distribute the bits according to the scene. Some frames for instance only need a little bit whereas some (mostly due to fast motion) require more.

So if you do a single pass encode then every frame gets the same amount of bits. Some might have more than they really need while other's might not have enough ... and not having enough causes compression artifacts.

So the 2-pass or multipass mode attempts to lower the bitrate when it can (on low motion or static frames) while increasing it when it needs too (fast motion frames) ... thus attempting to avoid compression artifacts.

- John "FulciLives" Coleman

This isn't quite completely true. Even with single pass you can have VBR. It's just that 2-pass has a much better chance of distributing the bits where they are really needed. Any example of single pass VBR is the CQ mode for TMPGEnc.

Single pass does not necessarily mean CBR

[FulciLives]

This isn't quite completely true. Even with single pass you can have VBR. It's just that 2-pass has a much better chance of distributing the bits where they are really needed. Any example of single pass VBR is the CQ mode for TMPGEnc.

Single pass does not necessarily mean CBR

Well I was trying to keep it general since he didn't say what format he was talking about. I am unsure if all formats can do a single pass "VBR" but most will tell you that a single pass "VBR" is barely better than a CBR except for maybe TMPGEnc CQ mode which seems to do something more than most single pass "VBR" modes but then again that only applies to that one program using MPEG-1/MPEG-2 so like I said I was keeping it general.

- John "FulciLives" Coleman

P.S.
Some programs even let you do a 2-pass CBR if you really want to get into it all