HCEnc vs MVBR

[awesomer]

TMPGEnc has this feature where you can specify the bit rate manually for sections of the video (Manual VBR). I can't find anything called that for HCEnc. The best I can tell is that "Zones" is something like it. I'm guessing that 1 = max bitrate and 0.5 would equal half max bitrate. Is that right? If so, what effect will the average bitrate setting have if I use zones?

[45tripp]

none.
avg bitrate remains,
but bitrate distribution per section is manually (relatively) overriden

[awesomer]

none.
avg bitrate remains,
but bitrate distribution per section is manually (relatively) overriden

You can enter a value of 0.2 to 5 for each zone, but the manual doesn't say how the value really affects the bitrate. It only says that you can raise and lower it: 1 makes it normal and 0.5 (example given in program) makes it "lower". Does 5 make it 5 times the normal bitrate? What is the "normal" bitrate?

Is there a special HCEnc forum where the author hangs out?

[45tripp]

http://forum.doom9.org/showthread.php?t=137666

[AlanHK]

From TFM:

*ZONE
parameter nr.of zones type integer Status not required

Example:
*ZONE 3
1200 1.3
1500 1.
2700 0.5

This command raises or lowers the bitrate for parts of the video.
The example will raise the bitrate starting at frame 1200, reset to normal at frame 1500 and lowers
the bitrate starting at frame 2700.
The number of zones is limited to 6400.

You specify the (average) bitrate separately. So it looks like "ZONE" multiplies that rate in the specified range of frames.

You can do this in the GUI, see "Preview/Zones" tab.

[hank315]

TMPGEnc has this feature where you can specify the bit rate manually for sections of the video (Manual VBR). I can't find anything called that for HCEnc. The best I can tell is that "Zones" is something like it. I'm guessing that 1 = max bitrate and 0.5 would equal half max bitrate. Is that right?

How zones is implemented in HCenc (2 pass encode):
The first pass is always done with a fixed Quantizer, resulting in a compression curve for the whole movie which will be scaled and tweaked, giving the frame sizes for the second pass.
The zones command will linear scale the compression curve but the final change of the curve using zones is limited because of other constraints like min/max bitrate and VBV.

[awesomer]

TMPGEnc has this feature where you can specify the bit rate manually for sections of the video (Manual VBR). I can't find anything called that for HCEnc. The best I can tell is that "Zones" is something like it. I'm guessing that 1 = max bitrate and 0.5 would equal half max bitrate. Is that right?

How zones is implemented in HCenc (2 pass encode):
The first pass is always done with a fixed Quantizer, resulting in a compression curve for the whole movie which will be scaled and tweaked, giving the frame sizes for the second pass.
The zones command will linear scale the compression curve but the final change of the curve using zones is limited because of other constraints like min/max bitrate and VBV.

So, if the first pass curve has already decided to give frames in a zone the max bitrate, then nothing really happens if you try to raise it?

I think I figured out why the 0.2 lower limit. "times 0.2" is like "divide by 5".

Since it's still only v0.23, will you be implementing true CBR or MVBR in the future, or does the way HCEnc works prevent those things entirely?

[hank315]

So, if the first pass curve has already decided to give frames in a zone the max bitrate, then nothing really happens if you try to raise it?

True, nothing happens.

Since it's still only v0.23, will you be implementing true CBR or MVBR in the future, or does the way HCEnc works prevent those things entirely?

Maybe CBR will be implemented some day...
I'm just not that keen to implement an encoding method which is IMHO not very good.