Settings for AVCHD 2.0 Progressive compliant file, playback

[Selur]

It looks like that Buffer Size values in Hybrid are actually set not as bits but as Mbits devided by 1000, not by 1024 as it should?

Hybrid doesn't change the set value, but gives it directly to x264.

So it's not that Hybrid does set something wrong here, but it's a question on interpretation.

In general:
k = 1000, is used for streams (bit rates)
k = 1024, is used for sizes of static data (file sizes)

So for (bit) rates that you would use k=1000.
But for file size you use k = 1024.
Problem is now whether a buffer is understood as a static buffer or a stream buffer.

It could be x264 encoder related how it interprets input values?

x264 uses k = 1000, seems like TMPGEnc in their restrictions uses k = 1024.
(iirc the specs always write the values in bit to avoid this interpretation issue)

Cu Selur

[Rokoko33]

I did some experiments checking encoded files compliancy, different settings, authoring, burning to discs.
Decided to use VBV Buffer 25500, Max Bitrate 25500, and using 2-pass encoding at 24000kbps bitrate.

A question to ask:
Using a "Slower" preset and 2-pass encoding makes kind of slow encoding process.
Using a "Fast 1-st pass" option increases encoding speed significantly with small quality loss.
Next step to speedup encoding process and have another step in quality loss is to use "Slow" preset vs. "Slower".
 
There is a Note at Hybrid:
"Fast 1-st pass - speeds-up the 1st pass of a 2-pass encoding, by lowering some settings. This will result in a small quality loss, which normally is not visible."

Trying to find an optimal quality/encoding speed ratio, curious is this is the right thinking that a slower encoding preset "Slower" and Fast 1-st pass will result in higher quality vs. faster presets such Slow", "Medium" with regular 2-pass encoding?

[Selur]

Trying to find an optimal quality/encoding speed ratio, curious is this is the right thinking that a slower encoding preset "Slower" and Fast 1-st pass will result in higher quality vs. faster presets such Slow", "Medium" with regular 2-pass encoding?

The assumption should be correct for most content. There's always the exception to the rule.

Cu Selur

[Rokoko33]

For 2-pass encoding with 24000kbps setting and Max Bitrate set for 25500kbps, is it enough freedom, headroom to maintain an average 24000 birate that will be limited to 25500?
Curious if a headroom of 1500kbps is enough to not have a bitrate continuously bouncing (getting clipped) to the max limited value and affect in a negative way an encoding flow?

[Selur]

For 2-pass encoding with 24000kbps setting and Max Bitrate set for 25500kbps, is it enough freedom, headroom to maintain an average 24000 birate that will be limited to 25500?

Probably totally depends on the content.
A bouncing bit rate and a constant average bit rate is usually what you want,...
My guess is that 2pass encoding should be able to handle it, but test it and see whether it worked or not.

Cu Selur

[Rokoko33]

It was all good until I reinstalled Hybrid.
I cannot get the same Input Lookahead value =12 as it was on my previous settings:
X264>Frames>General Frame Setting>Input Lookahead is minimize, value =1, cant be changed, grayed out.

I do not know how to change it to 12, or even does it have to be changed to 12?
I am not sure how I ended up with value 12 in the first place, playing with settings.

[Selur]

X264>Frames>General Frame Setting>Input Lookahead is minimize, value =1, cant be changed, grayed out.

Input lookahead mode:
off: disables the sync lookahead
minimize: minimizes the sync lookahead to: threads + max. b-frames (default)
manual: allows to set a specific sync lookahead value between 0 and 250

source: tool-tip
-> if you want to set it manually to 12 set it to manual and adjust it to 12, but it will have no effect on compatibility

Cu Selur

[Rokoko33]

I did not set sync lookahead value manually, it just came from some settings combination and kept staying.
I will not pay attention to it as it does not affect compression process, compatibility.

One more thing has changed since a fresh install, the Macroblock Settings.
I did not set them before either, they came by playing with some settings.
I am using "Slower" preset.

Before in the Command Line was:
--partitions all --8x8dct

And the Macroblock Settings:
x264>Motion Estimation>Macroblock Settings> "P4x4" and "Allow P4x4 at all levels" boxes were checked.

After reinstalling Hybrid, starting with Hardware restriction settings for BluRay and getting AVCHD 2.0 compliant settings, those two options are unchecked, in the Command Line:
--partitions i4x4,i8x8,p8x8,b8x8 --8x8dct

Is it OK, or should I check those options?

[Selur]

Enabling P4x4 for all levels, will violate against the level definitions, but will give better compression ratio.
So if you want it strict do not enable the option.
I argued about this with the x264 developers years ago, but they said that no hardware decoder would enforce this since p4x4 support would need to be supported for lower levels.
Personally I keep these options disabled.
-> I would not check them, but you probably won't run into problems because of them.

Cu Selur

[Rokoko33]

The new version rev 2021.04.06.1 looks like is broken.
Using x264 with all same settings, same test video clip, encoded file plays twice faster, file size is twice smaller, encoded file properties show correct clip length/time, twice lower bitrate (comparing to what was set for 2-pass encoding).

During encoding process in the status window/progress bar it shows that is encoding with correct bitrate, correct estimated file size but at the half of estimated encoding time (halfway through) it suddenly finishes job. And the job is finished indeed, just file is twice smaller size and plays twice faster. Playing with video player it finishes playing at half of the actual length (sine it plays twice faster) and remaining 50% of time video players plays/displays last frame to finish actual video clip length.