Comments

musicvid10 wrote on 9/15/2013, 6:33 PM
Divides the frame into rectangular sections (slices) and allows macroblocks in different slices to be isolated and processed simultaneously. Not available in all Profiles iirc. The defaults are fine, and may result in a slight encoding speed increase. "Number of slices" in Vegas probably refers to b-slices.
http://en.wikipedia.org/wiki/Video_compression_picture_types#Slices
skeeter123 wrote on 9/15/2013, 7:28 PM
Ahhh ha! Makes sense... I'll experiment when I get some free time.

Thanks much!
musicvid10 wrote on 9/15/2013, 7:36 PM
You'll not see any difference in the output, it's not a quality metric.
skeeter123 wrote on 9/15/2013, 8:20 PM
Will experiment with render times. See if there is any difference....

musicvid10 wrote on 9/15/2013, 8:37 PM
I don't think it would be much, but do post your results here!
NormanPCN wrote on 9/15/2013, 9:57 PM
A slice divides the frame into multiple independent pieces. Each encoded independently. So with more slices you lose some compression efficiency.

Blu-ray requires 4 slices in its specification for level 4.1 and higher.

It is easier to implement multiple slower very simple decoders in hardware than a faster more complex one. Blu-ray allows for very high bitrates and this (slices) was one way to lower cost of Blu-ray player decoders.

Sony AVC cannot reach high enough bitrates to require more than one slice.
Mainconcept AVC can specify these higher bitrates.

For anything other than Blu-ray, I am not sure anyone should care about slices. Go with 1 slice.
JohnnyT wrote on 5/14/2017, 4:18 AM

Well, does using more slices influence the size of the rendered file, or anything really, except speed and compression? I'm not using any compression, so that's not a problem

john_dennis wrote on 5/14/2017, 8:55 AM

"I'm not using any compression, so that's not a problem"

If you're using the Mainconcept AVC or Sony AVC encoders, then you ARE using compression.

JohnnyT wrote on 5/14/2017, 11:08 AM

I personally thought using slices when rendering using CPU, as many as your cores are, would improve at most possible the rendering speed, by splitting the work per core. I don't know if that's really what's happening, but if there are compression problems, I don't know if it's worth it. Sooo, stick with one slice?

john_dennis wrote on 5/14/2017, 6:40 PM

I ran a test using the Mainconcept AVC Blu-ray template.

Default 4 Slices:

12 Slices:

Mediainfo Report for the two files:

When I put the two files into a DVD Architect project, the 12 Slice sample got me this:

I was able to get the 12 slice render to pass through DVD Architect by lowering the maximum bit rate of the Mainconcept render template from 40 Mbps to 35 Mbps. Both my Sony Blu-ray players played the Blu-ray.

The bit rate distribution of the two files are shown here:

My conclusions:

The whole effort was a waste of time, though, I'm slightly less curious than I was yesterday.

1) For Blu-ray, you run the risk of compatibility problems.

2) The 27 seconds difference in render time in 10 minutes is not going to change your life. Experimental error could account for some of the difference. This was a small sample.

3) Most humans, especially me, don't understand the process enough to make good overall judgements about it.