Three Identical Clips Produced at 3 Different Bit Rates - Quality Comparison

CS2014

Senior Contributor Private Message Location: USA-Eastern Time Zone Joined: Sep 16, 2014 16:44 Messages: 629 Offline

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Jan 15, 2016 12:39

I have gotten a test pattern that Tony (ynotfish) supplied me (through tomasc) that pans and zooms in a little bit (did this in a PD14 thread). I "Produced" 3 different versions - that is I produced them at 3 different bitrates so that I could compare them and make the 'eureka' moment that higher bitrate DOES improve video quality.

Maybe I've reached my physical limit as I'm not 'seeing' drastic differences when I play them back either in my BD player and then through my TV or here on the computer. The BD player is capable of 1920x1080 60p - as is this computer and monitor I believe.

The test pattern appears to move - but I believe Tony took the test pattern and zoomed in, just a little and then panned and then zoomed back out. So is there something in particular that I should be observing when I watch these 3 productions to see the difference that higher bit rates make? Should I be looking at particular sections of the test pattern when certain movements occur?

All H.264 AVC productions - produced at 10 Mbps, (a custom profile), then a default profile of 28 Mbps, and then the last custom profile of 48.5 Mbps. MediaInfo shows that the 'video' portion of these files are a little less than these figures but I believe that is 'normal' as I think these bit rates stated in the Produced section of PD are 'overall' bit rates ... I think.

Appreciate any comments.

CS

This message was edited 2 times. Last update was at Jan 15. 2016 12:40

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tomasc

Senior Contributor Private Message Joined: Aug 25, 2011 12:33 Messages: 6364 Online

Jan 15, 2016 14:38

Look at the produced chart on the screen and write down the higest numbers next to the smallest set of lines that you see while the chart is not moving.

Look at the chart full screen while it is panning and pause it. Write down the time, the smallest horizontal line, and the vertical resolution line numbers that you can still see on the screen. Repeat for the two higher bit rates at the same time. You should see the higher resolution lines on the higher bit rates. Those vertical and horizontal lines are what you look at. They should be less blurred at higher bit rates.

Compare the numbers that you wrote down.

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Carl312

Senior Contributor Private Message Location: Texas, USA Joined: Mar 16, 2010 20:11 Messages: 9090 Offline

Jan 15, 2016 16:36

tomasc's description it right on.

If you look at the vertical and horizontal lines, as they get closer together, it is higher and higher resolution to display each line as a separate line, they will blur together when the resolution is not high enough.

The charts are made such that the lines never touch each other. Carl312: Windows 10 64-bit 8 GB RAM,AMD Phenom II X4 965 3.4 GHz,ATI Radeon HD 5770 1GB,240GB SSD,two 1TB HDs.

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CS2014

Senior Contributor Private Message Location: USA-Eastern Time Zone Joined: Sep 16, 2014 16:44 Messages: 629 Offline

Jan 16, 2016 09:25

I used to test picture tubes, THAT'S how ancient I am! We used 'Injun Joe' - not a politically correct term but that's what we used to call the test pattern that has the indian head on it - and this is what we used to resolution testing.

So I am familiar with trying to 'see' better resolution from an old picture tube at least. I'm thinking that this is similar to trying to see it in video. the way both of you describe it, is just how I thought and how we used to do it.

I must be running into my optical limit as when I compare the productions I made, I'm not seeing significant differences.

Thanks for the response guys - Carl, tomas

CS

This message was edited 1 time. Last update was at Jan 16. 2016 09:26

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Carl312

Senior Contributor Private Message Location: Texas, USA Joined: Mar 16, 2010 20:11 Messages: 9090 Offline

Jan 16, 2016 09:56

Quote: I used to test picture tubes, THAT'S how ancient I am! We used 'Injun Joe' - not a politically correct term but that's what we used to call the test pattern that has the indian head on it - and this is what we used to resolution testing.

I remember it well!

Click on the 1920x1080 version. http://fungi.yuggoth.org/testpattern/

So I am familiar with trying to 'see' better resolution from an old picture tube at least. I'm thinking that this is similar to trying to see it in video. the way both of you describe it, is just how I thought and how we used to do it.

You could use a magnifying glass.

I must be running into my optical limit as when I compare the productions I made, I'm not seeing significant differences.

Thanks for the response guys - Carl, tomas

CS

The eyes are not what they used to be.

Mine either. Carl312: Windows 10 64-bit 8 GB RAM,AMD Phenom II X4 965 3.4 GHz,ATI Radeon HD 5770 1GB,240GB SSD,two 1TB HDs.

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tomasc

Senior Contributor Private Message Joined: Aug 25, 2011 12:33 Messages: 6364 Online

Jan 16, 2016 12:51

Look at the attached screenshot. Look at the yellow knurled knob and then the metal surrounding it. The YT link is here: https://www.youtube.com/watch?v=PbC5jNQbj2M . This might illustrate bit rate better with still screenshots.


Filename	maxresdefault.jpg	Download
Description	See the yellow knob and metal surrounding for details.
Filesize	286 Kbytes
Downloaded:	118 time(s)

This message was edited 1 time. Last update was at Jan 16. 2016 12:53

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CS2014

Senior Contributor Private Message Location: USA-Eastern Time Zone Joined: Sep 16, 2014 16:44 Messages: 629 Offline

Jan 16, 2016 15:16

I see what you are referring to tomas, thanks!

Where I'm trying to go with this is - do we have any of this sort of choice when we want to burn a BD DVD? I haven't seen the ability in 'Burn to Disc' - to edit - like in Produce tab - to increase the bitrate.

Am I even asking a proper question? Does burning to disc not involve bit rate?

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tomasc

Senior Contributor Private Message Joined: Aug 25, 2011 12:33 Messages: 6364 Online

Jan 16, 2016 15:34

The standard for blu-ray is avchd or m2ts file format. The standard frame and bit rates are covered in the create disc page. There really is no need to produce at a higher bit rate than the original.

To me svrt is the best and the fastest which is covered in the create disc module. Others may and do disagree.

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ynotfish

Senior Contributor Private Message Location: N.S.W. Australia Joined: May 08, 2009 02:06 Messages: 9945 Offline

Jan 18, 2016 02:05

Hi CS -

tomasc's example says it all, but here's another. These are partial screenshots (taken mid motion) from the produced file of "that" test pattern project. I rendered at 6, 28 & 60Mbps. In lower bitrate renders, these sometimes show up as "jaggies" - it depends very much what you're shooting & whether you're panning across patterned surfaces (e.g. fences & rooftops).

Whilst you may have to look pretty hard to see the differences between the 28Mbps & 60Mbps renders, it's far more obvious watching the video.

Cheers - Tony
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CS2014

Senior Contributor Private Message Location: USA-Eastern Time Zone Joined: Sep 16, 2014 16:44 Messages: 629 Offline

Jan 18, 2016 08:53

I agree that looking at features in a video that exhibit straight lines are the areas that will 'show up' 'jaggedness' and thus poorer quality. Text too seems to be an area that may display the quality of rendering too - I believe.

I thought those were the areas as that was the features in the test pattern that my eyes were drawn to - to try to see differences in video quality Tony - Thanks!

I'll have a re-review of my 28 Mbps and 48.5 Mbps productions and see if I can 'see' the differences.

Thanks guys for all the response!

CS PD13 Ultimate - Build 3516, WIN 8.1, 64 Bit, 16G RAM, Intel Core i5 4460, CPU @ 3.2GHz, NVIDIA GeForce GT720, Graphics Memory(total avail.)-4093MB
LG WH14NS40 Blu-Ray Drive

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