Understanding bitrate

[Ron67]

I am running the latest version (build 4) of software.  I have a show that I have published using custom bitrate.  I read on the forum where software encoding would give me smoother transitions than hardware encoding, so I turned off HW acceleration.  It will not play well on my PC and not at all on my TV.  I had the bitrate jacked up to get the utmost detail on this OLED TV, so after many test runs I have discovered that I must have the bitrate at 45000 or lower to be successful with HW acceleration turned off.  I don't understand how the HW acceleration will handle extremely high bitrate and the software encoding bitrate has to be turned down to work?

[Lin Evans]

 Hi Ron,

It's all about the capability and limitations of the devices used both to encode and reproduce the effects. With hardware acceleration the specialized RAM in the GPU is used along with the RAM available in the CPU. This can be a blessing as well as sometimes a curse. When played back on a suitable device such as a computer with sufficient resources, high bitrates can produce butter-smooth effects, but when this same show encoded in a bitrate beyond the hardware capabilities of the display electronics, what was great on the computer becomes choppy and has numerous dropped frames on the TV or other decoding device, etc. 

These problems can be both the result of insufficient hardware resources or the result of faulty decoding algorithms. It's walking a tightrope to find a combination of bitrate and proper encoding which works well on most devices.

As our electronic devices evolve, eventually what is impossible or improbable today become commonplace tomorrow. For now lots of experimentation and reports by users are very helpful to chart the best course.

Best regards,

Lin

[Ron67]

Thanks, Lin, for the detailed explanation!

My old TV would play the software encoded well, but not the HW encoded.  This TV is the exact opposite!  I'm actually getting almost equal quality with both HW and software, I'm just trying to obtain the very best! 

Igor mentioned H265 in an earlier post!  From what I have read, I'm looking forward to that capability.

If we would get some better weather here, I'll get out and do something else with my life, lol.

Ron

[tom95521]

It's amazing how well some of the free screen recorders like Nvidia ShadowPlay and OBS Studio can record 1080p at 60 fps (My monitor resolution is not 4K).  I can't tell the difference in quality comparing to PTE video export. Even though I have Bandicam, Mirillis,  and a few other screen recorders, the free ones work just as well. They are both configured to use the Nvidia NVENC hardware encoder.

OBS can also record H.265 but I usually don't capture in that codec. So if you want to try HEVC/H.265 you could use Handbrake to convert or screen record with OBS Studio.

Tom

[Ron67]

Thanks, Tom!

There sure are a lot of variables to consider! 

Just curious as to what bitrate folks are using for 4K mp4 output?

Ron

[Igor]

Ron,

Did you try a preset 3840 x 2160, High quality, 60p, No Hardware acceleration (unticked) on this TV?

The latest version 10.0.6 Build 4 (in About window).

[Lin Evans]

Hi Tom,

Actually, nVidia ShadowPlay records in 4K just like it does in HD. When I trashed my 2650x1600 30 inch display somehow installing my new nVidea GTX 1660 ti video card, I replaced it with a 4K 28 inch Samsung. Once I got the proper nVidia drivers installed and ShadowPlay working, I use it each time I create a small video tutorial. Unfortunately, I have to load the 4K capture into PTE and output it as an HD because most users can't play the 4K files, but the original capture is essentially just like the HD except in 4K resolution. When I Preview in PTE and capture at 4K the action even on extreme animations is still butter smooth.

Best regards,

Lin

[tom95521]

Not sure what others are doing but from searching Google for a few minutes... One comparison was 32 Mbps for H.264 AVC compared to 15 Mbps for H.265 HEVC at 4K resolution.  If you're not streaming the video over a network or slow USB device you could increase the bitrate but might not notice any difference. The downside of HEVC is much slower encoding. There seems to be a consensus of 50% to 60% bitrate savings at 4K.

Tom

[tom95521]

Hi Lin,

That is good to know that it works. I have not bothered to use 4K mainly because I'm using four of my old 1920x1080 LCD monitors on my computer. The only 4K HDTV we have is in our living room for Netflix/Hulu.

Tom

[Ron67]

Thanks for all the help!

Igor,

I've been using bitrate since I had problems with the earlier version.  I just did a two minute text with High Quality, 60P, No Hardware acceleration and the results are very good.  I will encode the whole show and see how it does.  I will get back to you when I check it out.

Thanks again for such a responsive forum,

Ron

[Igor]

Ron,

"Quality" mode (High quality or custom value) works smarter than Bitrate mode. Because in Quality mode the encoder uses more bitrate for scenes with high details and animations, and less bitrate in scenes with static images, or slow panning. It works similar to JPEG quality in Photoshop. You declare desired image quality and the program automatically calculates optimal bitrate values for each scene to preserve the requested visual quality. You need not to calculate bitrate according width/height, frame rate and type of your scenes.

I very recommend to use High quality. Or Medium quality, if you want to reduce a file size keeping reasonable quality.

[Ron67]

Igor,

I encoded the project using HQ, 60P, hardware off.  It works perfectly!  I did try using HW on just for testing.  That did not do quite so well, quite a few drops on music and a number of stutters scattered along.

Thanks again for all your help, and from the other on this forum!

Ron

[Igor]

Ron,

I'm glad that you found the best solution!

[Ronniebootwest]

Hello Ron67. 

You seem to be very technically minded and I am not. I have followed this thread with great interest. I wonder if you would explain a little more about how you are setting the encoding that you are using in PTE (I assume that you are using version 10 AV Studio)

Ron West.

[Ron67]

6 hours ago, Igor said:

Ron,

I'm glad that you found the best solution!

Only because you pointed me in the right direction!

Ron

[Ron67]

4 hours ago, Ronniebootwest said:

Hello Ron67. 

You seem to be very technically minded and I am not. I have followed this thread with great interest. I wonder if you would explain a little more about how you are setting the encoding that you are using in PTE (I assume that you are using version 10 AV Studio)

Ron West.

Hi, Ronnie!

I am now just using the simple way as per Igor!  Choose "Publish Show", "HD and 4K Video".   At that point it will bring up a menu, choose  "3840x2160" (or whatever resolution you are encoding to), "High quality", "60p", leave Pan San Disabled and Motion Blur Disabled, and make sure "Hardware acceleration" is unchecked.

If you have any trouble playing this on your TV, move from High quality to Medium quality.

Hope this helps,

Ron

[Picsel]

On 1/29/2020 at 8:43 PM, Igor said:

Ron,

"Quality" mode (High quality or custom value) works smarter than Bitrate mode. Because in Quality mode the encoder uses more bitrate for scenes with high details and animations, and less bitrate in scenes with static images, or slow panning. It works similar to JPEG quality in Photoshop. You declare desired image quality and the program automatically calculates optimal bitrate values for each scene to preserve the requested visual quality. You need not to calculate bitrate according width/height, frame rate and type of your scenes.

I very recommend to use High quality. Or Medium quality, if you want to reduce a file size keeping reasonable quality.

Hi Igor,

Following the results of the tests I published on th 27th (see the link), using quality mode Q80 and hardware acceleration, the bitrate variation is very high :  mean data rate =25,1Mb/s  min = 24,8  / max =120 ( following information given by Mediainfo software). That is in line with what you said in your post, but without hardware acceleration it seems, always following Mediainfo information that the bitrate is roughly constant at 19,9 Mb/s and the encoding time is 3 times longer. Is that normal?

Daniel

)

[denisb]

Hi,

if we analyse the frames of a UHD video Quality 100 4'57"

We can see the difference between I-Frame and P-Frames or B-Frames

If we calculate the bitrate we obtain :

For a mean Bitrate of 28 Mb/s, you can see that the bitrate is not constant and sometimes had very high values.

 

Denis

 

[Ron67]

Denis,

It would be nice if we could set a "maximum" bitrate for encoding, especially when using hardware acceleration.

Ron

[denisb]

Ron,

 

I don't often use hardware acceleration (only for tests), so I don't know if it is possible. Without HA it is possible.

 

Denis

[Ron67]

Denis,

I would use HA more often, if I could control the max bitrate.  I can't tell much difference in quality, but I seem to always have at least one or two photos that don't play well because the bitrate shoots up above the capacity of my TV when using HA.

Ron