Low video bitrate after rendering

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AndreiBarbu

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Low video bitrate after rendering

PostSun Jan 29, 2023 6:26 pm

Hello everyone,

I am new to recordings and editing so your help is highly appreciated.

What I do is to record my screen with OBS, using in "Encoder Settings" CBR, Bitrate 15000 Kbps and in Video settings, both Base and Output Resolution are 1920x1080 and FPS 30. I mostly record Powerpoint Slideshow, browser like Google Chrome and Visual Studio Code.

I use Windows 11 and after I finish the recording, I confirm via -> Right click on the video file -> Properties -> Details -> under Video that Data rate and Total bitrate are ~15000 kbps.

However, after I edit the video in DaVinci Resolve 18.1.2 BUILD 6 and render it, I conclude, in Properties of the new file (rendered via DaVinci Resolve) that the Data rate and Total bitrate are lower, ~2500kbps.

When I render in DaVinci Resolve I use Custom Export with the following details:
-Format: MP4
-Codec: H.264
-Encoder: Native
-Network Optimization: not checked
-Resolution: 1920 x 1080 HD
-Use vertical resolution: not checked
-Frame rate: 30
-Chapters from Markers: not checked
-Quality: here I tried Automatic -> Best and also Restrict to 60000 and 80000 Kb/s but I saw no difference. In the end, similar Data rate and Total bitrate are concluded for the exported video
-Encoding Profile: Auto
-Key Frames: Automatic
-Frame reordering: checked

Advanced settings I didn't touch.

If I use other Video Editing Software and I set the bitrate, it will export the video with the selected bitrate (for example 15000 kbps).

If I change the format in DaVinci to QuickTime and codec to DNxHD, then I will get high video bitrate and of course, high file size. But if I watch the file with codec H.264 or DNxHD, for me it's the same.

I am trying to understand how DaVinci Resolve works when using H.264 that it provides a much lower bitrate after rendering comparing with the original file. Is it just smart and concludes there is no need for higher video bitrate for my video?

The reason I am worried is that I am recording this for a platform that recommends 1920x1080 @ 10 Mb/s bitrate.

Your opinion is highly appreciated. Thank you for your help!
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ZRGARDNE

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Re: Low video bitrate after rendering

PostMon Jan 30, 2023 11:12 am

You could read the manual, wait, BM has absolutely zero documentation for h264/265.

Look around and you will see many people, myself included, just don't use Mpeg4 out of resolve. It is clearly not a priority for BM.

Export DNxHR HQ (hqx for 10/12 bit) and use a properly supported tool like Handbrake for h264.
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Charles Bennett

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Re: Low video bitrate after rendering

PostMon Jan 30, 2023 2:35 pm

If you are using one of the YouTube presets you will get a low bit rate. Try these settings in the Deliver page using the Custom Export tab. Normally I would render at a much higher bit rate.
My render setting page may look a bit different to yours as this is the Studio version.
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AndreiBarbu

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Re: Low video bitrate after rendering

PostMon Jan 30, 2023 7:31 pm

ZRGARDNE, Charles Bennett thank you very much for your answers!

Unfortunately, I am not ready to purchase the Studio (paid) version yet. Or I will buy it after I realize this is the right option; for the moment I am trying to understand how things work.

Regarding exporting DNxHR HQ (hqx for 10/12 bit) and then using Handbrake to make it H.264 I find too time consuming and I am not sure I need to do that. And I really need to do this for many videos and I am long to find the optimal, long-term solution.

I am trying to understand, what is the logic behind the fact that DaVinci Resolve exports you a video with with a bitrate 6-7 times lower than the original one, even if you choose the Best option or restrict to a high bitrate.

If I check my original video and the one exported from DaVinci, I just switch between tabs and I don't see any difference, even if the one from DaVinci has a much lower bitrate than the original video.

I can assume you are asking now, why this guy insists about this if the quality is the same. The reason is that the platform I am looking to upload the edited videos, Udemy, re-encodes the video again. So I am afraid that, if the video is already with a low bitrate, the re-encode that Udemy does, may result in something low quality.

Does the tool consider you just don't need a higher bitrate when exporting or it behaves like this just to push you to buy the paid version?

Thank you for reading and help!
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AndreiBarbu

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How the exporting bitrate is decided by DaVinci Resolve?

PostTue Jan 31, 2023 12:32 pm

Hello everyone,

I am using DaVinci Resolve Free to edit my videos. The original videos have ~12000-15000kb/s but after I edit them and export with DaVinci, I only have 1000-2000 kb/s bitrate.

I use H.264 with Quality Automatic -> Best and also Restrict to 60000 and 80000 Kb/s and no matter what, I only get 1000-2000 kb/s bitrate. I understand that the Paid (Studio) version has the option to use Constant Bitrate, but I am not ready to buy it until I don't understand how that works.

What DaVinci Resolve does that even if I specify that I want Best for Quality, it just provides a 1000-2000 kb/s bitrate?

Could you please help me understand, does the tool consider I just don't need a higher bitrate when exporting or it behaves like this just to push you to buy the paid version?
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Uli Plank

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Re: How the exporting bitrate is decided by DaVinci Resolve?

PostTue Jan 31, 2023 12:40 pm

I suppose it's a bit of both. If you want more control, just export Cineform or DNxHR and compress with HandBrake (free).
And then, if your camera is using higher quality, like 10 bit and/or 4:2:2, the bitrate may be substantially higher than what's needed for distribution, which is normally 8 bit 4:2:0.
No, an iGPU is not enough, and you can't use HEVC 10 bit 4:2:2 in the free version.

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ZRGARDNE

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Re: How the exporting bitrate is decided by DaVinci Resolve?

PostTue Jan 31, 2023 12:59 pm

AndreiBarbu wrote:
What DaVinci Resolve does that even if I specify that I want Best for Quality, it just provides a 1000-2000 kb/s bitrate?




Yes H264/265 is clearly an afterthought for BM. You can see the effort they put into documentation of it in the manual, none.

Export DNxHR and use handbrake for Mpeg4.
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ZRGARDNE

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Re: Low video bitrate after rendering

PostTue Jan 31, 2023 1:03 pm

AndreiBarbu wrote:
Unfortunately, I am not ready to purchase the Studio (paid) version yet. Or I will buy it after I realize this is the right option; for the moment I am trying to understand how things work.


Buying studio won't change anything.

H265 Nvenc was added to Free in 17.4. So there is zero difference between paid and studio for h265 export.
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Michel Rabe

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Re: Low video bitrate after rendering

PostTue Jan 31, 2023 1:17 pm

This frustrated me in the past as well, I render a 10 bit master and use handbrake to compress. Which I can imagine is annoying if you render a lot. Didn't know Resolve still has this issue.
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Mario Kalogjera

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Re: Low video bitrate after rendering

PostTue Jan 31, 2023 1:22 pm

Yes, most likely the encoder thinks you don't need more bitrate for your content. What is your video like? Many static frames and/or flat color, like animation?

I had to encode in ffmpeg, forcing constant bitrate, or even intra-frame, because any software I tried, including AME, which wouldn't raise it even in constant bitrate mode, would use very low bitrate for VBR no matter the specified bitrate, since more was really not needed (flat color animation) and the festival required that the bitrate be very high otherwise they'd reject it. Idiots. Then why did they allow mpeg-based submissions in the first place.

If you don' see artefacts I wouldn't worry too much.
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Uli Plank

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Re: Low video bitrate after rendering

PostTue Jan 31, 2023 2:33 pm

And then there's Voukoder for the PC folks.
No, an iGPU is not enough, and you can't use HEVC 10 bit 4:2:2 in the free version.

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AndreiBarbu

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Re: Low video bitrate after rendering

PostTue Jan 31, 2023 7:34 pm

Thank you all for your answers.

As mentioned, I need to edit and export for Udemy, I need to use H264 and they recommend 10MB/s bitrate for video.

My recordings are nothing fancy, just normal stuff in Chrome like documentation and a portal, Powerpoint and Visual Studio Code.

Even if the bitrate is low after exporting with DaVinci Resolve, the quality is good in my opinion. The thing is that Udemy encodes on their end and I am afraid they will brake the quality if the bitrate of the video I upload is that low.
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Michel Rabe

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Re: Low video bitrate after rendering

PostTue Jan 31, 2023 8:13 pm

Did you try already? Maybe quality holds up.

Other than that, I ask myself if one could add something to force a higher bitrate, like super fine grain...anyone knows?
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AndreiBarbu

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Re: Low video bitrate after rendering

PostWed Feb 01, 2023 6:36 am

Hello Michael,

I didn't try because I need to have my course ready before uploading there, and that is 100+ videos, a total of ~12-15 hours, which will result in weeks of work. Due to that, I am looking to make sure I properly set everything fine from the beginning and avoid weeks of useless work.
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Andy Mees

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Re: Low video bitrate after rendering

PostWed Feb 01, 2023 10:18 am

Did you submit a Test Video yet?
Let's have a return to the glory days, when press releases for new versions included text like "...with over 300 new features and improvements that professional editors and colorists have asked for."
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Ashton Lamont

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Re: Low video bitrate after rendering

PostWed Feb 01, 2023 10:19 am

I have been doing multiple Delivers as tests in the past couple of days. Studio Version 18.1.2

I am not seeing the lower bitrate problem described by Andrei at all. I've attached JPEGs as a sample. Note: the settings are part of tests, they are not necessarily the best choices n.b. in this particular case the media and timeline are 1920x1080p but the Deliver is 3840x2160 as recommended by many Youtube users because apparently if you upload HD at 4k you get a higher quality result since Youtube uses a superior codec called VP9.

I've used H265 because that has become widely available now except on old devices. Interestingly my resulting bitrate does not change much at all whether I have variable or constant bitrate. The MediaInfo box shows "Frame Rate Mode" as Constant regardless of whether I set Davinci's Rate Control to Variable or Constant

The point is to illustrate that with "Quality Restrict To 50000kb/s" the result as seen in MediaInfo is "Overall Bit Rate 51.1 Mb/s" and "Video Bit Rate 50.9Mb/s". In this example I used 50,000 because various Youtubers recommend to use double my Frame Rate of 25 (UK-PAL) when uploading to Youtube whereas HD would be fine on 25,000. I'm fairly new to DVR so apologies if I've totally misunderstood.
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deliver query 02.jpg
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Mario Kalogjera

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Re: Low video bitrate after rendering

PostWed Feb 01, 2023 11:00 am

@Ashton Lamont: "Constant frame rate mode" has nothing to do with "constant or variable bitrate". It's about framerate not bitrate. ;)

So there is a bit of confusion here: are you exporting 25 fps as 50 fps for Youtube or are you confusing framerate to bitrate and actually mean that you are exporting UHD @ 50mbps vs HD @ 25 mbps?
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Ashton Lamont

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Re: Low video bitrate after rendering

PostWed Feb 01, 2023 11:22 am

Whoops, sorry I used Constant Frame Rate by mistake in the description of the example. I was actually meaning the Rate Control which in the Deliver dialogue box has the choices of ConstantQP, Variable Bitrate, and Constant Bitrate. The Frame Rate is always 25 in my usage.
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Michel Rabe

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Re: Low video bitrate after rendering

PostWed Feb 01, 2023 11:52 am

AndreiBarbu wrote:Hello Michael,

I didn't try because I need to have my course ready before uploading there, and that is 100+ videos, a total of ~12-15 hours, which will result in weeks of work. Due to that, I am looking to make sure I properly set everything fine from the beginning and avoid weeks of useless work.


So I understand you can't upload a test video to Udemy before creating the whole 100 videos? Is there no way to try first?

You could upload the two versions (15000 kbs from OBS and 2500 kbs from Resolve) to Youtube and Vimeo and check how they encode them. If they introduce significant degradation with the Resolve file, Udemy will certainly too. If they don't, there's a good chance Udemy won't either (but it doesn't replace a test directly with Udemy).


It might also just be that your screen recordings really do not need that much bitrate. I suppose there's no sensor noise or motion that need lots of processing.

Another thing to consider is rendering and uploading 4K versions. If Udemy encodes it to HD it might preserve more quality that way (like Youtube does). But that could also prolong render times.
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AndreiBarbu

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Re: Low video bitrate after rendering

PostThu Feb 02, 2023 7:34 pm

Thank you for all your answers!

Michael, I submitted test video and their feedback of good. But there is a limitation on Udemy for test videos as Udemy makes them at a maximum of 720p.

And my 720p in test video looks worst as any random 720p Udemy video. That is why I am afraid that after I upload my course, the 1080p will look worst than others 1080p. And Udemy's support is not useful at all. :(

I can also try to upload to Youtube and see how it goes, but I don't know if YouTube and Udemy's encoding are the same

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