Trying to edit a Zoom video and getting vastly different quality

[GoodEnough]

Zoom can record your meeting and render a video of the meeting. These are super compressed files. Zoom is typically headshots and screen shares. Not fast motion. At what bitrate did Zoom render the video conference ? The app renders it at Under 300 bps!!!** With no loss of clarity.* 45 mins video is only 70MB.

Here is the weird part. I had to make some edits to the video in Vegas. Cut some stuff out. I render at the same bitrate as the source file (300 bps), I get grainy resolution. No idea why.* I had to re-render at 2,000,000 bps to get the same clarity as the source video which is only at 300 bps. The encoding codec I am using is using Magix AVC/AAC MP4.

My Zoom laptop is 1366x728 so that is the resolution of the Zoom video.** Not changing the screen resolution also makes much faster rendering. I set resolution same as source file 1366x728 and render time was 5 mins. For a 40 min. video. w/ 2,000,000 bps* (File size 600MB)

Bottom line.* To render a video w/ Vegas with the SAME quality as Zoom’s raw output, my filesize needs to be TEN times bigger (60MB vs 600MB) and a bitrate of almost 10x as well. (300bps vs. 2mm bps)

Anyone know what is going on? I'd like to cut down the source file (300 bps, 60MB), and render something similar.

[jagabo]

Frame rate?

[GoodEnough]

25 fps

[poisondeathray]

Was it variable frame rate ? What does mediainfo (view=>text) say about the source file ?

You will always lose quality when re-encoding with a lossy codec. Expect it to be larger even with next generation codecs like AV1, HEVC for similar quality

For AVC, Magix AVC is unsuitable for very low bitrates, you will get higher compression efficiency using x264 with long GOP, many b-frames , slower settings. You can access it with voukoder in Magix, or x264vfw, or debugmode frameserver to another application


If you're only performing cut edits , consider using something else that is lossless so you don't have to re-encode. It's just stream copied with cuts. If you're only making rough edits, not frame accurate, you could use avidemux . If you need frame accurate precise edits, you'd have to use a smart renderer such as videoredo, solveigmm video splitter ; but they re-encode a few frames around the cutsite, so you lose some quality there

[GoodEnough]

Thanks for the help.

No, I want to figure this out with re-encoding.
I have a very fast PC and rendering is not an issue.

To review, if I re-render the actual ZOOM file
Using the SAME bitrate as the original ZOOM file
VEGAS is making the file THREE times bigger,
and having terrible quality.

Here is the main difference in the MediaInfo

ZOOM original
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L5
File size : 68.3 MiB
Overall bit rate : 215 kb/s

VEGAS re-render
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L3.2
File size : 143 MiB
Overall bit rate : 497 kb/s

[poisondeathray]

The low quality is normal for Magix AVC using low bitrates. It does not use features like b-frames. If you want to use AVC, you have to use another encoder, x264 . Alternatively you can use newer codecs like AV1, but they are not as supported as well yet

Where is the other information requested? Post the full report

[GoodEnough]

These are the formats in my Customize Template

https://forum.videohelp.com/images/imgfiles/MloogoH.jpg

[GoodEnough]

Other fields were all identical, so I left it off.
Here is the mediaInfo for the original Zoom file

ZOOM

General
Complete name : D:\ZoomSourceFile.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (isom/mp42)
File size : 68.3 MiB
Duration : 44 min 28 s
Overall bit rate mode : Variable
Overall bit rate : 215 kb/s
Encoded date : UTC 2021-01-05 18:47:24
Tagged date : UTC 2021-01-05 18:47:24

Video
ID : 2
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L5
Format settings : CABAC / 11 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 11 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 44 min 28 s
Bit rate : 86.5 kb/s
Width : 1 366 pixels
Height : 728 pixels
Display aspect ratio : 1.85:1
Frame rate mode : Constant
Frame rate : 25.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.003
Stream size : 27.5 MiB (40%)
Title : H.264/AVC video
Encoded date : UTC 2021-01-05 18:47:24
Tagged date : UTC 2021-01-05 18:47:24
Codec configuration box : avcC

Audio
ID : 1
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 44 min 28 s
Bit rate mode : Variable
Bit rate : 126 kb/s
Maximum bit rate : 151 kb/s
Channel(s) : 1 channel
Channel layout : C
Sampling rate : 32.0 kHz
Frame rate : 31.250 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 40.2 MiB (59%)
Title : AAC audio
Encoded date : UTC 2021-01-05 18:47:24
Tagged date : UTC 2021-01-05 18:47:24

[GoodEnough]

How do I get X264 variant of the AVC encoder?
That seems to be what the efficient Zoom raw used !

[poisondeathray]

For example, it's using 11 reference frames. Magix AVC I think uses 2, and zero b-frames (when it was Sony , at least) ie. It's not using all AVC features to improve compression, and you have to means to adjust them. It's a limited version that does not allow access or control of some important parameters

You can't use Magix AVC with low bitrates; if you want AVC video, you have to use another workflow, such as voukoder out of vegas, or debugmode frameserver , otherwise you're stuck with using higher bitrates to get decent quality
https://www.voukoder.org/

You can try Magix HEVC, not sure how good it is . It's HEVC, so 1 generation later than AVC. Potentially better. But there is wide variation in HEVC encoder quality .

[GoodEnough]

I tried the 2nd MAGIX option
HEVC

Same bitrate
WAY better quality
Only 115MB

So, for now
ditch AVC
And use HEVC
Better quality
Smaller file sizes

You're saying this only applies to low bitrate source files?
If I have a 4k file video, then just stick with AVC defaults and using 20,000,000 bps?

[poisondeathray]

You're saying this only applies to low bitrate source files?
If I have a 4k file video, then just stick with AVC defaults and using 20,000,000 bps?

No, in general, HEVC is going to be better than AVC, since it's 1 generation later. But there is wide variation in HEVC encoder quality/compression . And the settings make a big difference too, just like they do with AVC.

But HEVC is more difficult to encode/decode (slower), and fewer devices or software or hardware support it (e.g. you can't stream it on a website very easily)

The bitrate is depends on the content, how easy it is to compress. 20M might be too little for some, too much for others

[GoodEnough]

If this is all for Youtube, then always use HEVC over AVC?

[GoodEnough]

Here is what I still don't get.
How can the ZOOM file be only 60MB?
Why can't I re-encode that file and get the same exact size?
Can't I use the same exact encoder they are using, in theory?
Or am I missing something basic?

Any time you re-encode a video file, the result HAS to be bigger?
Why? What if you're not adding any "information"?

[poisondeathray]

If this is all for Youtube, then always use HEVC over AVC?

It does not matter much, because youtube re-encodes everything for their streaming distribution versions

Generally you want to upload something good in quality, and they actually archive the original file (owner can download it through google checkout)

[poisondeathray]

Here is what I still don't get.
How can the ZOOM file be only 60MB?
Why can't I re-encode that file and get the same exact size?
Can't I use the same exact encoder they are using, in theory?
Or am I missing something basic?

Any time you re-encode a video file, the result HAS to be bigger?
Why? What if you're not adding any "information"?

Because video is decoded to uncompressed video data, then recompressed with lossy compression. That's what lossy "re-encoding" means. That's why I suggested alternative methods, if you were just cut-editing , where you stream copy the data, where nothing is decoded and recompressed

The uncompressed state is much larger. The lossy recompression state throws away more bits

Zoom is 1 generation earlier than what you have, they look at the original data, then re-encode that with lossy compression. What you have is lossy compared to what zoom started with. You are suffering what's called "generation loss"

If you started with what zoom had to start with, you could make it smaller and higher quality than your original zoom recording, using AVC , with x264 . For example you could use 16 reference frames instead of 11. Many other settings too

[GoodEnough]

I don't want lossless cut editing like AVIDemus.
I like to edit in Vegas.

Ok, so re-encoding will ALWAYS result in a larger file.
Even if it's worse quality.

So, how can I explore the best encoder for me?
How can I get x264? That's different from AVC?

Friend just told me that HEVC looks worse than AVC.

[poisondeathray]

Ok, so re-encoding will ALWAYS result in a larger file.
Even if it's worse quality.

No;

Filesize is determined by the bitrate. Filesize = bitrate * running time . It might be larger, smaller , or the same

Filesize is technically independent of quality. But it's valid to say higher bitrates result in less loss (thus higher quality) if everything else is the same (e.g. using the same codec, same settings)

Lossless encoding (e.g. lossless codecs like ut video, lagarith, etc...) can be lossless if handled properly, but their filesizes are many times larger . Their "lossless" compression is in reference to the uncompressed data, not the original file's compressed data

Lossy encoding will always result in lower quality, regardless of filesize . But you can have "visually lossless" or basically you can't see the difference

So, how can I explore the best encoder for me?
How can I get x264? That's different from AVC?

x264 is a specific AVC encoder. I listed the ways you can use it in vegas above. There are guides on how to use them in various forums like the Magix forum. They have screenshots and video tutorials

Friend just told me that HEVC looks worse than AVC.

It's an unqualified statement. It's too broad to be true

Not at very low bitrates. Look at your Magix AVC encode if you need evidence

There are dozens of HEVC encoders, just like dozens of AVC encoders. The specific encoder implementation is more important, and the settings used

[jagabo]

Ok, so re-encoding will ALWAYS result in a larger file.

No. The file size depends on the bitrate. If you select the same bitrate (and the encoder can actually deliver it) you will get the same file size. But any time you (re)encode something with a lossy codec you will get losses. So if encode a video at some particular settings, the encode that encoded video again with the exactly the same setttings the newest video will lose some quality. And you will continue loosing quality with every generation. You can reduce those losses by using a higher bitrate than the source at each reencoding -- but you cannot eliminate them unless you go to lossless encoding.

How can I get x264?

You can frame serve to x264 -- pdr can probably tell you how to do that.

That's different from AVC?

AVC (aka h.264) is the specification. x264 is an open source implementation of that specification. There are many AVC encoders, some better than others.

Friend just told me that HEVC looks worse than AVC.

It depends. Any encoder can deliver good or bad quality depending on the settings used.

[GoodEnough]

Ok, that's why the same bitrate result is totally different quality ?
ZOOM bitrate is 300 and 60MB
VEGAS bitrate is 300 and 150MB and looks like garbage (pixelization)

So, there is no way around larger filesizes and higher bitrates.
Like 10x higher bitrate to get same quality as ZOOM 1st gen

[GoodEnough]

Ok, so x264 is a better AVC encoder than MAGIX AVC ?

[poisondeathray]

Ok, so x264 is a better AVC encoder than MAGIX AVC ?

Yes, and you have access to advanced settings like GOP size, reference frames, bframes - things that will help compression for any encoder

Look at the mediainfo report, zoom uses 11 reference frames. Magix AVC uses 2 I think, you didn't post it but you can check

[GoodEnough]

11 vs 3.
What are reference frames?

[GoodEnough]

Here is what I still can't fathom.
The SAME bitrate results in a file that is 3x larger.
How? I get the lossy quality, but why is the filesize tripling in size for the same bitrate?

[jagabo]

Here is what I still can't fathom.
The SAME bitrate results in a file that is 3x larger.

Then the bitrate isn't the same (for example, some encoders can't provide very low bitrates or very high bitrates, depending on the settings used). Or something else is taking up a lot of space. For example, if the source had aac audio and you converted to uncompressed PCM. And sometimes mediainfo is just wrong about bitrates.

[poisondeathray]

11 vs 3.
What are reference frames?

https://en.wikipedia.org/wiki/Reference_frame_(video)

[GoodEnough]

Vegas MAGIX AVC file was 600MB @ 3000 kbps
I ran my Vegas MAGIX AVC file through Handbrake. I think Handbrake uses H.264.
The Handbrake encoded file is 90MB @ 300 kbps and seems to have the same quality as the 600MB file.
This seems like a great way to compress files and save storage space.

[poisondeathray]

Vegas MAGIX AVC file was 600MB @ 3000 kbps
I ran my Vegas MAGIX AVC file through Handbrake. I think Handbrake uses H.264.
The Handbrake encoded file is 90MB @ 300 kbps and seems to have the same quality as the 600MB file.
This seems like a great way to compress files and save storage space.

handbrake uses x264 for it's AVC encoder;

It's not ideal - the way you are doing it - because you're losing quality twice instead of once, not to mention it's slower because you're encoding twice instead of once

You can frameserve to handbrake or encode using voukoder directly out of vegas, and it will be faster, and higher quality at the same or smaller filesize


As mentioned earlier, there are guides e.g vegas to handbrake . Not sure how up to date this one is, but search google - but this only works for vegas pro
https://www.moviestudiozen.com/free-tutorials/sony-vegas-pro/590-render-video-from-veg...o-to-handbrake

[GoodEnough]

I am recording video using a GoPro.
Resolution is 2.7k (2704x1520)
60fps

I am using Vegas Movie Studio 16 Platinum.

I only see output settings for 4k and 1080p.
So, I think the render is taking a lot longer since it is rescaling the frames.

How can I output without resize and just stick to 2.7k output video ?

Make Movie -> Advanced Options?
MAGIX AVC/AAC MP4 ?
MAGIX HEVC/AAC MP4 ?