I'm trying to get a good understanding of the relation between video file size and quality. I've done a lot of reading and testing and think that I have a reasonable preliminary understanding. However, I'd appreciate it if someone could confirm (or correct) what I understand.
I want my edited project to have the same settings and quality as the original material.
Ultimately, I followed the instructions in the following link:
http://phpbb.ulead.com.tw/EN/viewtopic. ... bb4ae9f225
My original MPEG material had the following properties:
- Variable Bit Rate (Max 9496 Kbps)
- Resolution 24 Bits 720x480
- 56% Compression
When I use the same bit rate and resolution but set the compression at 100% (as suggested), the output video file is larger than the original material. If change the compression from 100% to the same as the input clip, then the output video file is approximately the same as the original.
As a frame of reference, I know that repeatedly saving a JPG file will degrade the photo quality. Therefore, I am assuming that if I set the my project compression to 100% (all other properties the same) that my edited output will retain the picture quality of the original material. On the other hand, if I set my Compression to anything lower than 100% (say to 56% like the original) that my edited video will be lower in quality than the original clip. (Because it is being compressed twice)
Am I correct in my understanding?
Video Size/Quality
Moderator: Ken Berry
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heinz-oz
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cottage
Maybe I didn't fully explain. I'm not trying to get better quality than the MPEG file. I'm only trying to avoid making it worse than the MPEG. In this specific example, I'm working with source material that has been recorded on my set top DVD-Recorder which will only record MPEG2 (i.e. from television).heinz-oz wrote:If you set it to 100%, the file size is going to be bigger while the quality will still be less. You are still compressing a compressed source. You cannot recreate detail that's not there anymore.
If you want quality, don't capture to mpeg.
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heinz-oz
As I said, setting at 100% will give you a bigger file size but the quality will still be less because you have to re-render (compress) an already compressed file. You will have to be the judge if the results are going to be acceptable. Don't expect a better result of a larger file than the original, that's all.
Let us know how you go.
Let us know how you go.
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Trevor Andrew
Hi
As I see it--
First of all I have never altered the quality setting from their defaults.
I have been working with Constant bit rate for a long time.
I get very good results.
Video Studio templates can be used to convert / create a video file to the industries standards.
You need to select Pal-Dvd or Ntsc-Dvd not Mpeg2.
You can use the Make Movie Manager to create your own templates.
The easiest way Tools – Make Movie Manager-Add-search for your Mpeg file—this will create a template the same as your files. Now edit and change the bitrate to 8000.
The new template will show in Share--Create Video File.
The standard template:-
MPEG files
24 Bits, 720 x 480, 29.97 fps
Lower Field First
(DVD-NTSC), 4:3
Video data rate: Variable (Max. 8000 kbps)
Audio data rate: 256 kbps
Dolby Digital Audio, 48 KHz, 2/0(L,R)
As a Guide.
A bit rate of 8000 produces a top quality dvd for approximately 60 minutes.
A bit rate of 6000 produces a very good quality dvd for approximately 90 minutes.
A bit rate of 4000 produces a good VHS quality dvd for approximately 120 minutes.
These are akin to the compression of Jpeg images. Its just we have the other dimension time.
Audio:
You have three options, I have used Digital Dolby since I started with VS 9.
I think your file with Variable Bit Rate (Max 9496 Kbps) properties will have to be re-coded to one of the standard templates in order to burn to disc. That is 8000 bit rate or below. I doubt if you will notice any quality difference.
Hope this Helps
Trevor
As I see it--
First of all I have never altered the quality setting from their defaults.
I have been working with Constant bit rate for a long time.
I get very good results.
Video Studio templates can be used to convert / create a video file to the industries standards.
You need to select Pal-Dvd or Ntsc-Dvd not Mpeg2.
You can use the Make Movie Manager to create your own templates.
The easiest way Tools – Make Movie Manager-Add-search for your Mpeg file—this will create a template the same as your files. Now edit and change the bitrate to 8000.
The new template will show in Share--Create Video File.
The standard template:-
MPEG files
24 Bits, 720 x 480, 29.97 fps
Lower Field First
(DVD-NTSC), 4:3
Video data rate: Variable (Max. 8000 kbps)
Audio data rate: 256 kbps
Dolby Digital Audio, 48 KHz, 2/0(L,R)
As a Guide.
A bit rate of 8000 produces a top quality dvd for approximately 60 minutes.
A bit rate of 6000 produces a very good quality dvd for approximately 90 minutes.
A bit rate of 4000 produces a good VHS quality dvd for approximately 120 minutes.
These are akin to the compression of Jpeg images. Its just we have the other dimension time.
Audio:
You have three options, I have used Digital Dolby since I started with VS 9.
I think your file with Variable Bit Rate (Max 9496 Kbps) properties will have to be re-coded to one of the standard templates in order to burn to disc. That is 8000 bit rate or below. I doubt if you will notice any quality difference.
Hope this Helps
Trevor