Comments

johnebaker wrote on 5/14/2020, 12:14 PM

@Alan-D

Hi and welcome to the forum.

. . . . When using VBR in the MainConcept encoder you have to put in a value for maximum bitrate, average bitrate, and minimum bitrate. . . . .

The export presets should already have sets of values value in them, for the particular preset scenario you use.

The best advice is to leave those settings alone, they have been optimised for image quality vs file size, and device compatibility. Change the settings, especially winding up to very high bitrate values in pursuit of best quality can render the video unplayable, and result in very large file sizes and very little gain in percieved quality - Perceived quality is a very variable quantity and depends on the viewer.

Average bitrate of the video is exactly what is says it is the average when using VBR which should be used rather than CBR.

The bitrate can vary within the video from moment to moment depending on how much data is required to maintain quality ie in static or low detail scenes less data is required compared to a scene with a lot of detail or movement.

Maximum bitrate is what the encoder should be limited to, which can, if it is too low, lead to loss of perceived quality eg: blockiness or a solarized effect, however, winding the value up to very high bitrate values in pursuit of best quality can render the video unplayable, result in very large file sizes and for very little gain - Perceived quality is a very variable quantity and depends on the viewer.

AFAIK the Maximum bitrate is included in the file header data so that the decoder can check whether the video is playable ie that it is not suddenly hit with a bitrate that is higher than its capabilities which can cause a crash.

. . . . Is what you put as the average bitrate the same as what you would put for CBR . . . .

No it is not - Constant bitrate means exactly what it says the video is encoded at a constant bitrate irrespective of the scene contents ie C onstant bitrate forces the encoder to use excessive data when it is not required eg in static or low detail scenes where less data is required and may not be enough where there is a lot of detail or action in the scene leading to quality issues with the video.

The other downside of using CBR is larger file sizes.

HTH

John EB

 

 

Lateral thinking can get things done!

VPX, MEP Premium, MEP 2016, and earlier versions, Music Maker Premium, Music Maker 2016, 2015.

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Alan-D wrote on 5/14/2020, 3:11 PM

@Alan-D

Hi and welcome to the forum.

. . . . When using VBR in the MainConcept encoder you have to put in a value for maximum bitrate, average bitrate, and minimum bitrate. . . . .

The export presets should already have sets of values value in them, for the particular preset scenario you use.

The best advice is to leave those settings alone, they have been optimised for image quality vs file size, and device compatibility. Change the settings, especially winding up to very high bitrate values in pursuit of best quality can render the video unplayable, and result in very large file sizes and very little gain in percieved quality - Perceived quality is a very variable quantity and depends on the viewer.

Average bitrate of the video is exactly what is says it is the average when using VBR which should be used rather than CBR.

The bitrate can vary within the video from moment to moment depending on how much data is required to maintain quality ie in static or low detail scenes less data is required compared to a scene with a lot of detail or movement.

Maximum bitrate is what the encoder should be limited to, which can, if it is too low, lead to loss of perceived quality eg: blockiness or a solarized effect, however, winding the value up to very high bitrate values in pursuit of best quality can render the video unplayable, result in very large file sizes and for very little gain - Perceived quality is a very variable quantity and depends on the viewer.

AFAIK the Maximum bitrate is included in the file header data so that the decoder can check whether the video is playable ie that it is not suddenly hit with a bitrate that is higher than its capabilities which can cause a crash.

. . . . Is what you put as the average bitrate the same as what you would put for CBR . . . .

No it is not - Constant bitrate means exactly what it says the video is encoded at a constant bitrate irrespective of the scene contents ie C onstant bitrate forces the encoder to use excessive data when it is not required eg in static or low detail scenes where less data is required and may not be enough where there is a lot of detail or action in the scene leading to quality issues with the video.

The other downside of using CBR is larger file sizes.

HTH

John EB

 

 

Hi

So which one of these has the most influence on the quality of the output video? Average bitrate or maximum bitrate?

CubeAce wrote on 5/14/2020, 4:16 PM

@Alan-D

Neither. Both. Depends on how close you can get to the original recording in structure. Most devices will record a variable bit rate file but they vary dependant on device and manufacturer. If you go over you waste bits, making a larger file with no improvement in quality. Too low and you start seeing variation from the original. It's not just the bit rate though but how each frame is recorded and how many of each type of frame is recorded. I don't even pretend to understand half this stuff. I barely understand GOP structures and their hit on quality let alone how many times each frame gets checked before encoding.

We tend to talk about perceived quality rather than exact amounts of change as the program doesn't know what it's recording, it just follows instruction sets. It the end user that decides on how close to the original it is. Some degradation is inevitable if files are edited rather than copied as the file structure changes and has to be re-coded into a single file again with new beginning and end points to the clips involved. Because the encoding invariably involves an amount of compression there will be some quality loss or if not loss, alteration in the frame recorded from the original.

Personally I try to stick to the method of the original recording. Film editing is like stills editing. It's part technical and part art and not always easy.

Ray.

Last changed by CubeAce on 5/14/2020, 4:18 PM, changed a total of 1 times.

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AAProds wrote on 5/26/2020, 3:25 AM

I'm being short-changed as well. I set 12k average bitrate, 18k max, but Mediainfo is showing average encoded BR of 8.6k. I take John EB's point of using less data during quiet scenes, but we should still get 12k average, shouldn't we? I can't find an option for double-pass encoding, so it appears to me that ME could never give me an average because it doesn't know the material is is encoding "in the future" so it can adjust the current bitrate.

The other issue is selection of constant bitrate. I can't see any option for MPEG 4 encoding. MPEG has the option of constant. Any ideas there?

johnebaker wrote on 5/26/2020, 11:38 AM

@AAProds

Hi Alwyn

. . . . I set 12k average bitrate, 18k max, but Mediainfo is showing average encoded BR of 8.6k . . . .

What resolution are you exporting at - if I export with those settings for 1920 x 1080 h.264 MP4, MediaInfo returns Ave BR 12.0 Mb/s and Max BR 18 Mb/s

John EB

Last changed by johnebaker on 5/26/2020, 11:38 AM, changed a total of 1 times.

Lateral thinking can get things done!

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Scenestealer wrote on 5/26/2020, 7:25 PM

@AAProds

Hi Al

Also what is the Avg. bitrate of the material in your project? If that is very low then the encoder might deem a lower bitrate is adequate.

The CBR is absent in the Intel encoder settings because Magix maybe consider it redundant and I would never use it for the reasons JohnEB has described unless some particular application like a streaming service requires it. It will usually give you lower quality for the same file size.

You can still select CBR in the Mainconcept encoder > advanced settings.

Peter

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AAProds wrote on 5/27/2020, 9:41 AM

@johnebaker, @Scenestealer

An imponderable. I tried on two different movies: both have 1920x1080 source material. One resulted in an average of 9.8, the other bang on 12. Peter, one of my others was a Lag Lossless at 500mb/min! Moving on! 🙂

Peter, re the Main Concept encoder, how does one actually get to it's settings? Is it only for MPEG?

 

johnebaker wrote on 5/27/2020, 12:12 PM

@AAProds

Hi Alwyn

. . . . I tried on two different movies: both have 1920x1080 source material . . . .

What export settings or preset are you using?

John EB

Lateral thinking can get things done!

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AAProds wrote on 5/28/2020, 1:32 AM

@AAProds

Hi Alwyn

. . . . I tried on two different movies: both have 1920x1080 source material . . . .

What export settings or preset are you using?

John EB

Same for both, John, 1920x1080, 12k Av, 18k Max.

johnebaker wrote on 5/28/2020, 2:50 AM

@AAProds

Hi Alwyn

I cannot reproduce even when using ridiculously low settings and the Default (Intel) codec - I do not have the MC codec installed any more.

MEP delivers what I set - in quality sucks at the low levels.

John EB

Lateral thinking can get things done!

VPX, MEP Premium, MEP 2016, and earlier versions, Music Maker Premium, Music Maker 2016, 2015.

Running Windows 10 64bit on Intel i7-8700K 3.2 GHz, 16Gb RAM, 1Tb + 2 x 2Tb internal HDD + 60Gb internal SSD, + 6 x 2Tb ext HDDs, Sony FDR-AX53 Video camera, Contour HD 1080 and Sony HDR-AS30V Sports cams.

Scenestealer wrote on 5/28/2020, 9:24 PM

@Alan-D @AAProds

For VBR encoding, I think what may be shown as average bitrate is probably better described as Target Bitrate and is a setting that is there to create a reasonable size of file. That is - to give an approximate size of file at the end that will allow sufficient BR to encode while retaining quality from scene to scene, within the variations of the content (detail, movement) bounded by the Max. BR.

The Media Info reported BR or Overall BR is just the file size MBytes x 8 = Mbits divided by the duration in secs to give Mbits per sec. It can only be because Media Info is not able to analise every frame of the video and can only report what is in the file header, as John has explained.

Al - you need to download the Mainconcept encoder via the Help>Install additional content download menu for $5 or if you have it from an earlier version of MEP it just needs activating from the same menu. It will then appear as a choice in Program Settings> Import Export>Codecs section as another choice from Default codec after restarting MEP when you choose an export template> advanced settings you will see a different adv. settings window.

Peter

 

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