A number of you have asked for a detailed breakdown of the "Video rendering quality" settings found in the .avi render dialog.
The simple explanation is to use "Good" most of the time. This is the default setting. If you want more info, read on...
Quality: Best
Scaling: bi-cubic/integration
Field Handling: on
Field Rendering: on (setting dependent)
Framerate Resample/IFR: on (switch dependent)
Quality: Good
Scaling: bi-linear
Field Handling: on
Field Rendering: on (setting dependent)
Framerate Resample/IFR: on (switch dependent)
Quality: Preview
Scaling: bi-linear
Field Handling: off
Field Rendering: off
Framerate Resample/IFR: always off
Quality: Draft
Scaling: point sample
Field Handling: off
Field Rendering: off
Framerate Resample/IFR: always off
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Scaling:
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These methods come into play when conforming sources that differ from the output size. They are also used when panned, cropped or resized in track motion.
Bi-Cubic/Integration - Best image resizing algorithm available in Vegas. Quality differences will be most noticeable when using very large stills or stretching small sources.
Bi-linear - Best compromise between speed and quality. This method will produce good results in most cases.
Point Sampling - Fast but produces poor results.
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Field Handling:
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This refers to the field conformance stage of Vegas's video engine. This includes Interlaced to Progressive conversion, Interlaced to interlaced output when scaling, motion or geometric Video FX and Transitions are involved. Skipping this stage can sometimes result in bad artifacts when high motion interlaced sources are used.
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Field Rendering:
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When the output format is interlaced, Vegas will internally render at the field rate (twice the frame rate) to achieve smooth motion and FX interpolation.
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Frame Rate Resample / IFR (Interlace Flicker Reduction):
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Frame Rate Resample:
This kicks in when speed changes are made through Velocity Envelopes and/or event stretching. In can also be used when up-converting low frame rate sources. This only kicks in if the resample switch is turned on _and_ quality is set to good or best.
Interlace Flicker Reduction:
This kicks in if the event switch is turned on and quality is set to good or best. See Vegas' documentation for a description of this switch.
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Lastly, please note that Vegas will bypass any or all of these potentially expensive processing stages if the resulting output won't be affected by the process (e.g. no-recompress pass-through, field render bypass when settings don't change and so on ...). Differences in the output between different quality settings may not always be noticeable, but that largely depends on various attributes of the source media being used. If you want to see some of these differences first hand, trying using extremely large or small sources or high-motion interlaced shots with extreme pan/crop operations.
Please note that you should never render your final project using anything other than good or best when interlaced sources are involved unless the project only contains cuts. If preview quality is used, the resulting video will vary between acceptable to disastrous depending on your project and its media content.
The simple explanation is to use "Good" most of the time. This is the default setting. If you want more info, read on...
Quality: Best
Scaling: bi-cubic/integration
Field Handling: on
Field Rendering: on (setting dependent)
Framerate Resample/IFR: on (switch dependent)
Quality: Good
Scaling: bi-linear
Field Handling: on
Field Rendering: on (setting dependent)
Framerate Resample/IFR: on (switch dependent)
Quality: Preview
Scaling: bi-linear
Field Handling: off
Field Rendering: off
Framerate Resample/IFR: always off
Quality: Draft
Scaling: point sample
Field Handling: off
Field Rendering: off
Framerate Resample/IFR: always off
------------------------------
Scaling:
------------------------------
These methods come into play when conforming sources that differ from the output size. They are also used when panned, cropped or resized in track motion.
Bi-Cubic/Integration - Best image resizing algorithm available in Vegas. Quality differences will be most noticeable when using very large stills or stretching small sources.
Bi-linear - Best compromise between speed and quality. This method will produce good results in most cases.
Point Sampling - Fast but produces poor results.
------------------------------
Field Handling:
------------------------------
This refers to the field conformance stage of Vegas's video engine. This includes Interlaced to Progressive conversion, Interlaced to interlaced output when scaling, motion or geometric Video FX and Transitions are involved. Skipping this stage can sometimes result in bad artifacts when high motion interlaced sources are used.
---------------------------------
Field Rendering:
---------------------------------
When the output format is interlaced, Vegas will internally render at the field rate (twice the frame rate) to achieve smooth motion and FX interpolation.
---------------------------------
Frame Rate Resample / IFR (Interlace Flicker Reduction):
---------------------------------
Frame Rate Resample:
This kicks in when speed changes are made through Velocity Envelopes and/or event stretching. In can also be used when up-converting low frame rate sources. This only kicks in if the resample switch is turned on _and_ quality is set to good or best.
Interlace Flicker Reduction:
This kicks in if the event switch is turned on and quality is set to good or best. See Vegas' documentation for a description of this switch.
---------------------------------
Lastly, please note that Vegas will bypass any or all of these potentially expensive processing stages if the resulting output won't be affected by the process (e.g. no-recompress pass-through, field render bypass when settings don't change and so on ...). Differences in the output between different quality settings may not always be noticeable, but that largely depends on various attributes of the source media being used. If you want to see some of these differences first hand, trying using extremely large or small sources or high-motion interlaced shots with extreme pan/crop operations.
Please note that you should never render your final project using anything other than good or best when interlaced sources are involved unless the project only contains cuts. If preview quality is used, the resulting video will vary between acceptable to disastrous depending on your project and its media content.