DivX 5.x Codec Setup Guide

1-Pass Encoding :

1. Configure the Profile Setup settings
2. Set the Variable bit-rate mode to "1-pass"
3. Set the Performance/Quality setting
4. Set the Encoding bit-rate
5. Go to the "Video" tab
6. Adjust the Video Settings
7. Adjust the Advanced Settings

1-Pass Quality-Based Encoding :

1. Configure the Profile Setup settings, and select "Disable profiles"
2. Set the Variable bit-rate mode to "1-pass quality-based"
3. Set the Performance/Quality setting
4. Set the Quantizer setting
5. Set the Encoding bit-rate
6. Go to the "Video" tab
7. Adjust the Video Settings
8. Adjust the Advanced Settings

Multi-Pass Encoding :

1. Configure the Profile Setup settings
2. Set the Variable bit-rate mode to "Multipass, 1st pass"
3. Set the Performance/Quality setting
4. Set the Encoding Log File setting
5. Set the Encoding bit-rate (note that some tools like GordianKnot sets this for you automatically)
6. Go to the "Video" tab
7. Adjust the Video Settings
8. Adjust the Advanced Settings
9. Go back to your encoding software and either start the encoding, or prepare to setup the next pass options
10. Set the Variable bit-rate mode to "Multipass, nth pass"
11. Set the Performance/Quality setting (Optional)
12. Set the Encoding Log File setting
13. Set the Bitrate Modulation setting
14. Leave all other settings unchanged (or rather, make sure they match the same settings you used for "Multipass, 1st pass" above)

DivX Pro 5.2.x Codec Configuration Reference

1. Open the Profile Wizard

Profiles are pre-programmed settings for the DivX codec that conform to standards set by DivX.com, hence ensuring maximum compatibility with DivX devices. This will make sure your encoded video files are compatible with DivX enabled devices that are available on the market (like standard DVD/DivX players).

To select a profile, click on the "Select DivX Certified Profile" button.

2. Step 1 - Select a DivX Certified Profile

Here, you can select the preset DivX profiles to use. The four profiles currently available are Handheld, Portable, Home Theatre and High Definition, and a description is provided for them in this screen.



If you de-select "DivX Certified", this will basically allow you to have access to more options, but at the expense of compatibility.

3. Step 2 - MPEG4 Tools

These options allows you to select the three special encoding methods that will try to improve the quality of the encoding, while decreasing the file size.

DivX's use of profiles limits the use of these tools, and you may only be able to select some of these options if you disable the use of profiles.

Use Quarter Pixel - Quarter pixels increases the resolution of motion search, and hence, will improve quality, especially with the fluidity in motion of objects in the distance. The motion search resolution is increased, the search time will be longer and hence, encoding time will be longer as well.

Use GMC - Global Motion Compensation (GMC) is useful in improving the quality of scenes where lots of movement (especially panning, zooming) occur. You should enable this option. Not available when profiles are used

Bidirectional Encoding - Bidirectional encoding allows for the use of B frames in the encoding, in addition to the I-frame (data for this frame is completely stored) and the P-Frame (predicted frame). There are two available options, "Adaptive Single Consecutive" and "Adaptive Multiple Consecutive", otherwise known as single and multiple B frames (may not be supported by DivX certified devices). It is recommended that you enable this option, although if you use high bit-rates or have set performance/quality to "Fastest", it's better to not enable it. Not available for the "Handheld" profile

4. Step 3 - Profile Validation

If you didn't disable profiles, then you will be able to enter the resolution/framerate of your video. Doing this allows the DivX codec to check that your encoded video will conform to whatever profile/standard you have selected, although it will not affect the actual video encoding. Press "Finish" to end profile configuration.

General Setup :

Encoding Performance :

Determines tradeoff between performance and quality. Leaving it as Standard gives you the best possible picture/encoding speed ratio, but the "Fast" option has been improved in DivX 5.2 to provide a good quality with added performance gain. The graphic on the right provides a good indication of the quality/speed tradeoffs. A setting of Standard correponds to the "Slowest" setting in the 5.0 version of the DivX Codec, and this is the recommended setting (the quality gains from setting it to a slower setting may not be worth the trouble). If you really want to use the "Slow" or "Slowest" settings (which uses a new "rate-distortion" algorithm), then use it during the last pass, as otherwise, the encoding will take hours for just a minute of video. Not available when Quarter Pixel MPEG4 mode is selected.

Encoding Mode :

Choose the type of encoding method for this codec.

1-pass encoding is similar to DivX 3.11 Alpha's "low motion" encoding, allowing you to specify an adverage bit-rate, which the encode will try to achieve.



1-pass quality-based encoding is basically constant quantizer encoding (same quantizer used for every frame, and the bit-rate will be adjusted to ensure the quantizer/quality level is reached), but you specify the quality of the output (using the "Quantizer" slider - the lower the quantizer, the higher the quality. Think of the "%" value given as the quality as defined by a percentage of the original source quality), rather than the bit-rate directly. File size, unfortunately, becomes unpredicatable as a result. This option is not available when a profile is selected.



multi-pass is the best encoding option (for smallest file size, and best quality) - multi-pass encoding takes longer than 1-pass encoding : the encoding time is roughly the encoding time of a "1-pass" encoding multiplied by the number of passes (eg. 2-pass takes twice as long, 3-pass takes three times as long ...), but the results may be worth it - multi-pass uses the bitrate you selected as appropriately as possible, to give you both an accurate file size and the best possible looking picture given that bitrate.

DivX 5.0.3 Pro added Nth pass encoding. Previously, only 2-passes were available. Now, you can have as many passes as you want, with each pass giving the DivX codec more information to work with, and hence, achieve a higher quality encoding (at the expense of time, of course). Note that it is very hard to achieve any noticeable quality improvments after 3-passes.

Using Nth pass encoding is similar to using 2-pass encoding : you have a common first pass using the "Multipass - 1st pass", and then subsequent passes can be performed using the "Multipass - nth pass" settings.

Bitrate Calculator :

DivX 5.2 now has a built-in bit-rate calculator, which can help you figure out the exact bit-rate you need to ensure the output file is limited to a certain size. The idea here is to provide the length of the video and the audio properties, and then enter a desired file size to get the required bit-rate.

Encoding bitrate :

This is the bit rate setting for the video. A setting of 1500 will produce very good quality video (lower will mean a smaller file size, but poorer quality). Don't go below 650 (650-1000 for 1 CD movies), and there is probably not too much point in going over 2000 (1300-2000 for 2 CDs).

Bitrate modulation : - (for "Multipass - nth pass" mode only)

This allows you to tell how much motion your source video has, and let the DivX codec decide on the best way to encode this video source. Drag the slider towards "high-motion" or "low-motion" depending on your source. As an example, an action movie will usually have lots of high-motion scenes (where the camera pans and zooms quickly), and a drama will probably have lots of low-motion scenes. Selecting the right bitrate modulation setting will help the DivX codec to better use available bit-rate.

Multipass encoding log files :

Log file - 2-pass encoding requires the information in the first pass to be stored in a LOG file - you can specify the location to store the log file by using this option. You can also specify whether to write/update this log file (the log file only needs to be updated if you plan on doing another pass after the current pass).

MV file - DivX 5.2.x adds MV files, which contains Motion Vector data. This type of logging is no longer recommended by DivXNetworks.

Video Setup :

Psychovisual Enhancement :

Just like how MP3 encoding removes bits that the human ear can't hear, to decrease file size, psychovisual enhancement does the same with the video.

Enable Crop :

Cropping allows you to remove a part of the picture that you don't want encoded - for example, the black bars on widescreen movies (they will be added back by your DivX player anyway, so there is no point wasting bitrate on them). Generally, your conversion tool will have a similar feature, so you should just disable and ignore this section.

Enable Resize :

Same deal as cropping, except this is for resizing the overall picture - you should just disable and ignore this section.

Advanced :

Source Pre-processing :

This option should really be renamed to "Noise Reduction", as this is what it really does. Unless your source has lots of noise in it (which shouldn't be the case if you are converting from a DVD), so you should just disable it.

Scene change threshold

This setting determines the percentage of blocks not tracked by the motion search algorithm to trigger a scene change. Leave this at 50%, but if you do need to change it, make sure it is between 40% and 60%. This option is ignored when the "Performance/Quality" mode is set to "Slowest".

Interlacing :

You can encode the video as progressive or interlaced. If your original source is interlaced, then encoding it as interlaced may result in a better looking picture, although it may increase file size. Similarly, encoding the video as progressive if the source is progressive will be benefitial. There are many ways to check if your video source is interlaced or progressive, but using DVD2AVI and checking for the "Frame Type" is a good way to achieve this.

The last option allows you to "Deinterlace all frames", which is just a way to convert the interlaced source into a progressive one. This is not really recommended, as it can lower picture quality.

Max Keyframe interval

Keyframes helps you to skip forward/backwards (seek) through the movie (when you skip, the picture has to land on a keyframe first). Keyframe are automatically inserted at scene changes, but in case you have a movie where the scene never changes, then set this to a reasonable value to avoid having no keyframes. For example, you can insert a keyframe every 10 seconds by multiplying the framerate of the movie (eg. 23.976 or 25 or 29.97) by 10 (eg. 240, 250, 300), and entering it here. Keyframes will still be inserted at scenes changes, but if the interval between keyframes (or scenes) is greater than the specified number of frames, then another keyframe will be inserted.

Quantization Type

New in DivX 5.2, you can now select between H.263 and MPEG-2 quantization. The recommended quantization is H.263 (the DivX 5 standard), and is recommended for low to high bit-rates. MPEG-2 quantization may not be supported by all DivX certified devices, and hence only recommended for very high bit-rate videos, but with possibly increased artifacts for other types of videos.

1-Pass Encoding :

1. Configure the Profile Setup settings
2. Set the Variable bit-rate mode to "1-pass"
3. Set the Performance/Quality setting
4. Set the Encoding bit-rate
5. Go to the "Video" tab
6. Adjust the Video Settings
7. Adjust the Advanced Settings

1-Pass Quality-Based Encoding :

1. Configure the Profile Setup settings, and select "Disable profiles"
2. Set the Variable bit-rate mode to "1-pass quality-based"
3. Set the Performance/Quality setting
4. Set the Quantizer setting
5. Set the Encoding bit-rate
6. Go to the "Video" tab
7. Adjust the Video Settings
8. Adjust the Advanced Settings

Multi-Pass Encoding :

1. Configure the Profile Setup settings
2. Set the Variable bit-rate mode to "Multipass, 1st pass"
3. Set the Performance/Quality setting
4. Set the Encoding Log File setting
5. Set the Encoding bit-rate (note that some tools like GordianKnot sets this for you automatically)
6. Go to the "Video" tab
7. Adjust the Video Settings
8. Adjust the Advanced Settings
9. Go back to your encoding software and either start the encoding, or prepare to setup the next pass options
10. Set the Variable bit-rate mode to "Multipass, nth pass"
11. Set the Performance/Quality setting (Optional)
12. Set the Encoding Log File setting
13. Set the Bitrate Modulation setting
14. Leave all other settings unchanged (or rather, make sure they match the same settings you used for "Multipass, 1st pass" above)

DivX Pro 5.1.x Codec Configuration Reference

1. Open the Profile Wizard

Profiles are pre-programmed settings for the DivX codec that conform to standards set by DivX.com, hence ensuring maximum compatibility with DivX devices. This will be more helpful in the future, when DivX enabled devices are available, and you want to make sure your DivX encodings will playback on these devices.

To select a profile, click on the "Select Profile Wizard" button.

2. Step 1 - Profile Select?

Here, you can select the preset DivX profiles to use. The four profiles currently available are Handheld, Portable, Home Theatre and High Definition, and a description is provided for them in this screen.



If you choose "Disable Profiles", this will basically allow you to have access to more options, but at the expense of compatibility.

3. Step 2 - MPEG4 Tools

These options allows you to select the three special encoding methods that will try to improve the quality of the encoding, while decreasing the file size.

DivX's use of profiles limits the use of these tools, and you may only be able to select some of these options if you disable the use of profiles.

Use Quarter Pixel - Quarter pixels increases the resolution of motion search, and hence, will improve quality, especially with the fluidity in motion of objects in the distance. The motion search resolution is increased, the search time will be longer and hence, encoding time will be longer as well.

Use GMC - Global Motion Compensation (GMC) is useful in improving the quality of scenes where lots of movement (especially panning, zooming) occur. You should enable this option. Not available when profiles are used

Use Bidirectional Encoding - Bidirectional encoding allows for the use of B frames in the encoding, in addition to the I-frame (data for this frame is completely stored) and the P-Frame (predicted frame). This option also increases quality, so enable it as well. Not available for the "Handheld" profile

4. Step 3 - Profile Validation

If you didn't disable profiles, then you will be able to enter the resolution/framerate of your video. Doing this allows the DivX codec to check that your encoded video will conform to whatever profile/standard you have selected, although it will not affect the actual video encoding.

General Setup :

Performance/quality :

Determines tradeoff between performance and quality. Leaving it as Standard gives you the best possible picture/encoding speed ratio. A setting of Standard correponds to the "Slowest" setting in previous version of the DivX Codec, and this is the recommended setting (the quality gains from setting it to a slower setting may not be worth the trouble). If you really want to use the "Slow" or "Slowest" settings (which uses a new "rate-distortion" algorithm), then use it during the last pass, as otherwise, the encoding will take hours for just a minute of video. Not available when Quarter Pixel MPEG4 mode is selected.

Variable bitrate Mode

Choose the type of encoding method for this codec.

1-pass encoding is similar to DivX 3.11 Alpha's "low motion" encoding, allowing you to specify an adverage bit-rate, which the encode will try to achieve.

1-pass quality-based encoding is basically constant quantizer encoding (same quantizer used for every frame, and the bit-rate will be adjusted to ensure the quantizer/quality level is reached), but you specify the quality of the output, rather than the bit-rate directly. File size, unfortunately, becomes unpredicatable as a result. This option is not available when a profile is selected.

multi-pass is the best encoding option (for smallest file size, and best quality) - multi-pass encoding takes longer than 1-pass encoding : the encoding time is roughly the encoding time of a "1-pass" encoding multiplied by the number of passes (eg. 2-pass takes twice as long, 3-pass takes three times as long ...), but the results may be worth it - multi-pass uses the bitrate you selected as appropriately as possible, to give you both an accurate file size (good if you are using bitrate calculators - make sure you get a DivX 4.x/5.1.x compatible calculator) and the best possible looking picture given that bitrate.

DivX 5.0.3 Pro added Nth pass encoding. Previously, only 2-passes were available. Now, you can have as many passes as you want, with each pass giving the DivX codec more information to work with, and hence, achieve a higher quality encoding (at the expense of time, of course). Note that it is very hard to achieve any noticeable quality improvments after 3-passes.

Using Nth pass encoding is similar to using 2-pass encoding : you have a common first pass using the "Multipass - 1st pass", and then subsequent passes can be performed using the "Multipass - nth pass" settings.

Quantizer : - (for "1-pass quality-based" mode only)

The lower the quantizer, the higher the quality. Think of the "%" value given as the quality as defined by a percentage of the original source quality.

Encoding bitrate :

This is the bit rate setting for the video. A setting of 1500 will produce very good quality video (lower will mean a smaller file size, but poorer quality). Don't go below 650 (650-1000 for 1 CD movies), and there is probably not too much point in going over 2000 (1300-2000 for 2 CDs).

Bitrate modulation : - (for "Multipass - nth pass" mode only)

This allows you to tell how much motion your source video has, and let the DivX codec decide on the best way to encode this video source. Drag the slider towards "high-motion" or "low-motion" depending on your source. As an example, an action movie will usually have lots of high-motion scenes (where the camera pans and zooms quickly), and a drama will probably have lots of low-motion scenes. Selecting the right bitrate modulation setting will help the DivX codec to better use available bit-rate.

Multipass encoding log files :

Log file - 2-pass encoding requires the information in the first pass to be stored in a LOG file - you can specify the location to store the log file by using this option. You can also specify whether to write/update this log file (the log file only needs to be updated if you plan on doing another pass after the current pass).

MV file - DivX 5.1.x adds MV files, which contains Motion Vector data. This type of logging is no longer recommended by DivXNetworks.

Video Setup :

Psychovisual Enhancement :

Just like how MP3 encoding removes bits that the human ear can't hear, to decrease file size, psychovisual enhancement does the same with the video.

Enable Crop :

Cropping allows you to remove a part of the picture that you don't want encoded - for example, the black bars on widescreen movies (they will be added back by your DivX player anyway, so there is no point wasting bitrate on them). Generally, your conversion tool will have a similar feature, so you should just disable and ignore this section.

Enable Resize :

Same deal as cropping, except this is for resizing the overall picture - you should just disable and ignore this section.

Advanced :

Pre Processing Source :

This option should really be renamed to "Noise Reduction", as this is what it really does. Unless your source has lots of noise in it (which shouldn't be the case if you are converting from a DVD), so you should just disable it.

Scene change threshold

This setting determines the percentage of blocks not tracked by the motion search algorithm to trigger a scene change. Leave this at 50%, but if you do need to change it, make sure it is between 40% and 60%. This option is ignored when the "Performance/Quality" mode is set to "Slowest".

Source Interlace :

You can encode the video as progressive or interlaced. If your original source is interlaced, then encoding it as interlaced may result in a better looking picture, although it may increase file size. Similarly, encoding the video as progressive if the source is progressive will be benefitial. There are many ways to check if your video source is interlaced or progressive, but using DVD2AVI and checking for the "Frame Type" is a good way to achieve this.

The last option allows you to "Deinterlace all frames", which is just a way to convert the interlaced source into a progressive one. This is not really recommended, as it can lower picture quality.

Max Keyframe interval

Keyframes helps you to skip forward/backwards (seek) through the movie (when you skip, the picture has to land on a keyframe first). Keyframe are automatically inserted at scene changes, but in case you have a movie where the scene never changes, then set this to a reasonable value to avoid having no keyframes. For example, you can insert a keyframe every 10 seconds by multiplying the framerate of the movie (eg. 23.976 or 25 or 29.97) by 10 (eg. 240, 250, 300), and entering it here. Keyframes will still be inserted at scenes changes, but if the interval between keyframes (or scenes) is greater than the specified number of frames, then another keyframe will be inserted.

Profiles Setup :

1. Choose your Profile

DivX 5.0.3 introduces the notion of profiles (or standards). Basically, these are pre-programmed settings for the DivX 5.0.3 codec that conform to standards set by DivX.com. This will be more helpful in the future, when DivX enabled devices are available, and you want to make sure your DivX encodings will playback on these devices.

The four profiles currently available are Handheld, Portable, Home Theatre and High Definition.

2. What is the resolution of your video?

Enter the resolution of your video here and the DivX codec will test and see if this resolution conforms to the profile/standard you have selected.

3. What is the framerate of your video?

Enter the framerate of your video here and the DivX codec will test and see if this framerate conforms to the profile/standard you have selected.

MPEG4 Tools :

These options allows you to select the three special encoding methods that will try to improve the quality of the encoding, while decreasing the file size.

DivX 5.0.3's use of profiles now limits the use of these tools, and you may only be able to select some of these options if you disable the use of profiles.

Use Quarter Pixel - This feature is not working properly in build 413 of the DivX 5.0 codec, so disable it. Not available when profiles are used

Use GMC - Global Motion Compensation (GMC) is useful in improving the quality of scenes where lots of movement (especially panning, zooming) occur. You should enable this option. Not available when profiles are used

Use Bidirectional Encoding - Bidirectional encoding allows for the use of B frames in the encoding, in addition to the I-frame (data for this frame is completely stored) and the P-Frame (predicted frame). This option also increases quality, so enable it as well. Not available for the "Handheld" profile

Bitrate Control Setup :

Variable bitrate Mode

Choose the type of encoding method for this codec. "1-pass" encoding is similar to DivX 3.11 Alpha's "low motion" encoding. "1-pass quality based" encoding is basically constant bitrate encoding (same bitrate used for every frame), and is similar to the compression used in MPEG-1 movies (ie. crappy compression). "2-pass" is the best encoding option (for smallest file size, and best quality) - unfortunately, it takes twice the time of "1-pass" encoding, but the results may be worth it - 2-pass uses the bitrate you selected as appropriately as possible, to give you both an accurate file size (good if you are using bitrate calculators - make sure you get a DivX 4.x/5.0.x compatible calculator) and the best possible looking picture given that bitrate.

New in Version 5.0.3 : DivX 5.0.3 Pro adds Nth pass encoding. Previously, only 2-passes were available. Now, you can have as many passes as you want, with each pass giving the DivX codec more information to work with, and hence, achieve a higher quality encoding (at the expense of time, of course).

Using Nth pass encoding is similar to using 2-pass encoding : you have a common first pass using the "Multipass - 1st pass", and then subsequent passes can be performed using the "Multipass - nth pass" settings.

Max bitrate : - New in Version 5.0.3 (for profile-less "Multipass - nth pass" mode only)

The maximum bit-rate to use during encoding - required by certain DivX/MPEG-4 devices that cannot handle large bit-rates. Max bitrate is not yet implemented in the DivX 5.0.3.

Encoding bitrate :

This is the bit rate setting for the video. A setting of 1500 will produce very good quality video (lower will mean a smaller file size, but poorer quality). Don't go below 650 (650-1000 for 1 CD movies), and there is probably not too much point in going over 2000 (1300-2000 for 2 CDs).

Bitrate modulation : - New in Version 5.0.3 (for "Multipass - nth pass" mode only)

This allows you to tell how much motion your source video has, and let the DivX codec decide on the best way to encode this video source. Drag the slider towards "high-motion" or "low-motion" depending on your source.

Multipass encoding log files :

Log file - 2-pass encoding requires the information in the first pass to be stored in a LOG file - you can specify the location to store the log file by using this option. You can also specify whether to update this log file (the log file only needs to be updated if you plan on doing another pass after the current pass).

MV file - DivX 5.0.x adds MV files, which contains Motion Vector data. Having a MV file will speed up the 2-pass encoding process, as motion compensation is performed during the first pass, and will not need to be done on the second pass again.

MPEG4 Tools :

The MPEG-4 Tools (Quarter Pixel, GMC, Bidirectional Encoding) have been moved to the "Profiles" setup area (see above) in version 5.0.3.

General Parameters Setup :

Enable Crop :

Cropping allows you to remove a part of the picture that you don't want encoded - for example, the black bars on widescreen movies (they will be added back by your DivX player anyway, so there is no point wasting bitrate on them). Generally, your conversion tool will have a similar feature, so you should just disable and ignore this section.

Enable Resize :

Same deal as cropping, except this is for resizing the overall picture - you should just disable and ignore this section.

Psychovisual Enhancement :

Just like how MP3 encoding removes bits that the human ear can't hear, to decrease file size, psychovisual enhancement does the same with the video.

Pre Processing Source :

This option should really be renamed to "Noise Reduction", as this is what it really does. Unless your source has lots of noise in it (which shouldn't be the case if you are converting from a DVD), so you should just disable it.

Keyframe :

Max Keyframe interval - Keyframes helps you to skip forward/backwards (seek) through the movie (when you skip, the picture has to land on a keyframe first). Keyframe are automatically inserted at scene changes, but in case you have a movie where the scene never changes, then set this to a reasonable value to avoid having no keyframes. For example, you can insert a keyframe every 10 seconds by multiplying the framerate of the movie (eg. 23.976 or 25 or 29.97) by 10 (eg. 240, 250, 300), and entering it here.

scene change threshold - Set this to 50%

Performance/quality :

Determines tradeoff between performance and quality. Leaving it as Slowest gives you the best possible picture, and this is what I would set it at, since the speedup in compression is not reason enough to lose all that quality.

Source Interlace :

This option has been drastically changed for version 5.0.3.

You can now encode the video as progressive or interlaced. If your original source is interlaced, then encoding it as interlaced may result in a better looking picture, although it may increase file size. Similarly, encoding the video as progressive if the source is progressive will be benefitial. There are many ways to check if your video source is interlaced or progressive, but using DVD2AVI and checking for the "Frame Type" is a good way to achieve this.

The last option allows you to "Deinterlace all frames", which is just a way to convert the interlaced source into a progressive one. This is not really recommended, as it can lower picture quality.

Advanced Parameters Setup :

Date Rate Control(RC) :

Below are very important settings in determining quality. These settings are now only accessible through the Windows Registry, at the location HKEY_CURRENT_USER\Software\DivXNetworks\DivX4Windows. Do not change these settings unless you know what you are doing, as it can mess up your encoding, or worse, destroy your Windows registry.

Maximum Quantizer - A higher setting (eg. 20) will mean a more compression, hence less picture quality. Lowering the value will increase the file size.

Minimum Quantizer - A lower setting (eg. 2) will mean a more clear picture (less blocky), but will increase the file size.

RC averaging period, frames - This setting determines how the bitrate should be averaged out (eg. if there was a spike in bitrate used in previous frames). Leaving this at 2000 seems to work fine, but experiment by increasing this value, may bring better quality.

RC reaction period, frames - This setting determines how fast the codec should react the scene changes. The default value seems to work fine.

Rate control down/up reaction - The default value also seems to work fine here.

Use data partitioning :

Useful for video streaming, but otherwise, leave it disabled.

Performance/quality :

This setting has been moved to the "General Parameters" setup area (see above) in version 5.0.3.

DivX MP4 Creator :

As mentioned before, MPEG-4 writing does not yet support audio, so ignore this section. No longer available in version 5.0.3

Hier is hij dan eindelijk: de DivX 5.0 Pro handleiding! Het vervolg op DivX 4.X!
Ik hoop dat je er veel aan hebt. Er is in ieder geval veel tijd in gekropen. Met eventuele vragen en/of opmerkingen kan u altijd hier terecht. Gelieve eventuele spellingsfouten te melden ;-)

1. DivX Decoder

Post Processing:



2 soorten filters: horizontale en verticale de-blocking en de-ringing filters. Post-processing is zeer CPU intensief! Er zijn 7 verschillende niveaus: minimum (level 0: geen post-processing) tot en met maximum (level 6). Gebruik het maximum enkel indien je een Pentium III of nieuwere processor hebt!

Post processing level Horizontal deblocking luminance Vertical deblocking luminance Horizontal deblocking chrominance Vertical deblocking chrominance Horizontal deringing Vertical deringing 1           2         3       4     5 6

2. DivX Encoder

a. DivX Codec Hoofdmenu

• Bitrate Modes:
1. 1-pass (variable bitrate mode):
De encoder zal trachten aan de film een gemiddelde bitrate toe te kennen ongeveer gelijk aan de opgegeven waarde. Low-motion scènes zullen minder data krijgen dan high-motion scènes.
2. 1-pass quality based:
De encoder zal elk frame coderen tegen dezelfde absolute hoeveelheid, zonder rekening te houden met de hoeveelheid "motion" (beweging).
3. 2-pass (variable bitrate mode):
Alvorens werkelijk te coderen, zal de video geanalyseerd worden op zijn complexiteit, om zo complexere scènes meer data te geven dan minder complexe scènes. Dit gebeurt nauwkeuriger dan bij 1-pass encoding. Deze operatie heeft wel 2 stappen nodig (2-pass): Analyse fase (first pass) en Codeer fase (second pass).
Tijdens de analyse worden de resultaten in een log file weggeschreven om nadien tijdens de second pass te gebruiken. De "Protect Log/My File" optie voorkomt het overschrijven van een bestaande log file. Dezelfde settings moeten tijdens beide fases gebruikt worden!


• MPEG4-Tools:
1. Bi-directional encoding:
Er bestaan 3 soorten frames in een DivX video stream: I-frames (Intra), P-frames (Predicted) en B-frames (Bi-directional). In vorige versies van DivX waren er enkel I-frames en P-frames.
I-frames worden gecodeerd aan de hand van informatie binnenin zijn eigen frame. Er wordt geen informatie gebruikt uit andere frames! Vergelijk het met een enkele frame waar je gebruik maakt van JPEG-compressie
P-frames worden gecodeerd aan de hand van hun voorgaande frame. Dikwijls veranderen er maar enkele pixels gedurende een bepaalde opeenvolging van video frames. In plaats van elke frame afzonderlijk te coderen zoals een JPEG afbeelding, wordt er gebruik gemaakt van de "overtollige informatie": Een P-frame is een toekomstige frame die detecteert waar een blok in het vorige frame naar toe verplaatst is in de huidige P-frame. Men geeft dus aan naar waar een bepaald blok verplaatst is.
DivX 5.0 codec introduceert de mogelijkheid om ook B-frames te gebruiken. Een B-frame gebruikt niet enkel de vorige frame om te "voorspellen", maar ook de volgende frame! Hierdoor is minder data nodig om een frame te coderen, en de kwaliteit wordt verhoogd!
2. Global Motion Compensation (GMC):
GMC helpt complexe scènes, waar "zooming" en "panning" gebruikt worden, te verbeteren: aangezien opeenvolgende frames sterk verwant zijn (wegens "zooming" en "panning") kan men de benodigde data reduceren.
3. Quarter Pixel:
De hoeveelheid data wordt gereduceerd door aan te geven naar waar en bepaald blok verplaatst is, zoals vermeld hierboven. met andere woorden 2 blokken worden met elkaar vergeleken en men ziet wat het "verschil" is tussen beiden. Dit gebeurd normaal aan de hand van een macroblok-bij-macroblok basis (16x16 pixels) of een blok-bij-blok basis (8x8 pixels). Om de nauwkeurigheid van de verplaatsing (verschil) te vergroten maakt DivX gebruik van een Half Pixel. Dit wil zeggen dat je de verplaatsing kan uitdrukken met 0.5 pixel in plaats van enkel integer waarden (verplaatsing met 1 pixel) te gebruiken.
Om nog nauwkeuriger te werken kan je de berekeningen uitvoeren aan de hand van Quarter Pixels: 0.25 pixel!


• MP4 File Creator:

Deze optie laat je toe een file te maken in het ".divx" formaat of een MPEG-4 compatibele file. Enkele nieuwe features werken enkel met het nieuwe ".divx" formaat.


• Quick Config CLI:

Command Line Interface: de geselecteerde opties kan je ook via de command line ingeven. Tevens krijg je hier te zien wat de command line parameters zijn voor de gekozen opties, waardoor je makkelijk instellingen kunt uitwisselen met andere gebruikers (door de command line te kopiëren).
Meer uitleg vind je in de Appendix over de CLI parameters.

b. General Parameters Menu

• Enable Crop:

Aan de hand van "cropping" kan je niet gewenste randen verwijderen. Zo voorkom je dat er nodeloos data aan de niet gewenste randen gespendeerd wordt.
Specificeer het aantal pixels die aan elke rand moeten weggeknipt worden.


• Enable Resize:

Resize laat toe de video stream te coderen naar een welbepaalde resolutie.
Er zijn 4 opties beschikbaar:
1. Bilinear (Very Soft):
2. Bicubic (Soft)
3. Bicubic (Normal)
4. Bicubic (Sharp)
Welke optie het best gebruikt wordt is niet helemaal duidelijk. In de officiële handleiding staat:
"From a mathematical viewpoint, it could be argued that the bicubic resize algorithm is best for enlarging the image while bilinear is more suited to size reduction. From our own experience, the opposite appears to be true."
Ik zelf hou het bij het "wiskundig standpunt", dus gebruik het bilineaire resize algoritme wanneer je wil verkleinen en het bicubic resize algoritme wanneer je wil vergroten. Bovendien is het bilineaire algoritme behoorlijk minder CPU intensief!
Meer uitleg over bilineair vs bicubic vindt u op Nicky's Pages Digital Solutions.


• Psychovisual Enhancements:

Letterlijk vertaald: psychovisuele verbeteringen.
Door de kennis in verband met de "Human Visual System" (HVS) uit te buiten is de efficiëntie van video data opslag verbeterd met als doel de waarneming van kwaliteit in de video te vergroten! HVS is de manier waarop wij als mens beelden bekijken en interpreteren.
Met andere woorden: aan de hand van psychovisuele modelleer technieken wordt er minder data toegekend daar waar ons "Human Visual System" minder gevoelig is, en meer data daar waar ons HVS veel gevoeliger is. Belangrijk hierbij is dat er geen rekening wordt gehouden met één enkel frame, maar wel met een sequentie van frames! Dit is de sleutel tot data-reductie: we moeten data toekennen op een manier zoals ons HVS doet bij een video sequentie aan een welbepaalde frame rate (bv 25 frames per seconde), en NIET door elk frame afzonderlijk te behandelen!
DivX Pro 5.0 is de eerste wijd verspreidde codec die van deze innoverende techniek gebruik maakt! Aanvankelijk werd psychovisueel modelleren bijna uitsluitend gebruikt in academische onderzoekscentra. Dit is een onderzoeksdomein met nog vele mogelijkheden!


• Pre-Processing:

Noise (ruis) kan een groot probleem vormen tijdens de video compressie, omdat de noise relatief veel beschikbare bits (voor de video stream) in beslag kan nemen. De pre-processing filter maakt gebruik van digitale signaal verwerkingstechnieken om noise te verwijderen uit het bronmateriaal, alvorens daadwerkelijk te coderen. Er wordt gebruik gemaakt van 2 filters. Veronderstel één enkele pixel ergens in het beeld:
1. Spatial Filter:
er wordt gekeken naar de omliggende pixels binnen hetzelfde frame en op basis hiervan wordt een "smoothing"-functie (gelijkmaken) toegepast.
2. Temporal Filter:
pixels op dezelfde positie over een aantal opeenvolgende frames worden gelijkgemaakt.
Door deze technieken te gebruiken en zo noise te verminderen kunnen we in zekere maten de kwaliteit verhogen.

Er zijn 4 opties mogelijk: Light, Normal, Strong en Extreme.
Normal pre-processing zou geen merkbare achteruitgang mogen veroorzaken van de source file, maar voor een echt gevoelige source file is er de Light optie. Strong en extreme zullen een deel van de data verwijderen en kan best gebruikt worden wanneer file size belangrijker is dan kwaliteit of bij video materiaal met erg veel ruis.


• Keyframe
De DivX encoder zal, telkens wanneer er een scène verandering wordt gedetecteerd, automatisch een keyframe invoeren. Wanneer er echter gedurende een relatief lange tijd geen scène overgang gedetecteerd wordt zal de encoder automatisch keyframes toevoegen met een frequentie gespecificeerd door de gebruiker. Aangezien keyframes het "grootst" zijn van alle frames zal de frequentie een drastisch effect hebben op de uiteindelijke gecodeerde file grootte!
Aangeraden wordt minstens elke 10 seconden een keyframe in te voegen, dus wanneer je een frame rate hebt van 25 fps betekent dit om de 250 frames!


• Intelligent De-Interlace/Inverse Telecine (Source Interlace):
Interlacing is uitgevonden in de jaren '40: in plaats van elke seconde 60 frames te zenden worden er afwisselend even en oneven "lijnen" verzonden (film is opgebouwd uit lijnen). Een interlaced scherm zal deze lijnen vervolgens "interlacen" (ineenvoegen) op een correcte manier.
Een camera zal bv 1/60 van een seconde een oneven lijn opnemen, en de volgende 1/60 seconde een even lijn. Dit kan bij snel bewegende objecten gekartelde randen geven tijdens het afspelen. Het is mogelijk deze gekartelde (scherpe) randen weg te krijgen aan de hand van de-interlacing. De DivX codec kan, alvorens te coderen, de source file de-interlacen. Belangrijk hierbij is wel dat de video niet geresized wordt door een extern programma!
Een film wordt meestal gemaakt aan 24 fps, terwijl de NTSC standaard 30 fps bedraagt. De film wordt daarom geconverteerd naar 30 fps door sommige video velden te dupliceren (telecine genaamd). Hierdoor bekomt men de gewenste 30 fps. Inverse-Telecine (IVTC) is het omgekeerde van wat hier boven staat: de gedupliceerde velden worden terug verwijderd! De DivX codec heeft 3 opties voor de-interlacing en IVTC:
1. All frames are progressive:
default optie: de-interlacing en IVTC worden niet gebruikt!
2. All frames are interlaced:
de codec zal alvorens te resizen en coderen een de-interlace algoritme uitvoeren.
3. Intelligent IVTC/de-interlace:
de codec zal automatisch uitzoeken wanneer IVTC en de-interlacing gebruikt moet worden.

Er is ook nog een optie beschikbaar voor gebruikers wiens hoofdzorg de codeer snelheid is: "Basic Video Deinterlace". Deze optie mag niet gebruikt worden wanneer er ook aan "resizing" wordt gedaan! Verder moet de Source Interlace optie op "All frames are progressive" staan.

c. Advanced Parameters Menu

• Data Rate Control Parameters (RC):

Met een aantal opties kan je experimenteren, maar hou er rekening mee dat kleine veranderingen merkbare effecten tot gevolg kunnen hebben! Daarom zijn deze features bedoeld voor ervaren gebruikers: zelfs de ontwikkelaars begrijpen niet 100% hoe elke parameter juist werkt!

1. Maximum and Minimum Quantizers:
De quantizer is één van de belangrijkste parameters tijdens het coderen! De quantizer bepaalt hoe mooi de encoder de video sequentie codeert. De algemene regel is:

lage quantizer waarde = beter kwaliteit + grotere file!

De default waarden zouden min of meer een optimaal resultaat moeten geven.
Als je toch wil experimenteren, hou dan rekening met het volgende:
Wanneer je een low-motion scène hebt gecodeerd en je bent niet helemaal tevreden over het resultaat probeer dan de Minimum Quantizer waarde te verlagen. Merk wel op dat je uiteindelijke file grootte hierdoor zal toenemen.
Wanneer je een high-motion scène hebt gecodeerd en je bent niet helemaal tevreden over het resultaat probeer dan de Maximum Quantizer waarde te verlagen. Merk ook hier op dat je uiteindelijke file grootte hierdoor zal toenemen.

Om de juiste settings te vinden kan je als volgt te werk gaan: zet de quantizer waarden tamelijk hoog en codeer een high-motion scene van 30 à 60 sec. Bekijk nu dit fragment en verlaag de maximum-quantizer waarde totdat het blokeffect niet of weinig meer voorkomt. Doe nu hetzelfde met een low-motion scene (bv waar mensen enkel aan het spreken zijn met elkaar). Bekijk het resultaat en verlaag de minimum-quantizer waarde totdat het blokeffect (zo goed als) verdwenen is.
2. RC Averaging Period, frames:
Controleert hoeveel frames er gebruikt moeten worden bij het bepalen hoe de bitrate verdeeld moet worden. De default waarde zou normaal goed moeten werken!
3. RC Reaction Period, frames:
Regelt de balans tussen low-motion en high-motion scenes. Hogere waarden resulteren meestal in betere high-motion scenes en slechtere low-motion scenes. De default waarde zou normaal goed moeten werken.
4. Rate Control Down/Up Reaction:
Deze optie controleert de gevoeligheid waarmee bepaald wordt met welke motion (bewegingsgraad) we te maken hebben: high-motion of low-motion. Hoe hoger het nummer, hoe gevoeliger de codec wordt voor beweging. Hogere waarden zorgen meestal voor betere high-motion scènes, maar ook voor extra benodigde bits! De default waarde zou normaal goed moeten werken.

Al deze parameters staan in relatie met elkaar! Het effect van een bepaalde optie hangt vaak af van de andere parameters!


• Data Partitioning:

Data Partitioning kan nuttig zijn wanneer transmissie errors kunnen voorkomen zoals in broadcast omgevingen. Data Partitioning zal de data in de stream op een andere manier organizeren zodanig dat men aan "error recovery" en "packet re-synchronization" kan doen.


• Performance/Quality:

De kern van de zaak is:
wanneer een betere kwaliteit verlangd wordt, heb je meer CPU tijd nodig!
Je zal zelden of nooit de Quality optie op iets anders dan "slowest" moeten zetten, aangezien dit de BESTE kwaliteit geeft! Laat deze optie op "slowest" staan tenzij noodzakelijk van niet!


• DivX MP4 Creator:

Hiermee kan je een DivX avi file (of DivX file) converteren naar een DivX MP4 file.

That 's it!
Ik hoop dat ik je heb kunnen helpen!

Greetz,
Diederik