MainConcept H.264 Preset Customization

Last Updated: Apr 24, 2014 04:25PM PDT
The MainConcept H.264 codec Is available to use in the following formats: MP4, MOV, blu-ray .264 and .ts with a digital signage format constraint.

The MP4 "H264_1200Kbps_480p" preset is one of the best quality presets to use for that general frame size (pictured below). Right-click the preset name and choose "Edit Preset" to see the following screen. (Make sure you click Advanced on the bottom of the settings window to make all settings visible.)

Squeeze 8 has greatly increased the number of options for preset modifications that can be made.

The top left corner has the preset name. If you wish to change the name of a default preset a good idea is to make a copy of the preset (right-click and choose "Copy Preset") and change the name of the copy.

The top right corner has the total data rate, which is a combination of video and audio data rates. This box can cannot be selected, you must modify audio and video data rates separately.

Format Constraints is the next line.

If your output file is meant for general purposes or web viewing, then you should leave this set to None.

The other format constraints are self explanatory.

*Note: if you choose a specific format constraint, it may constrain the data rate and frame size so as to conform with the needs of the format.

Stream Type is the next option.

If you are preparing your file for web streaming, you will want to select hinted, because the file will more easily start playing.
For all other purposes, choose non-hinted.

The default Codec on most h.264 presets is Main Concept H.264.

Thecodec is the actual element that takes the original video file and processes it to what you see in the output. Main Concept is default because it generally provides the highest quality output out of all the H.264 presets that come with Squeeze.

*Note: A limitation of the MainConcept H.264 is the frame size width must be divisible by 16 and height divisible by 8. For example, if you wanted a frame dimension with a height of 258, the preset will snap the number to the nearest multiple of 8 - 256.

Simple settings

Method will allow you to choose the number of passes as well as the type of bitrate, constant or variable.

The Variable bitrate (VBR) method varies the amount of output data per time segment. VBR allows a higher bitrate to the more complex segments of media files while a lower data rate is allocated to less complex segments. This keeps the quality consistant while keeping file size low.

With VBR, you have the option of 1 pass, 2, pass or multipass (4 pass). Multiple passes will provide a superior output quality, but will also multiply the amount of time it takes to complete the encoding job.

Constant bitrate (CBR) keep a consistent bit rate throughout the duration of the file. This can be helpful when using a streaming server that needs a constant bit rate stream. Because the data rate is consistent regardless of complexity of video content CBR encoded files usually need a higher data rate and produce larger file sizes than files using the VBR method.

Frame Rate will determine how many frames per second your output file will play back.

By default the frame rate is set to 1:1, which means the same as your source file. If your source file is 30 frames per second, your output wil be 30 fps. 2:1 means half of your source files frame rate, so a 30 fps source file will output to 15 fps.

A frame rate of 1:1 should work for most purposes, but if your source has a frame rate higher than 30 fps, you are best lowering it to 30 or 29.970 fps for web and mobile device playback.

Data Rate (bit rate) is the main determining factor for overall size of your file.

Higher data rates will usually give you greater quality, but will also output larger file sizes. This especially important to consider when playing over the internet, as the bandwidth of the user will determine how smoothly your files download and playback.

The Target Data Rate for the preset used in the example is 1228kbps, which is fairly standard for a file with a frame height of 480. If you are dealing with a standard definition frame size, your target data rate should be between 1000-1500 kbps.

If you are dealing with a frame size around 1280x720, your data rate should be between 2000-4000 kpbs.

For 1920x1080 frame sizes, you will want a data rate of 5,000 kbps at the minimum for web streaming on sites like youtube and vimeo, and much higher for broadcast or high quality archiving. For an example, Most HDSLR cameras encode the source file to h.264 around 40,000 kbps.

At the top of the right column is the Frame Size options
  • Same as Source will ignore any of the numbers you type in the Frame Size field and output a file with the identical frame size as the source file.
  • Unconstrained will contort the source file to fit the designated frame size, and if the source file has a different aspect ratio than the designated output frame size, you will see stretching or squishing of the image.
  • Maintain Aspect Ratio will change the designated frame size to something in accordance with the aspect ratio of the source file. i.e. after applying the preset to a source file. If you select Maintain Aspect ratio and change the horizontal frame size, it will automatically change the vertical frame size to be in accordance with the aspect ratio of the source file.
  • Letterbox or Pillar will apply bars on either the top and bottom, or sides of the output file if the aspect ratio of the source is different than that of the designated output.
Note: If your output frame size is the same as your source aspect ratio choosing Unconstrained, Maintain Aspect Ratio, or Letterbox or Pillar will all give you the same result. You will only get a different result from these three options if your source file and output frame aspect ratios are different.

The last of the Simple settings is Keyframes

A key frame, also known as an i-frame or Intra Frame, is a frame in which a complete image is stored in the data stream. Whenever a drastic change to the image occurs, such as when switching from one camera shot to another, or at a scene change, a key frame must be created. Checking Auto Key Frame on Scene Change will ensure this.

Squeeze will include key frames at arbitrary intervals while encoding video. For example, a key frame may be output once for each 10 seconds of video, (or once every 300 frames, which is default) even though the video image does not change enough visually to warrant the automatic creation of the key frame. This will allow seeking within the video stream at a minimum of 10 second intervals.

The higher the number the less keyframes will be use. Entering "300" would put one keyframe every 300 frames (or one keyframe per 10 seconds of video). Entering "1" would put a keyframe in each frame.

The more key frames you add, the higher the bit rate you will need to keep the same quality. This is because keyframes are less compressed frames and therefore need a higher bit rate per frame to keep the same quality as a more compressed frame type such as b-frames and p-frames.

For video with a lot of motion, transitions or other visually complex effects will benefit by keyframing more often, and by moving the slider towards more frequent auto keyframes.

Advanced settings

The following settings are more complex. For a better grasp of the following concepts, you may want to research the following articles:

Squeeze 8 will give brief explanations for many of these highly technical advanced settings by hovering over them with your mouse. Either way they are largely meant for expert compressionists and should be left at their default unless one has a working knowledge of them. Here we will cover some of the more easily accessible of the settings and give brief explanations of them.

Performance Slider

This setting is the easiest way to control much of the advanced settings. The slider moves from a scale of 1 to 16, 1 being the fastest/poorest quality and 16 being the slowest/best quality. You will notice as this slider is moved, that the advanced settings change automatically in conjunction. Thus the slider acts like a "preset" within the codec settings.

Interlace Mode should be set to progressive for web, computer, or mobile device

If you do select interlace, you will have the options of top or bottom field first. Interlacing would only be for files to be played back on a television.

Pixel Aspect Ratio is mainly for users with non-square pixel files.

If your file is square pixels, then the default setting will be sufficient. If your file is non-square pixels, you can choose the more appropriate aspect ratio.

AVC Profile (advanced video codec) settings help you control the profile of your output file

Different profiles have different features and work best on different devices and software.
  • Baseline Profile is primarily for low-cost applications that require additional data loss robustness. This profile is used in some videoconferencing and mobile applications.
  • Main Profile is used for standard-definition digital TV broadcasts that use the MPEG-4 format.
  • High Profile is the primary profile for broadcast and disc storage applications, particularly for high-definition television applications. This setting is recommended for optimal quality at the expense of file size and data rate.

Note: Higher profiles will be less compatible with older mobile devices such as iPhone 3g etc. To ensure maximum compatibility use the preset that corresponds with the device in which you care to ensure compatibility.


Squeeze will have the option of a checkbox labeled Auto Level, which if deselected, will allow you to choose the encoding level numerically from a drop-down menu.

Higher data rates will require higher encoding levels, but if you're not sure, it's best to leave the Auto checkbox selected.

Pyramidal Structure for B-Frame

B frames are bi-directional frames, which mean they are 'helper' frames that refer to frames that come before and after the video to render the frame. B pictures are more efficient at compressing data, therefore more b pictures allow for more compression and higher quality at lower bit rates and file sizes.
Squeeze 8 now allows for a Pyramidal Structure for B frames, which will render 3 b frames in a row, with the middle B frame used as reference for the b frames on either side. This is a means of achieving an even more efficient compression.
Note: The AVC profile must be set to Main or higher, and B Picures must be set to 3 in order to be able to use the Pyramidal Sructure.
You can select 0-10 b-pictures depending on the level and profile you are using. B frames also are more difficult to decode, so if you are encoding your file to be more compatible with older, slower computers or less-capable mobile devices you will want to use fewer b pictures or even none at all.

B-Frames as Reference are multi‑frame motion estimation and will allow increases in the quality of the video while allowing the same compression ratio.

Entropy Coding Mode

Context-adaptive binary arithmetic coding (CABAC) compresses data more efficiently than CAVLC but requires considerably more processing to decode.

Context-adaptive variable-length coding (CAVLC), is a lower-complexity alternative to CABAC and is more simple to decode.

Set Black Normalization to 16. The main concept h.264 codec had a resulting gamma shift, which checking this box should correct.

Color Range and Coefficients:

This setting will allow you to change the range of color that squeeze will use to complete the output.
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