[JIM] H.264 Settings for just:in mac explained v.5.5

Owned by Christian Schabasser
Last updated: Jul 19, 2023 by Manuel Grund
2 min read

There are different values and settings that can be customised within a just:in mac H.264 Capture Preset. Initially, the container type can be selected. There are two container options available:

  • AVFoundation QuickTime (with Timecode Track)

  • MP4 (no Timecode Track)

H.264 is a complex codec standard and is a bit more tedious to set up. Therefore, just:in mac provides various options, which can be modified within an “H.264 preset”. After choosing the container type, you have to define two general settings:

After choosing the container type, you have to define two general settings:

  • Resolution

  • Frame rate (has to match the Video Mode of the Channel)

Next, you need to select the H.264 profile. Three options are available:

  • “Baseline” - Baseline encodes are the most basic form of encoding. While decoding is much easier, it may also require much higher bit rates to maintain the same level of quality.

  • “Main” - The middle ground. Most modern/current devices will support this profile.

  • “High Profile” - For best quality and file size at the expense of CPU time in both decoding and encoding.

Then you can set the Bitrate in bit/s.

B-Frame - Short for bidirectional frame, or bidirectional predictive frame. As the name suggests, B-frames rely on the frames preceding and following them. B-frames contain only the data that has changed from the preceding frame or is different from the data in the very next frame. B-frames increase compression efficiency, particularly at lower bitrates. We recommend having this option enabled.

The GOP-Size determines the maximum distance between I-frames. Very high GOP lengths will result in a slightly more efficient compression but will make seeking/scratching in the video somewhat more difficult. The recommended default is 0, which sets the encoder to Auto-GOP.

Lastly, you can define the Entropy Mode. When you select the “Main “or “High Profile” (“Baseline” is “CAVLC” only), you have two options:

  • “CAVLC”: Context-based adaptive variable-length coding

  • “CABAC”: Context-based adaptive binary arithmetic coding

“CAVLC” is the lower-quality, easier-to-decode option, “CABAC” is the higher-quality, harder-to-decode option.

Recommended settings for HD presets:

  • Resolution: custom

  • Frame rate: custom

  • Profile: “Main” or “High”

  • Bitrate: custom

  • Allow B-Frames: Activated

  • GOP-Size: “0”

  • Entropy Mode: “CABAC”

Recommended settings for SD presets:

  • Resolution: custom

  • Frame rate: custom

  • Profile: “Baseline” or “Main”

  • Bitrate: custom

  • Allow B-Frames: Activated

  • GOP-Size: “0”

  • Entropy Mode: “CAVLC”

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