H.264 Settings

Encoding recommendations

In addition to settings found on this page, you may want to include the following general video settings.

• video_reference_frames
• video_codec_profile
• video_codec_level
• video_bframes

tuning

API Versions: V1, V2

Parent: outputs

Valid Values: film, animation, grain, psnr, ssim, fastdecode, or zerolatency

Compatible Job Types: All

Example: film

Description:

Tune the output video to optimize for a specific content type, or a specific encoding priority.

Behind the scenes, this sets the x264 --tune option.

Possible values:

• film - optimized for most non-animated video content (not only feature films).
• animation - optimized for animation. Note that most 3D animation behaves more like film and not like hand-drawn animation, so only use this for hand-drawn animation (anime, classic Disney, etc.).
• grain - optimized for film with high levels of grain.
• psnr - uses "peak signal-to-noise ratio" to optimize video quality.
• ssim - uses "structural similarity" to optimize video quality.
• fastdecode - reduces encoding complexity, to allow for easier decoding.
• zerolatency - x264 will keep an internal buffer of frames to improve quality; this setting removes that buffer, but reduces quality.

{
  "input": "s3://zencodertesting/test.mov",
  "outputs": [
    {
      "tuning": "film"
    }
  ]
}

crf

API Versions: V1, V2

Parent: outputs

Valid Values: 1-51

Compatible Job Types: All

Example: 26

Description:

CRF is a bitrate-control setting, and sets a constant ratefactor. This is closely related to constant quantizer encoding, though CRF mode generally achieves better compression than constant Q encoding by reducing the quantizer quality on "less important" frames. Read more about crf.

The Zencoder Quality setting determines an appropriate CRF for a given video. So if you set both Quality and CRF, the CRF setting will override Quality.

Valid values are 0-51, with lower values being better quality. Generally speaking, you shouldn't have to go below 16; 16 is nearly lossless for most files. Around 24 usually looks pretty good. Around 35 looks pretty compressed.

{
  "input": "s3://zencodertesting/test.mov",
  "outputs": [
    {
      "crf": "26"
    }
  ]
}