Configuration examples

This page shows some configuration examples for the encoding of an input media file (that is, an ElementaryStream).

Video stream

VideoStream properties do not have dependencies on each other. You can set properties such as resolution (height and width), bit rate, and frame rate independently.

{
  "videoStream": {
    "h264": {
      "profile": "high",
      "preset": "veryfast",
      "heightPixels": 360,
      "widthPixels": 640,
      "pixelFormat": "yuv420p",
      "bitrateBps": 550000,
      "rateControlMode": "vbr",
      "crfLevel": 21,
      "vbvSizeBits": 550000,
      "vbvFullnessBits": 495000,
      "gopDuration": "3s",
      "entropyCoder": "cabac",
      "bFrameCount": 3,
      "frameRate": 30,
      "aqStrength": 1
    }
  },
  "key": "video-stream0"
}

Audio stream

Certain AudioStream properties are dependent on each other. The channelCount property value must equal the number of layouts in the channelLayout array. This value must also equal the number of channels in a mapped input stream.

Basic audio stream

The following is an example of a non-mapped, non-mixed audio stream.

{
  "audioStream": {
    "codec": "aac",
    "bitrateBps": 64000,
    "channelCount": 2,
    "channelLayout": [
      "fl",
      "fr"
    ],
    "sampleRateHertz": 48000
  },
  "key": "audio-stream0"
}

Audio stream with mapping

The following is an example of a input-mapped audio stream. The output stereo AudioStream is composed of the following inputs:

  • Track 1
    • Channel 0
  • Track 1
    • Channel 1

Note that the channelCount property value must equal the number of objects defined under mapping, each with its own outputChannel.

{
  "key":  "audio-stream0",
  "audioStream": {
    "codec": "aac",
    "bitrateBps": 64000,
    "channelCount": 2,
    "channelLayout": [
      "fl",
      "fr"
    ],
    "sampleRateHertz": 48000,
    "mapping": [
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 1,
        "inputChannel": 0,
        "outputChannel": 0,
        "gainDb": 0
      },
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 1,
        "inputChannel": 1,
        "outputChannel": 1,
        "gainDb": 0
      }
    ]
  }
}

Audio stream with mixing

The following is an example of a mixed audio stream. The output stereo AudioStream is composed of the following inputs:

  • Track 2
    • Channel 0
    • Channel 2
    • Channel 4
  • Track 2
    • Channel 1
    • Channel 3
    • Channel 5
{
  "key":  "audio-stream0",
  "audioStream":  {
    "codec":  "aac",
    "bitrateBps":  128000,
    "channelCount":  2,
    "mapping":  [
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 2,
        "inputChannel": 0,
        "outputChannel": 0,
        "gainDb": 0
      },
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 2,
        "inputChannel": 2,
        "outputChannel": 0,
        "gainDb": 0
      },
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 2,
        "inputChannel": 4,
        "outputChannel": 0,
        "gainDb": 0
      },
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 2,
        "inputChannel": 1,
        "outputChannel": 1,
        "gainDb": 0
      },
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 2,
        "inputChannel": 3,
        "outputChannel": 1,
        "gainDb": 0
      },
      {
        "atomKey": "atom0",
        "inputKey": "video_and_stereo_audio",
        "inputTrack": 2,
        "inputChannel": 5,
        "outputChannel": 1,
        "gainDb": 0
      },
    "sampleRateHertz":  44100
  }
}

Text stream

TextStream properties do not have dependencies on each other. You can set properties independently.

Text streams may use an edit list to modify the output file. The following sections highlight the use of the edit list to provide captions.

The following example shows a text stream with one atom in edit list.

{
  "editList":[
     {
        "key":"atom0",
        "inputs":[
           "video_input0",
           "caption_input0"
        ],
        "startTimeOffset":"0s",
        "endTimeOffset":"300s"
     }
  ],
  "elementaryStreams":[
    {
      "key": "cea-stream0",
      "textStream": {
        "codec": "cea708",
        "mapping": [
          {
            "atomKey": "atom0",
            "inputKey": "caption_input0",
            "inputTrack": 0
          }
        ]
      }
    }
  ]
}

The following example shows a text stream with two atoms in edit list.

{
  "editList":[
     {
        "key":"atom0",
        "inputs":[
           "video_input0",
           "caption_input0"
        ],
        "startTimeOffset":"0s",
        "endTimeOffset":"300s"
     },
     {
        "key":"atom1",
        "inputs":[
           "video_input1",
           "caption_input1"
        ],
        "startTimeOffset":"0s",
        "endTimeOffset":"300s"
     }
  ],
  "elementaryStreams":[
    {
      "key": "cea-stream0",
      "textStream": {
        "codec": "cea708",
        "mapping": [
          {
          "atomKey": "atom0",
          "inputKey": "caption_input0",
          "inputTrack": 0
          },
          {
          "atomKey": "atom1",
          "inputKey": "caption_input1",
          "inputTrack": 0
          }
        ]
      }
    }
  ]
}

Advanced

The following sections outline various advanced configurations.

MuxStream and fmp4

A MuxStream that uses the fmp4 container can only contain a single ElementaryStream. For this container, use two MuxStreams: one for audio and one for video:

"muxStreams":[
  {
    "key": "hd3-video",
    "container": "fmp4",
    "elementaryStreams":["video-stream1"]
  },
  {
    "key": "hd3-audio",
    "container": "fmp4",
    "elementaryStreams":["audio-stream1"]
  }
],

Reusing streams in multiple manifests

The following example configuration shows two video and one audio encodings being used in both HLS and DASH manifests:

{
  "config": {
    "inputs": [
      {
        "key": "input0",
        "uri": "gs://GCS_BUCKET_NAME/GCS_INPUT_VIDEO"
      }
    ],
    "elementaryStreams": [
      {
        "videoStream": {
          "h264": {
            "heightPixels": 360,
            "widthPixels": 640,
            "bitrateBps": 500000,
            "frameRate": 30
          }
        },
        "key": "video-stream0"
      },
      {
        "videoStream": {
          "h264": {
            "heightPixels": 720,
            "widthPixels": 1280,
            "bitrateBps": 3200000,
            "frameRate": 30
          }
        },
        "key": "video-stream1"
      },
      {
        "audioStream": {
          "codec": "aac",
          "bitrateBps": 64000,
          "sampleRateHertz": 48000
        },
        "key": "audio-stream0"
      }
    ],
    "muxStreams": [
      {
        "key": "video-only-sd",
        "container": "fmp4",
        "elementaryStreams": [
          "video-stream0"
        ]
      },
      {
        "key": "video-only-hd",
        "container": "fmp4",
        "elementaryStreams": [
          "video-stream1"
        ]
      },
      {
        "key": "audio-only",
        "container": "fmp4",
        "elementaryStreams": [
          "audio-stream0"
        ]
      }
    ],
    "manifests": [
      {
        "fileName": "manifest.m3u8",
        "type": "HLS",
        "muxStreams": [
          "video-only-sd",
          "video-only-hd",
          "audio-only"
        ]
      },
      {
        "fileName": "manifest.mpd",
        "type": "DASH",
        "muxStreams": [
          "video-only-sd",
          "video-only-hd",
          "audio-only"
        ]
      }
    ],
    "output": {
      "uri": "gs://GCS_BUCKET_NAME/GCS_OUTPUT_VIDEO"

    }
  }
}