#The OutputSpec object

The OutputSpec object defines a single output rendition within a transcoding job. Each job can have 1—10 output specifications, and each output can produce a progressive download file or a streaming package with multiple variants.

Output specifications are passed in the outputs array when creating a job. You can define outputs inline with full configuration, or reference a preset for reusable encoding settings.

#Fields

{
  "type": "hls",
  "video": [
    {"codec": "h264", "resolution": "1080p", "quality": "standard"},
    {"codec": "h264", "resolution": "720p", "quality": "standard"},
    {"codec": "h264", "resolution": "480p", "quality": "economy"}
  ],
  "audio": [
    {"language": "eng", "label": "English", "is_default": true}
  ],
  "hls": {
    "manifest": "master",
    "segment_format": "fmp4",
    "playlist_type": "vod"
  },
  "segments": {
    "duration": 6,
    "gop_alignment": "aligned"
  }
}

#Output types

Progressive types (mp4, webm, mkv, mov) accept exactly one video variant. Streaming types (hls, dash, adaptive) accept up to 20 variants for ABR ladders.

Container codec compatibility. Each container only carries specific video codecs. mp4: h264, h265, av1. webm: vp9, av1. mkv: h264, h265, av1, vp9. mov: h264, h265. hls: h264, h265. dash: h264, h265, av1, vp9. Requests using an unsupported combination (e.g. vp9 in mp4 or mov, av1 in mov or hls) are rejected at job creation. adaptive (CMAF) is not restricted at this layer.

#Inline vs preset

There are two ways to define an output: inline with full configuration, or by referencing a saved preset.

#Inline

Specify type and video directly on the output. This gives you full control over every encoding parameter.

{
  "type": "mp4",
  "video": [
    {"codec": "h264", "resolution": "1080p", "quality": "standard"}
  ]
}

#Preset

Reference a saved configuration by preset ID or slug. The preset supplies type, video, and any other saved settings.

{
  "preset": "pst_x9y8z7w6v5"
}

{
  "preset": "web_1080p_standard"
}

The preset supplies the base configuration, and any inline field you set on the output overrides the corresponding preset value field-by-field. This applies to every field — type, video, audio, hls, dash, segments, subtitle_tracks, drm, content_aware, encoding_mode, disable_audio, and path_template. For example, providing an explicit video[] array fully replaces the preset’s ABR ladder, while providing only path_template overrides just the path and keeps everything else from the preset.

preset and inline fields are not mutually exclusive — you can reference a preset and override any field inline on the same output, and the inline value wins. At minimum, each output must provide either a preset or type + video.

#Audio tracks

The audio array configures multi-language audio tracks for streaming outputs. Each track maps to an audio rendition in the HLS/DASH manifest. Audio tracks are only valid for streaming types (hls, dash, adaptive).

#Attributes

{
  "type": "hls",
  "video": [
    {"codec": "h264", "resolution": "1080p", "quality": "standard"},
    {"codec": "h264", "resolution": "720p", "quality": "standard"}
  ],
  "audio": [
    {"language": "eng", "label": "English", "source_track": 0, "is_default": true},
    {"language": "spa", "label": "Spanish", "source_track": 1},
    {"language": "fra", "label": "French", "source_track": 2}
  ]
}

Audio tracks are free — they do not add to the per-minute cost. Progressive outputs (mp4, webm, mkv, mov) automatically include the default audio track without explicit configuration.

#HLS configuration

The hls object configures HLS-specific settings. Only valid when type is hls or adaptive.

#Attributes

{
  "hls": {
    "manifest": "master",
    "segment_format": "fmp4",
    "playlist_type": "vod",
    "variant_pattern": "{codec}_{resolution}"
  }
}

Use fmp4 segment format when targeting modern players and devices. It enables CMAF compatibility, which means HLS and DASH can share the same segments when using the adaptive output type. Use ts only when you need to support legacy devices that do not support fragmented MP4.

#DASH configuration

The dash object configures DASH-specific settings. Only valid when type is dash or adaptive.

#Attributes

{
  "dash": {
    "manifest": "stream"
  }
}

#Segment configuration

The segments object controls how streaming outputs are segmented. Only valid for streaming types (hls, dash, adaptive).

#Attributes

{
  "segments": {
    "duration": 4,
    "gop_alignment": "aligned"
  }
}

aligned is recommended for ABR streaming. It ensures all variants have keyframes at the same timestamps, enabling instant quality switching without buffering or visual glitches.

#Path templates

Customize output file paths using template variables. The path_template field on an output composes additively with the job-level output_path_template: the effective template is <output_path_template>/<path_template>. When the job-level template is unset, the per-output path_template is used on its own.

#Variables

{
  "path_template": "{date}/{job_id}/{type}/{codec}_{resolution}"
}

Produces: 2025-02-28/job_a1b2c3d4e5f6/hls/h264_1080p

Path templates are appended to the output origin’s base path. For streaming outputs with multiple variants, the {codec} and {resolution} variables resolve per-variant within the output directory structure.

#Validation rules

Transcodely validates output specification configuration at job creation time. The following constraints are enforced:

#Examples

#Simple MP4 output

A single progressive MP4 file with H.264 encoding at 1080p.

{
  "type": "mp4",
  "video": [
    {"codec": "h264", "resolution": "1080p", "quality": "standard"}
  ]
}

#HLS ABR ladder with multi-language audio

An HLS streaming package with three quality tiers and three audio languages. Uses CMAF segments with aligned GOPs for seamless ABR switching.

{
  "type": "hls",
  "video": [
    {"codec": "h264", "resolution": "1080p", "quality": "standard"},
    {"codec": "h264", "resolution": "720p", "quality": "standard"},
    {"codec": "h264", "resolution": "480p", "quality": "economy"}
  ],
  "audio": [
    {"language": "eng", "label": "English", "source_track": 0, "is_default": true},
    {"language": "spa", "label": "Spanish", "source_track": 1},
    {"language": "fra", "label": "French", "source_track": 2}
  ],
  "hls": {
    "manifest": "master",
    "segment_format": "fmp4",
    "playlist_type": "vod"
  },
  "segments": {
    "duration": 6,
    "gop_alignment": "aligned"
  }
}

#Adaptive output with DRM, subtitles, and content-aware encoding

A full-featured adaptive output that produces both HLS and DASH manifests from shared CMAF segments:

• Ladder: four H.265 variants stepping from 2160p premium down to 480p economy.
• DRM: Widevine and FairPlay under the cbcs scheme, keyed by an external license server.
• Tracks & tuning: English (default) and Spanish audio, two WebVTT subtitle tracks, and per-title content-aware encoding targeting VMAF 95.

{
  "type": "adaptive",
  "video": [
    {"codec": "h265", "resolution": "2160p", "quality": "premium"},
    {"codec": "h265", "resolution": "1080p", "quality": "standard"},
    {"codec": "h265", "resolution": "720p", "quality": "standard"},
    {"codec": "h265", "resolution": "480p", "quality": "economy"}
  ],
  "audio": [
    {"language": "eng", "label": "English", "is_default": true},
    {"language": "spa", "label": "Spanish"}
  ],
  "hls": {
    "manifest": "master",
    "segment_format": "fmp4"
  },
  "dash": {
    "manifest": "manifest"
  },
  "segments": {
    "duration": 4,
    "gop_alignment": "aligned"
  },
  "subtitle_tracks": [
    {
      "operation": "convert",
      "source_url": "gs://my-bucket/subs/en.srt",
      "output_format": "webvtt",
      "language": "eng",
      "label": "English",
      "is_default": true
    },
    {
      "operation": "convert",
      "source_url": "gs://my-bucket/subs/es.srt",
      "output_format": "webvtt",
      "language": "spa",
      "label": "Spanish"
    }
  ],
  "drm": {
    "systems": ["widevine", "fairplay"],
    "scheme": "cbcs",
    "key_server": {
      "license_server_url": "https://drm.example.com/v1/keys",
      "auth_token": "Bearer eyJhbGciOiJIUzI1NiJ9..."
    }
  },
  "content_aware": {
    "mode": "per_title",
    "vmaf_target": 95
  },
  "path_template": "{date}/{job_id}/adaptive"
}

#Preset-based output with overrides

Reference a saved preset and add subtitle tracks and a custom path template on top.

{
  "preset": "web_1080p_standard",
  "subtitle_tracks": [
    {
      "operation": "passthrough",
      "source_stream_index": 0,
      "language": "eng",
      "label": "English",
      "is_default": true
    }
  ],
  "path_template": "{date}/{job_id}/preset"
}