Output metadata

Artikel
01/10/2023

Warning

Azure Media Services will be retired June 30th, 2024. For more information, see the AMS Retirement Guide.

An encoding job is associated with an input asset (or assets) on which you want to perform some encoding tasks. For example, encode an MP4 file to H.264 MP4 adaptive bitrate sets; create a thumbnail; create overlays. Upon completion of a task, an output asset is produced. The output asset contains video, audio, thumbnails, and other files. The output asset also contains a file with metadata about the output asset. The name of the metadata JSON file has the following format: <source_file_name>_manifest.json (for example, BigBuckBunny_manifest.json). You should scan for any *_metadata.json and query the filepath string within to find the source filename (without truncation).

Media Services does not preemptively scan input assets to generate metadata. Input metadata is generated only as an artifact when an input asset is processed in a job. Hence this artifact is written to the output asset. Different tools are used to generate metadata for input assets and output assets. Therefore, the input metadata has a slightly different schema than the output metadata.

This article discusses the elements and types of the JSON schema on which the output metadata (<source_file_name>_manifest.json) is based.

BaseName character length when using CopyVideo or CopyAudio presets

The {baseName} file naming macro used in the naming of the output metadata file is shortened to 32 chars when using any standard encoding preset or custom preset. However, to avoid a naming conflict when using one of the CopyCodec operations (CopyAudio or CopyVideo) in a custom preset, the {Basename} is limited to 64 chars. This is to support scenarios where customers want to archive all of the output files in their asset. If the filename is very long, the first 32 chars might be the same across multiple output files. In this case, the first 32 chars would produce duplicated output files when using CopyVideo or CopyAudio. As a result, the {Basename} behavior is to retain 64 chars if CopyCodec is used in the preset.

You can find the complete schema code and JSON example at the end of this article.

AssetFile

Collection of AssetFile entries for the encoding job.

Name	Description
Sources	Collection of input/source media files, that was processed in order to produce this AssetFile. Example: `"Sources": [{"Name": "Ignite-short_1280x720_AACAudio_3551.mp4"}]`
VideoTracks	Each physical AssetFile can contain in it zero or more videos tracks interleaved into an appropriate container format. See VideoTracks.
AudioTracks	Each physical AssetFile can contain in it zero or more audio tracks interleaved into an appropriate container format. This is the collection of all those audio tracks. For more information, see AudioTracks.
Name Required	The media asset file name. Example: `"Name": "Ignite-short_1280x720_AACAudio_3551.mp4"`
Size Required	Size of the asset file in bytes. Example: `"Size": 32414631`
Duration Required	Content play back duration. For more information, see the ISO8601 format. Example: `"Duration": "PT1M10.315S"`

VideoTracks

Each physical AssetFile can contain in it zero or more videos tracks interleaved into an appropriate container format. The VideoTracks element represents a collection of all the video tracks.

Name	Description
Id Required	Zero-based index of this video track. Note: This Id is not necessarily the TrackID as used in an MP4 file. Example: `"Id": 1`
FourCC Required	Video codec FourCC code that is reported by ffmpeg. Example: `"FourCC": "avc1" \| "hev1" \| "hvc1"`
Profile	H264 profile (only applicable to H264 codec) Example: `"Profile": "High"`
Level	H264 level (only applicable to H264 codec). Example: `"Level": "3.2"`
Width Required	Encoded video width in pixels. Example: `"Width": "1280"`
Height Required	Encoded video height in pixels. Example: `"Height": "720"`
DisplayAspectRatioNumerator Required	Video display aspect ratio numerator. Example: `"DisplayAspectRatioNumerator": 16.0`
DisplayAspectRatioDenominator Required	Video display aspect ratio denominator. Example: `"DisplayAspectRatioDenominator": 9.0`
Framerate Required	Measured video frame rate in .3f format. Example: `"Framerate": 29.970`
Bitrate Required	Average video bit rate in bits per second, as calculated from the AssetFile. Counts only the elementary stream payload, and does not include the packaging overhead. Example: `"Bitrate": 3551567`
TargetBitrate Required	Target average bitrate for this video track, as requested via the encoding preset, in bits per second. Example: `"TargetBitrate": 3520000`

AudioTracks

Each physical AssetFile can contain in it zero or more audio tracks interleaved into an appropriate container format. The AudioTracks element represents a collection of all those audio tracks.

Name	Description
Id Required	Zero-based index of this audio track. Note: This is not necessarily the TrackID as used in an MP4 file. Example: `"Id": 2`
Codec	Audio track codec string. Example: `"Codec": "aac"`
Language	Example: `"Language": "eng"`
Channels Required	Number of audio channels. Example: `"Channels": 2`
SamplingRate Required	Audio sampling rate in samples/sec or Hz. Example: `"SamplingRate": 48000`
Bitrate Required	Average audio bit rate in bits per second, as calculated from the AssetFile. Counts only the elementary stream payload, and does not include the packaging overhead. Example: `"Bitrate": 128041`

JSON schema example

{
  "AssetFile": [
    {
      "Sources": [
        {
          "Name": "Ignite-short_1280x720_AACAudio_3551.mp4"
        }
      ],
      "VideoTracks": [
        {
          "Id": 1,
          "FourCC": "avc1",
          "Profile": "High",
          "Level": "3.2",
          "Width": "1280",
          "Height": "720",
          "DisplayAspectRatioNumerator": 16.0,
          "DisplayAspectRatioDenominator": 9.0,
          "Framerate": 29.970,
          "Bitrate": 3551567,
          "TargetBitrate": 3520000
        }
      ],
      "AudioTracks": [
        {
          "Id": 2,
          "Codec": "aac",
          "Language": "eng",
          "Channels": 2,
          "SamplingRate": 48000,
          "Bitrate": 128041
        }
      ],
      "Name": "Ignite-short_1280x720_AACAudio_3551.mp4",
      "Size": 32414631,
      "Duration": "PT1M10.315S"
    },
    {
      "Sources": [
        {
          "Name": "Ignite-short_960x540_AACAudio_2216.mp4"
        }
      ],
      "VideoTracks": [
        {
          "Id": 1,
          "FourCC": "avc1",
          "Profile": "High",
          "Level": "3.1",
          "Width": "960",
          "Height": "540",
          "DisplayAspectRatioNumerator": 16.0,
          "DisplayAspectRatioDenominator": 9.0,
          "Framerate": 29.970,
          "Bitrate": 2216326,
          "TargetBitrate": 2210000
        }
      ],
      "AudioTracks": [
        {
          "Id": 2,
          "Codec": "aac",
          "Language": "eng",
          "Channels": 2,
          "SamplingRate": 48000,
          "Bitrate": 128041
        }
      ],
      "Name": "Ignite-short_960x540_AACAudio_2216.mp4",
      "Size": 20680897,
      "Duration": "PT1M10.315S"
    },
    {
      "Sources": [
        {
          "Name": "Ignite-short_640x360_AACAudio_1150.mp4"
        }
      ],
      "VideoTracks": [
        {
          "Id": 1,
          "FourCC": "avc1",
          "Profile": "High",
          "Level": "3.0",
          "Width": "640",
          "Height": "360",
          "DisplayAspectRatioNumerator": 16.0,
          "DisplayAspectRatioDenominator": 9.0,
          "Framerate": 29.970,
          "Bitrate": 1150440,
          "TargetBitrate": 1150000
        }
      ],
      "AudioTracks": [
        {
          "Id": 2,
          "Codec": "aac",
          "Language": "eng",
          "Channels": 2,
          "SamplingRate": 48000,
          "Bitrate": 128041
        }
      ],
      "Name": "Ignite-short_640x360_AACAudio_1150.mp4",
      "Size": 11313920,
      "Duration": "PT1M10.315S"
    },
    {
      "Sources": [
        {
          "Name": "Ignite-short_480x270_AACAudio_722.mp4"
        }
      ],
      "VideoTracks": [
        {
          "Id": 1,
          "FourCC": "avc1",
          "Profile": "High",
          "Level": "2.1",
          "Width": "480",
          "Height": "270",
          "DisplayAspectRatioNumerator": 16.0,
          "DisplayAspectRatioDenominator": 9.0,
          "Framerate": 29.970,
          "Bitrate": 722682,
          "TargetBitrate": 720000
        }
      ],
      "AudioTracks": [
        {
          "Id": 2,
          "Codec": "aac",
          "Language": "eng",
          "Channels": 2,
          "SamplingRate": 48000,
          "Bitrate": 128041
        }
      ],
      "Name": "Ignite-short_480x270_AACAudio_722.mp4",
      "Size": 7554708,
      "Duration": "PT1M10.315S"
    },
    {
      "Sources": [
        {
          "Name": "Ignite-short_320x180_AACAudio_380.mp4"
        }
      ],
      "VideoTracks": [
        {
          "Id": 1,
          "FourCC": "avc1",
          "Profile": "High",
          "Level": "1.3",
          "Width": "320",
          "Height": "180",
          "DisplayAspectRatioNumerator": 16.0,
          "DisplayAspectRatioDenominator": 9.0,
          "Framerate": 29.970,
          "Bitrate": 380655,
          "TargetBitrate": 380000
        }
      ],
      "AudioTracks": [
        {
          "Id": 2,
          "Codec": "aac",
          "Language": "eng",
          "Channels": 2,
          "SamplingRate": 48000,
          "Bitrate": 128041
        }`
      ],
      "Name": "Ignite-short_320x180_AACAudio_380.mp4",
      "Size": 4548932,
      "Duration": "PT1M10.315S"
    }
  ]
}

Get help and support

You can contact Media Services with questions or follow our updates by one of the following methods:

Q & A
Stack Overflow. Tag questions with azure-media-services.
@MSFTAzureMedia or use @AzureSupport to request support.
Open a support ticket through the Azure portal.