Input metadata

Article
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. Upon completion of a task, an output asset is produced. The output asset contains video, audio, thumbnails, manifest, and other files.

The output asset also contains a file with metadata about the input asset. The name of the metadata JSON file has a random ID, do not use it to identify the input asset that output asset belongs to. To identify the input asset it belongs to, use the Uri field (for more information, see Other child elements).

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 input metada (<asset_id>_metadata.json ) is based. For information about the file that contains metadata about the output asset, see Output metadata.

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

Note

All time is based on the ISO-8601 format. For more information about duration formatting, see Times and Durations in the same article.

AssetFile

Contains a collection of AssetFile elements for the encoding job.

Note

The following four child elements must appear in a sequence.

Name	Description
VideoTracks	Each physical asset file can contain zero or more videos tracks interleaved into an appropriate container format. For more information, see VideoTracks.
AudioTracks	Each physical asset file can contain zero or more audio tracks interleaved into an appropriate container format. For more information, see AudioTracks
Metadata	Asset file’s metadata represented as key\value strings. For example: `<Metadata key="language" value="eng" />`

Other child elements

Name	Description
Name Required	Asset file name. Example: `"Name": "Ignite-short.mp4"`
Uri Required	The URL where the input asset is located. To identify the input asset the output asset belongs to, use the `Uri` field instead of ID.
Size Required	Size of the asset file in bytes. Example: `"Size": 75739259`
Duration Required	Content play back duration. Example: `"Duration": "PT1M10.304S"`.
NumberOfStreams Required	Number of streams in the asset file. Example: `"NumberOfStreams": 2`
FormatNames Required	Format names. Example: `"FormatNames": "mov,mp4,m4a,3gp,3g2,mj2"`
FormatVerboseName Required	Format verbose names. Example: `"FormatVerboseName": "QuickTime / MOV"`
StartTime	Content start time. Example: `"StartTime": "PT0S"`
OverallBitRate	Average bitrate of the asset file in bits per second. Example: `"OverallBitRate": 8618539`

VideoTracks

Name	Description
FourCC Required	Video codec FourCC code that is reported by ffmpeg. Example: `"FourCC": "avc1" \| "hev1" \| "hvc1"`
Profile	Video track's profile. Example: `"Profile": "Main"`
Level	Video track's level. Example: `"Level": "3.2"`
PixelFormat	Video track's pixel format. Example: `"PixelFormat": "yuv420p"`
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`
SampleAspectRatioNumerator	Video sample aspect ratio numerator. Example: `"SampleAspectRatioNumerator": 1.0`
SampleAspectRatioDenominator	Example: `"SampleAspectRatioDenominator": 1.0`
FrameRate Required	Measured video frame rate in .3f format. Example: `"FrameRate": 29.970`
Bitrate	Average video bit rate in bits per second, as calculated from the asset file. Only the elementary stream payload is counted, and the packaging overhead is not included. Example: `"Bitrate": 8421583`
HasBFrames	Video track number of B frames. Example: `"HasBFrames": 2`
Metadata	Generic key/value strings that can be used to hold a variety of information. See the full example at the end of the article.
Id Required	Zero-based index of this audio or video track. This Id is not necessarily the TrackID as used in an MP4 file. Example: `"Id": 2`
Codec	Video track codec string. Example: `"Codec": "h264 \| hev1"`
CodecLongName	Audio or video track codec long name. Example: `"CodecLongName": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"`
Codec	Video track codec string. Example: `"Codec": "h264 \| hev1"`
TimeBase Required	Time base. Example: `"TimeBase": "1/30000"`
NumberOfFrames	Number of frames (present for video tracks). Example: `"NumberOfFrames": 2107`
StartTime	Track start time. Example: `"StartTime": "PT0.033S"`
Duration	Track duration. Example: `"Duration": "PT1M10.304S"`

AudioTracks

Name	Description
SampleFormat	Sample format. Example: `"SampleFormat": "fltp"`
ChannelLayout	Channel layout. Example: `"ChannelLayout": "stereo"`
Channels Required	Number (0 or more) of audio channels. Example: `"Channels": 2`
SamplingRate Required	Audio sampling rate in samples/sec or Hz. Example: `"SamplingRate": 48000`
Bitrate	Average audio bit rate in bits per second, as calculated from the asset file. Only the elementary stream payload is counted, and the packaging overhead is not included in this count. Example: `"Bitrate": 192080`
Metadata	Generic key/value strings that can be used to hold a variety of information. See the full example at the end of the article.
Id Required	Zero-based index of this audio or video track. This is not necessarily that the TrackID as used in an MP4 file. Example: `"Id": 1`
Codec	Video track codec string. Example: `"Codec": "aac"`
CodecLongName	Audio or video track codec long name. Example: `"CodecLongName": "AAC (Advanced Audio Coding)"`
TimeBase Required	Time base. Example: `"TimeBase": "1/48000"`
NumberOfFrames	Number of frames (present for video tracks). Example: `"NumberOfFrames": 3294`
StartTime	Track start time. Example: `"StartTime": "PT0S"`
Duration	Track duration. Example: `"Duration": "PT1M10.272S"`

Metadata

Name	Description
key Required	The key in the key/value pair.
value Required	The value in the key/value pair.

Schema example

{
  "AssetFile": [
    {
      "VideoTracks": [
        {
          "FourCC": "avc1",
          "Profile": "Main",
          "Level": "3.2",
          "PixelFormat": "yuv420p",
          "Width": "1280",
          "Height": "720",
          "DisplayAspectRatioNumerator": 16.0,
          "DisplayAspectRatioDenominator": 9.0,
          "SampleAspectRatioNumerator": 1.0,
          "SampleAspectRatioNumeratorSpecified": true,
          "SampleAspectRatioDenominator": 1.0,
          "SampleAspectRatioDenominatorSpecified": true,
          "FrameRate": 29.970,
          "Bitrate": 8421583,
          "BitrateSpecified": true,
          "HasBFrames": 2,
          "HasBFramesSpecified": true,
          "Disposition": {
            "Default": 1
          },
          "Metadata": [
            {
              "key": "creation_time",
              "value": "2018-02-21T21:42:08.000000Z"
            },
            {
              "key": "language",
              "value": "eng"
            },
            {
              "key": "handler_name",
              "value": "Video Media Handler"
            },
            {
              "key": "encoder",
              "value": "AVC Coding"
            }
          ],
          "Id": 2,
          "Codec": "h264",
          "CodecLongName": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
          "TimeBase": "1/30000",
          "NumberOfFrames": 2107,
          "NumberOfFramesSpecified": true,
          "StartTime": "PT0.033S",
          "Duration": "PT1M10.304S"
        }
      ],
      "AudioTracks": [
        {
          "SampleFormat": "fltp",
          "ChannelLayout": "stereo",
          "Channels": 2,
          "SamplingRate": 48000,
          "Bitrate": 192080,
          "BitrateSpecified": true,
          "BitsPerSampleSpecified": true,
          "Disposition": {
            "Default": 1
          },
          "Metadata": [
            {
              "key": "creation_time",
              "value": "2018-02-21T21:42:08.000000Z"
            },
            {
              "key": "language",
              "value": "eng"
            },
            {
              "key": "handler_name",
              "value": "Sound Media Handler"
            }
          ],
          "Id": 1,
          "Codec": "aac",
          "CodecLongName": "AAC (Advanced Audio Coding)",
          "TimeBase": "1/48000",
          "NumberOfFrames": 3294,
          "NumberOfFramesSpecified": true,
          "StartTime": "PT0S",
          "Duration": "PT1M10.272S"
        }
      ],
      "Metadata": [
        {
          "key": "major_brand",
          "value": "mp42"
        },
        {
          "key": "minor_version",
          "value": "19529854"
        },
        {
          "key": "compatible_brands",
          "value": "mp42isom"
        },
        {
          "key": "creation_time",
          "value": "2018-02-21T21:42:08.000000Z"
        }
      ],
      "Name": "Ignite-short.mp4",
      "Uri": "https://amsstorageacct.blob.core.windows.net/asset-00000000-0000-0000-000000000000/ignite.mp4",
      "Size": 75739259,
      "Duration": "PT1M10.304S",
      "NumberOfStreams": 2,
      "FormatNames": "mov,mp4,m4a,3gp,3g2,mj2",
      "FormatVerboseName": "QuickTime / MOV",
      "StartTime": "PT0S",
      "OverallBitRate": 8618539,
      "OverallBitRateSpecified": true
    }
  ]
}

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.