NEWDolby Media Processing APIs are now the Dolby.io Media APIs Learn More >
X

Media Info

Guide to media file formats and metadata

Whether your application is dealing with archive media or user-generated content you may encounter a range of media formats. Digital media takes the form of a large binary file in a wrapper called a container. There is a wide range of containers and standards for how audio and video is encoded.

Media Analyze API

The Dolby.io Media Analyze API can be used to get information about the media format including details on the container, audio, and video components. The Supported Media Formats lists the types of media that can be analyzed.

{
  "media_info": {
    "audio": {
      "bitrate": 256001,
      "channel_order": "L R",
      "channels": 2,
      "codec": "aac",
      "duration": 97.685,
      "sample_rate": 48000
    },
    "container": {
      "bitrate": 1651700,
      "duration": 97.685,
      "kind": "mp4",
      "size": 20168287
    },
    "video": {
      "bitrate": 1391583,
      "codec": "h264",
      "duration": 97.685,
      "frame_rate": 25,
      "height": 720,
      "width": 1280
    }
  },
  ...
}

📘

Does Dolby.io support your media format?

See the Supported Media Formats guide for the containers and codecs that are supported by Media APIs.

Media Containers

The container details include information about the container type. This can be informative for a few reasons. Knowing the kind of container can help identify how metadata is stored within the file such as artist, track name, etc. Knowing the kind of container can help identify whether a piece of media can be played or ingested as part of a media workflow process or other transcoding service.

The following information about the container is determined:

  • kind: a description of the type of media container
  • duration: the media duration (in seconds)
  • bitrate: media bitrate (in bits per second)
  • size: media size (in bytes)

Audio Information

The audio information includes details about the audio stream. Similar to the
container type, the audio type is important to understand compatibility of a
file with any downstream processing your application might require such as
transcoding.

You can also use these details as an indicator of the quality of the audio in a file if a lot of data compression has been used. The size and duration are also useful indicators for a user interface to help end-users understand if media has been
truncated or lost from the creators intent.

If the duration of the audio and video are significantly different this can
also be an issue. The number of channels is useful to know if channels are
missing, or if a multichannel audio is available.

The following information about the audio stream is determined:

  • duration: audio duration (in seconds)
  • codec: identifier for the compression codec
  • sample_rate: audio sample-rate, generally 44100 or 48000
  • bitrate - audio bitrate (in bits per second)
  • channels: the number of channels, generally mono (1) or stereo (2)
  • channel_order: a comma separated list of channel identifiers if there are more than two channels
  • bit_depth: generally 16, 24, or 32-bit

Video Information

The video information includes details about the video stream. Similar to the audio and container type, the video type is important to understand compatibility of a file with downstream processing, transcoding, and delivery. For audio files, the video information may not be returned.

The video details can provide hints to the quality of the video contained. For example, a lot of data compression could cause distortion and other undesirable
effects. Presenting a user interface with the duration and file size are a good indicator of a successful delivery.

The following information about the video stream is determined:

  • codec: identifies the compression codec
  • frame_rate: the number of frames per second (as a floating-point number)
  • height: picture height (in pixels)
  • width: picture width (in pixels)
  • duration: video duration (in seconds)
  • bitrate: video bitrate (in bits per second)

Did this page help you?