File upload specifications

File upload specifications



1. Video

A video file must consist of one MP4 file, which may contain:

  • one video track
  • one or more audio tracks
Make sure your mp4 video files match the specifications in the table below, as closely as possible. After uploading, our platform will (re)encode your video and attempt to enforce these specifications whever possible. For instance if you upload video with 4:3 aspect ratio, we will enforce an out format of 16:9 by adding the appropriate "black bars" on the sides to ensure optimal playback performance on modern devices (which almost all are 16:9).

In general, we can handle almost any type of mp4 video file, but for an optimal result we advise you to try to match your default specifications as close as possible. When deviating from this format, cross-platform compatibility is not guaranteed.

Video container        

MP4

Video codec
H.264 (the output format will be H.264 for maximum device compatibility).
☞ Sample Aspect Ratio (SAR) 1:1 is required (i.e. square pixel).
☞ HDR currently not supported, export your file with Rec.709 profile.

Video minimum bitrate (kbps)

6000 (for HD), 20000 (for 4K).

Video frame rate

25 fps (fixed frame rate required)

Video width (pixels)

1920 (for HD) or 3840 (for 4K)

Video height pixels)

1080 (for HD) or 2160 (for 4K)

Audio codec

AACAudio

Audio minimum bitrate (kbps)

128 (consider 384 for 5.1 surround profiles)

Audio channels

2 (6 when 5.1 audio is desired, please indicate this to the team before uploading)

Multi-audio tracks considerations

The metadata attribute "language" must be properly filled with a 3-character language code (ISO 639.2), e.g. “eng”, “nld”.

The metadata attribute "title" must be properly field with the language name (e.g. "Nederlands", "Français")

The order of the audio tracks must reflect the intended order with the intended default language first: e.g. track[0] is original English, track[1] is dubbed French.

Filename considerations

Though all ascii characters are supported in filenames, it is highly recommended to not use spaces and only use alphanumeric characters combined with dots, hyphens and/or underscores, i.e.: [A-Za-z0-9\-_\.]+

    


Processing time

First your video needs to be uploaded. The time this takes depends on the size of your video file, and the speed of your internet connection. As video files are typically quite large, note that even with a fast internet connection it can take quite some time for a video file to upload.
Encoding starts as soon as the file has been completely uploaded. Encoding happens roughly "real-time”, so if you have uploaded a file with a duration of e.g. 1 hour, you may expect the encoding process to take at least that long. AudiencePlayer creates different bitrates, 1080p, 720p etc.etc., and that takes time. In order to save time, as many videos as possible will be processed in parallel whenever possible.

2. Subtitles

The preferred subtitle file is a WebVTT file, since this is the official standard we support. Make sure the subtitles files match the specifications in the table below.
(However, it is possible to upload an SRT file. If you upload SRT, AudiencePlayer will automatically attempt to convert your file to WebVTT.)

Type

WebVTT (.vtt), with character encoding UTF-8.

Filename format

Filename must be identical (including lower/uppercase) to the related video asset, with the following notes:

  • Extension must be .vtt or .srt

  • Encoding: UTF-8

  • File may be prefixed or suffixed with the "two character" language locale including an underscore
     

Example:

  • Video asset: FOObar-video.mp4

  • Subtitle asset (Dutch): nl_FOObar-video.vtt OR FOObar-video_nl.vtt

  • Subtitle asset (English): en_FOObar-video.vtt OR FOObar-video_en.vtt

Subtitle syntax considerations

The videos and subtitles will be delivered to a wide variety of devices, some of which are more or less flexible when it comes to their interpretation of WebVTT syntax.


When ingesting subtitles our platform performs a strict validation check on all files conform the WebVTT specifications outlined conform the published spec on w3.org.


Even if a subtitle asset is compliant, it is still recommended to not use e.g. enriched text markup, as compatibility issues on several (lower-end) devices have frequently been observed.


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