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 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 whenever 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.

☞ If you handle processing your video content by yourself, without a video lab and/or media-partner, these articles might be of value as well, they outline freely available open source tooling to help you prepare your video content for upload: Please see doc section: Tools.

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 48 kHz

Audio bitrate (kbps)

128 (for stereo)
384 (5.1 surround)

☞ Please also see multi-audio track considerations below.

Audio channels

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

Multi-audio track 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").

☞ Ensure the exact same bitrate for each audio channel in the mp4-file: All stereo channels should have same bitrate (128), and all surround channels should have the same bitrate (384).

☞ Note that not all devices properly handle surround channels, ensure your Asset always has a normal stereo track as well to accommodate legacy devices!

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\-_\.]+

If your filename (including the ".mp4" extension) contains more than 64 characters, it will automatically be truncated to prevent certain (device)limitations with long filenames when your file ultimately is processed and streamed.
We strongly advise you to keep your filenames shorter than 64 characters.

Filesize considerations

Limit the file size per single mp4 file to 25 Gigabytes.

    

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.


    • Related Articles

    • Bulk video upload

      Video and subtitle files can be uploaded in bulk, directly from your computer. For this, you will need to download specialized file transfer software. This software needs to be installed and configured with the secret credentials that the platform ...