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Specification for Apps

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2022

Version: 4.2022

Date: 20202021-0912-0728

CONTENTS

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2. INTRODUCTION

2.1 Scope

This document specifies the requirements for Vewd TV Applications and provides guidelines on how to develop Vewd-compliant apps. It is primarily aimed at app developers and owners.

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We also use an additional compliance term not described in RFC2119:

• CONDITIONALLY REQUIRED - an item or a feature is supported in the browser if the underlying platform supports this capability.

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3. REQUIREMENTS

This section outlines the requirements for an app to be certified to run on Vewd TV  Devices.

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This is normally supported on high-end devices, but typically require  requires more platform resources than CSS/HTML/JavaScript.

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3.3.2.1 Restrictions for HLS content

1. Audio/video encoding

1. The same codec MUST be used across all variant streams (all quality levels).

2. Audio parameters (number of channels and sample rates) MUST be the same across all variant streams.

2. Media segments

1. All media segments MUST be independently decodable. Consequently, the first video frame in every segment that contains video MUST be an IDR frame.

2. Discontinuities in timestamps, frame rate, encoding profiles, or audio/video parameters MUST NOT occur within segments.

3. Playlist files (M3U8)

1. Audio and video playlists MUST use the same target duration and MUST contain the same duration of the content.

2. A playlist MUST NOT contain invalid URLs.

3. Media sequence numbers MUST be aligned across all variant streams (quality levels), so that media sequence numbers can be used to identify matching content.

4. For live streams, media segments MUST remain available on the server for at least one target duration after the segment disappears from the playlist.

5. Playlists MUST use sufficiently accurate segment durations to ensure that the sum of the #EXTINF durations of any contiguous group of segments is within one video frame duration of the actual duration.

6. Playlists MUST provide at least 6 segments in live/linear streams.

7. Discontinuities in timestamps, frame rate, encoding profiles, or audio/video parameters MAY occur between segments, but such discontinuities MUST be indicated using the #EXT-X-DISCONTINUITY tag.

8. EXT-X-STREAM-INF tags MUST always provide CODECS and RESOLUTION attributes.

4. Subtitles

1. The app MUST support subtitles that conform to the Subtitles and Closed Captions section.

5. DRM

1. The decryption key MUST be directly downloadable via an HTTP or HTTPS URLs

2. Note that with AES-128 encrypted HLS, segments are completely encrypted.

3.3.2.2 Restrictions for MPEG-DASH content

• The media segment container format MUST be the ISO Base Media File Format (aka MP4).

• All media segments MUST be independently decodable. Consequently, the first video frame in every segment that contains video MUST be an IDR frame.

• Manifest URLs MAY include the MPD anchor, but MUST NOT use any other than the ‘t’ parameter ([3] section C.4)

• The app MAY support multiple audio tracks associated with multiple Adaptation Sets defined in an MPD of MPEG-DASH.

• Each audio track MUST be a separate media stream.

• Support for the <SegmentList> element is NOT REQUIRED.

• The app MAY support multiple Periods defined in an MPD of MPEG-DASH.

3.3.2.3 Restrictions for MSS content

• All media segments MUST be independently decodable. Consequently, the first video frame in every segment that contains video MUST be an IDR frame.

• For live streams that use FragmentLookahead, segments MUST remain available on the server for one DVRWindowLength after they disappear from the Manifest file.

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• Supported with EME
• Supported with WebInitiator
• PlayReady Header Object v4.0.0.0 is supported
• PlayReady Header Object v4.1.0.0 may be supportedSupported for security level 
• Supported for security level "2000"
 or higher
• If supported, supported with security level "3000" on devices supporting Ultra HD/4K (2160p) resolution

For an example of implementing PlayReady with WebInitiator, see: 6.1

3.3.5.3 Playready License Acquisition

• The app MAY rely on automatic license acquisition, supporting the following:
  • License Acquisition URLs provided in the manifest
  • License Acquisition URL provided in the WebInitiator

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• Supported if the platform has Widevine DRM installed
• If supported, supported with EME
• If supported, supported with EMEsecurity level “L2”
• If supported, supported with security level “L2” or higher“L1” on devices supporting Ultra HD/4K (2160p) resolution
• MAY support "server certificate" and "privacy mode" features

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• Supported for Apple HLS streams
• Supported for at least one of the following encryption algorithms:
• AES 128 bit keys in CENC mode: Counter Mode (AES-CTR) and Full-Sample encryption
• AES 128 bit keys in CBCS mode: Cipher Block Chaining mode (AES-CBC) and Sub-Sample encryption

For more information about Media streaming and DRM, refer to the Specification for Devices [1].

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Apps MUST NOT rely on devices having support for 4K resolution. If the device does support 4K resolution, it will be available in Vewd. See the Specification for Devices [1] for more details.

3.3.

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7 CMAF multimedia format

Common Media Application Format (CMAF) [34] combines and constrains several MPEG specifications to define a multimedia format optimized for delivery of a single adaptive multimedia presentation to a variety of devices, using various adaptive streaming formats, broadcast, download, and storage methods. The device MUST support this standard.

For more information, refer to the Specification for Devices [1] section 3.6.4. “CMAF multimedia format”.

3.3.

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8 High Dynamic Range

Apps MUST NOT rely on devices having support for High Dynamic Range (HDR). If the devices do support HDR, it will be available in Vewd. See the Specification for Devices [1] for more details.

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Printable versions of specifications

Current version:

Not yet available

Apps Requirements 2022

Version: 4.22

Date: 2021-12-28

PDF: VCA_4.22.pdf

Older versions:

Apps Requirements 2021

Version: 4.21

Date: 2021-12-28

PDF: VCA_4.21.pdf

Apps Requirements 2020

Version: 4.20

Date: 2020-09-07

PDF:VCA_4.20.pdf

Apps Requirements 2018

Version: 4.11

Date: 2018-02-22

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