- A profile of the features defined in MPEG DASH (referred to by MPEG as an "interoperability point") largely based on the "ISOBMFF live" profile defined by MPEG.
- Constraints on the sizes or complexity of various parameters defined in the MPEG DASH specification.
- A selection of the video and audio codecs from the DVB toolbox that are technically appropriate with MPEG DASH constraints and/or requirements for the use of these, without mandating any particular codec.
- Using MPEG Common Encryption for content delivered according to the present document.
- Use of TTML subtitles with MPEG DASH.
- Requirements on Player behaviour needed to give inter-operable presentation of services.
- Guidelines for content providers on how to use MPEG DASH.
HTTP Streaming is a recent topic in multimedia communications with on-going standardization activities, especially with the MPEG DASH standard which covers on demand and live services. One of the main issues in live services deployment is the reduction of the overall latency. Low or very low latency streaming is still a challenge.
In this paper, we push the use of DASH to its limits with regards to latency, down to fragments being only one frame, and evaluate the overhead introduced by that approach and the combination of: low latency video coding techniques, in particular Gradual Decoding Refresh; low latency HTTP streaming, in particular using chunked-transfer encoding; and associated ISOBMF packaging.
We experiment DASH streaming using these techniques in local networks to measure the actual end-to-end latency, as low as 240 milliseconds, for an encoding and packaging overhead in the order of 13% for HD sequences and thus validate the feasibility of very low latency DASH live streaming in local networks.
By Nassima Bouzakaria, Cyril Concolato and Jean Le Feuvre
Wednesday, July 16, 2014
Labels: MPEG DASH
A significant step in the road to Ultra High Definition TV services has been taken with the approval of the DVB-UHDTV Phase 1 specification at the 77th meeting of the DVB Steering Board. The specification includes an HEVC Profile for DVB broadcasting services that draws, from the options available with HEVC, those that will match the requirements for delivery of UHDTV Phase 1 and other formats. The specification updates ETSI TS 101 154 (Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG-2 Transport Stream).
The new DVB-UHDTV Phase 1 will allow images with four times the static resolution of the 1080p HDTV format, at frame rates of up to 60 images per second. Contrast will be drastically improved by increasing the number of bits per pixel to 10 bit. From the wide range of options defined in the HEVC Main 10 profile, Level 5.1 is specified for UHD content for resolutions up to 2160p. For HD content, HEVC Main profile level 4.1 is specified for supporting resolutions up to 1080p.
The DVB-UHDTV Phase 1 specification takes into account the possibility that UHDTV Phase 2 may use higher frame rates in a compatible way, which will add further to the image quality of UHDTV Phase 1.
“HEVC is the most recently-developed compression technology and, among other uses, it is the key that will unlock UHDTV broadcasting,” said DVB Steering Board Chairman, Phil Laven. “This new DVB–UHDTV Phase 1 specification not only opens the door to the age of UHDTV delivery but also potentially sets the stage for Phase 2, the next level of UHDTV quality, which will be considered in upcoming DVB work,” he continued.
Also approved was the specification for Companion Screens and Streams, Part 2: Content Identification and Media Synchronization. Companion Devices (tablets, smart phones) enable new user experiences for broadcast service consumption. Many of these require synchronisation between the Broadcast Service at the TV Device and the Timed Content presented at the Companion Device. This specification focuses on the identification and synchronisation of a Broadcast Service on a TV Device (Connected TV or STB and screen) and Timed Content on a Companion Screen Application running on a Companion Device. Part 2 outlines the enabling factors for the identification of, and synchronisation with, broadcast content, timed content and trigger events on TV devices (for example a Connected TV or STB) and related content presented by an application running on a personal device.
Another specification to gain approval from the Steering Board was the MPEG-DASH Profile for Transport of ISO BMFF Based DVB Services over IP Based Networks. This specification defines the delivery of TV content via HTTP adaptive streaming. MPEG-DASH covers a wide range of use cases and options. Transmission of audiovisual content is based on the ISOBMFF file specification. Video and audio codecs from the DVB toolbox that are technically appropriate with MPEG-DASH have been selected. Conditional Access is based on MPEG Common Encryption and delivery of subtitles will be XML based. The DVB Profile of MPEG-DASH reduces the number of options and also the complexity for implementers. The new specification will facilitate implementation and usage of MPEG-DASH in a DVB environment.
The three new specifications will now be sent to ICT standards body ETSI for formal standardisation and the relevant BlueBooks will be published shortly.
Source: Advanced Television
The Consumer Electronics Association has announced updated core characteristics for ultra high-definition TVs, monitors and projectors for the home. As devised and approved by CEA’s Video Division Board, these characteristics build on the first-generation UHD characteristics released by CEA in October 2012.
These expanded display characteristics (CEA’s Ultra High-Definition Display Characteristics V2) – voluntary guidelines that take effect in September 2014 – are designed to address various attributes of picture quality and help move toward interoperability, while providing clarity for consumers and retailers alike.
Under CEA’s expanded characteristics, a TV, monitor or projector may be referred to as Ultra High-Definition if it meets the following minimum performance attributes:
- Display Resolution – Has at least eight million active pixels, with at least 3,840 horizontally and at least 2,160 vertically.
- Aspect Ratio – Has a width to height ratio of the display’s native resolution of 16:9 or wider.
- Upconversion – Is capable of upscaling HD video and displaying it at ultra high-definition resolution.
- Digital Input – Has one or more HDMI inputs supporting at least 3840x2160 native content resolution at 24p, 30p and 60p frames per second. At least one of the 3840x2160 HDMI inputs shall support HDCP revision 2.2 or equivalent content protection.
- Colorimetry – Processes 2160p video inputs encoded according to ITU-R BT.709 color space and may support wider colorimetry standards.
- Bit Depth – Has a minimum color bit depth of eight bits.
Because one of the first ways consumers will have access to native 4K content is via Internet streaming on connected ultra HDTVs, CEA has defined new characteristics for connected UHDTV displays. Under these new characteristics, which complement the updated core UHD attributes, a display system may be referred to as a connected ultra HD device if it meets the following minimum performance attributes:
- Ultra High-Definition Capability – Meets all of the requirements of the CEA Ultra High-Definition Display Characteristics V2 (listed above).
- Video Codec – Decodes IP-delivered video of 3840x2160 resolution that has been compressed using HEVC* and may decode video from other standard encoders.
- Audio Codec – Receives and reproduces, and/or outputs multichannel audio.
- IP and Networking – Receives IP-delivered Ultra HD video through a Wi-Fi, Ethernet or other appropriate connection.
- Application Services – Supports IP-delivered Ultra HD video through services or applications on the platform of the manufacturer’s choosing.
CEA’s expanded display characteristics also include guidance on nomenclature designed to help provide manufacturers with marketing flexibility while still providing clarity for consumers. Specifically, the guidance states, “The terms ‘Ultra High-Definition,’ ‘Ultra HD’ or ‘UHD’ may be used in conjunction with other modifiers,” for example “Ultra High-Definition TV 4K”.
*High Efficiency Video Compression Main Profile, Level 5, Main tier, as defined in ISO/IEC 23008-2 MPEG-H Part 2 or ITU-T H.265, and may support higher profiles, levels or tiers.
Source: TV Technology
Tuesday, July 01, 2014