Multimedia Standards

Transcription

1 Multimedia Standards SS 2017 Lecture 12/13/14 Prof. Dr.-Ing. Karlheinz Brandenburg Contact: Dipl.-Inf. Thomas Köllmer 1

2 SYSTEM STANDARDS AUDIO BROADCAST VIDEO BROADCAST STREAMING 2

3 DAB - Digital Audio Broadcasting Overview: Eureka-147-project Founded in 1986 with 16 partners (A partners) International consortium consisting of: Broadcasters Network operators Consumer electronics industry Research institutes Opening the consortium for further partners:

4 DAB: Regional Coverage 4 Source: June 2017

5 DAB: Regional Coverage 5 Source: Digitisation report 2015, 015/Digitisation_2015_english.pdf

6 DAB Main Standards DAB (1995) Main Document: ETSI EN Guidelines of Use and Operation: ETSI TR DAB+ (2007) Transport of AAC Audio: ETSI TS

7 DAB - Digital Audio Broadcasting Block Diagram Transmitter 7

8 DAB - Digital Audio Broadcasting Transmission channels 1. Synchronization channel Zero and phase reference symbol 2. FIC (Fast Information Channel) After analysis of the FIC the receiver can decode the payload 3. MSC (Main Service Channel) Payload (programs and data services of the ensemble) 8

9 DAB - Digital Audio Broadcasting Example Service Structure 9

10 DAB - Digital Audio Broadcasting Stream & Packet Mode Stream Mode Packet Mode Transmission of data streams Constant data rate: n x 8kBit/s E.g. radio programs, audio coded with MPEG-1 Layer II Transmission of data streams With low data rates (<8kBit/s) or Temporal varying data rates Asynchronous data rates Pure data services 10

11 DAB - Digital Audio Broadcasting Transport mechanisms for data services Fast Information Data Channel (FIDC) Traffic Message Channel (TMC) TS (Extendend) Programme Associated Data (PAD/X-Pad) Dynamic Label Sequence (DLS) for Text EN Slide Show Images (SLS) TS Electronic Program Guide (EPG) TS Packet Mode 11

12 DAB - Digital Audio Broadcasting Additional Services Dynamic Label (DLS) Displaying of short text messages on an alpha numerical display (labels) For the Transport: Segmentation of the labels in up to 8 segments with up to 18 characters, limited formatting possible Typical applications: Short messages Weather forecast Title / artist of a song Basic structure of a X-PAD data group: Prefix (2 Bytes) Character field (n Bytes) CRC (2 Bytes) 12

13 DAB - Digital Audio Broadcasting Additional Services Slide Show (SLS) Transmission of sequence of images for Logos, News, cover art, etc. Embedded within X-PAD Data stream using the MOT protocol (Multimedia Object Transfer) Most common resolution: px Formats: JPEG (non-progressive) (animated) PNG 13

14 DAB - Digital Audio Broadcasting Additional Services Traffic Message Channel (TMC) Data service based on Alert C protocol digital coded traffic message Reference of the numerically coded values to the information tables Event Location Severity Duration Alternative routes Organization of the numerically coded values in groups consisting of < 38 Bit of information Transport of the messages in the FIDC in FIGs 14

15 DAB - Digital Audio Broadcasting Transmission Frequencies & Modes Transmi ssion Mode Frame Duration #FIB I 96ms 12 4 II 24ms 3 1 III 24ms 4 1 IV 48ms 6 2 #CIF Band III L-Band E.g. f= 224,25 MHz = TV channel 12 Mode I f= MHz Mode II or IV Terrestrial network = Single frequency network Spectrum and power efficient technologies ETS (30 MHz 3 GHz) Mode III 15

16 DAB+ DAB+ : ETSI TS : Digital Audio Broadcasting (DAB); Transport of Advanced Audio Coding (AAC) audio HE-AAC V2 audio coder Audio Super Framing Reed-Solomon Coder And Virtual interleaver DAB main service channel multiplexer Scope of ETSI TS Receivers are backwards compatible to DAB More programs inside the same multiplex Surround possible Improved error correction more stable reception Prof. Dr.-Ing. Karlheinz Brandenburg, karlheinz.brandenburg@tu-ilmenau.de Seite 16

17 DAB - Digital Audio Broadcasting Relevant Standards (ETSI/CENELEC/IEC): EN V1.4.1 (June 2006): Digital Audio Broadcasting (DAB); DAB to mobile, portable and fixed receivers EN V1.2.1: Digital Audio Broadcasting (DAB); Distribution interfaces; Service Transport Interface (STI) EN V1.1.1: Digital Audio Broadcasting (DAB); Distribution interfaces; Digital baseband In-phase and Quadrature (DIQ) Interface ETS : Digital Audio Broadcasting (DAB); Distribution interfaces; Ensemble Transport Interface (ETI) EN V2.1.1: Digital Audio Broadcasting (DAB); Multimedia Object Transfer (MOT) protocol EN V1.1.1: Digital Audio Broadcasting (DAB); Service Referencing from FM-RDS; Definition and use of RDS-ODA 17

18 DAB - Digital Audio Broadcasting Relevant Standards (ETSI/CENELEC/IEC): ES : Digital Audio Broadcasting4 (DAB); Internet Protocol Datagram Tunneling ES V1.1.1: Digital Audio Broadcasting (DAB); Network Independent Protocols for Interactive Services ES V1.1.1: Digital Audio Broadcasting (DAB); DAB Interaction Channel through GSM / PSTN / ISDN / DECT EN 50255/ IEC 62105: Digital Audio Broadcasting system - Specification of the Receiver Data Interface (RDI) EN 50248/IEC 62104: Characteristics of DAB receivers EN 50320: The DAB Command Set for receivers 18

19 Digital Video Broadcast Prof. Dr.-Ing. Karlheinz Brandenburg, Seite 19

20 Digital Video Broadcast Situation in Germany» TV Analog and digital reception in Germany 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Exclusively Analog Exclusively Digital Mixed

21 Digital Video Broadcast Situation in Germany Prof. Dr.-Ing. Karlheinz Brandenburg, Seite 21

22 DVB - Digital Video Broadcasting EN EN EN EN EN EN EN And many more: 22

23 DVB - Digital Video Broadcasting Overview of the family of DVB Standards EN : Framing structure, channel coding and modulation for 11/12 GHz satellite services EN : Framing structure, channel coding and modulation forcable systems EN : Specification for Service Information (SI) in DVB systems EN : Specification for conveying ITU-R System B Teletext indvb bit streams EN : Satellite Master Antenna Television (SMATV) distribution systems ETS : Subtitling systems EN : Framing structure, channel coding and modulation fordigital terrestrial television EN : Multipoint Video Distribution Systems (MVDS) at 10GHz and above 23

24 DVB - Digital Video Broadcasting Overview of the family of DVB Standards EN : Interaction channel through the Digital Enhanced Cordless Telecommunications (DECT) EN : Interaction channel through the Global System for Mobile communications (GSM) EN : Interaction channel for Local Multipoint Distribution Systems (LMDS) EN : Framing structure, channel coding and modulation for Digital Satellite News Gathering (DSNG) and other contribution applications by satellite EN : Co-ordination channels associated with Digital Satellite News Gathering (DSNG) EN : OFDM modulation for microwave digital terrestrial television EN : Specification for the carriage of Vertical Blanking Information (VBI) data in DVB bitstreams 24

25 DVB - Digital Video Broadcasting What shall be provided: More channels using the same bandwidth Flexible selection of the audio and video quality Transmission of additional services Several subtitles Internet access Paid additional content Interaction via backchannel 25

26 DVB - Digital Video Broadcasting Combined Baseband Processing 26

27 DVB - S Overview Satellite Transmission Uplink in frequency multiplex Allocation of single frequencies to transponders Downlink in frequency multiplex Full scale amplification No amplitude modulation Uniform power distribution Sufficient bandwidth available Typical transponder bandwidth 27 MHz in the gigahertz range Quadrature Phase Shift Keying (QPSK) Satellites on different geo stationary positions can use the same frequency 27

28 DVB - S Overview of the transmitting end 28

29 DVB - C Overview Cable Transmission High SNR Relatively low bandwidth: Requirements: Channel spacing of TV n * 7 MHz VHF n * 8 MHz UHF Existing networks must be usable Compability to the satellite channel Decoder hardware preferably similar to the satellite decoder (QPSK = 4 QAM) 29

30 DVB - C Overview of the transmitting end 30

31 DVB - C Overview of the receiving end 31

32 DVB - T Overview Terrestrial Transmission Channel properties Requirements: Multipath propagation In house reception Coding similar to the satellite- and cable standard Transmission in 8 MHz bands (7Mhz and 6 MHz bands are possible as well) Possibility for Single Frequency Networks Good area coverage for roof antennas (mobile reception desirable but not mandatory) Orthogonal Frequency Division Multiplex (OFDM) 32

33 DVB - T Overview of the transmitting end 33

34 DVB - Digital Video Broadcasting Comparison of the DVB- transmission systems 34

35 DVB - Digital Video Broadcasting Comparison of the DVB- transmission systems 35

36 DVB - Digital Video Broadcasting Payload MPEG bit stream PES Packetized elementary stream 36

37 DVB - Digital Video Broadcasting Program multiplex 37

38 DVB - Digital Video Broadcasting Service Hierarchy 38

39 DVB - Digital Video Broadcasting Additional Data / Program Content Description of the transport stream data Control of the receiver EPG (Electronic Service Guide) Table mapping via PID (Packet Identifier) Program Association Table (PAT) mapping of the PID to the corresponding program Network Information Table (NIT) System specific information (e.g. network name) Event Information Table (EIT) Name of a broadcast, EPG Service Description Table (SDT) Description of single programs 39

40 DVB Second Generation Modernization of all versions of DVB DVB-S2, -C2, -T2 Goals: More efficient usage of the channels (up to 30%) More robust reception (HDTV) Approaches: More efficient modulation More efficient error correction mechanisms Modern codecs H.264 and H.265 DVB-S2 already in use ETSI EN DVB-T2 already in use in Austria, Sweden, UK, Germany (since March 2017) 40

41 DVB - Second Generation: Forward Error Correction DVB, 1st Generation DVB-X2, 2nd Generation 41

42 DVB-X2 Type of modulation: DVB-C: single carrier 16QAM, 32QAM, 64QAM, 128QAM, 256QAM DVB-S: single carrier QPSK DVB-T: OFDM QPSK, 16QAM, 64QAM Type of modulation: DVB-C2: OFDM 16QAM, 32QAM, 64QAM, 128QAM, 256QAM, 1024QAM, 4096QAM DVB-S2: single carrier QPSK, 8PSK, 16APSK, 32APSK DVB-T2: OFDM QPSK,16QAM, 64QAM, 256QAM 42

43 DVB-S2 43

44 DVB-C2 44

45 DVB-C2 45

46 DVB-T2 46

47 More DVB-Standards DVB-SI Service-Information Standard (EN ) Integrate service information (e.g., EPG inside DVB Bitstream) DVB-CI (1997) / DVB-CI+ (2007) Describes interface between Conditional Acess Module (CAM) and Host (i.e., TV-set) Used for authentication and encryption DVB-TXT Standard Insert teletext into the MPEG-2 transport multiplex (EN ) DVB-3DTV, DVB-IPTV, DVB-M (Measurement), DVB-S2X, 47

48 Streaming

49 What is Streaming? Simultaneous download and playout of media data (via Internet) Live Video, Movies, Music, etc. Additional Data: Additional tracks or camera views Subtitles Arbitrary media objects, advertisement

50 Streaming Implementations 1998: Real Time Transport Protocol (RTP) RTCP (Control Protocol) RTSP (Streaming Protocol) E.g. implemented in Darwin Streaming Manager / Quicktime Streaming But: Nowadays, the majority of streaming is done via HTTP Proprietary approaches: RTMP (Real Time Messaging Protocol), HTTP-encapsulation possible Apple HTTP Live Streaming Adobe HTTP Dynamic Streaming Microsoft Smooth Streaming

51 MPEG DASH Dynamic Adaptive Streaming over HTTP Standard for HTTP-streaming, organized by DASH-IF (Industry forum) Members: : Akamai, Microsoft, Adobe, Netflix, Cisco,... Released in April 2012 as ISO/IEC :2012, update in May 2014 Does not specify the client or used codecs! (still, implementation guidelines exist) Features: Dynamic switching between codecs DRM / Encryption Interoperability (Cients may exist for any platform)

52 MPEG DASH Client controls what he wants to receive, not the server (in contrast to RTP) Structure of a Stream Period: independent time frame E.g,. 3 Periods: Movie 1 Ads Movie 2 Adaptation Set: Variants of a Period (e.g., Camera views, Languages) Representation: Link to the actual media data Representations are a list of Segments Installation Segments Media Segment Everything inside a Period is synchronized Dynamic switching possible

53 Media Presentation Description Dash specifies the format of the data on the HTTP server A client chooses representation by downloading from different urls Description is inside the Media Presentation Description (MPD) as XML Periods, Representations, Segments <Representation id="0" codecs="avc1" mimetype="video/mp4" width="320" height="240" startwithsap="1" bandwidth="45652"> <SegmentList duration="2">... <SegmentURL media="bunny_2s_50kbit/bunny_50kbit_dashnonseg.mp4" mediarange=" " />... </SegmentList> </Representation> <Representation id="1" codecs="avc1" mimetype="video/mp4" width="320" height="240" startwithsap="1" bandwidth="89283">... <Representation id="18" codecs="avc1" mimetype="video/mp4" width="1920" height="1080" startwithsap="1" bandwidth=" ">

54 MPEG DASH Many clients are available:

55 Organisational issues Preliminary list of lectures updated version is on the website Tuesday, 17:00, K-Hs1 Thursday, 13:00, K-Hs2 CW* 14 Introduction CW15 Standardization I Standardization II CW16 CW17 CW18 Video Coding I CW19 Video Coding II Video Coding III CW20 CW21 Psychoacoustic Fundamentals CW22 Metadata Standards CW23 MPEG Audio I MPEG Audio II CW24 Speech Coding CW25 CW26 CW27 System Standards I CW28 System Standards II System Standards III Regular Date Alternate Date * ISO 8601 Representation of dates and times ch : calendar week number: ordinal number which identifies a calendar week within its calendar year according to the rule that the first calendar week of a year is that one which includes the first Thursday of that year and that the last calendar week of a calendar year is the week immediately preceding the first calendar week of the next calendar year 55