Digital Radio – Production & Transmission Technologies Yogendra Pal Presentation by: Yogendra Pal Director (Engg.) All India Radio, New Delhi

Agenda Vinyl Disc to Optical & Magneto-optical Discs Tape to Hard Disc & Flash Memory Digital Audio Workstations Solid-state Recorders Digital Interfaces IP-based audio networks Issues for consideration

Vinyl Discs to Optical & Magneto-optical Discs MO Disc MO Disc

Tape to Hard Disc & Flash Memory Solid-state Recorders DAW

Digital Audio Workstation (DAW) Complete automation, scheduling, production, play out, archiving etc. Familiar transport control: Play, stop, forward, rewind, pause Keyboard short cuts Touch screens Nonlinear access Waveform with zoom facility Metadata Large storage capacity

DAW – Controls & features

DAW -- Metadata

DAW -- Recording Two or more tracks Insert markers Play & edit while recording Recording by time & level Selectable: –Sampling frequency –Bit resolution –Compressed/uncompressed

DAW -- Editing Non-destructive with: Cut/trim Cut & paste Copy & paste Fade-in/out & cross-fade Slip Time indication Time stretch, compress Level changes Colours for cuts

DAW -- Scheduling Play list by drag & drop Fade-in/out & cross-fade Schedule part of programme without copy Block formation/insertion Monitoring & editing transition points Copy of schedules Last minute changes Automatic schedule preparation for criterion

DAW – Playback Manual, auto & live- assist play Two & more virtual play panels Monitoring start/end points Assignable hot keys Fader start/stop Auto play Protection from accidental exit

DAW – Effects & signal processing Processing of: Spectrum Time Amplitude Noise

DAW – Other features Traffic & Billing Report generation/printing Log printing Purging Logging Archiving Networking Storage Internet

Solid-state Recorders No moving parts Flash memory card as recording media: –PCMCIA card –Compact Flash –SD card –Smart Media Cards capacity: up to 16 GB Uncompressed & compressed recording Easy transfer to DAW

Solid-state Portable Recorders Sonifex (Courier) Fostex (FR-2) Marantz (PMD Series) YouCom (Parrot) Nagra (ARES-BB+)

Solid-state Handheld Recorders Edirol (R-09) AEQ (PAW 120) Nagra (ARES-M) Samson (H-4) HHB (DRM 85)

Land Lines Typical Set up of a Radio Station Transmitter Router From other Mixing Consoles Mixing Console

Scenario & Options? Audio Networking

Scenario Analog: Professional & consumer, with XLR, RCA, DB-9, DB-15, ¼ phone, mini phone and RJ-45 connectors Digital: AES3, TDIF, MADI etc. Digital: Proprietary systems over fiber & copper Ethernet: Networking of DAWs

AES3 One-way communication Single source per cable limitation Control and data possible but for very simple, low rate functions Lack of flexibility

USB and FireWire Good for data transfer into and out of computer Cant extend to multiple ports

Proprietary Audio networks Used for connecting routers to each other and terminals Expensive Closed – all components from single vendor Connection to outside world still via analog, AES or MADI etc.

Ethernet Already in use: Computer network Packet-switched network Fast developments: 10 to 100 to 1000 Mbps speed & new protocol (IPv6) Low cost – economies of scale Standard, off-the-shelf products RJ-45 plugs – fast & easy to install Single network for audio, data, telephony etc Scalable

Ethernet – Issues & Options Not designed for continuous stream of time critical data A number of proprietary systems now available which tackle the issue: –Livewire from Axia Audio (Telos) –Visiblu from Digigram –CobraNet from CobraNet Audio –Wheatstone from Wheatstone Corporation

Livewire Uses Internet IP standard RTP/IP for audio No sound cards Full-duplex links with priority assignment to audio streams Two types of streams: –Live streams – small, fast packets –Standard streams – bigger, non-critical data Contd…

Livewire Livewire Contd.. Single Ethernet cable carries: –Real-time uncompressed digital audio –Device control messages –Programme associated data –Routine network traffic –Clock signal for synchronization 50 audio channels (48 kHz, 20-bit) Ethernet switch isolates links and route audio Converged network

Livewire -- Schematic

Visiblu

CobraNet

Wheatstone system

Issues for consideration Virus Backup Disaster management Sampling frequency and quantisation bits Compression Low cost systems

For further reference, please at: or

Compact Disc (CD) Developed as replacement of gramophone records Optical disc Type Diameter Storage Audio capacity Std 120 mm 650 & 700 MB 74 & 80 minutes Mini 80 mm 184 MB 21 minutes Format: 2-channel, 16-bit PCM at 44.1 kHz CD-ROM, CD-R & CD-RW came up later Back

DVD Diameter & thickness of CD High data capacity: up to 17.1 GB No. of Formats DVD-A: –Options for many channels at various sampling frequencies and sample rates –Distribution media for high-fidelity audio –Robust copy protection Back

Super Audio CD (SACD) Read-only, optical audio disc Looks exactly like CD Capacity: up to 7.95 GB Frequency response: DC to 100 kHz Dynamic range: 120 dB Audio format: Direct Stream Digital (DSD) Built-in copy protection features 3 types: –Hybrid, Single and Dual layer Back

Mini Disc Yamaha MD8 Mindisc in cartridge (left), exposed minidisc (right) and protective cartridge holder (rear) Back Sony MZ-NHF800 Removable, low cost & rewritable media Two types: Regular 74-minutes for 2- track Data disc for multitrack Records at 44.1 kHz, 16-bit. 24-bit also available ATRAC: Adaptive TRansform Acoustic Coding compression

MODisc MO Disc 5.25 & 3.5 form factors Casing Information checking, reporting & correction (Not available in CD-R & DVD-R) Dirt & scratch resistant: –Wide diameter of laser beam on disc surface but narrow towards recording layer –Dropouts reproduced by error correction –No direct contact with disc surface High transfer speed – 5.92 MB/s Capacity – up to 1.3GB (3.5), 2.6GB (5.25) Back

AES/EBU (AES3) Serial transmission of 2-channel digital audio Balanced, 3-conductor, 110-ohm shielded twisted pair cable with XLR connectors Data rate depends on sampling rate Mb/s at 48kHz Distance: up to 100 meters Clock rate recovered by encoding data For professional equipment Can also be carried over an Asynchronous Transfer Mode (ATM) network

AES/EBU (AES3)

SPDIF Digital Audio standard developed by Sony/Philips Consumer version of AES3 Unbalanced interface 75-ohm coaxial with RCA jacks or fiber cable with TOSLINK connectors Back

USB (Universal Serial Bus) Serial bus standard Max. devices: 127 per host Originally designed for computers No termination needed Hot plugging of devices Latest version: USB 2.0 Transfer speeds: 1.5, 12 & 480 Mbps Connectors: Series A, Series B, Mini A, Mini B & Mini AB Mini-A plug (left), Mini-B plug (right) Series A Plug

FireWire Serial bus standard Proprietary name of Apple Inc. Max. devices: 63 in tree topology Designed to replace parallel SCSI Supports multiple hosts per bus Supports plug-&-play and Hot swapping Transfer speeds: 100,200 & 400 Mbps for FireWire 400 and 800, 1600 & 3200 Mbps for FireWire 800 Connectors: 4, 6 and 9 pins 9-pin connector 4-pin and 6-pin Plugs Back

TDIF Tascam Digital Interface Proprietary format Bi-directional connection to transmit and/or receive up to 8- channels Separate cable for wordclock required in TDIF-1 but not in TDIF-2 protocol Uses 25-pin D-sub cable

MADI MADI (Multichannel Audio Digital Interface) Serial digital transmission over coaxial cable or fiber-optic line Supports 28, 56 or 64 channels, with sampling rates up to 96 kHz & resolution up to 24-bit per channel Bit-level description and features of AES3 Known as AES10 Back