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Cbaa Ip Workshop
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Cbaa Ip Workshop

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  • 1. A new technique for low cost, near real time IP based audio distribution for community radio CBAA National Conference Chris Deacon Vice President General Manager Engineering & Development November 2007 © ArtSound Incorporated
  • 2. IP audio streaming Allows audio connections to be established over LAN/WAN and internet environments. – Permits near real time applications – Low latency (No significant delays). Allows for cost effective audio distribution from anywhere to anywhere – As long as a reliable internet connection is available Amount of digital information that is needed to represent high-quality raw digital audio requires several Megabits per second – Therefore digital audio is compressed to allow transmission via Internet. Several different IP Audio compression methods and protocols are available (such as MP3 and AAC). – There are cost and quality tradeoffs along with some common problem areas and risks . ©ArtSound Incorporated 2 30/11/2007
  • 3. Audio via IP An IP audio system digitizes and reformats the original audio, codes and/or compresses the data, adds IP address information to each packet, transfers the packets through the Internet, recombines the packets and extracts the digitized audio, decodes the data and converts the digital audio back into its original audio form. ©ArtSound Incorporated 3 30/11/2007
  • 4. Digital Distortion Audio signals are digitized, compressed and error protection coded prior to transmission. During the transmission process, some packets are lost or corrupted – can result in the temporary interruption of the audio signal. Because data compression process represents sounds by different codes, packet corruption alters sound that was originally transmitted. If significant data corruption occurs, this can create unusual sounds (artifacts, “warbling”, or “smearing”). ©ArtSound Incorporated 4 30/11/2007
  • 5. Digital Audio Quality Issues Crosstalk Digital Audio Quality (DAQ) Noise Level Key Quality Indicators (KQI) Signal to Noise Ratio (SNR) Bit Error Rate (BER) Quality of Experience (QoE) Packet Loss Rate (PLR) Connection Success Rate Packet Delay Variation (PDV) (CSR) Audio Fidelity Connect Time Mean Opinion Score (MOS) Buffer Time Frequency Response (FR) Rebuffer Events Total Harmonic Distortion (THD) Rebuffer Time Latency ©ArtSound Incorporated 5 30/11/2007
  • 6. Audio IP Features Unlike ISDN or POTS codecs, Audio IP: can be implemented in software or lower cost hardware will run on an inexpensive PC or in most cases a laptop can use existing high-speed Internet connection (LAN or 3G bandwidth from a phone, wireless datacard, wireless router/modem). no additional charges other than standard Internet data charge - you can stay connected all month but pay only for data sent; unlimited plan may be best option. ©ArtSound Incorporated 6 30/11/2007
  • 7. Audio IP features (cont) Many ISP’s offer upstreaming of data at no volume charge! Each link requires one transmit unit and one receive unit (or software application) The effects of packet loss on the transmission of streamed audio over Internet protocol (IP) can be mitigated by the inclusion of redundancy in the transmitted stream. Buffer ensures that temporary glitches or connectivity issues with your Internet connection will not affect the high-quality audio connection from the transmit end to the receiver. Latency is an important issue for live radio. ©ArtSound Incorporated 7 30/11/2007
  • 8. Audio IP Applications Inexpensive outside broadcasts - quality good enough to send stereo music and speech from the OB site back to the studio. Studio To Transmitter (STL) links - a cost effective alternative to RF links with high-quality audio from the Studio to Transmitter and a telemetry link back to the studio for confidence monitoring. Link distant facilities for transfer of audio feeds from one computer to the other - distance no object. Easy to setup and operate and can be operated on virtually any Internet ready computer with reasonable sound card. ©ArtSound Incorporated 8 30/11/2007
  • 9. Instreamer Real time audio encoder Audio streaming encoder with multiple operating modes (push/ pull, http, RTP etc), control via webbrowser or open API (UDP, TCP, cgi or serial). SNMP monitoring for device supervision. Configurable MP3 encoding (8kbit to 192kbit VBR, 16-48kHz sample rate), G.711 (aLaw/uLaw) and 16bit PCM (both 8 and 24kHz sample rate). Network interface: 10/100Mbit Ethernet. Audio Inputs: 2-channel stereo, analog (RCA), coaxial and optical S/PDIF. Headphone output. Control: IR output, serial RS-232 port. Power supply: 9..30VDC /12..24VAC. ©ArtSound Incorporated 9 30/11/2007
  • 10. Extreamer Real time audio decoder Audio streaming decoder with multiple operating modes (push/pull, http, RTP etc), control via web browser or open API (UDP,TCP, cgi or serial). USB memory interface. Supports MP3 (up to 320kbit/s FBR & VBR) and WMA (5-384kbit/s). Network interface: 10/100Mbit Ethernet, audio outputs: 2-channel stereo analog (RCA and headphone). Control: optional IR receiver for IR remote, serial RS-232 port. Power supply: 9..30VDC /12..24VAC. ©ArtSound Incorporated 10 30/11/2007
  • 11. Instreamer/Exstreamer devices Allow unidirectional, low latency, high quality audio distribution over satellite or terrestrial IP systems. They support RTP/Multicast, and can also transport control signals. Backup/emergency STL; OB; No PC required at either end Instreamer encodes the audio in real time, the stream is distributed via the internet and at the remote sites, the IP feed received is decoded into audio and control by the Exstreamer. The Exstreamer can be controlled to select one of multiple channels. ©ArtSound Incorporated 11 30/11/2007
  • 12. Instreamer/Exstreamer audio Using realtime MP3 encoding, achievable audio quality better than CD at 192 kbps max. in highest quality settings. Compression rate can be increased and sample rate can be set lower so a typical “FM” stereo audio signal can easily be streamed at 128 kbps. Barix IP Audio products are standalone, hardware based devices which are easy to set up, low power (<6 W power consumption), based on embedded technologies (non-PC architecture) and low cost. A typical STL link setup can be achieved with one Instreamer and Exstreamer at a total cost of approx. $700 (not including the DSL line or equipment). A single Instreamer can serve up to 8 concurrent streams allowing multiple transmitter sites with Exstreamers to be linked. Instreamer can also serve to stream to an Icecast/Shoutcast server for internet radio applications, or provide a stream into an audio recording solution ©ArtSound Incorporated 12 30/11/2007
  • 13. RTP reliability RTP (Real Time Protocol) - a stream of UDP frames containing audio content plus a small header with time sequence information. – used by the receiving party (e.g. Exstreamer) to detect and replace lost frames. If Exstreamer detects lost frame(s), it will replace the missing audio information with repetition(s) of the next incoming frame. Sound quality is good because the replacement is usually short and fits well into its surrounding audio. – Even with massive packet loss, music and speech are still intelligible. – Rhythm of music or speech can be preserved even when packets are lost during transmission. RTP is an Internet standard – is interoperable with a wide range of other RTP supporting applications and hardware devices. BRTP – a Barix variation to facilitate easier use behind LAN firewalls ©ArtSound Incorporated 13 30/11/2007
  • 14. IP Multicasting Project A non-profit subscriber-supported digital audio service for remote and/or isolated Australian citizens Seniors confined to nursing homes and hospices Handicapped or infirm confined to home or hospital Dwellers in remote and underserved rural/outback areas Retirement homes Disadvantaged citizens denied ready access to health, social and educational services Uses innovative internet multicast streaming audio technology Local, regional and national components ©ArtSound Incorporated 14 30/11/2007
  • 15. Features Builds on existing community radio expertise, infrastructure and content Largely volunteer driven: users have the opportunity to participate directly in the service as program presenters and organisers Content tailored to regional and local communities National distribution with regional/local hubs ©ArtSound Incorporated 15 30/11/2007
  • 16. Project Consortium Initial “core” partners are five of Australia’s community FM radio stations (Fine Music Network): ArtSound FM Canberra 2MBS FM Sydney 3MBS FM Melbourne 4MBS FM Brisbane 5MBS FM Adelaide Act as regional distribution/production centres in NSW, Vic, Qld, SA, ACT regions • WA, NT, Tas, to be added later ©ArtSound Incorporated 16 30/11/2007
  • 17. How does it work? Uses low cost, next generation IP- based technology to encode, distribute and decode in real time Point to multipoint IP streaming over the internet (or digital sub-carriers in metropolitan area) – restricted to private users Uses an intelligent network-based audio decoder that can pull digital audio from multiple IP network sources and convert it to audio. Software-controlled switchover to alternative streaming sources, such as regional or locally originated programs ©ArtSound Incorporated 17 30/11/2007
  • 18. Technical Configuration Easy and simple internet based distribution – No expensive satellite dish, no dedicated Telco lines – No broadcast licences required INTERNET ENCODER Localised content customisation – per region, town or subscribing organisation Inexpensive and simple installation DECODER DECODER and usage – Plug a small decoder device into the broadband network Compatible with IP based LAN, WLAN technology ©ArtSound Incorporated 18 30/11/2007
  • 19. User hardware Simple, easy to install decoders Cost ~ $300-500 No PC required No complicated software Fed by LAN or direct from ADSL modem/router Feeds existing domestic audio or hospital broadcast distribution PA equipment, or wireless LAN No tuning or antennas required No training course necessary High quality stereo audio Remote programmable from program origination centre ©ArtSound Incorporated 19 30/11/2007
  • 20. Further information? chris.deacon@artsound.com.au or 02-6295-7444 ©ArtSound Incorporated 20 30/11/2007