1. Preparing Audio for the Internet - Nick Kereakos - MPR Topics Covered: Topics Covered:  Static Audio Files  Audio Streams  Automation

2. Static Audio Files What is it? What is it?  Standard computer data file  Data reduced for internet broadcast  Audio encoded using a bit reduced perceptual audio coder.

3. What do I need? Digital Audio Workstation (DAW) Digital Audio Workstation (DAW)  Personal Computer with an audio card.  Digital Audio Workstation software. Ex.) Protools, Cubase, Sonic Solutions, Peak Audio, Sonic Foundry, Cool Edit, etc…

4. Digital Audio Workstation Protools Example

5. Perceptual Audio Coder Standard Coders include: Standard Coders include:  RealNetwork’s RealAudio  Windows Media Player  MPEG Layer III - MP3  Apple’s QuickTime

6. Perceptual Audio Coding Principles: Principles:  Aims to achieve fidelity perceivable by humans.  This means removing sound we cannot hear.  Reproducing sound we can hear.

9. Preparing Audio for the Web Step 1 - Convert Analog source to Digital

10. Method’s Use DAW: Use DAW:  Prepare & Edit Digital Audio File  Process the file  Encode file with Encoder of choice Use Only Encoder: Use Only Encoder:  Record audio source with Encoder  Create an encoded audio file.

11. MPR’s Method Use a DAW: Use a DAW:  Increased flexibility  Original Source file  Can be use for multiple Encoders  Ability to edit content  Better sound quality  Integration with Broadcasting & Automation systems.

12. Digital Audio Workstation Protools Example

13. DAW and Sound files: Sound file formats: Sound file formats: .WAV (Apple & Windows) .AIFF (Apple) .SND (Apple)  Sound Designer II (Apple)

14. Sound Files PCM Linear Audio File: PCM Linear Audio File:  CD Quality 44.1 kHz, 16bit  Broadcasting standard audio file  Non data reduced  Cross platform

15. Sound Files Broadcasting Systems using files: Broadcasting Systems using files:  Audiovault  Enco - Dad Pro32  DCart

16. Preparing Audio for the Web Step 2 - Prepare Soundfile for Encoding

17. Audio Processing & Dynamics Process the sound file: Process the sound file:  Compression - reduces dynamic range  Limiting - to set brick wall upper audio limit  EQ, to soften upper frequencies

18. Audio Processing & Dynamics MPR uses WaveConvert: MPR uses WaveConvert:

19. Audio Processing & Dynamics  Compression - Reduces dynamic range the Encoder needs to calculate. For lower bit rates, this is especially important and effective.  Limiting - This avoids distortion for the end user listening via the Web.  EQ - Softens inherent harshness of low bit rate encoded audio.

21. Digital Audio Levels Analog Meter Digital Meter

22. Digital Audio Levels Analog Meter Digital Meter

23. Waveform View Audio Sample - 44.1 kHz 16bit Mono Audio Sample - 44.1 kHz 16bit Mono Original Source

24. Waveform View Audio Sample - 44.1 kHz 16bit Mono Audio Sample - 44.1 kHz 16bit Mono Processed Soundfile

25. Before and after processing Original Source Processed File

26. Preparing Audio for the Web Step 3 - Real Audio Encoding

27. Audio Sample - 44.1 kHz 16bitMono Audio Sample - 44.1 kHz 16bitMono O=ginal urce

33. Real Audio Encoded

34. Coding Effects Comparison  Original Source File  Wave Convert Processed file  Real Audio Encoded

35. Web Audio Stream Uses same exact principles Uses same exact principles  Audio is sent as a continuous data stream rather than existing as a static file.  Data is reduced for internet broadcast  Audio encoded using a bit reduced perceptual audio coder.

36. Audio Processing & Dynamics Process the source: Process the source:  Compression - reduces dynamic range  Limiting - to set brick wall upper audio limit  EQ, to soften upper frequencies Use outboard audio equipment: Use outboard audio equipment:  Compressor/Limiter  EQ, to manipulate frequencies

37. Audio source flow Source Encoder

38. Audio source flow End User EncoderRealServer

39. What if there are problems? Monitor your stream: Monitor your stream:  Install a PC to playback the stream.  Wire the output of the PC’s audio card to a silence sensor.  When the alarm goes off, you know there is a problem with the stream.

40. Monitoring the Stream will alert you when:  The Encoder fails  The source is interrupted or fails  Your Network fails

41. Automated Static Web Encoding Process: Process:  Source Audio file is compiled/recorded  Dynamics are applied to the audio file  File is processed in Real Producer  Web Encoded file is delivered to destination

42. MPR’s Design ENCO - Dad Pro 32: ENCO - Dad Pro 32:  Controls SAS Router  Records appropriate source to a PCM Linear.WAV file.

43. MPR’s Design Static Encode Box: Static Encode Box:  Running Windows NT 4.0  NT script moves file from ENCO drive  WaveConvert Pro applies dynamics to.WAV file and creates new file  Real Producer encodes new.WAV file  Newly encoded file waits for delivery

44. MPR’s Design Caravan: Caravan:  Developed by MPR Online personnel  Script runs 24 days monitoring directory contents  When a new Real Audio file is delivered, Caravan moves it to its proper location

45. Overall Goals Reduce Bit Rate: Reduce Bit Rate:  Keeps data costs down.  Reaches more people simultaneously.  Allows access to people on a dial up modem.

46. Online Resources Real Networks: Real Networks:  http://www.real.com  Real Producer is free  Real Player is free  User forums and FAQS are helpful  http://service.real.com/help/library/guides/production/ht mfiles/whatsnew.htm

47. Online Resources Helpful articles to read: Helpful articles to read:  http://www.sospubs.co.uk/sos/may00/articles/mp3.html  http://www.iis.fhg.de/amm/index.html  http://www.minidisc.org/PerceptualCoding.html  http://www.wired.com/wired/archive/7.08/codecs.html  http://www.webdeveloper.com/multimedia/multimedia _guide_realaudio_2.html