1 / 47

Preparing Audio for the Internet -Nick Kereakos - MPR

Preparing Audio for the Internet -Nick Kereakos - MPR. Topics Covered: Static Audio Files Audio Streams Automation. Static Audio Files. What is it? Standard computer data file Data reduced for internet broadcast Audio encoded using a bit reduced perceptual audio coder. What do I need?.

neil
Télécharger la présentation

Preparing Audio for the Internet -Nick Kereakos - MPR

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. Static Audio Files • 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) • 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: • RealNetwork’s RealAudio • Windows Media Player • MPEG Layer III - MP3 • Apple’s QuickTime

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

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

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

  9. MPR’s Method • 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.

  10. Digital Audio Workstation Protools Example

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

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

  13. Sound Files • Broadcasting Systems using files: • Audiovault • Enco - Dad Pro32 • DCart

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

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

  16. Audio Processing & Dynamics • MPR uses WaveConvert:

  17. 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.

  18. Digital Audio Levels Analog Meter Digital Meter

  19. Digital Audio Levels Analog Meter Digital Meter

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

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

  22. Before and after processing Original Source Processed File

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

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

  25. Real Audio Encoded

  26. Coding Effects Comparison • Original Source File • Wave Convert Processed file • Real Audio Encoded

  27. Web Audio Stream • 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.

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

  29. Audio source flow Compressor/Limiter Source Encoder

  30. Audio source flow Encoder RealServer End User

  31. What if there are problems? • 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.

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

  33. Automated Static Web Encoding • 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

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

  35. MPR’s Design • 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

  36. MPR’s Design • 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

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

  38. Online Resources • 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/htmfiles/whatsnew.htm

  39. Online Resources • 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

More Related