preparing audio for the internet -nick kereakos - mpr
DESCRIPTION
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?. - PowerPoint PPT PresentationTRANSCRIPT
Preparing Audio for the Internet -Nick Kereakos - MPR Topics Covered:Topics Covered:
Static Audio FilesStatic Audio Files Audio StreamsAudio Streams AutomationAutomation
Static Audio Files
What is it?What is it? Standard computer data fileStandard computer data file Data reduced for internet broadcastData reduced for internet broadcast Audio encoded using a bit reduced Audio encoded using a bit reduced
perceptual audio coder.perceptual audio coder.
What do I need?
Digital Audio Workstation (DAW)Digital Audio Workstation (DAW) Personal Computer with an audio card.Personal Computer with an audio card. Digital Audio Workstation software.Digital Audio Workstation software.
Ex.) Protools, Cubase, Sonic Solutions, Ex.) Protools, Cubase, Sonic Solutions, Peak Audio, Sonic Foundry, Cool Edit, Peak Audio, Sonic Foundry, Cool Edit, etc…etc…
Digital Audio WorkstationProtools Example
Perceptual Audio Coder
Standard Coders include:Standard Coders include: RealNetwork’s RealAudioRealNetwork’s RealAudio Windows Media PlayerWindows Media Player MPEG Layer III - MP3MPEG Layer III - MP3 Apple’s QuickTimeApple’s QuickTime
Perceptual Audio Coding
Principles:Principles: Aims to achieve fidelity perceivable by Aims to achieve fidelity perceivable by
humans.humans. This means removing sound we cannot hear.This means removing sound we cannot hear. Reproducing sound we can hear.Reproducing sound we can hear.
Preparing Audio for the Web
Step 1 - Convert Analog source to DigitalStep 1 - Convert Analog source to Digital
Method’s Use DAW:Use DAW:
Prepare & Edit Digital Audio FilePrepare & Edit Digital Audio File Process the fileProcess the file Encode file with Encoder of choiceEncode file with Encoder of choice
Use Only Encoder:Use Only Encoder: Record audio source with EncoderRecord audio source with Encoder Create an encoded audio file.Create an encoded audio file.
MPR’s Method
Use a DAW:Use a DAW: Increased flexibilityIncreased flexibility Original Source fileOriginal Source file Can be use for multiple EncodersCan be use for multiple Encoders Ability to edit contentAbility to edit content Better sound qualityBetter sound quality Integration with Broadcasting & Automation Integration with Broadcasting & Automation
systems.systems.
Digital Audio WorkstationProtools Example
DAW and Sound files:
Sound file formats:Sound file formats: .WAV (Apple & Windows).WAV (Apple & Windows) .AIFF (Apple).AIFF (Apple) .SND (Apple).SND (Apple) Sound Designer II (Apple)Sound Designer II (Apple)
Sound Files
PCM Linear Audio File:PCM Linear Audio File: CD Quality 44.1 kHz, 16bitCD Quality 44.1 kHz, 16bit Broadcasting standard audio fileBroadcasting standard audio file Non data reducedNon data reduced Cross platformCross platform
Sound Files
Broadcasting Systems using files:Broadcasting Systems using files: AudiovaultAudiovault Enco - Dad Pro32Enco - Dad Pro32 DCartDCart
Preparing Audio for the WebStep 2 - Prepare Soundfile for EncodingStep 2 - Prepare Soundfile for Encoding
Audio Processing & Dynamics
Process the sound file:Process the sound file: Compression - reduces dynamic rangeCompression - reduces dynamic range Limiting - to set brick wall upper audio limitLimiting - to set brick wall upper audio limit EQ, to soften upper frequenciesEQ, to soften upper frequencies
Audio Processing & Dynamics
MPR uses WaveConvert:MPR uses WaveConvert:
Audio Processing & Dynamics
Compression - Reduces dynamic range the Compression - Reduces dynamic range the Encoder needs to calculate. For lower bit rates, Encoder needs to calculate. For lower bit rates, this is especially important and effective.this is especially important and effective.
Limiting - This avoids distortion for the end Limiting - This avoids distortion for the end user listening via the Web.user listening via the Web.
EQ - Softens inherent harshness of low bit rate EQ - Softens inherent harshness of low bit rate encoded audio.encoded audio.
Digital Audio LevelsAnalog Meter
Digital Meter
Digital Audio LevelsAnalog Meter
Digital Meter
Waveform View
Audio Sample - 44.1 kHz 16bit MonoAudio Sample - 44.1 kHz 16bit Mono
Original Source
Waveform View
Audio Sample - 44.1 kHz 16bit MonoAudio Sample - 44.1 kHz 16bit Mono
Processed Soundfile
Before and after processing
Original Source
Processed File
Preparing Audio for the WebStep 3 - Real Audio EncodingStep 3 - Real Audio Encoding
Audio Sample - 44.1 kHz 16bitMonoAudio Sample - 44.1 kHz 16bitMono
O=ginal urce
Real Audio Encoded
Coding Effects Comparison Original Source FileOriginal Source File
Wave Convert Processed file Wave Convert Processed file
Real Audio Encoded Real Audio Encoded
Web Audio Stream
Uses same exact principlesUses same exact principles Audio is sent as a continuous data stream Audio is sent as a continuous data stream
rather than existing as a static file.rather than existing as a static file. Data is reduced for internet broadcastData is reduced for internet broadcast Audio encoded using a bit reduced Audio encoded using a bit reduced
perceptual audio coder.perceptual audio coder.
Audio Processing & Dynamics Process the Process the sourcesource::
Compression - reduces dynamic rangeCompression - reduces dynamic range Limiting - to set brick wall upper audio limitLimiting - to set brick wall upper audio limit EQ, to soften upper frequenciesEQ, to soften upper frequencies
Use outboard audio equipment:Use outboard audio equipment: Compressor/LimiterCompressor/Limiter EQ, to manipulate frequenciesEQ, to manipulate frequencies
Audio source flow
Source
Encoder
Audio source flow
End User
Encoder RealServer
What if there are problems?
Monitor your stream:Monitor your stream: Install a PC to playback the stream.Install a PC to playback the stream. Wire the output of the PC’s audio card to a Wire the output of the PC’s audio card to a
silence sensor.silence sensor. When the alarm goes off, you know there is a When the alarm goes off, you know there is a
problem with the stream.problem with the stream.
Monitoring the Stream will alert you when:
The Encoder failsThe Encoder fails
The source is interrupted or failsThe source is interrupted or fails
Your Network failsYour Network fails
Automated Static Web Encoding
Process:Process: Source Audio file is compiled/recordedSource Audio file is compiled/recorded Dynamics are applied to the audio fileDynamics are applied to the audio file File is processed in Real ProducerFile is processed in Real Producer Web Encoded file is delivered to destinationWeb Encoded file is delivered to destination
MPR’s Design
ENCO - Dad Pro 32:ENCO - Dad Pro 32: Controls SAS RouterControls SAS Router Records appropriate source to a PCM Records appropriate source to a PCM
Linear .WAV file.Linear .WAV file.
MPR’s Design Static Encode Box:Static Encode Box:
Running Windows NT 4.0Running Windows NT 4.0 NT script moves file from ENCO driveNT script moves file from ENCO drive WaveConvert Pro applies dynamics to .WAV file and WaveConvert Pro applies dynamics to .WAV file and
creates new filecreates new file Real Producer encodes new .WAV fileReal Producer encodes new .WAV file Newly encoded file waits for deliveryNewly encoded file waits for delivery
MPR’s Design Caravan:Caravan:
Developed by MPR Online personnelDeveloped by MPR Online personnel Script runs 24 days monitoring directory Script runs 24 days monitoring directory
contentscontents When a new Real Audio file is delivered, When a new Real Audio file is delivered,
Caravan moves it to its proper locationCaravan moves it to its proper location
Overall Goals Reduce Bit Rate:Reduce Bit Rate:
Keeps data costs down.Keeps data costs down. Reaches more people simultaneously.Reaches more people simultaneously. Allows access to people on a dial up modem.Allows access to people on a dial up modem.
Online Resources Real Networks:Real Networks:
http://www.real.comhttp://www.real.com Real Producer is freeReal Producer is free Real Player is freeReal Player is free User forums and FAQS are helpfulUser forums and FAQS are helpful
http://service.real.com/help/library/guides/production/http://service.real.com/help/library/guides/production/htmfiles/whatsnew.htmhtmfiles/whatsnew.htm
Online Resources Helpful articles to read:Helpful articles to read:
http://www.sospubs.co.uk/sos/may00/articles/mp3.htmlhttp://www.sospubs.co.uk/sos/may00/articles/mp3.html
http://www.iis.fhg.de/amm/index.htmlhttp://www.iis.fhg.de/amm/index.html
http://www.minidisc.org/PerceptualCoding.htmlhttp://www.minidisc.org/PerceptualCoding.html
http://www.wired.com/wired/archive/7.08/codecs.htmlhttp://www.wired.com/wired/archive/7.08/codecs.html
http://www.webdeveloper.com/multimedia/http://www.webdeveloper.com/multimedia/multimedia_guide_realaudio_2.htmlmultimedia_guide_realaudio_2.html