DOCSLIB.ORG

Audio Coding

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Audio Coding Friday, March 29, 2019 29.3.2019 Audio Coding ELEC-E5620 - Audio Signal Processing, Lecture #10 Vesa Välimäki Sound check Course Schedule in 2019 (Periods III-VI) 0. General issues (Vesa & Benoit) 11.1.2019 1. History and future of audio DSP (Vesa) 18.1.2019 2. Digital filters in audio (Vesa) 25.1.2019 3. Audio filter design (Vesa) 1.2.2019 4. Analysis of audio signals (Vesa) 8.2.2019 5. Audio effects processing (Benoit Vesa) 15.2.2019 * No lecture (Evaluation week for Period III) 22.2.2019 6. Synthesis of audio signals (Fabian) 1.3.2019 7. Reverberation and 3-D sound (Benoit) 8.3.2019 8. Physics-based sound synthesis (Vesa) 15.3.2019 9. Sampling rate conversion (Vesa) 22.3.2019 10. Audio coding (Vesa) 29.3.2019 ©2001-2019 Vesa Välimäki 29.3.2019 2 1 Friday, March 29, 2019 Outline • Introduction • Lossless Audio Coding • Perceptual (Lossy) Audio Coding – Subband coding, time-to-frequency mapping, psychoacoustic models, parametric coding • MPEG standards and some new codes – MP3, AAC, USAC, OPUS • Applications Part of this lecture material was produced by Ms. Azadeh Haghparast (TKK Dept. of Signal Processing and Acoustics, 2007) 29.3.2019 ©2001-2019 Vesa Välimäki 3 Bit-rate of Audio Signals • Bit-rate of one audio channel without compression (at 44.1 kHz): 16 bit 44100 samples/s = 700 kbit/s • Stereo signal (44.1 kHz): 2 16 bit 44100 samples/s = 1.4 Mbit/s • Additionally, bits are needed for error correction and synchronization – On a CD disk, 33 extra bits for each 16 bits of audio data are needed, so the total bit-rate is 4.3 Mbit/s 29.3.2019 ©2001-2019 Vesa Välimäki 4 2 Friday, March 29, 2019 Bit-Rate for Various Digital Audio Schemes Application Format Sample Audio Overhead Total bit- rate bit-rate bit-rate rate Compact Disc PCM 44.1 kHz 1.41 Mb/s 2.91 Mb/s 4.32 Mb/s (CD) Digital Audio Tape PCM 44.1 kHz 1.41 Mb/s 1.67 Mb/s 3.08 Mb/s (DAT) MiniDisc (MD) ATRAC 44.1 kHz 292 kb/s 718 kb/s 1.01 Mb/s Digital Audio MPEG-1 48 kHz 256 kb/s 256 kb/s 512 kb/s Broadcast (DAB) Layer II,III 29.3.2019 ©2001-2019 Vesa Välimäki 5 Applications of Audio Coding • Storage – Music archives – Movie soundtracks – Music for electronic games • Communication – Mobile multimedia – Internet streaming • Broadcasting – Digital radio and TV • Wireless audio – Hands-free headphones and headsets – Wireless speakers 29.3.2019 ©2001-2019 Vesa Välimäki 6 3 Friday, March 29, 2019 Classification of Audio Coding Techniques • Lossless Audio Coding – Reducing the size of audio signal using redundancy reduction, such as sample value distribution – The original signal values can be obtained by decoding – Shorten, FLAC, Monkey’s Audio, MPEG-4 ALS, Windows Media Audio 9 Lossless, RealAudio Lossless, APT-X… • Lossy Audio Coding – Reducing the size of audio signal using irrelevancy reduction – Use of limitations of human hearing, e.g., auditory masking – MPEG Audio (Layer 1, 2, 3), Dolby Digital, Ogg Vorbis, MPEG-AAC, HILN (MPEG-4 Parametric Audio Coding), WMA (Windows Media Audio), … 29.3.2019 ©2001-2019 Vesa Välimäki 7 Applications of Lossless Audio Coding • Archiving of original recordings • Studio operations, such as mixing • Digital music distribution over the Internet • Portable music players/recorders • Multi-channel audio (e.g., DVD-Audio) • Bluetooth audio (headsets, speakers) 29.3.2019 ©2001-2019 Vesa Välimäki 8 4 Friday, March 29, 2019 Principles of Lossless Audio Coding • A lossless audio coder comprises of three main blocks: – Framing Divides the audio signal into frames, e.g., 100 ms – Decorrelation Removes redundancy (spectral whitening) – Entropy encoding Statistically efficient code book The histogram of audio signals is often close to Laplace distribution: more small sample values than large ones Short code for common sample values Long code for rare sample values 29.3.2019 ©2001-2019 Vesa Välimäki 9 Principles of Lossless Audio Coding • Two approaches to decorrelate the audio signal 1. Linear predictive model – Lossless representation Predictor coefficients + Error signal 2. Linear transform model – Lossless representation Transform coefficients + Error signal 29.3.2019 ©2001-2019 Vesa Välimäki 10 5 Friday, March 29, 2019 Linear Prediction • Predictor coefficients are determined – Usually using the Autocorrelation or Covariance method • Each sample is estimated from its previous samples using predictor coefficients kM xˆn Q a k x n k , k 1 29.3.2019 ©2001-2019 Vesa Välimäki 11 Decorrelation With a Polynomial Predictor • Try several simple polynomial predictors and select the best one – The best predictor is the one that produces error signal with the smallest amplitude – The spectrum is whitened – Integer coefficients to avoid rounding errors – For example, try the following polynomial predictors • xp0(n) = 0 (next sample is zero) • xp1(n) = x(n – 1) (same value repeats) • xp2(n) = 2x(n –1) –x(n – 2) (linear trend) • xp3(n) = 3x(n –1) –3x(n –2) + x(n –3) (Ref. Hans and Schafer 2001) 29.3.2019 ©2001-2019 Vesa Välimäki 12 6 Friday, March 29, 2019 Principles of Lossless Audio Coding • Decorrelation by Linear Transform Model 29.3.2019 ©2001-2019 Vesa Välimäki 13 LTAC • LTAC: Lossless Transform Audio Coding • Fixed or variable frame length • Orthonormal Discrete Cosine Transform (DCT) • Groups of 32 adjoining transform coefficients • Rice coding for transform coefficients • Arithmetic coding for the error signal 29.3.2019 ©2001-2019 Vesa Välimäki 14 7 Friday, March 29, 2019 MPEG-4 ALS • MPEG-4 Audio Lossless Coding standard, 2005- 29.3.2019 ©2001-2019 Vesa Välimäki 15 MPEG-4 ALS • Based on Linear Prediction – Optimal predictor coefficients are calculated based on an iterative procedure • Optimal order of predictor optimal predictor coefficients the smallest bit-rate • Coefficients converted to arcsine • Linear 8-bit quantization of arcsine coefficients • Rice entropy coding 29.3.2019 ©2001-2019 Vesa Välimäki 16 8 Friday, March 29, 2019 Comparison of Lossless Audio Codecs ≈ 50% Ref: Coalson, 2005. http://flac.sourceforge.net/comparison.html 29.3.2019 ©2001-2019 Vesa Välimäki 17 Lossy Audio Coding • High compression ratios can be achieved, when the signal is allowed to change – The goal is the minimal disturbance for human listeners • Technology for end users – Listen to the coded material as is (no further processing, EQ etc.) – Unsuitable for high-quality recordings or archiving • Subband audio coding – MP3, Dolby AC-3, Vorbis, WMA (Windows Media Player) • Parametric audio coding – HILN (MPEG-4) 29.3.2019 ©2001-2019 Vesa Välimäki 18 9 Friday, March 29, 2019 Applications of Lossy Audio Coding • Portable music players and mobile phones – Also MiniDisk players • Internet audio • Digital TV • Digital radio • Movie soundtracks 29.3.2019 ©2001-2019 Vesa Välimäki 19 Subband Audio Coding • A.k.a. perceptual audio coding • Frequency-domain representation of audio signal • Based on a psychoacoustic model – Model of the threshold of hearing – Shape the quantization below the threshold of hearing 29.3.2019 ©2001-2019 Vesa Välimäki 20 10 Friday, March 29, 2019 Subband Audio Coding • General block diagram of subband coder 29.3.2019 ©2001-2019 Vesa Välimäki 21 Time to Frequency Mapping • Time to frequency mapping techniques – The simplest technique Fourier Transform (FFT) – Filter bank technique – Pseudo-Quadrature Mirror Filter bank (PQMF) – Modified Discrete Cosine Transform (MDCT) 29.3.2019 ©2001-2019 Vesa Välimäki 22 11 Friday, March 29, 2019 Filter Bank • N-channel filter bank N parallel bandpass filters • Uniform or non-uniform bandwidth • Magnitude response of a uniform bandwidth N-channel filter bank 29.3.2019 ©2001-2019 Vesa Välimäki 23 Filter Bank • Analysis-synthesis filter bank Perfect Reconstruction filter bank 29.3.2019 ©2001-2019 Vesa Välimäki 24 12 Friday, March 29, 2019 Filter Bank • Down-sampling – Preserves data rate – Problem: limiting the spectral bandwidth aliasing (folding) • Up-sampling – Restores data rate – Problem: expanding the spectral bandwidth imaging distortion 29.3.2019 ©2001-2019 Vesa Välimäki 25 Pseudo-Quadrature Mirror Filter Bank • Pseudo-Quadrature Mirror Filter (PQMF) Bank • Design a narrow lowpass filter Prototype filter • Other filters obtained by cosine modulation of the prototype filter • MPEG-1 and MPEG-2 – 32 channels – Prototype filter of order 512 29.3.2019 ©2001-2019 Vesa Välimäki 26 13 Friday, March 29, 2019 2-Channel PQMF • Design of a 2-channel analysis-synthesis filter bank • Challenge: – Define the filters H 0 (z), H 1 ( z ) , G 0 ( z ) , G 1 ( z ) – For Perfect Reconstruction: G0 z H1 (z), G1 z H 0 z . – and also H1z H0 z . 29.3.2019 ©2001-2019 Vesa Välimäki 27 Modified DCT Filter Bank • Modified Discrete Cosine Transform Filter Bank • Also called Time-Domain Aliasing Cancellation (TDAC) • Special case of PQMF – Length of the prototype filter is twice that of the PQMF – 50% overlap with the previous frame • Prototype filter Sine function • Choice of window length – Long window length good for stationary signal – Short window length suitable for transients 29.3.2019 ©2001-2019 Vesa Välimäki 28 14 Friday, March 29, 2019 Subband Coding • General block diagram of subband coder 29.3.2019 ©2001-2019 Vesa Välimäki 29 Psychoacoustics • Absolute threshold of hearing • Masking phenomenon – Simultaneous masking, also called frequency masking – Non-simultaneous masking, also called temporal masking • Critical bandwidth • Spread of masking 29.3.2019 ©2001-2019 Vesa Välimäki 30 15 Friday, March 29, 2019 Sound Pressure Level • Quantity for measuring the sound pressure P 2 SPL(dB)10log10 ( ) ,
Load more

Recommended publications
  • An Introduction to Mpeg-4 Audio Lossless Coding
    « ¬ AN INTRODUCTION TO MPEG-4 AUDIO LOSSLESS CODING Tilman Liebchen Technical University of Berlin ABSTRACT encoding process has to be perfectly reversible without loss of in- formation, several parts of both encoder and decoder have to be Lossless coding will become the latest extension of the MPEG-4 implemented in a deterministic way. audio standard. In response to a call for proposals, many com- The MPEG-4 ALS codec uses forward-adaptive Linear Pre- panies have submitted lossless audio codecs for evaluation. The dictive Coding (LPC) to reduce bit rates compared to PCM, leav- codec of the Technical University of Berlin was chosen as refer- ing the optimization entirely to the encoder. Thus, various encoder ence model for MPEG-4 Audio Lossless Coding (ALS), attaining implementations are possible, offering a certain range in terms of working draft status in July 2003. The encoder is based on linear efficiency and complexity. This section gives an overview of the prediction, which enables high compression even with moderate basic encoder and decoder functionality. complexity, while the corresponding decoder is straightforward. The paper describes the basic elements of the codec, points out 2.1. Encoder Overview envisaged applications, and gives an outline of the standardization process. The MPEG-4 ALS encoder (Figure 1) typically consists of these main building blocks: • 1. INTRODUCTION Buffer: Stores one audio frame. A frame is divided into blocks of samples, typically one for each channel. Lossless audio coding enables the compression of digital audio • Coefficients Estimation and Quantization: Estimates (and data without any loss in quality due to a perfect reconstruction quantizes) the optimum predictor coefficients for each of the original signal.
    [Show full text]
  • User's Manual CW200
    PORTABLE DIGITAL AUDIO PLAYER iAUDIO CW200 User’s Manual CW200 CW200 COPYRIGHT NOTICE This document is Copyright © 2003 by COWON SYSTEMS, Inc. Redistribution of all or portions of the contents in this manual without the permission of COWON SYSTEMS is prohibited. iAUDIO is a registered trademark of COWON SYSTEMS. COWON SYSTEMS also holds the copyrights of JetShell, JetAudio, and JetVoiceMail. Illegal distribution or commercial usage of these products is prohibited without the written consent from COWON SYSTEMS, Inc. Also, we announce that usage of MP3 files created using JetShell or JetAudio MP3 conversion methods should be limited to personal usage, not for commercial purposes. We inform you that violating the items stated above is an action that infringes the domestic copyright law. All rights reserved by COWON SYSTEMS, Inc. 2003 2 CW200 CW200 WARRANTY WARRANTY This product has been manufactured according to strict quality management and verification standards. If in any case the product produces a manufactural flaw or natural failure during the quality guarantee term stated below, COWON SYSTEMS will pay due responsibility according to the contents stated in this warranty. Product MP3 Player Model IAUDIO CW200 Serial Number Warranty Term 1 year from purchase (body : 1year, components : 6 months) Date of Purchase Verify if there are any items unlisted in the designated items of this warranty. Always show this warranty when receiving service. Be sure not to lose this warranty for it cannot be reissued. Contents of Product Warranty 1. In any case the product produces a failure during normal operation within the warranty term, COWON SYSTEMS will repair the product free of charge or provide compensations in accordance with the compensation rule for consumer damages.
    [Show full text]
  • Implementing Object-Based Audio in Radio Broadcasting
    Object-based Audio in Radio Broadcast Implementing Object-based audio in radio broadcasting Diplomarbeit Ausgeführt zum Zweck der Erlangung des akademischen Grades Dipl.-Ing. für technisch-wissenschaftliche Berufe am Masterstudiengang Digitale Medientechnologien and der Fachhochschule St. Pölten, Masterkalsse Audio Design von: Baran Vlad DM161567 Betreuer/in und Erstbegutachter/in: FH-Prof. Dipl.-Ing Franz Zotlöterer Zweitbegutacher/in:FH Lektor. Dipl.-Ing Stefan Lainer [Wien, 09.09.2019] I Ehrenwörtliche Erklärung Ich versichere, dass - ich diese Arbeit selbständig verfasst, andere als die angegebenen Quellen und Hilfsmittel nicht benutzt und mich auch sonst keiner unerlaubten Hilfe bedient habe. - ich dieses Thema bisher weder im Inland noch im Ausland einem Begutachter/einer Begutachterin zur Beurteilung oder in irgendeiner Form als Prüfungsarbeit vorgelegt habe. Diese Arbeit stimmt mit der vom Begutachter bzw. der Begutachterin beurteilten Arbeit überein. .................................................. ................................................ Ort, Datum Unterschrift II Kurzfassung Die Wissenschaft der objektbasierten Tonherstellung befasst sich mit einer neuen Art der Übermittlung von räumlichen Informationen, die sich von kanalbasierten Systemen wegbewegen, hin zu einem Ansatz, der Ton unabhängig von dem Gerät verarbeitet, auf dem es gerendert wird. Diese objektbasierten Systeme behandeln Tonelemente als Objekte, die mit Metadaten verknüpft sind, welche ihr Verhalten beschreiben. Bisher wurde diese Forschungen vorwiegend
    [Show full text]
  • Acoustica-Mp3-Audio-Mixer-Manual.Pdf
    Acoustica Registration Overview Quick Start Version History Using MP3 Audio Mixer Working with Sounds Working with Sound Groups Main Window Exporting to MP3, WMA, WAV, or Realaudio™ Preferences Troubleshooting Menu Reference File Edit Sound Group Sound Menu Toolbar Copyright and Ownership Notices MP3 Audio Mixer © Copyright 1998-2002 Acoustica. All Rights Reserved. Includes Xaudio software Copyright © 1996-2002 Xaudio Corporation. All Rights Reserved. RealAudio® encoding components © 1996-2002 by Real Networks, Inc. Windows Media Format © 2000-2002 Microsoft Corporation. All rights reserved. Quick Start So you want to get started in a hurry? Follow "SoundWarrior" through the steps to MP3 Audio Mixer mastery! 1. Start MP3 Audio Mixer SoundWarrior double clicks the MP3 Audio Mixer icon on his desktop. Okay, we could have left this step out. J 2. Drag in some sounds. SoundWarrior has a good sound of a cave-woman scream called arghhh1.wav. The sound is located in "c:\cavescreams\", which he finds, and then drags the sound’s icon onto the MP3 Audio Mixer window. See working with sounds. 3. Drag in some more sounds. SoundWarrior also drags in stampede.wav, the sound of a herd of Mastodons stampeding by his cave. Finally, he drags in an MP3 called "rockrolls.mp3", some of the latest music from "The Stoners" 4. Make a recording if you want. SoundWarrior hits the record button and the record dialog comes up. He punches the record button on the dialog and screams into his microphone "You make fire now! I make fire yesterday!" He then hits the stop button, previews the sound and saves it as "me_talk1.wav".
    [Show full text]
  • Audio Coding for Digital Broadcasting
    Recommendation ITU-R BS.1196-7 (01/2019) Audio coding for digital broadcasting BS Series Broadcasting service (sound) ii Rec. ITU-R BS.1196-7 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio- frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http://www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http://www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1.
    [Show full text]
  • Real-Time Programming and Processing of Music Signals Arshia Cont
    Real-time Programming and Processing of Music Signals Arshia Cont To cite this version: Arshia Cont. Real-time Programming and Processing of Music Signals. Sound [cs.SD]. Université Pierre et Marie Curie - Paris VI, 2013. tel-00829771 HAL Id: tel-00829771 https://tel.archives-ouvertes.fr/tel-00829771 Submitted on 3 Jun 2013 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Realtime Programming & Processing of Music Signals by ARSHIA CONT Ircam-CNRS-UPMC Mixed Research Unit MuTant Team-Project (INRIA) Musical Representations Team, Ircam-Centre Pompidou 1 Place Igor Stravinsky, 75004 Paris, France. Habilitation à diriger la recherche Defended on May 30th in front of the jury composed of: Gérard Berry Collège de France Professor Roger Dannanberg Carnegie Mellon University Professor Carlos Agon UPMC - Ircam Professor François Pachet Sony CSL Senior Researcher Miller Puckette UCSD Professor Marco Stroppa Composer ii à Marie le sel de ma vie iv CONTENTS 1. Introduction1 1.1. Synthetic Summary .................. 1 1.2. Publication List 2007-2012 ................ 3 1.3. Research Advising Summary ............... 5 2. Realtime Machine Listening7 2.1. Automatic Transcription................. 7 2.2. Automatic Alignment .................. 10 2.2.1.
    [Show full text]
  • Detail Streaming Support Protocols
    Encore+ User Guide Detail Streaming Support Protocols Supported Audio Codecs Supported Container Formats • MP3 • WAV • AAC • M4A • FLAC • OGG • LPCM/WAV/AIFF • AIFF • ALAC Supported Protocols • WMA, WMA9 • SHOUTcast • Ogg Vorbis • HTTPS Supported Playlist • WMA streaming • ASX • RTSP/SDP • M3U • PLS • WPL 43 Detail Audio Codec Support Encore+ User Guide Supported MP3 encoding parameters • Sampling rates [kHz]: 32, 44.1, 48 • Resolution [bits]: 16 • Bit rate [kbps]: 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, VBR • Channels: stereo, joined stereo, mono • MP3PRO playback • MP3 File extensions: *.mp3 • Decoding of ID3v1, ID3v2, MP3 ID tags including optional album art in .jpeg format up to 2 megapixels • Gapless MP3: Playback is gapless if the container provides LAME encoder delay and padding tags. Supported Vorbis encoding parameters • Sampling rates [kHz]: 32, 44.1, 48 • Resolution [bits]: 16 • Nominal bit rate [kbps] (quality level): 80 (Q1), 96 (Q2), 112 (Q3), 128 (Q4), 160 (Q5), 192 (Q6), • Channels: stereo • The audio player supports reading of Vorbis content stored in Ogg containers. Supported file name extensions: *.ogg and *.oga. • The audio player supports decoding of Vorbis comments. NOTE: There is no specification for tag names. The system relies on the OSS implementation. • Tag names decoded: TITLE, ALBUM, ARTIST, GENRE. • Binary data (e.g. for album art) is not supported. • The audio player supports gapless Vorbis playback. Supported FLAC encoding parameters • Sampling rates [kHz]: 44.1, 48, 88.2, 96, 176.4, 192 • Resolution [bits]: 16, 24 • Channels: stereo, mono • The audio player supports reading of FLAC content stored in native FLAC containers.
    [Show full text]
  • User's Manual
    User’s Manual ver. 1.0 (EN) 2 iAUDIO 7 Before Using Your iAUDIO 7 3 Legal Notice • COWON is a registered trademark of COWON SYSTEMS, INC. • This product is intended for personal use only and may not be used for any commercial purpose without the written consent of COWN SYSTEMS, INC. • Information in this document is copyrighted by COWON SYSTEMS, INC. and no part of this manual may be reproduced or distributed without the written permission of COWN SYSTEMS, INC. • The software described in this document including JetAudio are copyrighted by COWON SYSTEMS, INC. • JetAudio may only be used in accordance with the terms of license agreement and cannot be used for any other purposes. • The media conversion feature in JetAudio may only be used for personal use only. Use of this feature for any other purposes may be considered a violation of the international copyright law. • COWON SYSTEMS, INC. complies with the laws and regulations related to records, videos and games. Comply- ing with all other laws and regulations regarding consumer use of such media is the responsibility of the users. • Information in this manual including contents of product features and specifications is subject to change without notice as updates may be made. • This product has been produced under the license of BBE Sound, Inc. (USP4638258, 5510752 and 5736897). BBE and the BBE symbol are the registered trademarks of BBE Sound, Inc. On-line registration and support • Users are strongly encouraged to complete customer registration at http://www.COWON.com. After filling out our customer registration form using the CD-Key and serial numbers, you can receive various benefits offered only to official members.
    [Show full text]
  • Realaudio and Realvideo Content Creation Guide
    RealAudioâ and RealVideoâ Content Creation Guide Version 5.0 RealNetworks, Inc. Contents Contents Introduction......................................................................................................................... 1 Streaming and Real-Time Delivery................................................................................... 1 Performance Range .......................................................................................................... 1 Content Sources ............................................................................................................... 2 Web Page Creation and Publishing................................................................................... 2 Basic Steps to Adding Streaming Media to Your Web Site ............................................... 3 Using this Guide .............................................................................................................. 4 Overview ............................................................................................................................. 6 RealAudio and RealVideo Clips ....................................................................................... 6 Components of RealSystem 5.0 ........................................................................................ 6 RealAudio and RealVideo Files and Metafiles .................................................................. 8 Delivering a RealAudio or RealVideo Clip ......................................................................
    [Show full text]
  • A Practical Approach to Spatiotemporal Data Compression
    A Practical Approach to Spatiotemporal Data Compres- sion Niall H. Robinson1, Rachel Prudden1 & Alberto Arribas1 1Informatics Lab, Met Office, Exeter, UK. Datasets representing the world around us are becoming ever more unwieldy as data vol- umes grow. This is largely due to increased measurement and modelling resolution, but the problem is often exacerbated when data are stored at spuriously high precisions. In an effort to facilitate analysis of these datasets, computationally intensive calculations are increasingly being performed on specialised remote servers before the reduced data are transferred to the consumer. Due to bandwidth limitations, this often means data are displayed as simple 2D data visualisations, such as scatter plots or images. We present here a novel way to efficiently encode and transmit 4D data fields on-demand so that they can be locally visualised and interrogated. This nascent “4D video” format allows us to more flexibly move the bound- ary between data server and consumer client. However, it has applications beyond purely scientific visualisation, in the transmission of data to virtual and augmented reality. arXiv:1604.03688v2 [cs.MM] 27 Apr 2016 With the rise of high resolution environmental measurements and simulation, extremely large scientific datasets are becoming increasingly ubiquitous. The scientific community is in the pro- cess of learning how to efficiently make use of these unwieldy datasets. Increasingly, people are interacting with this data via relatively thin clients, with data analysis and storage being managed by a remote server. The web browser is emerging as a useful interface which allows intensive 1 operations to be performed on a remote bespoke analysis server, but with the resultant information visualised and interrogated locally on the client1, 2.
    [Show full text]
  • (A/V Codecs) REDCODE RAW (.R3D) ARRIRAW
    What is a Codec? Codec is a portmanteau of either "Compressor-Decompressor" or "Coder-Decoder," which describes a device or program capable of performing transformations on a data stream or signal. Codecs encode a stream or signal for transmission, storage or encryption and decode it for viewing or editing. Codecs are often used in videoconferencing and streaming media solutions. A video codec converts analog video signals from a video camera into digital signals for transmission. It then converts the digital signals back to analog for display. An audio codec converts analog audio signals from a microphone into digital signals for transmission. It then converts the digital signals back to analog for playing. The raw encoded form of audio and video data is often called essence, to distinguish it from the metadata information that together make up the information content of the stream and any "wrapper" data that is then added to aid access to or improve the robustness of the stream. Most codecs are lossy, in order to get a reasonably small file size. There are lossless codecs as well, but for most purposes the almost imperceptible increase in quality is not worth the considerable increase in data size. The main exception is if the data will undergo more processing in the future, in which case the repeated lossy encoding would damage the eventual quality too much. Many multimedia data streams need to contain both audio and video data, and often some form of metadata that permits synchronization of the audio and video. Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data stream to be useful in stored or transmitted form, they must be encapsulated together in a container format.
    [Show full text]
  • Ogg Audio Codec Download
    Ogg audio codec download click here to download To obtain the source code, please see the xiph download page. To get set up to listen to Ogg Vorbis music, begin by selecting your operating system above. Check out the latest royalty-free audio codec from Xiph. To obtain the source code, please see the xiph download page. Ogg Vorbis is Vorbis is everywhere! Download music Music sites Donate today. Get Set Up To Listen: Windows. Playback: These DirectShow filters will let you play your Ogg Vorbis files in Windows Media Player, and other OggDropXPd: A graphical encoder for Vorbis. Download Ogg Vorbis Ogg Vorbis is a lossy audio codec which allows you to create and play Ogg Vorbis files using the command-line. The following end-user download links are provided for convenience: The www.doorway.ru DirectShow filters support playing of files encoded with Vorbis, Speex, Ogg Codecs for Windows, version , ; project page - for other. Vorbis Banner Xiph Banner. In our effort to bring Ogg: Media container. This is our native format and the recommended container for all Xiph codecs. Easy, fast, no torrents, no waiting, no surveys, % free, working www.doorway.ru Free Download Ogg Vorbis ACM Codec - A new audio compression codec. Ogg Codecs is a set of encoders and deocoders for Ogg Vorbis, Speex, Theora and FLAC. Once installed you will be able to play Vorbis. Ogg Vorbis MSACM Codec was added to www.doorway.ru by Bjarne (). Type: Freeware. Updated: Audiotags: , 0x Used to play digital music, such as MP3, VQF, AAC, and other digital audio formats.
    [Show full text]