Audio Lossless Coding

Streaming. Error correction mechanisms. Optional storage in MP4 file format. Can be multiplexed with video data using MP4 file format. An MPEG-4 Audio profile "ALS Simple Profile". Lossless Predictive Audio Compression (predecessor). Lossless Transform Audio Compression (pre-predecessor). MPEG-4 SLS (MPEG-4 Scalable Lossless Coding). MPEG-4. MPEG-4 ALS homepage - Technical University of Berlin. MPEG-4 Audio Lossless Coding (ALS) - MultimediaWiki. MPEG-4 ALS: Performance, Applications, and Related Standardization Activities - NTT (2007). Technical papers describing design of residual coding and quantization algorithms in MPEG-4 ALS codec. Announcement on ACN Newswire.

VLC media player

VLCVLC playerlibVLC
Container formats: ASF, AVI, FLAC, FLV, Fraps, Matroska, MP4, MPJPEG, MPEG-2 (ES, MP3), Ogg, PS, PVA, QuickTime File Format, TS, WAV, WebM. Audio coding formats: AAC, AC-3, DV Audio, FLAC, MP3, Speex, Vorbis. Streaming protocols: HTTP, MMS, RTSP, RTP, UDP. Video coding formats: Dirac, DV, H.263, H.264/MPEG-4 AVC, H.265/MPEG-H HEVC, MJPEG, MPEG-1, MPEG-2, MPEG-4 Part 2, Theora, VP5, VP6, VP8, VP9. Comparison of video player software. List of codecs. List of music software.

Dolby Digital

Dolby Digital 5.1AC3AC-3
Some Sony PlayStation 2 console games are able to output AC-3 standard audio as well, primarily during pre-rendered cutscenes. Dolby is part of a group of organizations involved in the development of AAC (Advanced Audio Coding), part of MPEG specifications, and considered the successor to MP3. Dolby Digital Plus (DD-Plus) and TrueHD are supported in HD DVD, as mandatory codecs, and in Blu-ray Disc, as optional codecs. In the LaserDisc world AC3RF is the acronym widely placed on connectors of players that support Dolby Digital. Specific demodulators and receivers from the LaserDisc era (1990s thru early 2000s) also include placement of this acronym on connectors.

Code-excited linear prediction

CELPCode Excited Linear PredictionCode-excited linear prediction (CELP)
MPEG-4 Part 3 (CELP as an MPEG-4 Audio Object Type). G.728 – Coding of speech at 16 kbit/s using low-delay code excited linear prediction. G.718 – uses CELP for the lower two layers for the band (50–6400 Hz) in a two-stage coding structure. G.729.1 – uses CELP coding for the lower band (50–4000 Hz) in a three-stage coding structure. Comparison of audio coding formats. CELT is a related audio codec that borrows some ideas from CELP. B.S. Atal, "The History of Linear Prediction," IEEE Signal Processing Magazine, vol. 23, no. 2, March 2006, pp. 154–161. M. R. Schroeder and B. S.


OGM.oggOgg Writ
., MP3/MP4), it was commonly used to encode free content (such as free music, multimedia on Wikimedia Foundation projects and Creative Commons files) and had started to be supported by a significant minority of digital audio players. Also supporting the Ogg format were many popular video game engines, including Doom 3, Unreal Tournament 2004, Halo: Combat Evolved, Jets n Guns, Mafia: The City of Lost Heaven, Myst IV: Revelation, Stepmania, Serious Sam: The Second Encounter, Lineage 2, Vendetta Online, Battlefield 2, and the Grand Theft Auto engines, as well as the audio files of the Java-based game, Minecraft.


ID3v2ID3 tagID3 tags
ID3 is a metadata container most often used in conjunction with the MP3 audio file format. It allows information such as the title, artist, album, track number, and other information about the file to be stored in the file itself. ID3 is also specified by Apple as a timed metadata in HTTP Live Streaming, carried as a PID in the main transport stream or in separate audio TS. There are two unrelated versions of ID3: ID3v1 and ID3v2. ID3v1 takes the form of a 128-byte segment at the end of an MP3 file containing a fixed set of data fields. ID3v1.1 is a slight modification which adds a "track number" field at the expense of a slight shortening of the "comment" field.


Real AlternativeRealOneRealOne Player
Streaming: RealTime Streaming Protocol (rtsp://), Progressive Networks Streaming Protocols (pna://, pnm://), Microsoft Windows Media Streaming Protocol (mms://), Real Scalable Multicast (*.sdp), Synchronized Multimedia Integration Language (*.smil, *.smi). Audio: MP3 (*.mp3, *.mp2, *.mp2, *.m3u), CD Audio (*.cda), WAV (*.wav), AAC/aacPlus v1 (*.aac, *.m4a, *.m4b, *.mp4, *.acp, *.m4p), Apple Lossless, AIFF (*.aif, *.aiff), AU Audio Files (*.au), Panasonic AAC (*.acp). Video: DVD (*.vob), Video CD (*.dat), MPEG Video (*.mpg, *.mpeg, *.m2v, *.mpe etc.), AVI (*.avi, *.divx), MJPEG video playback from .avi files, Windows Media (*.wma, *.wmv etc.)

Comparison of video container formats

Comparison of container formatsComparison of (audio/video) container formatscontainer files
In high bitrate encodings, the content payload is usually large enough to make the overhead data relatively insignificant, but in low bitrate encodings, the inefficiency of the overhead can significantly affect the resulting file size if the container uses large stream packet headers or a large number of packets. In general, Matroska offers the least overhead, followed by MP4, AVI and Ogg. MPEG-PS. MPEG-TS. M2TS. VOB. EVOB. QTFF. ISO BMFF. 3GPP, 3GPP2. F4V. MP4. MCF. Matroska. WebM. RIFF. AVI. DMF. RM. RMVB. List of codecs. List of open-source codecs. Comparison of video codecs. Comparison of audio coding formats. Enhanced podcast.

High-Efficiency Advanced Audio Coding

High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio defined as an MPEG-4 Audio profile in ISO/IEC 14496-3. It is an extension of Low Complexity AAC (AAC LC) optimized for low-bitrate applications such as streaming audio. HE-AAC version 1 profile (HE-AAC v1) uses spectral band replication (SBR) to enhance the modified discrete cosine transform (MDCT) compression efficiency in the frequency domain. HE-AAC version 2 profile (HE-AAC v2) couples SBR with Parametric Stereo (PS) to enhance the compression efficiency of stereo signals. It is a standardized and improved version of the AACplus codec.

Video coding format

video coding standardsvideo codingvideo coding standard
Video content encoded using a particular video coding format is normally bundled with an audio stream (encoded using an audio coding format) inside a multimedia container format such as AVI, MP4, FLV, RealMedia, or Matroska. As such, the user normally doesn't have a H.264 file, but instead has a .mp4 video file, which is an MP4 container containing H.264-encoded video, normally alongside AAC-encoded audio. Multimedia container formats can contain any one of a number of different video coding formats; for example the MP4 container format can contain video in either the MPEG-2 Part 2 or the H.264 video coding format, among others.

Audible (store)

AudibleAudible.comAudible Studios
Books purchased on iTunes would have a .m4b extension (a variation on MP4) and would contain AAC audio covered by Apple's FairPlay Digital Rights Management. Audible's success began to increase interest in the profile of Audible's founder, Don Katz. Consequently, he had his profile highlighted by AudioFile magazine in early 2003, was called upon to give a recorded talk on IT Conversations in May 2005 about the early history of Audible, and was tapped to deliver the keynote address at the Podcast Expo in November 2005.

Sampling (signal processing)

sampling ratesamplingsample rate
Digital audio uses pulse-code modulation and digital signals for sound reproduction. This includes analog-to-digital conversion (ADC), digital-to-analog conversion (DAC), storage, and transmission. In effect, the system commonly referred to as digital is in fact a discrete-time, discrete-level analog of a previous electrical analog. While modern systems can be quite subtle in their methods, the primary usefulness of a digital system is the ability to store, retrieve and transmit signals without any loss of quality. A commonly seen unit of sampling rate is Hz, which stands for Hertz and means "samples per second". As an example, 48 kHz is 48,000 samples per second.


Scalable Lossless CodingHD-AACMPEG-4 Scalable To Lossless (SLS)
MPEG-4 SLS, or MPEG-4 Scalable to Lossless as per ISO/IEC 14496-3:2005/Amd 3:2006 (Scalable Lossless Coding), is an extension to the MPEG-4 Part 3 (MPEG-4 Audio) standard to allow lossless audio compression scalable to lossy MPEG-4 General Audio coding methods (e.g., variations of AAC). It was developed jointly by the Institute for Infocomm Research (I 2 R) and Fraunhofer, which commercializes its implementation of a limited subset of the standard under the name of HD-AAC. Standardization of the HD-AAC profile for MPEG-4 Audio is under development (as of September 2009).

Bit rate

bitratedata ratedata transfer rate
Plus), an enhanced coding system based on the AC-3 codec. 9.6 Mbit/s – DVD-Audio, a digital format for delivering high-fidelity audio content on a DVD.

Digital media

digital editingdigitalonline media
The development of the modified discrete cosine transform (MDCT) algorithm led to the MP3 audio coding format in 1994, and the Advanced Audio Coding (AAC) format in 1999. Since the 1960s, computing power and storage capacity have increased exponentially, largely as a result of MOSFET scaling which enables MOS transistor counts to increase at a rapid pace predicted by Moore's law. Personal computers and smartphones put the ability to access, modify, store and share digital media in the hands of billions of people. Many electronic devices, from digital cameras to drones have the ability to create, transmit and view digital media.

Digital Audio Broadcasting

DABDAB+DAB Digital Radio
The newer DAB+ standard adopted the HE-AAC version 2 audio codec, commonly known as 'AAC+' or 'aacPlus'. AAC+ uses a modified discrete cosine transform (MDCT) algorithm, and is approximately three times more efficient than MP2, which means that broadcasters using DAB+ are able to provide far higher audio quality or far more stations than they could with DAB, or a combination of both higher audio quality and more stations.

Audio bit depth

24-bitbit depthresolution
Bits are the basic unit of data used in computing and digital communications. Bit rate refers to the amount of data, specifically bits, transmitted or received per second. In MP3, Ogg and other compressed file format, bit rate is used to encode the number of bits to be transmitted into the particular audio aspect. It is usually measured in kb/s. * Audio system measurements. Color depth—corresponding concept for digital images. Effective number of bits.

Digital Video Broadcasting

DVBDigital Video BroadcastDVB Project
Modes and features of latest DVB-x2 system standards in comparison: Digital video content is encoded using discrete cosine transform (DCT) based video coding standards, such as the H.26x and MPEG formats. Digital audio content is encoded using modified discrete cosine transform (MDCT) based audio coding standards, such as Advanced Audio Coding (AAC), Dolby Digital (AC-3) and MP3. Besides digital audio and digital video transmission, DVB also defines data connections (DVB-DATA - EN 301 192) with return channels (DVB-RC) for several media (DECT, GSM, PSTN/ISDN, satellite etc.) and protocols (DVB-IPTV: Internet Protocol; DVB-NPI: network protocol independent).


Bento BrowserDosampWinamp 5.58
After beta testing, AMP was discontinued in 2005, but portions lived on in AOL's Web-based player. * * Playback formats: Winamp supports music playback using MP3, MIDI, MOD, MPEG-1 audio layers 1 and 2, AAC, M4A, FLAC, WAV, and WMA. Winamp was one of the first widely used music players on Windows to support playback of Ogg Vorbis by default. It supports gapless playback for MP3 and AAC and ReplayGain for volume leveling across tracks. CD support includes playing and importing music from audio CDs, optionally with CD-Text, and burning music to CDs. The standard version limits maximum burn speed and datarate; the "Pro" version removes these limitations.


QuickTime PlayerQuickTime XApple QuickTime
This is especially true on hardware devices, such as the Sony PSP and various DVD players; on the software side, most DirectShow / Video for Windows codec packs include a MP4 parser, but not one for MOV. In QuickTime Pro's MPEG-4 Export dialog, an option called "Passthrough" allows a clean export to MP4 without affecting the audio or video streams. QuickTime 7 now supports multi-channel AAC-LC and HE-AAC audio (used, for example, in the high-definition trailers on Apple's site ), for both .MOV and .MP4 containers. Apple released the first version of QuickTime on December 2, 1991 as a multimedia add-on for System 6 and later.

MPEG-4 Part 3

TwinVQ – one of the object types defined in MPEG-4 Audio version 1. MPEG-4 Part 2. MPEG-4 Part 14 container format (MP4). Digital rights management. Advanced Audio Coding (AAC). ISO/IEC JTC 1/SC 29. Apple: MPEG-4: AAC. "AAC" (VideoLAN WIKI). EBU subjective listening tests on low-bitrate audio codecs. AAC radio stations – Online radio stations in AAC format. Tuner2 – Directory of radio stations in AAC+ format at various bitrates. RadioFeeds UK & Ireland – Page containing plenty of terrestrial stations webcasting in AAC+ format. A page comparing codecs including HE-AAC @64 kbit/s by listening tests. (Page is offline). Official MPEG web site.


Apple iTunesApple PodcastsiTunes India
The software supports importing digital audio tracks that can then be transferred to iOS devices, as well as supporting ripping content from CDs. iTunes supports WAV, AIFF, Apple Lossless, AAC, and MP3 audio formats. It uses the Gracenote music database to provide track name listings for audio CDs. When users rip content from a CD, iTunes attempts to match songs to the Gracenote service. For self-published CDs, or those from obscure record labels, iTunes will normally only list tracks as numbered entries ("Track 1", "Track 2") on an unnamed album by an unknown artist, requiring manual input of data.

Apple Inc.

AppleApple ComputerApple Inc
The new device is 1/4 the size, runs quieter, and replaces the need for a hard drive with media streaming from any iTunes library on the network along with 8 GB of flash memory to cache downloaded media. Like the iPad and the iPhone, Apple TV runs on an A4 processor. The memory included in the device is half of that in the iPhone 4 at 256 MB; the same as the iPad, iPhone 3GS, third and fourth-generation iPod Touch. It has HDMI out as the only video output source. Features include access to the iTunes Store to rent movies and TV shows (purchasing has been discontinued), streaming from internet video sources, including YouTube and Netflix, and media streaming from an iTunes library.

Bell Labs

Bell LaboratoriesBell Telephone LaboratoriesAT&T Bell Laboratories
In 1943, Bell developed SIGSALY, the first digital scrambled speech transmission system, used by the Allies in World War II. The British wartime codebreaker Alan Turing visited the labs at this time, working on speech encryption and meeting Claude Shannon. Bell Labs Quality Assurance Department gave the world and the United States such statisticians as Walter A. Shewhart, W. Edwards Deming, Harold F. Dodge, George D. Edwards, Harry Romig, R. L. Jones, Paul Olmstead, E.G.D. Paterson, and Mary N. Torrey.

K. R. Rao

K.R. Rao
He also teaches graduate courses on Digital Video Coding, Digital Image Processing, Discrete Transforms and Multimedia Processing. His recent graduate thesis student is Swaroop Krishna Rao and current Graduate Student Assistant is Anusha Venkatasivareddy. He has been an external examiner for graduate students from universities in Australia, Canada, Hong Kong, India, Singapore, Thailand and Taiwan. He was a visiting professor in several Universities – 3 weeks to 7 and 1/2 months – (Australia, India, Japan, Korea, Singapore and Thailand). He has conducted workshops/tutorials on video/audio coding/standards worldwide.