Mpeg-4 Structured Audio
tarix 11.08.2018 ölçüsü 461 b. #69119
Eric D. Scheirer eds@media.mit.edu Machine Listening Group MIT Media Laboratory Editor, ISO 14496-3 (MPEG-4 Audio) MPEG-4 Structured Audio, A New Standard for Interactive Sound, in the Creation of Which Tom White did not Run the Whole Show, but Only Played a Small (Though Valuable) Part Eric D. Scheirer eds@media.mit.edu Machine Listening Group MIT Media Laboratory Editor, ISO 14496-3 (MPEG-4 Audio) What’s this all about? MPEG-4 is not just about compression Overview What is MPEG? What is MPEG-4 Structured Audio? Why was it created? How does it work? How can it be used in IA applications? What is its current status? A brief note on MPEG-4 AudioBIFS Intellectual property in MPEG-4 Structured Audio and AudioBIFS are free All patentable IP has been released to public domain No licensing or other costs to build tools & players (Standard itself costs $300 for printing/bureaucracy) Companies competing through cooperation Interoperability makes the whole pie bigger MPEG processes for improving/correcting standard MIT has no veto over the future of the standard What is MPEG? MPEG is ISO/IEC JTC1 SC29 WG11 A subcommittee of the Int’l Standards Organization The “Moving Pictures Experts Group” MPEG-1 : 1993 (ISO 11172) Digital audio/video coding (MP3) MPEG-2 : 1994-7 (ISO 13818) Digital coding for broadcast MPEG-4: 1998 (ISO 14496) Object based, synthetic/natural, interactive coding MPEG Marketplace Model
MPEG Marketplace Model
MPEG Marketplace Model
MPEG-4 Audio High-quality sound Based on MPEG-AAC algorithm: twice as good as MP3 Low-bitrate sound For WWW and cellular: speech/music as low as 4 kbps Synthetic sound AudioBIFS Mix and postproduce multi-track sound streams MPEG-4 Structured Audio Transmit structured description of sound Use real-time synthesis to play sound “PostScript for audio” Based on new (to MPEG) technology SAOL: New music synthesis language SASL: New music control format A lot of related technology in academia Csound, Music-11, SynthScript, Nyquist, CLM, ... Standardization goals Provide synthetic sound in MPEG-4 Standardize academic state-of-the-art; don’t innovate Get new companies to work on synthesis Implementation required for full MPEG-4 system Set a higher bar for PC sound architecture Drive forward the world of sound on PCs! MPEG-4 SA decoding process
What SAOL looks like A C-like language Based on the Music-N model Variables hold audio signals Unit generators do basic functions SAOL capabilities Many nice features built in Wavetable manipulation FFT/IFFT Multitap delay lines Arrays of signals FIR & IIR filters Effects routing Granular synthesis 3-D audio interface Dynamic layering and triggering SAOL is extensible-from-within (Allows encapsulation and structured programming) Any kind of synthesis can be used in SAOL Example “Xanadu” (Joseph Kung) 60 seconds long, 44 KHz stereo (10.5 MB as WAVE) 2.2 KB in header 4.2 KB in bitstream (= 0.07 kbps) No samples anywhere , only algorithmic synthesis More than 1200:1 “compression”, no loss of quality Could be controlled/restructured interactively MPEG-MMA relationship MIDI can control MPEG-4 SA synth SASL = more flexible, more tightly coupled DLS-2 synthesis embedded in SA synth Do wavetable in series or parallel with other techniques “Wavetable-only” profile of MPEG-4 MIDI + DLS-2 + compressed audio + video (no SAOL) Logical path of progression from today to tomorrow Lots of help from MMA - appreciated! MPEG is ready to help in the other direction (MIDI-DLA?) Applications ideas MPEG-4 is not an application! It’s a tool - enables functionality and interoperability Implementations could be hardware, software, both Authoring tools also very important Use MPEG-4 SA like Staccato Synthcore Use MPEG-4 SA like Beatnik Use MPEG-4 SA like Koan Use MPEG-4 SA for new music applications Application example: Gaming
Current status Standard and reference software finished Many implementation projects starting Creative Tech Center: Compression & Interactive Audio Studer + EPFL: “ThreeDSpace” project Hobbyist projects (Java API, ActiveX plugin) Others: Be Inc., Sseyo, Kings College , UC Berkeley, Catholic U. Leuven, Q-Team DE, Nokia, ... 3 complete implementations already! A few authoring tools projects Active mailing list for developers A brief note on AudioBIFS BIFS is scene-description part of MPEG-4 “Binary Format for Scenes” Based on VRML, but with many new features AudioBIFS is the audio mixing part Stream audio in multitrack format Deliver mixdown instructions in AudioBIFS Mixing, spatialization, effects in SAOL , multichannel Terminal-adaptive capability Candidate for “PC DSP architecture”? AudioBIFS - scene graph model
Summary MPEG-4 Structured Audio The international standard for algorithmic sound synthesis MPEG-4 AudioBIFS The international standard for audio postproduction New market opportunities for Hardware/software MPEG-4 players (embedded or not) Authoring tools (editors, sequencers) Advanced interactive audio content What was this all about? MPEG-4 is not just about compression MPEG-4 shows one way for the IA world to move beyond wavetable synthesis For more information MPEG home page http://www.cselt.it/mpeg Requirements, future of MPEG MPEG-4 SA home page http://sound.media.mit.edu/mpeg4 Draft standard, code, mailing lists, matchmaking Contact eds@media.mit.edu Slides, technical papers, discussion available Dostları ilə paylaş:
