Windows Media Windows Media 格式内幕格式内幕

凌梅凌梅Development LeadDevelopment LeadWindows Digital Media DivisionWindows Digital Media DivisionMicrosoft CorporationMicrosoft Corporation

AgendaAgenda

Opportunities with WMOpportunities with WM Windows Media Format SDKWindows Media Format SDK

Windows Media 9 Series Windows Media 9 Series Core PromisesCore Promises

UnmatchedUnmatchedAudio/VideoAudio/Video

QualityQuality

DramaticallyDramaticallyImprovedImprovedPlaybackPlayback

MostMostComprehensiveComprehensive

PlatformPlatform

• 20% better compression across the board extends industry lead20% better compression across the board extends industry lead

• New voice/screen codecs, video smoothing boost dial-up New voice/screen codecs, video smoothing boost dial-up

qualityquality

• New HD video & 5.1 audio delivers home-theater experiencesNew HD video & 5.1 audio delivers home-theater experiences

• Fast Streaming provides instant-on/always-on experienceFast Streaming provides instant-on/always-on experience

• Intelligent Streaming optimizes the experience Intelligent Streaming optimizes the experience

• Fast & flexible player with industry’s first Smart JukeboxFast & flexible player with industry’s first Smart Jukebox

• Industry’s best scalability, reliability & manageabilityIndustry’s best scalability, reliability & manageability

• End-to-end extensible architectureEnd-to-end extensible architecture

• Improved economics throughoutImproved economics throughout

File

Codecs

DShow

DRM Networking

DShow

DRM License Acquisition

Windows Media Server

WMS Admin Object

WM Server MMC Admin

WM Server Web Admin

Server ServicesServer Services

WM Format SDK

Movie Maker

Producer

Third Party Tools

WM Encoder & OCX

DRM LicenseCreation

Content Discovery/Metadata

IIS

Networking DRM Codecs

File

WM Format SDK

WMP.DLL

WindowsMedia Player

Windows Media Player OCX

AuthoringAuthoring On-Line ServicesOn-Line Services PlaybackPlayback

Windows Media 9 SeriesWindows Media 9 SeriesPlatform Component Drill-downPlatform Component Drill-down

WM Codec ParametersWM Codec Parameters

Into 3rd generation codecs v8Into 3rd generation codecs v8 Encoding utilityEncoding utility

Support streamed / local playbackSupport streamed / local playback WM isWM is

ASF (WMV / WMA)ASF (WMV / WMA) CodecsCodecs DRM v1 and v7DRM v1 and v7

GOALGOAL Smallest size for quality (e.g. 1/2 MP3)Smallest size for quality (e.g. 1/2 MP3) Near DVD @ 500kbpsNear DVD @ 500kbps Maintain consistent qualityMaintain consistent quality

Video Smoothing (Frame Video Smoothing (Frame Interpolation)Interpolation) Generates missing frames at playback time Generates missing frames at playback time

using optical-flow analysis using optical-flow analysis Improves perceived video quality (motion Improves perceived video quality (motion

smoothness) at lower data ratessmoothness) at lower data rates Can be used to improve quality or save Can be used to improve quality or save

bandwidth by encoding fewer framesbandwidth by encoding fewer frames Bandwidth reduction reduces operating cost for Bandwidth reduction reduces operating cost for

ICPsICPs E.g. MSNBC encodes only 15 frames/sec, but E.g. MSNBC encodes only 15 frames/sec, but

user of WM9 Player will experience full frame user of WM9 Player will experience full frame raterate

Video SmoothingVideo Smoothing

demodemo demodemo

WMV Screen 9WMV Screen 9

Highly efficient compression engine for Highly efficient compression engine for “palletized video”“palletized video” Typical scenario is capturing application/desktop Typical scenario is capturing application/desktop

output for training/demooutput for training/demo Entire desktop can be compressed and transmitted Entire desktop can be compressed and transmitted

at rates as low as 28kbps!at rates as low as 28kbps! Up to 100X more efficient than commonly used Run-Up to 100X more efficient than commonly used Run-

length-encoding (RLE)length-encoding (RLE)

Original Version (V7) shipped in 2000Original Version (V7) shipped in 2000 Version 9 improves in both picture quality and Version 9 improves in both picture quality and

CPU usageCPU usage More efficient handling of continuous-tone images More efficient handling of continuous-tone images

and window dragging/scrollingand window dragging/scrolling

Screen CodecScreen Codec

demodemo

WMA Professional 9WMA Professional 9

NewNew high-performance audio codec to handle high-performance audio codec to handle greater than CD resolution/channelsgreater than CD resolution/channels Up to 96Khz sampling rate, 24-bits, and 8 channels Up to 96Khz sampling rate, 24-bits, and 8 channels

(“7.1”)(“7.1”) CD is stereo at 44Khz using 16-bit samplesCD is stereo at 44Khz using 16-bit samples

Targets are multi-channel music distribution and Targets are multi-channel music distribution and movie sound tracks at broadband ratesmovie sound tracks at broadband rates

More efficient than existing technologies:More efficient than existing technologies: Twice as good as Dolby Digital (AC-3) and DTS used in Twice as good as Dolby Digital (AC-3) and DTS used in

DVDsDVDs Blind listening test shows WMA Pro at 768Kbps Blind listening test shows WMA Pro at 768Kbps

outperforms all existing codecs in the marketoutperforms all existing codecs in the market

WMA 9 Pro CodecWMA 9 Pro Codec

demodemo

192K WMA Pro 5.1 vs. 192K MP3192K WMA Pro 5.1 vs. 192K MP3

WMA Voice 9WMA Voice 9

Unique “hybrid” voice and music coder for low Unique “hybrid” voice and music coder for low data rates (<= 20Kbps).data rates (<= 20Kbps). First codec to properly handle mixed mode content First codec to properly handle mixed mode content

(e.g. news plus musical commercial)(e.g. news plus musical commercial) Uses an auto/manual classifier to detect Uses an auto/manual classifier to detect

voice/music voice/music Applies appropriate coding mode for each segmentApplies appropriate coding mode for each segment

Voice mode: new proprietary voice codecVoice mode: new proprietary voice codec 20% better than ACELP shipping today (used by 20% better than ACELP shipping today (used by

Real and WM)Real and WM)

Music mode: WMA algorithmsMusic mode: WMA algorithms

WMA 9 Voice CodecWMA 9 Voice Codec

demodemo

WMA Voice vs. AMR (3G-GSM)WMA Voice vs. AMR (3G-GSM)

Windows Media FormatWindows Media Format Our AdvantagesOur Advantages

Extensible file formatExtensible file format Support advanced MS and 3rd party codecsSupport advanced MS and 3rd party codecs Support rich mediaSupport rich media

ScalableScalable Efficient local playbackEfficient local playback Efficient Streaming (HTTP +)Efficient Streaming (HTTP +) High capacity Media ServersHigh capacity Media Servers

Author once, playback anywhereAuthor once, playback anywhere Streams 28.8Kbps Streams 28.8Kbps 1Mbps broadband 1Mbps broadband Replay PC’s, PDA’s, Consumer Elec.Replay PC’s, PDA’s, Consumer Elec.

Car stereos, Cellphones, In home Car stereos, Cellphones, In home devices, PD’sdevices, PD’s

Windows Media FormatWindows Media FormatFile ContainerFile Container Supports files as large as 17 million terabytesSupports files as large as 17 million terabytes Supports multi-bitrate audio, video streams in a fileSupports multi-bitrate audio, video streams in a file Stores media and metadata in one fileStores media and metadata in one file

MetadataMetadata Title, copyright, author, markers, script commands, etc.Title, copyright, author, markers, script commands, etc. ID3 v1, v2 music meta-informationID3 v1, v2 music meta-information

MediaMedia Audio, Video, rich media and Script Commands (URLs, CC)Audio, Video, rich media and Script Commands (URLs, CC)

AudioStreamAudioStream

Video Stream #1Video Stream #1

Video Stream Video Stream

#n#n

Script StreamScript Stream

TimelineTimeline

Rich StreamRich Stream

Windows Media FormatWindows Media FormatFile Container (Cont.)File Container (Cont.) Able to select a stream, based on available bandwidth Able to select a stream, based on available bandwidth Interleaved data is optimal for HTTPInterleaved data is optimal for HTTP Files can be read sequentially, avoiding expensive seeksFiles can be read sequentially, avoiding expensive seeks Timeline based synchronizationTimeline based synchronization Bursty data can be smoothedBursty data can be smoothed

Send Timestamp Send Timestamp (milliseconds)(milliseconds)

Presentation Timestamp Presentation Timestamp (Rational time units)(Rational time units)

PresentationPresentationTimeTime

PresentationPresentationTimeTime

SendSendTimeTime

Rich Feature SetRich Feature Set

Time-code with Frame accurate seeking Time-code with Frame accurate seeking supportsupport

Live DRMLive DRM Video Smoothing (Frame Interpolation)Video Smoothing (Frame Interpolation) Rich Media StreamingRich Media Streaming VBR streaming/progressive down-load VBR streaming/progressive down-load

optimizationsoptimizations Bandwidth sharingBandwidth sharing Enables fast streamEnables fast stream MBR audio and multiple resolution MBR MBR audio and multiple resolution MBR

VideoVideo PhotoMotionPhotoMotion

Photo MotionPhoto Motion

demodemo

Windows Media Format SDKWindows Media Format SDK Win32 only (Win98, WinMe,Win2000, WinXP) Win32 only (Win98, WinMe,Win2000, WinXP) COM-style interfaceCOM-style interface Support audio/video/script authoring and playbackSupport audio/video/script authoring and playback Enhance metadata authoring and playbackEnhance metadata authoring and playback DRM support (encryption and decryption)DRM support (encryption and decryption) Streaming support (“net-read”, “net-write”)Streaming support (“net-read”, “net-write”) Ideal for applications that handle dataflowIdeal for applications that handle dataflow Target solutionsTarget solutions

Jukebox, Jukebox, Live Live Encoder, Encoder, Video EditorVideo Editor

WriteWriteInterfaceInterface

ReadReadInterfaceInterface

.wma or.wma or.wmv file.wmv file

Raw or Compressed AudioRaw or Compressed AudioRaw or Compressed VideoRaw or Compressed Video

Script CommandsScript CommandsHeader MetaDataHeader MetaData IPIP

NetworkNetwork

Raw or Compressed AudioRaw or Compressed AudioRaw or Compressed VideoRaw or Compressed Video

Script CommandsScript CommandsHeader MetaDataHeader MetaData

Read with WM Format SDKRead with WM Format SDK IWMReaderIWMReader

Read WM data.Read WM data. WMCreateReaderWMCreateReader

IWMReaderAdvancedIWMReaderAdvanced User driven clockUser driven clock Manual stream selectionManual stream selection Custom buffer allocationCustom buffer allocation QI from IWMReaderQI from IWMReader

IWMSyncReaderIWMSyncReader Synchronous ReadSynchronous Read No streaming supportNo streaming support Ideal for editing appIdeal for editing app WMCreateSyncReaderWMCreateSyncReader

Encode with WM Format Encode with WM Format SDKSDK IWMWriterIWMWriter

Encode and write WM dataEncode and write WM data WMCreateWriterWMCreateWriter

IWMWriterAdvancedIWMWriterAdvanced Set output sink(s)Set output sink(s) Directly write compressed dataDirectly write compressed data QI from IWMWriterQI from IWMWriter

Output to different destinationsOutput to different destinations Output to file (WMCreateWriterFileSink)Output to file (WMCreateWriterFileSink) Output to port (WMCreateWriterNetworkSink)Output to port (WMCreateWriterNetworkSink) Output to WM Server (WMCreateWriterPushSink)Output to WM Server (WMCreateWriterPushSink) Custom sinkCustom sink

Encode with Encode with WM Format SDK (Cont.)WM Format SDK (Cont.) Basic callsBasic calls

hr = WMCreateWriter( NULL, &pWriter );hr = WMCreateWriter( NULL, &pWriter ); hr = pWriter->QueryInterface( IID_IWMWriter, hr = pWriter->QueryInterface( IID_IWMWriter,

( VOID ** )&pWriter );( VOID ** )&pWriter ); hr = pWriter->SetProfile( pProfile );hr = pWriter->SetProfile( pProfile ); hr = pWriter->SetOutputFilename( outfile );hr = pWriter->SetOutputFilename( outfile ); hr = pWriter->BeginWriting( );hr = pWriter->BeginWriting( ); Hr = pWriter->WriteSample();Hr = pWriter->WriteSample(); …… Hr = pWriter/->EndWriting ();Hr = pWriter/->EndWriting ();

Edit with WM Format SDKEdit with WM Format SDK

IWMMetadataEditorIWMMetadataEditor WMCreateEditorWMCreateEditor OpenOpen CloseClose QI for IWMHeaderInfoQI for IWMHeaderInfo

IWMHeaderInfoIWMHeaderInfo Read and edit header attributesRead and edit header attributes

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© 2002 Microsoft Corporation. All rights reserved.© 2002 Microsoft Corporation. All rights reserved.This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.