dave maccarn wgbh thomas edwards pbs carl fleischhauer library of congress an overview of mxf and...

Dave MacCarnWGBH

Thomas EdwardsPBS

Carl FleischhauerLibrary of Congress

An Overview of MXF and the Search for the Video

File Wrapper.

NDIIPPPreserving Digital Public

Television

JTS 2007Toronto

Dave MacCarnWGBH

Thomas EdwardsPBS


Universal Preservation Format

• Self describing storage– Must know the coding of the file.– Must know the coding of the essence

within the file.

Dave MacCarnWGBH

Thomas EdwardsPBS


Universal Preservation Format

• Wrapper contains both essence and metadata– Must know the location of the essence

and metadata within the file.

Dave MacCarnWGBH

Thomas EdwardsPBS


Open Source Codecs

• Report on File Formats and Packages– http://www.ptvdigitalarchive.org

• VLAN– http://www.videolan.org/

• FFMPEG– http://ffmpeg.sourceforge.net/index.php

Dave MacCarnWGBH

Thomas EdwardsPBS


Source Code Links

• http://www.free-codecs.com/• http://www.avsmedia.com/downloads/

codecs.aspx• http://forum.doom9.org/• http://sourceforge.net/projects/libdv/• http://www.openquicktime.org/

– http://www.free-codecs.com/download/QuickTime_Alternative.htm

• http://dirac.sourceforge.net/• http://www.avid.com/forms/DNxHDinfo.asp

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF Background & MXF - AS/PBS

Thomas EdwardsPBS

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF – What is It?

• Material eXchange Format• Influenced by the “EBU/SMPTE Joint

Task Force for Harmonised Standards for the Exchange of Television Programmes as bit streams”

• A “wrapper format” that ties together essence and metadata elements into a coherent whole

Dave MacCarnWGBH

Thomas EdwardsPBS


What can you do with MXF?

• Store simple completed works with metadata

• Store files in a streamable format• Wrap up a playlist/EDL and essence

with synchronization information• Wrap a wide variety of compression

formats

Dave MacCarnWGBH

Thomas EdwardsPBS


KLV Coding (SMPTE 336M)

– K= Key: a unique identifier– L= Length: how long is the field

Encoded with ASN.1 BER, so can be as big as needed

– < 0x80 is actual length (0-127 decimal)– 0x8Y implies next Y bytes contain actual length– Example: 0x82.10.00, length is 0x1000 = 4096

decimal

– V= Value: what is the value of the field

Dave MacCarnWGBH

Thomas EdwardsPBS


KLV Using SMPTE MDD

06.0E.2B.34.01.01.01.02.01.05.08.00.00.00.00.00

SMPTE Designator SMPTE Item

14 47 6F 6E 65 20 57 …

Length

“Colonial House”(in ISO-7 bit code)

Value

“Version Title”

UL – SMPTE Universal Label

(16 bytes)

Dave MacCarnWGBH

Thomas EdwardsPBS


Simple Versus Complex

• MXF files can be very simple– “Just wrap up my essence”– E-VTRs, Video Servers

• MXF files can be very complex– EDL’s, alternate packages– Self-referential clips– Software implementations

Dave MacCarnWGBH

Thomas EdwardsPBS


Simple MXF File

• Partitions– Logical division of a file for easier parsing

• Header– Has metadata about whole file

• Body– Contains essence

• Footer– Terminates file & can have updated metadata

Dave MacCarnWGBH

Thomas EdwardsPBS


Metadata in MXF• Structural Metadata

– Capability of a file & how it is constructed

• Descriptive Metadata– Editorial aspects of the file– Several “schemes” available, such as DMS-1

• Dark Metadata– Metadata unknown by some applications

• Static Metadata– Doesn’t change over entire output– e.g. Show title, producer, etc.

• Time-Dependent Metadata– Timeline or Event– e.g. “This part was shot by Bob”

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF Object Model

• Packages– A logical grouping of metadata sets

• Material Package– Represents output timeline– Owns Tracks

• File Package– Represents actual essence in the file

Dave MacCarnWGBH

Thomas EdwardsPBS


Physical vs Logicalphysical - how the bytes are stored (essence container)

logical - what the bytes are intended to represent (packages)

PartitionPack

SoundElementK L fil

lK L

Hdr.

set

PictureElementK L

Hdr.

set

K L

Hdr.

set

K L

Hdr.

set

K L K L K L

Stored Picture Track

Stored Sound TrackFile Package

“played” PictureTrack“played” SoundTrack

Material Package

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF Object Model cont.

Dave MacCarnWGBH

Thomas EdwardsPBS


“Frame Wrapped”

“Clip Wrapped”

KLV Wrapping of Essence

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF Standards• SMPTE 377M MXF File Format

Specification • Essence Containers:

– SMPTE 385M SDTI-CP – SMPTE 381M MPEG (including long-GOP) – SMPTE 382M AES3 and Broadcast Wave Audio – SMPTE 383M DV 25/50 – SMPTE 386M D-10 (IMX 50 Mbps I-frame

MPEG2) – SMPTE 387M D-11 (HDCAM)

• Descriptive Metadata – SMPTE 380M MXF Descriptive Metadata

Scheme - 1 (DMS-1)

Dave MacCarnWGBH

Thomas EdwardsPBS


Why Bother?

• MXF is a good way to wrap up video essence into files

• MXF is a good way to link rich metadata to video essence

• MXF has support from many vendors for interoperation (but this is a work-in-progress)

• MXF and file transfer may provide significant benefits for an IT-oriented workflow

Dave MacCarnWGBH

Thomas EdwardsPBS


PBS File Delivery Project(NGIS)

• Distribute long-form, broadcast-quality video as files

• To 180 independent public television organizations

• Five major video server vendors, and some smaller vendors

Dave MacCarnWGBH

Thomas EdwardsPBS


NGIS in Operation

Cloud

LBand

Station Equipment

NGIS Equipment

PBS

VPN

Demod Reception/Deletion/Server

4 TB

Request Automation

TrafficServerConfirmation

ArrivalNotice

TransferCommand

Monitor &Resend

OfferSchedule

FTP / CIFS

Translation(if needed)

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF Format Woes

• MXF can wrap many different types of audio and video essence

• There are a number of ways that variable size edit unit essence can be indexed

• MXF has ten different “Operational Patterns” (OPs)

• MXF can carry a wide range of descriptive metadata schemes

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF – AS/PBS

• An MXF Application Specification for PBS• Base Requirements:

– Single file per program distribution mechanism.

– Direct play back (or import) into MXF compatible servers

– Otherwise easy to translate into non-MXF compatible servers

Dave MacCarnWGBH

Thomas EdwardsPBS


AS-PBS Development

• Began in 2004 based on “AS-CNN”

• Five key server vendors to public television initially involved

• Expanded to include other server and translation vendors

• Iterative process w. teleconferences and email distribution

• SD targeted first

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF/AS-PBS Essence

• Video essence type:– MPEG-2 4:2:0

• Video bitrate:– 8 Mbps

• Audio essence type:– Uncompressed, 16-bit PCM audio in BWF

• VBI (CC/XDS):– SMPTE 334M ANC carried in SMPTE 436M for

MXF

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF/AS-PBSMXF Features

• OP1a

• Partitions no longer than 30 minutes

• Index Table segments in partition after the Essence they index

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF/AS-PBS Future

• To be defined:– HD Version– Archive version

Dave MacCarnWGBH

Thomas EdwardsPBS


MXF/AS-PBS

• Short “Golden Files” available

• Actual full-length program example to be distributed shortly (MPEG pre-charge issue being worked out)

• AS-PBS specification is available to those who want to see it, email:

[email protected]

Dave MacCarnWGBH

Thomas EdwardsPBS


Library of Congress Stake

Carl Fleischhauer

National Digital Information Infrastructure and Preservation

Program

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Thomas EdwardsPBS


Video Reformatting at the National Audio-Visual Conservation Center