<Page>
EXHIBIT 21
AS OF DECEMBER 31, 2004
A TABLE OF SUBSIDIARIES OF LIBERTY MEDIA CORPORATION IS SET FORTH BELOW,
INDICATING AS TO EACH THE STATE OR JURISDICTION OF ORGANIZATION AND THE NAMES
UNDER WHICH SUCH SUBSIDIARIES DO BUSINESS. SUBSIDIARIES NOT INCLUDED IN THE
TABLE ARE INACTIVE OR, CONSIDERED IN THE AGGREGATE AS A SINGLE SUBSIDIARY, WOULD
NOT CONSTITUTE A SIGNIFICANT SUBSIDIARY.
A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
1227844 Ontario Ltd. CANADA (Ontario)
A.F. Associates, Inc. DE
AEI Collingham Holdings Co. Ltd. CAYMAN
AEI France S.P.R.L. FRANCE
AEI Holding Inc. CAYMAN
AEI Music Eastern Europe B.V. NETHERLANDS
AEI Music Europe BV NETHERLANDS
AEI Music Network, Inc. WA
AEI Reditune Music BV NETHERLANDS
AEI Satellite Media Polska POLAND
AEI Satellite Media Spo. CZECH REPUBLIC
AFA Products Group, Inc. NJ
Affiliate Marks Investments, Inc. DE
Affiliate Investment, Inc. DE
Affiliate Relations Holdings, Inc. DE
Affiliate Sales & Marketing, Inc. DE
Animal Planet, L.P. DE
Aries Pictures LLC CO
Ascent Entertainment Group, Inc. DE
Ascent Media Creative Services, Inc. [dba Enciore Video; Riot; E-Finish] CA
Ascent media Creative Sound Services, Inc. NY
Ascent Media Debt, Inc. DE
Ascent Media Group Limited UK
Ascent Media Group, Inc. [dba Visiontext] DE
Ascent Media Holdings Limited UK
Ascent Media Holdings Ltd. SINGAPORE
Ascent Media Limited UK
Ascent Media Management Services, Inc.[dba Level 3 Post; Digital Transform] DE
Ascent Media Network Services Europe Limited UK
Ascent Media Network Services, Inc. CA
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
Ascent Media Pte. Ltd. SINGAPORE
Ascent Media Systems and Technology Services, LLC DE
Associated Information Services Corporation DE
Associated PCN Company
Associated PCN Holding Corporation DE
Background Music BV NETHERLANDS
BDTV II Inc. DE
BDTV III Inc. DE
BDTV Inc. DE
BDTV IV, Inc. DE
BET Movies/STARZ!3, LLC DE
CDirect Mexico I, Inc. DE
CDirect Mexico II, Inc. DE
Chinese Movie and Drama Channel Venture LLC CO
Commerce Technologies, Inc. NY
Communication Capital Corp. DE
Company 3 New York, Inc. DE
Company 3, Inc. DE
CVN Companies, Inc. MN
CVN Direct Marketing Corp. MN
CVN Distribution Co., Inc. MN
CVN Management, Inc. MN
CVN Michigan, Inc. MN
Diamonique Corporation NJ
DMX Music GERMANY
DMX Music Australia Pty Limited AUSTRALIA
DMX Music Canada, Inc. BC
DMX Music Choice Investment Co. UK
DMX Music Germany GmbH GERMANY
DMX Music GmbH & Co. GERMANY
DMX Music Ltd. UK
DMX Music UK Ltd. UK
DMX Music, Inc. DE
DMX-Europe N.V. NETHERLANDS
Dry Creek Productions LLC CO
Encore Asia, Inc. CO
Encore Australia Management, Inc. DE
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
Encore International Newco, Inc. CO
Encore International, Inc. CO
Encore London Limited UK
Equipment OCV, Inc. DE
ER Development International, Inc. PA
ER Marks, Inc. DE
EZShop International, Inc. DE
Fine Music Servicos de Programacao Ltd. BRAZIL
Four Media Company [dba Digital Image, Image Laboratory; Method; Todd Studios Burbank; Todd Burbank;
Stream] DE
Four Media Company Canada Ltd. BC
Goosetray Investments Ltd. MAURITIUS
Group W Broadcast Pte. Ltd. SINGAPORE
Health Ventures Partners G.P. PA
Hotel Digital Network Inc. CA
Hotelevision, Inc DE
IC Marks, Inc. DE
IM Experience, Inc. PA
Influence Marketing Corp [dba QVC @ theMall] NOVA SCOTIA
Influence Marketing Services, Inc. CANADA (Ontario)
Ingenius CO
Innovative Retailing, Inc. DE
Interactive Technology Acquisitions, Inc. DE
Interactive Technology Holdings, L.L.C. DE
iQVC GmbH GERMANY
KSI, Inc. DE
LBTW I, Inc. CO
LBTW II, Inc. CO
LBTW III, Inc. CO
LDIG Aloy, Inc. DE
LDIG Cars, Inc. DE
LDIG Film, Inc. DE
LDIG Financing LLC DE
LDIG Food, Inc. DE
LDIG Gamenet, Inc. DE
LDIG House, Inc. DE
LDIG ICTV Corp. DE
LDIG Koz, Inc. DE
LDIG Music Online, Inc. DE
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
LDIG NL, Inc. DE
LDIG Online Retail, Inc. DE
LDIG Order, Inc. DE
LDIG OTV, Inc. DE
LDIG Respond, Inc. DE
LDIG UGON, Inc. DE
LDIG, LLC DE
Liberty Academic Systems Holdings, Inc. CO
Liberty AEG, Inc. DE
Liberty Aero, LLC DE
Liberty AGI, LLC DE
Liberty Animal, Inc. DE
Liberty Associated Holdings LLC DE
Liberty Associated, Inc. DE
Liberty ATCL, Inc. CO
Liberty Auction Holdings LLC DE
Liberty Auction, Inc. DE
Liberty BBandnow Holdings, LLC DE
Liberty BBandnow, Inc. DE
Liberty BETI, Inc. DE
Liberty Broadband Interactive Television, Inc. DE
Liberty Centennial Holdings, Inc. DE
Liberty Challenger, LLC DE
Liberty Citation, Inc. DE
Liberty CM, Inc. DE
Liberty CNBC, Inc. CO
Liberty Court II, Inc. CO
Liberty Court, Inc. WY
Liberty Crown, Inc. DE
Liberty CSG Cash, LLC DE
Liberty CSG Warrants, LLC DE
Liberty Denver Arena LLC DE
Liberty Equator, Inc. DE
Liberty ETC Holdings, LLC DE
Liberty ETC, LLC DE
Liberty EVNT, Inc. DE
Liberty Family Preferred, LLC DE
Liberty Finance LLC DE
Liberty Geonet, Inc. DE
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
Liberty GI II, Inc. DE
Liberty GI, Inc. DE
Liberty GIC. Inc. CO
Liberty HSN II, Inc. DE
Liberty IATV Events, Inc. DE
Liberty IATV Holdings, Inc. DE
Liberty IATV, Inc. DE
Liberty IB2, LLC DE
Liberty ICGX, Inc. DE
Liberty IDTC 2, Inc. DE
Liberty IDTC 3, Inc. DE
Liberty IDTC 4, Inc. DE
Liberty IDTC, Inc. DE
Liberty IDTel Holdings, Inc. DE
Liberty IDTel, Inc. DE
Liberty IDTMED, Inc. DE
Liberty International B-L LLC DE
Liberty Java, Inc. CO
Liberty KI, Inc. DE
Liberty KV Holdings, Inc. DE
Liberty KV Partners I, LLC DE
Liberty Lightspan Holdings, Inc. CO
Liberty Livewire LLC DE
Liberty LQ VII, LLC DE
Liberty LSAT II, Inc. DE
Liberty LSAT, Inc. DE
Liberty LWR, Inc. DE
Liberty MCNS Holdings, Inc. CO
Liberty MicroUnity Holdings, Inc. CO
Liberty MLP, Inc. CO
Liberty N2P II, Inc. DE
Liberty N2P III, Inc. DE
Liberty N2P, Inc. DE
Liberty NC II, Inc. DE
Liberty NC III, Inc. DE
Liberty NC IV, Inc. DE
Liberty NC IX, Inc. DE
Liberty NC V, Inc. DE
Liberty NC VI, Inc. DE
</Table>
<Page>
A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
Liberty NC VII, Inc. DE
Liberty NC VIII, Inc. DE
Liberty NC XII, Inc. DE
Liberty NC XIII, Inc. DE
Liberty NC, Inc. DE
Liberty NEA, Inc. DE
Liberty Next, Inc. DE
Liberty NP, Inc. DE
Liberty Online Health KI Holdings, Inc. CO
Liberty Online Health RN Holdings, Inc. CO
Liberty PCLN, Inc. DE
Liberty PL2, Inc. DE
Liberty PL3, LLC DE
Liberty Prime, Inc. DE
Liberty Programming Company LLC DE
Liberty Property Holdings, Inc. DE
Liberty QS, Inc. DE
Liberty QVC Holding, LLC DE
Liberty QVC, Inc. CO
Liberty Replay, Inc. DE
Liberty Satellite & Technology, Inc. DE
Liberty Satellite, LLC DE
Liberty SMTRK of Texas, Inc. CO
Liberty SMTRK, LLC DE
Liberty Sportsouth, Inc. GA
Liberty Tower, Inc. DE
Liberty TP Holdings, Inc. DE
Liberty TP Investment, LLC DE
Liberty TP LLC DE
Liberty TP Management, Inc. DE
Liberty TSAT, Inc. DE
Liberty VF, Inc. DE
Liberty Virtual I/O, Inc. CO
Liberty WDIG, Inc. DE
Liberty WF Holdings LLC DE
Liberty WF, Inc. DE
Liberty Wireless 1, Inc. DE
Liberty Wireless 10, Inc. DE
Liberty Wireless 11, Inc. DE
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
Liberty Wireless 2, Inc. DE
Liberty Wireless 3, Inc. DE
Liberty Wireless 4, Inc. DE
Liberty Wireless 5, Inc. DE
Liberty Wireless 6, Inc. DE
Liberty Wireless 7, Inc. DE
Liberty Wireless 8, Inc. DE
Liberty Wireless 9, Inc. DE
Liberty XMSR, Inc. DE
LMC Animal Planet, Inc. CO
LMC Bay Area Sports, Inc. CO
LMC BET Holdings LLC DE
LMC BET, Inc. CO
LMC Capital LLC DE
LMC Denver Arena, Inc. DE
LMC Discovery, Inc. CO
LMC IATV Events, LLC DE
LMC Information Services, LLC DE
LMC Request, Inc. CO
LMC Silver King, Inc. CO
LMC Southeast Sports, Inc. CO
LMC USA IX, Inc. DE
LMC USA VIII, Inc. DE
LMC USA XI, Inc. DE
LMC USA XII, Inc. DE
LMC USA XIII, Inc. DE
LMC USA XIV, Inc. DE
LMC USA XV, Inc. DE
LMC Wireless 1, LLC DE
LMC Wireless 2, LLC DE
LMC Wireless 2, LLC DE
LMC Wireless 3, LLC DE
LMC Wireless 4, LLC DE
LMC Wireless 5, LLC DE
LMC Wireless 6, LLC DE
LMC Wireless Holdings, Inc. DE
LMC Wireless IV, LLC DE
LMC/LSAT Holdings, Inc. DE
LQ I, Inc. CO
</Table>
<Page>
A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
LQ II, Inc. CO
LQ III, Inc. DE
LQ IV, Inc. DE
LQ V, Inc. DE
LQ VI, Inc. DE
LSAT Astro LLC DE
LSAT Astro LLC DE
LTP Wireless 1, LLC DE
LTWX I, Inc. CO
LTWX II, Inc. CO
LTWX III, Inc. CO
LTWX IV, Inc. CO
LTWX V, Inc. CO
MacNeil/Lehrer Productions [gp] NY
Maxide Acquisition, Inc. DE
MediaView LLC CO
OCV Iberia, SA
On Command Argentina, SRL
On Command Canada, Inc.
On Command Corporation DE
On Command Development Corporation DE
On Command Video Corporation DE
ONCO-HTV, Inc. DE
One Post Limited UK
Pioneer Studios, Inc. DE
Project Discovery, Inc. DE
Puerto Rico Video Entertainment Corporation DE
Purple Demon, Inc. NY
Q Fit, Inc. DE
Q The Music, Inc. DE
Q2, Inc. NY
QC Marks, Inc. DE
QDirect Ventures, Inc. DE
QExhibits, Inc. DE
QFlight, Inc. DE
QHealth, Inc. DE
QK Holdings, Inc. DE
QS Holdings, Inc. DE
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
QVC GREAT BRITAIN
QVC Britain ENGLAND
QVC Britain I Limited ENGLAND
QVC Britain I, Inc. DE
QVC Britain II, Inc. DE
QVC Britain III, Inc. DE
QVC Call Center GmbH & Co. KG GERMANY
QVC Call Center Verwaltungs-GmbH GERMANY
QVC Chesapeake, Inc. VA
QVC China Domain Limited HONG KONG
QVC China, Inc. DE
QVC de Mexico de S. de R.L. de C.V. MEXICO
QVC Delaware, Inc. DE
QVC Deutschland GmbH GERMANY
QVC eDistribution Inc. & Co. KG GERMANY
QVC EDV-Service GmbH GERMANY
QVC eService Inc. & Co. KG GERMANY
QVC Germany I, Inc. DE
QVC Germany II, Inc. DE
QVC Grundstucksverwaltungs GmbH GERMANY
QVC Handel GmbH GERMANY
QVC Handel GmbH GERMANY
QVC Holdings, Inc. DE
QVC International, Inc. DE
QVC Investment, Inc. CO
QVC Japan Holdings, Inc. DE
QVC Japan Services, Inc. DE
QVC Japan, Inc. JAPAN
QVC Local, Inc. DE
QVC Mexico II, Inc. DE
QVC Mexico III, Inc. DE
QVC Mexico, Inc. DE
QVC Middle East, Inc. DE
QVC of Thailand, Inc. DE
QVC Productworks, Inc. DE
QVC Properties, Inc. BRITAIN
QVC Publishing, Inc. DE
QVC Realty, Inc. PA
QVC Rocky Mount, Inc. NC
</Table>
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A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
QVC RS Naples, Inc. FL
QVC San Antonio, Inc. TX
QVC Satellite, Ltd JAPAN
QVC St. Lucie, Inc. FL
QVC Studio GmbH GERMANY
QVC Virginia, Inc. VA
QVC, Inc. DE
QVC-QRT, Inc. DE
Rediffusion Music Ltd. UK
Reditune Achergrondmuzlirk en Reklame BV NETHERLANDS
Request Holdings, Inc. DE
RS Marks, Inc. DE
RS Myrtle Beach, Inc. SC
RTV Associates, L.P. (lp) DE
Rushes PostProduction Limited UK
Rushes Television S.A. de C.V. MEXICO
Satellite MGT, Inc. DE
SEG Investments, Inc. DE
Servicios Administrativos de Post Produccion S.A. de C.V. MEXICO
SonicNet, Inc. DE
Sound One Corporation NY
Spectradyne International, Inc. DE
Starz Entertainment Group LLC CO
SVC Television Limited UK
TATV, Inc. DE
TBH Marks, Inc. DE
TCI Cathay TV, Inc. CO
TEMPO Sound, Inc. OK
The Box Music Network S.L. SPAIN
The Box Worldwide-Europe, B.V. NETHERLANDS
TOBH, Inc. DE
Todd-AO, Espana CA
TruePosition, Inc. DE
TSAT Holding 1, Inc. DE
TSAT Holding 2, Inc. DE
TVI Limited [dormant] UK
Video Jukebox Network Europe, Ltd. UK
Virgin Islands Video Entertainment Corporation [dba Hotel Video Services] DE
</Table>
<Page>
A B C D E F G H I J K L M N
<Table>
<Caption>
State/Country
Name of Formation
---- -------------
VLG Argentina LLC DE
VSC MAL CORP. DE
X*PRESS Electronic Services, Ltd. CO
X*PRESS Information Services, Ltd. CO
</Table>