over-the-air (ota) bit management david felland jim kutzner

QG WGBH Public Television Quality Workshop 1

Over-the-Air (OTA) Bit Management

David FellandJim Kutzner


OTA Bit Management New impacts on your transport stream

Better coding efficiency in new HD encoders○ Claims of 10-15% improvement realized○ Potential for two 720p HD services in one

transport stream – or other servicesMore SD services from which to chooseMobile DTVFixed and Mobile DTV Data Services


OTA Bit Management Options for broadcasters

Reduced horizontal resolution (1440 vs 1920)Noise reduction of both HD and SDModern statistical multiplexing720p vs. 1080i

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Sampling of Current Practice Surveyed the ETAC

1-3 OTA servicesDifferent services plans among all membersFocus on HD + national/local SD services

Surveyed the Washington stationsCommercial stations have a much more consistent

approach: ○ HD + Weather (and perhaps one other service)


HD SD1 SD2 SD3 SD4 PSIP Data

#1 15 3 - - - 150k 128k

#2 12 2.5 2.5 - - 250k 1M+

128k

#3a 12 3 1.5 - - 565k 128k

#3b - 4 2 - - 256k 100k

ETAC Members’ OTA

Italics = Stat Mux Pool



#4 16 2 - - - 300k 128k+

100k

#5a 18 - - - - ~200k 128k

#5b - 4 3.5 0.7 0.7 242k 128k

#6 14 - - - - 200k 1M

ETAC Members’ OTA

(x4) (x2) (x2)




#7 11 2 2 2 - 250k -

#8 11.5 4 4 0.3 - 250k 250k+

128k

#9 - 3 3 3 3 150k 6M

#10 11 1.5 3.5 - - 2M -

ETAC Members’ OTA




#11a 12.5 3.4 3.4 - - 150k 128k+110k

#11b - 3.4 3.4 3.4 3.4 150k 128k+

110k

#11c 12.5 3.4 3.4 - - 150k 128k+110k

#12 12 2.1 2.1 - - 200k -

ETAC Members’ OTA

(x2)




#13 11 6 - - - 180k 128k

#14 10 3 3 - - 150k 1M+

300k

ETAC Members’ OTA



Comparison of Video Performance Clip #1: 1080i @ 14 Mbps (MV500) Clip #2: 1080i @ 12 Mbps (MV500) Clip #3: 1080i @ 10 Mbps (MV500) Clip #4: 720p @ 12 Mbps (MV500) Clip #5: 720p @ 10 Mbps (MV500) Clip #6: 720p @ 8 Mbps (MV500) Clip #7: 720p @ 9 Mbps (Electra 8000)


Mobile DTV Bandwidth UsageHow much OTA spectrum do I need?

Mobile / Handheld service requirementsMultiple modes – e.g., “Half-rate”,

“Quarter-rate”, or a variety of “Mixed Modes”

Most broadcasters will use Quarter or Mixed○Quarter ~17% payload (83% FEC)○Mixed (e.g., ½, ¼, ¼, ¼) ~ 26% (74% FEC)○Half ~34% payload (66% FEC)


Bandwidth Usage (bits)How much OTA spectrum do I need?

Mixed Mode examples (26%):One 500 kbps stream ~1.92 Mbps

○Video@400kbps; Audio@64kbps; Data@30kbpsTwo 500 kbps streams ~3.85 Mbps

Quarter Rate examples (17%):One 500 kbps stream ~2.94 Mbps

○Video@400kbps; Audio@64kbps; Data@30kbpsTwo 500 kbps streams ~5.88 Mbps


DTV Spectrum Usage:ETAC Member #1

~15 Mbps

~3 Mbps

150 kbps128 kbps

• HD program

• PSIP• SD program

• Data/Ancillary

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol



~12 Mbps

~2.5 Mbps250 kbps

1Mbps+128 kbps

• HD program

• PSIP

• SD program

• Data/Ancillary

~2.5 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol


ETAC Member #1:One Mobile Service (Mixed)

~13.5 Mbps

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

~2.5 Mbps

150 kbps128 kbps

• HD program


• Data/Ancillary~2 Mbps • Mobile program

Sta

t M

ux

Po

ol


ETAC Member #2:One Mobile Service (Mixed)

~11 Mbps

~2 Mbps250 kbps

1Mbps+128 kbps

• HD program


• Data/Ancillary

~2 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

~2 Mbps • Mobile program


Suggested Mobile Services Simulcast of Local HD Service Simulcast of National HD Service Independent Local Mobile Service PBS or Local Kids Service Radio Services

Audio Only – 16 – 48 kbps“Audio with Pictures” – same as Video/Audio



~10 Mbps

~3 Mbps

150 kbps

1Mbps

• HD program


• Data/Ancillary

~3 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol


ETAC Member #14:Multiple Mobile Services (Mixed)

~9.5 Mbps

~1.8 Mbps250 kbps

1Mbps

• HD program


• Data/Ancillary

~1.8 Mbps • SD program

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

Po

ol

~2 Mbps • Mobile program~2 Mbps • Mobile program

• Radio Services (100k)


HD SD1 SD2 SD3 PSIP MH Data

#1 11.7 2.9 - - 110k 3.7 1.8

#2 8.7 2.0 2.9 - 135k 4.6 -

#3 12.0 1.6 - - 80k 3.7 -

#4 13.7 1.1 2.3 - 58k 1.8 -

DC/Baltimore Stations’ OTA

1080i

1080i

1080i

720p



HD SD1 SD2 SD3 PSIP MH Data

#5 8.6 2.4 4.5 2.2 180k - -

#6 9.6 3.8 5.2 - 130k - -

#7 10.0 2.5 - - 40k 3.7 1.8

#8 13.2 3.2 2.2 - 50k - -1080i

720p

720p

720p




16 Stations received at PBS Eng LabEight are 720pFive are 1920x1080iOne is 1440x1080iTwo are SD-only @720x480i

8 Stations are broadcasting Mobile DTVWith one to five mobile services

No station is changing their transport stream



Other Stations:Possible Mobile Services (Mixed)

~11 Mbps

250 kbps

• HD program

• PSIP

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

P

oo

l~2 Mbps • Mobile program~2 Mbps • Mobile program~2 Mbps

~2 Mbps • Weather

• Mobile program


Other Stations:Possible Mobile Services (1/4 rate)

~11 Mbps

250 kbps

• HD program

• PSIP

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

Sta

t M

ux

P

oo

l~3 Mbps • Mobile program

~3 Mbps • Mobile program

~2 Mbps • Weather


Other Stations:Possible Mobile Services (Mixed)

~4.5 Mbps

100 kbps

• SD program

• PSIP

19

.4 M

b/s

DT

V T

ran

sp

ort

S

tre

am

~2 Mbps • Mobile program• Mobile program• Mobile program

~2 Mbps~2 Mbps~2 Mbps~2 Mbps~2 Mbps~2 Mbps

• Mobile program• Mobile program• Mobile program• Mobile program


Public television has used its spectrum to serve more diverse audiences with more variety in content (“narrowcasting”)Pluses: greater range of services; higher value to

individual communitiesMinuses: locked into audience expectations;

stations are forced to balance video quality with service quantity

Observations:


Observations : Many stations are moving to 720p replacing spatial

resolution with temporal resolutionSignificantly reducing their blocking artifactsReducing horizontal resolution

With an increase in demand for more services stations can improve their performance byMoving to 720pReplacing their HD encoders with the next generation

QG 39

Video Examples

QG 40

Questions?

over-the-air (ota) bit management david felland jim kutzner

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