QG WGBH Public Television Quality Workshop 1
Over-the-Air (OTA) Bit Management
David FellandJim Kutzner
QG WGBH Public Television Quality Workshop 2
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
QG WGBH Public Television Quality Workshop 3
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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QG WGBH Public Television Quality Workshop 4
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)
QG WGBH Public Television Quality Workshop 5
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
QG WGBH Public Television Quality Workshop 6
HD SD1 SD2 SD3 SD4 PSIP Data
#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)
Italics = Stat Mux Pool
QG WGBH Public Television Quality Workshop 7
HD SD1 SD2 SD3 SD4 PSIP Data
#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
Italics = Stat Mux Pool
QG WGBH Public Television Quality Workshop 8
HD SD1 SD2 SD3 SD4 PSIP Data
#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)
Italics = Stat Mux Pool
QG WGBH Public Television Quality Workshop 9
HD SD1 SD2 SD3 SD4 PSIP Data
#13 11 6 - - - 180k 128k
#14 10 3 3 - - 150k 1M+
300k
ETAC Members’ OTA
Italics = Stat Mux Pool
QG WGBH Public Television Quality Workshop 10
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)
QG WGBH Public Television Quality Workshop 11
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)
QG WGBH Public Television Quality Workshop 12
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
QG WGBH Public Television Quality Workshop 13
DTV Spectrum Usage:ETAC Member #1
~15 Mbps
~3 Mbps
150 kbps128 kbps
• HD program
• PSIP• SD program
• Data/Ancillary
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QG WGBH Public Television Quality Workshop 14
DTV Spectrum Usage:ETAC Member #2
~12 Mbps
~2.5 Mbps250 kbps
1Mbps+128 kbps
• HD program
• PSIP
• SD program
• Data/Ancillary
~2.5 Mbps • SD program
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QG WGBH Public Television Quality Workshop 15
ETAC Member #1:One Mobile Service (Mixed)
~13.5 Mbps
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~2.5 Mbps
150 kbps128 kbps
• HD program
• PSIP• SD program
• Data/Ancillary~2 Mbps • Mobile program
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QG WGBH Public Television Quality Workshop 16
ETAC Member #2:One Mobile Service (Mixed)
~11 Mbps
~2 Mbps250 kbps
1Mbps+128 kbps
• HD program
• PSIP• SD program
• Data/Ancillary
~2 Mbps • SD program
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~2 Mbps • Mobile program
QG WGBH Public Television Quality Workshop 17
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
QG WGBH Public Television Quality Workshop 18
DTV Spectrum Usage:ETAC Member #14
~10 Mbps
~3 Mbps
150 kbps
1Mbps
• HD program
• PSIP• SD program
• Data/Ancillary
~3 Mbps • SD program
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QG WGBH Public Television Quality Workshop 19
ETAC Member #14:Multiple Mobile Services (Mixed)
~9.5 Mbps
~1.8 Mbps250 kbps
1Mbps
• HD program
• PSIP• SD program
• Data/Ancillary
~1.8 Mbps • SD program
19
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~2 Mbps • Mobile program~2 Mbps • Mobile program
• Radio Services (100k)
QG WGBH Public Television Quality Workshop 20
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
Italics = Stat Mux Pool
QG WGBH Public Television Quality Workshop 21
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
Italics = Stat Mux Pool
DC/Baltimore Stations’ OTA
QG WGBH Public Television Quality Workshop 22
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
DC/Baltimore Stations’ OTA
QG WGBH Public Television Quality Workshop 23
Other Stations:Possible Mobile Services (Mixed)
~11 Mbps
250 kbps
• HD program
• PSIP
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l~2 Mbps • Mobile program~2 Mbps • Mobile program~2 Mbps
~2 Mbps • Weather
• Mobile program
QG WGBH Public Television Quality Workshop 24
Other Stations:Possible Mobile Services (1/4 rate)
~11 Mbps
250 kbps
• HD program
• PSIP
19
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l~3 Mbps • Mobile program
~3 Mbps • Mobile program
~2 Mbps • Weather
QG WGBH Public Television Quality Workshop 25
Other Stations:Possible Mobile Services (Mixed)
~4.5 Mbps
100 kbps
• SD program
• PSIP
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~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
QG WGBH Public Television Quality Workshop 26
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:
QG WGBH Public Television Quality Workshop 27
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
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Video Examples
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Questions?