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Over-the-Air (OTA) Bit Management. David Felland Milwaukee Public Television. Acquisition and Distribution. New impacts on broadcast transport stream Better coding efficiency in new HD encoders Claims of 10-15% improvement

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over the air ota bit management

Over-the-Air (OTA) Bit Management

  • David Felland
  • Milwaukee Public Television
acquisition and distribution
Acquisition and Distribution

New impacts on broadcast transport stream

Better coding efficiency in new HD encoders

Claims of 10-15% improvement

Potential for two 720p HD services in one transport stream – or other services

More SD services from which to choose

Mobile DTV

Fixed and Mobile DTV Data Services

tradeoffs affect quality
Public television has used its spectrum to serve diverse audiences with more variety in content (“multicasting”)

Pluses: greater range of services; potential higher value to individual communities

Minuses: locked into audience expectations; stations are forced to balance video quality with service quantity

Tradeoffs affect Quality:
bit management
Bit Management

Some options for broadcasters

Reduced horizontal resolution (1440 vs 1920)

Noise reduction of both HD and SD

Modern statistical multiplexing

720p vs. 1080i

X

X

what are stations doing
What are stations doing?

Surveyed the ETAC

1-3 OTA services

Different services plans among all members

Focus on HD + national / local SD services

slide6

ETAC Members’ OTA

Italics = Stat Mux Pool

slide7

ETAC Members’ OTA

(x4)

(x2)

(x2)

Italics = Stat Mux Pool

slide8

ETAC Members’ OTA

Italics = Stat Mux Pool

slide9

ETAC Members’ OTA

(x2)

Italics = Stat Mux Pool

slide10

ETAC Members’ OTA

Italics = Stat Mux Pool

mobile dtv bandwidth usage how much ota spectrum is needed
Mobile DTV Bandwidth UsageHow much OTA spectrum is needed?

Mobile / Handheld service requirements

Multiple modes – e.g., “Half-rate”, “Quarter-rate”, or a variety of “Mixed Modes”

Many 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 is needed
Bandwidth Usage (bits)How much OTA spectrum is needed?

Mixed Mode examples (26%):

One 500 kbps stream  ~1.92 Mbps

Video@400kbps; Audio@64kbps; Data@30kbps

Two 500 kbps streams  ~3.85 Mbps

Quarter Rate examples (17%):

One 500 kbps stream  ~2.94 Mbps

Video@400kbps; Audio@64kbps; Data@30kbps

Two 500 kbps streams  ~5.88 Mbps

some mobile ptv services
Some Mobile PTV Services

Simulcast of Local HD or SD Services

Simulcast of National HD or SD Services

Stand alone Local Mobile Services

National or Local Kids Service

“Radio” Services

Audio Only – 16 – 48 kbps

“Audio with Pictures” – same as Video/Audio

slide14

DTV Spectrum Usage:ETAC Member #1

128 kbps

  • Data/Ancillary
  • PSIP

150 kbps

~3 Mbps

  • SD program

19.4 Mb/s DTV Transport Stream

~15 Mbps

Stat Mux Pool

  • HD program
slide15

DTV Spectrum Usage:ETAC Member #2

1Mbps+128 kbps

  • Data/Ancillary
  • PSIP

250 kbps

~2.5 Mbps

  • SD program

19.4 Mb/s DTV Transport Stream

~2.5 Mbps

  • SD program

~12 Mbps

Stat Mux Pool

  • HD program
slide16

ETAC Member #1:One Mobile Service (Mixed)

~2 Mbps

  • Mobile program

128 kbps

  • Data/Ancillary
  • PSIP

150 kbps

~2.5 Mbps

  • SD program

19.4 Mb/s DTV Transport Stream

~13.5 Mbps

Stat Mux Pool

  • HD program
slide17

ETAC Member #2:One Mobile Service (Mixed)

~2 Mbps

  • Mobile program

1Mbps+128 kbps

  • Data/Ancillary
  • PSIP

250 kbps

19.4 Mb/s DTV Transport Stream

~2 Mbps

  • SD program

~2 Mbps

  • SD program

~11 Mbps

Stat Mux Pool

  • HD program
slide18

DTV Spectrum Usage:ETAC Member #14

1Mbps

  • Data/Ancillary
  • PSIP

150 kbps

~3 Mbps

  • SD program

19.4 Mb/s DTV Transport Stream

~3 Mbps

  • SD program

Stat Mux Pool

~10 Mbps

  • HD program
slide19

ETAC Member #14:Multiple Mobile Services (Mixed)

~2 Mbps

  • Mobile program

~2 Mbps

  • Mobile program
  • Radio Services (100k)

1Mbps

  • Data/Ancillary

19.4 Mb/s DTV Transport Stream

  • PSIP

250 kbps

  • SD program

~1.8 Mbps

  • SD program

~1.8 Mbps

Stat Mux Pool

~9.5 Mbps

  • HD program
slide20

Other Stations:Possible Mobile Services (Mixed)

~2 Mbps

  • Mobile program

~2 Mbps

  • Mobile program

~2 Mbps

  • Mobile program
  • PSIP

250 kbps

19.4 Mb/s DTV Transport Stream

  • Weather

~2 Mbps

~11 Mbps

Stat Mux Pool

  • HD program
slide21

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

~3 Mbps

  • Mobile program

~3 Mbps

  • Mobile program
  • PSIP

250 kbps

19.4 Mb/s DTV Transport Stream

  • Weather

~2 Mbps

~11 Mbps

Stat Mux Pool

  • HD program
slide22

Other Stations:Possible Mobile Services (Mixed)

  • Mobile program

~2 Mbps

  • Mobile program

~2 Mbps

  • Mobile program

~2 Mbps

  • Mobile program

~2 Mbps

19.4 Mb/s DTV Transport Stream

  • Mobile program

~2 Mbps

  • Mobile program

~2 Mbps

  • Mobile program

~2 Mbps

  • PSIP

100 kbps

~4.5 Mbps

  • SD program
sorry but no free lunch
Sorry but No Free Lunch!

MPEG very cleverly hides picture errors BUT

Errors hidden at one stage can appear downstream

Don’t use an extra codec cycle simply because you can

Use suitable workflow techniques

Don’t over compress master recordings

Plot your program performance to the end user

Test and understand how to use MPEG tools properly

how does my show look
How does my show look?

Examples of original video compared to:

720 progressive at different station presentation rates

1080 interlace at different station presentation rates

Producer tech choices drive the viewer experience

Downstream network workflow and distribution

Local station bandwidth constraints and practices

Quality pictures at home require Best Practices upstream

some best practices
Some Best Practices

Use progressive acquisition cameras

Use higher frame rates

Avoid interlace – Digital TV handles it inefficiently

Streamline post production workflow

Successive coders will reduce picture quality

Assume your show will look worse downstream

Prove that the tools you use “do minimal harm”

observations and suggestions
Observations and Suggestions:

Many stations are moving to 720p replacing spatial resolution with improved temporal resolution

Significantly reducing picture blocking artifacts

Reducing horizontal resolution

With an increase in demand for more services public television can improve performance by

Dropping interlace and moving to progressive pictures

Replacing older HD encoders with the next generation

Changing PBS satellite distribution to progressive