10bit 03-422 10 Bit Pristine Video Quality

7/31/2019 10bit 03-422 10 Bit Pristine Video Quality

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Keeping Video Quality Pristin

throughout the Production Proc

4:2:2 10-bit AVC/H.264 encodPierre Larbier

ATEME (Burbank, USA & Bievres, France


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Agenda

Current States

Talk about the AVC/H.264 4:2:2 10-bit profile Empirical comparisons against 4:2:0 8-bit &

4:2:2 8-bit

Multi-Generation Encoding

Production Cases

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Production & Transmission Proce

Production uses 4:2:2 10-bit over SDI

Used in video editing, tape decks, file storage, etc

Video needs to be transmitted by internal system or a

networks

Todays transmission mostly uses

4:2:0 8-bit (MPEG-2 or AVC/H.264) for consumer app

4:2:2 8-bit(MPEG-2) for contribution applications

20-60 Mbps with latency from 1 sec-250ms

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AVC/H.264 Studio Profile VS. CuImplementations

Most AVC/H.264 products are currently geare

towards consumer video market 4:2:0 8-bit and


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About 4:2:0 Compression

Professional video sources are 4:2:2

4:2:0 compression requires resampling filters

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Progressive and Interlace chroma location schemes are d Challenges for existing chroma resampling architecture:

o Possible mismatch between the 2 resampling filters

o Resampling filters quality not guaranteed

o Choosing between Progressive and Interlace filters is not obvious

4:2:2 4:2:2 4:2:0

Downscaling

4:2:0

Encoding

4:2:0 4:2:2

Upscaling

4:2:0

DecodingSDI

Encoder Decoder


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4:2:0 Chroma Artifacts Mainly caused by a mismatch between downscale/upscale filte

o Color bleeding

o Chroma detail loss

o Interlace/Progressive artifacts

Worsen with each generation

Difficult to control in a Production chain

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After 5 4:2:2 4:2:0 conversions Source picture

Detail Loss

Color

Smearing Interlace

artifacts


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About 4:2:2 Compression At the 1st generation, with perfect resampling filters, 4:2:2 and

overall quality is roughly the same:

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But in multi-generation and/or with mismatched sampling4:2:2 quality is much better than 4:2:0

CrowdRun, 1080i25

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20 40 60 80 100 120 140 160 180 200 220

Bitrate (Mbps)

CombinedPSNR(dB)

4:2:0

4:2:2

4:2:2 vs 4:2:0 with perfect resampling filters


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Current 8-bit Compression Professional video sources are 10-bit

8-bit compression requires rounding before compression

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Motion compensation and loop-filtering performed using 8-b

Challenges for 8-bit architecture:

o Scalers match and quality not guaranteed

o Reduced accuracy in the encoding process reduces coding effici

o Luma shift caused by lack of rounding control

10-bit 10-bit 8-bit

Downscaling

8-bit

Encoding

8-bit 10-bit

Upscaling

8-bit

DecodingSDI

Encoder Decoder


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10-bit compression: banding rem Processing video with 8-bit sample depth may create banding

shallow changing light scenes:o Blue skies

o Underwater scenes

o Sunsets

These defects are not visible at 10-bit or more

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10-bit compression8-bit compression

Banding artifacts


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10-bit compression: increased coding e Coding efficiency is increased: less bit-rate for the same quality

Rate saving between 5% and 20% on most sources

Most of the gain is provided with 10-bit coding. With 12-bit andcoding efficiency gain is there but much smaller

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Woman with a Bird Cage, 1080i30

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0 15 30 45 60 75 90 105 120 135 150

Bitrate (Mbps)

PSNR

Y(dB)

8 bit

10 bit12 bit


0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 20 40 60 80 100 120 140 160 180

Bitrate (Mbps)

PSNRYgainr

elativeto8-bit(dB)

RD curve at 8,10 and 12-bit Distortion gain vs 8-bit comp


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10-bit compression: artifacts redu 10-bit compression reduces 3 kind of artifacts:

o Contouring

o Smearing

o Mosquito noise

As a side-effect, 10-bit compression also reduces random distor

shallow textured objects (clouds for instance)

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Contouring

Mosquito

Noise

8-bit compression 10-bit compressio


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AVC H422Pvs MPEG-2 422P H.264 H422P outperforms MPEG-2 422P in Contribution applic

o 10-bit support

o More than 20Mbps saved at Contribution rates!

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CrowdRun, 1080i25

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0 20 40 60 80 100 120 140

Bitrate (Mbps)

CombinedPSNR(dB)


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4142

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0 20 40 60 80 100 120 140 160

Bitrate (Mbps)

CombinedPSNR(dB)

MPEG-2

AVC/H.264

Example 2Example 1


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GOP Structure Types for Contrib GOP structure needs to be carefully considered

Possible Contribution GOP Structures

Intra-only, AVC-I, Short GOP, Adaptive Long GOP

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0 20 40 60 80 100 120

Average

PSNR

Y

Bitrate (Mbps)

Into Tree, 1080i25

Importance of GOP strucefficiency

Adaptive Long GOP and Short GOP give

better performance at same bit rate

Guide: let encoder make picture type

decision wherever possible


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Role of GOP in Multi-Generation En 3-4 Re-encodes can happen in a production transmission workflo

Aligning Encodes at GOP Boundaries can retain quality

PSNR Drop 3dB (Aligned) Vs 5dB (non-aligned) @ 7th

GEN

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1 2 3 4 5 6 7

A

veragePSNR

Y(dB)

Generation

ParkJoy 1080i25 @ 60Mbps - Aligned GOP

I

IbBbI

Long GOP

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1 2 3 4 5 6

A

veragePSNR

Y(dB)

Generation

ParkJoy 1080i25 @ 60Mbps - Unalig

Multiple generations with aligned GOPS Multiple generations without a


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Production Uses Remote Truck Uplinks

Transmit in AVC 422 10-bit and at lower bit rates than MPEG-2 422P

Playout to Tape Infrastructures

Easily integrate transmission back into an SDI infrastructure (internationa

Remote Collaboration

Realtime 422 10-bit at lower bit rates

Multiple Generations Re-encodes

Typical Streams can re-encode 3-4 times before it gets to consumer, so tr

422 10-bit aligned GOP will preserve quality

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d


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Advantages Significantly lower transmission costs

Improve video quality on existing transmission links

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S


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SummaryUsing 4:2:2 10-bit allows:

Process original source video in as close to an original form

Enables most demanding application in terms of quality & rate

Offers significant gain in quality and/or rate over existing solut

Reduces banding, smearing, and mosquito noise

Retains quality in production processes

Integrates into an SDI infrastructure at highest allowable qualit

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Thank-You

[email protected]
mailto:[email protected]:[email protected]

10bit 03-422 10 Bit Pristine Video Quality

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