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Digital Audio 3 4 Sampling 44.1 kHz 48 kHz 96 kHz 192 kHz - - PowerPoint PPT Presentation

Feb 04, 2023 14 likes •148 views

On Audio-Visual File Formats Summary digital audio and digital video container, codec, raw data different formats for different purposes audio-visual data transformations Universit de Lausanne Option Archives Cinmathque

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SLIDE 1

Université de Lausanne Option «Archives» Cinémathèque suisse, Penthaz, 2017–01–02 Reto Kromer • AV Preservation by reto.ch

On Audio-Visual File Formats

1

Summary

  • digital audio and digital video
  • container, codec, raw data
  • different formats for different purposes
  • audio-visual data transformations

2

Digital Audio

3

Digital Audio

  • sampling
  • quantisation

4

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SLIDE 2

digitisation sampling quantisation = +

5

Sampling

  • 44.1 kHz
  • 48 kHz
  • 96 kHz
  • 192 kHz

6

Quantisation

  • 16 bit
  • 24 bit

7

Digital Video

8

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SLIDE 3

Digital Video

  • resolution
  • bit depth
  • linear vs. logarithmic
  • colour model
  • chroma subsampling
  • illuminant

9

Resolution

  • SD 480i / SD 576i
  • HD 720p / HD 1080i
  • 2K / HD 1080p
  • 4K / UHD-1
  • 8K / UHD-2

10

Bit Depth

  • 8 bit
  • 10 bit
  • 12 bit
  • 16 bit

11

Linear vs. Logarithmic

«medium grey»

  • linear: 18%
  • «logarithmic»: 50%

12

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SLIDE 4

13

Colour Model

  • XYZ
  • RGB / R′G′B′ / CMY / C′M′Y′
  • Y′IQ / Y′UV / Y′DBDR
  • Y′CBCR / Y′COCG
  • Y′PBPR

14 15

RGB24

00000000 00000000 00000000 11111111 00000000 00000000 00000000 11111111 00000000 00000000 00000000 11111111 00000000 11111111 11111111 11111111 00000000 11111111 11111111 11111111 00000000 11111111 11111111 11111111

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SLIDE 5

17

Chroma Subsampling

  • 4:4:4
  • 4:2:2
  • 4:2:0 / 4:1:1

18

4:4:4

4

  • ● ● ● ● ● ● ●

4

  • ● ● ● ● ● ● ●
  • ● ● ● ● ● ● ●
  • ● ● ● ● ● ● ●

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4:2:2

2

  • ○ ● ○ ● ○ ● ○

2

  • ○ ● ○ ● ○ ● ○
  • ○ ● ○ ● ○ ● ○
  • ○ ● ○ ● ○ ● ○

20

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SLIDE 6

4:2:0

2

  • ○ ● ○ ● ○ ● ○

○ ○ ○ ○ ○ ○ ○ ○

  • ○ ● ○ ● ○ ● ○

○ ○ ○ ○ ○ ○ ○ ○

21

4:1:1

1

  • ○ ○ ○ ● ○ ○ ○

1

  • ○ ○ ○ ● ○ ○ ○
  • ○ ○ ○ ● ○ ○ ○
  • ○ ○ ○ ● ○ ○ ○

22

Illuminant

  • D50
  • D55
  • D65
  • D75

23 24

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SLIDE 7

25

File Structure

26

File Structure

audio-visual container (wrapper) video codec audio codec video data audio data

27

Audio-Visual Container

  • MP4
  • MOV
  • AVI
  • MXF
  • Matroska (MKV)
  • Flash

28

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SLIDE 8

Audio Codec

  • WAVE
  • BWF
  • AIFF
  • FLAC
  • AAC
  • MP3

29

Video Codec

  • H.264
  • ProRes 422
  • DNxHD
  • FFV1

30

Data is anything but «raw».

31

Audio Data

  • mono (1.0)
  • stereo (2.0)
  • 5.1 (surround)

32

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SLIDE 9

Video Data

  • rgb48le
  • yuv444p16le
  • rgb24
  • yuv422p10le
  • uyvy422
  • yuv420p

33

«Image Codec»

  • TIFF
  • DPX
  • JPEG 2000
  • OpenEXR
  • FFV1

34

«Image Container»

  • folder
  • tar
  • MXF
  • Motion JPEG
  • Matroska

35

What is inside my DPX?

  • log neg encoding
  • log RGB encoding or quasi-log encoding
  • gamma encoding or power function

encoding

  • scene-linear encoding

36

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SLIDE 10

File Formats

37

Principles

  • The archive must be able to handle

the file formats it holds.

  • open source
  • simple to use and well documented
  • widely used by the community

38

Different Purposes

archive master format: ➔ for preservation mezzanine format: ➔ for professional use in postproduction dissemination formats: ➔ for widely spreading and easy access

39

Elena Rossi-Snook:

Archiving without access isn’t preservation, it’s hoarding.

40

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SLIDE 11

Archive Master

film

  • 2K, folder, TIFF, RGB, 4:4:4, 16 bit
  • 2K, MXF, DPX, R′G′B′, 4:4:4, 10 bit

video

  • HD, AVI, Y′CBCR, 4:2:2, 10 bit
  • HD, Matroska, FFV1, Y′CBCR, 4:2:2, 10 bit

audio

  • BWF, 96 kHz, 24 bit
  • FLAC, 96 kHz, 24 bit

41

Mezzanine

video

  • HD, Apple ProRes 422 HQ
  • HD, Avid DNxHD 175x

audio

  • BWF, 48 kHz, 24 bit
  • FLAC, 48 kHz, 24 bit

42

Dissemination

audio and video combined

  • MP4

video

  • SD, H.264, yuv420p
  • HD, H.264, yuv420p, «lossy»

audio

  • AAC, 44.1 kHz, 16 bit

43

Archive Master & Mezzanine

film

  • 2K, Matroska, FFV1, R′G′B′, 4:4:4, 16 bit

video

  • HD, Matroska, FFV1, Y′CBCR, 4:2:2, 10 bit

audio

  • Matroska, FLAC, 96 kHz, 24 bit

44

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SLIDE 12

Transformations

45

XYZ XYZ RGB RGB R′G′B′ R′G′B′ Y′CBCR 4:4:4 Y′CBCR 4:2:2 tristimulus tristimulus transfer function transfer function colour diff. encode colour diff. decode subsampling filter interpolation filter Y′CBCR 4:4:4

[M] [M] [M] [M]

46

Data Transformations

demultiplex filter multiplex decode encode

47

Audio Exemple

MOV AAC WAVE MP4 44.1 kHz 16 bit 48 kHz 24 bit demultiplex filter multiplex decode encode

48

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SLIDE 13

Video Exemple

MOV H.264 ProRes 422 HQ MP4 yuv420p yuv422p10le demultiplex filter multiplex decode encode

49

Audio-Visual Exemple

MOV AAC H.264 WAVE ProRes 422 HQ MP4 44.1 kHz 16 bit yuv420p 48 kHz 24 bit yuv422p10le demultiplex filter multiplex decode encode

50

Acknowledgements

  • Swiss Federal Institute of Technology
  • Massachusetts Institute of Technology
  • Kinemathek Lichtspiel, Bern
  • Charles Poynton
  • Dave Rice & Misty De Meo
  • Agathe Jarczyk & David Pfluger

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AV Preservation by reto.ch chemin du Suchet 5 1024 Écublens Switzerland Web: reto.ch Twitter: @retoch Email: info@reto.ch

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