Docstoc

Présentation PowerPoint

Document Sample
Présentation PowerPoint Powered By Docstoc
					   How will
   Archives
   deal with
     HD?

Jean VARRA   INA 2006   1
 Part 1:
HDTV at a
 glance

  Jean VARRA   INA 2006   2
           Why HDTV?


Offer better quality and more attractive
    programmes to the TV watcher.


          How is it be done?




             Jean VARRA   INA 2006         3
     SD/HD differences
     Increasing picture resolution
          and sound quality

                    SD                      HD


                                         1280 or 1920
             720 pixels per line         pixels per line
              576 Active lines            720 or 1080
 Image         ( from 200 000              active lines
definition    to 400 000 pixels)        ( from 900 000
                                      to 2 000 000 pixels)


                                         Sound 5.1
 Audio       Mono or Stereo             Digital Dolby
                                          6 tracks
             Jean VARRA    INA 2006                          4
              SD/HD differences
          Adopting 16/9 picture aspect ratio




standard definition                         Aspect ratio
    aspect ratio                                for
                                          SDTV television
     (SDTV)                                and for HDTV

                      Jean VARRA   INA 2006                 5
     SD/HD differences
    Allowing a new viewing distance



             d=3xH




                d=6xH
H




              SDTV: D= 6H
              HDTV: D=3H
            Jean VARRA   INA 2006     6
   SD/HD Differences
           Scanning modes



                   SD                   HD


                                    Interleaved ( i)

                Interleaved         Progressive (p)
                     (i)
Scanning                             Progressive
                                     Segmented
               50 or 60 Hz           Frame (PSF)

                                    50 , 60 ,24 Hz


            Jean VARRA   INA 2006                      7
                        SD/HD differences
                            Interleaved, Progressive,
Flicker and
feathering
                        Progressive Segmented Frames
                                -source Image
          interleaved                                    progressive
         scanning                                       scanning
         (2 passes)                                     (1 pass)
                                                                   No flicker,
                                                                       no
                                                                    featherin
       1st field
                                                                        g




          2nd field          Segment B                         Segment A




                                     Segmented frames    No flicker or feathering
                                                                and easier
                                                           compatibility with
                               Jean VARRA   INA 2006            interleave          8
Progressive/ Interleaved




       Jean VARRA   INA 2006   9
              Feathering




Progressive                           interleaved


              Jean VARRA   INA 2006                 10
Standards and formats
                    .
   A jungle of standards and formats




                                  SMPTE 295 M
                                     1998
MUSE

Vision 1250      SMPTE 296 M
        SMPTE 274 M
            1998

          Jean VARRA   INA 2006             11
                     What is a format?
                        Formats are described by:

    Number          Number
                                   Scanning              Picture       Frame rate
of active pixels of active lines
                                     mode              aspect ratio
     per line      per frame


                       Current main standards are:


          SMPTE 274 M        SMPTE 296 M              ITU-R BT.709-5




                              Jean VARRA   INA 2006                         12
  SMPTE 274 M
11 formats at 1920 X 1080,
8 progressive , 3 interleaved




     Jean VARRA   INA 2006      13
       SMPTE 296 M
8 formats at 1280 x 720, all progressive




         And a war of standards…
             Jean VARRA   INA 2006         14
              And then ITU-R BT.709-5…
 This standard unifies the different American, European and Japanese HD systems,
and establishes a bridge with digital cinema. It recommends:
    –A unique Common Image Format 1920 x 1080.
    –A common data bit rate 1,485 Gigabits/.s
    – Allowing all the picture rates of interleaved and progressive television and
    cinema picture rates:
    – ( 50i,60i,25p,25 psf,30p,30 psf,50p and 60 p) and(24 p and 24 psf)




                                Jean VARRA   INA 2006                         15
                   Run through
                   the jungle*….
    In the US, competition between 720p and 1080i is turning at
    the advantage of the latter!
    After long and “ stormy” debates, Europe (EBU) finally
    decided to support 1920X1080 and not 1280x720
   EBU supports interleaved formats for Television.
       Advantage: easy conversion to current SD formats
       Inconvenient: flicker.
   There is a general interest for 24p  as a «
    HD mastering format »
       Advantage: Good for film
       inconvenient: Not good enough for sport
                 24PsF?

                                               *Copyright: CCR
                       Jean VARRA   INA 2006                     16
                       Archiving High definition

             High definition video                                 Standard definition video
                1980 pixels 1080 lines                                    720 pixels 576 lines
            1- hour programme file size :                            1- hour programme file size :
               from374 GB to 673 GB*                                            72 GB


                                   To archive HD, Compression
                                         could be required.




*According frame rate, number of bits and sampling structure
                                               Jean VARRA      INA 2006                          17
                HDTV is there!
                             ..
 Production and display devices, HD/SD
  converters, compressions, and transport
  interfaces are available.
 HD recorders: HDCAM, DVC pro HD, Voodoo..
   SD to HD et HD to SD and cross formats converters
   HD Compressions: MPEG-2: (HP@HL; 422P@HL),
    MPEG-4 (AVC/H.264), JPEG2000
   Transport interfaces are standardised: HD SDI




                    Jean VARRA    INA 2006              18
                  HDTV is there!
   Broadcasting is possible through satellite and
    terrestrial means (DTT) with a reasonable
    compression MPEG2 at 19 Mb/s but it uses lot of
    bandwidth allowing only1 HD programme in a
    terrestrial channel and 2 in a satellite channel.

   Recent MPEG4 improvements (part 10 or AVC =
    Advanced Video Coding, or H.264) bring some
    hopes , allowing more HD programmes per channel.




                      Jean VARRA   INA 2006             19
     Part 2:
A closer look to
Up Conversion


   Jean VARRA   INA 2006   20
                  Up conversion
                  ( SD to HD conversion)

   The main functions that an up converter must
    achieve, are:
      Calculation of missing pixels and lines
     Frame rate conversion
     Resizing
     De-interleaving


 Quality of the output depends mainly on the
  de-interleaving process which is the most difficult to
  achieve.


                      Jean VARRA   INA 2006                21
      Resizing SD -> HD (1)
4:3                                 16:9




                        Zoom + Top/ Bottom Crop
4:3                                 16:9




           Jean VARRA    INA 2006                 22
                                Side Panel
      Resizing SD -> HD (1)
4:3                                 16:9




                         Stretching
4/3                                 16/9




                       left + right Stretching
          Jean VARRA     INA 2006                23
                    Up conversion
                       Quality issues
• It is clear that up conversion :
     •Emphasises noise
     •Introduces impairments:
         - in the transients,
         - in fast moving pictures
         -and in low light pictures ( Stairs effects, blocks,
         and shifts).
•Improved processes must be required to reduce these
artefacts as much as possible



                        Jean VARRA   INA 2006                   24
     Part 3:
what does it mean
  for archives?


     Jean VARRA   INA 2006   25
                  Issues…

 Archivists must deal with a great variety of
  media and formats of unequal quality.
 Sometimes, archivists have already digitised
  their original analogue archives in SD.
 How could these SD preservation masters be
   used and match the quality requirements of
                      HDTV?
 When will we need to reuse original media?

                 Jean VARRA   INA 2006       26
                                Uses
                       Archives are used as


               clips                OR               full programmes




                                    for



                                             Cinema
   HDTV                   HD                                     Internet
                                            screening
Broadcasting           Publishing




                          Jean VARRA      INA 2006                          27
           Using SD video archives
           2 inch
                         SD
                                               SD
           1 inch     Digitisation
                                          digital master
           B et C
                      ( Analogue                                              HD
Analogue                                                       SD->HD        Master
                        to digital
SD video                                                   (Up conversion)
             3/4       conversion
            inch     uncompressed          exploitation
                         And/ or              copy
                      compressed)
           Betacam
           BetaSP




                                      Digital
                                     Betacam
                         Digital
                        SD Video     DVCPro

                                     others…



                       Jean VARRA          INA 2006                             28
                      Using film archives

                                HD
       35 mm                  telecine
                negative



       super    positive




                                           ?
        16
                                                                                  Master
Film               Tele
                                                                                   HD
               recordings
                kinescope

               negative
       16mm
                            preservation       Digital
                positive                      SD Master           Conversion
                               ( SD                                SD->HD
                             telecine)      exploitation copy   (Up conversion)
                reversal




                               Jean VARRA      INA 2006                              29
            Comparing processes
                           INA experience

 Recently, INA contributed to produce a fiction programme for
  cinema : “Nocturnes” directed by Henry Colomer.( Co
  production INA- Archipel 33)
 This movie used a large amount of 35 and 16 mm film and
  video archives from various media ( about 20’ in a 76’ movie)
 43 archive items were used: 17 from digital BETA, one directly
  from 3/4 inch Umatic, 10 from 35 mm and 15 from 16 mm.
 Final result was expected in Black and White.
 High quality results were required.



 It was the opportunity to perform some tests and
  comparisons of various transfer chains.
                       Jean VARRA   INA 2006                   30
  Comparing processes for film
 HD telecine was performed on a selection of
  excerpts of various film qualities.
 In parallel, the same excerpts were up converted
  from our digital BETACAM masters ( issued from a
  SD telecine)
 All the HD results were recorded on HDCAM.
 HD results were displayed and compared
  subjectively on a HD monitor and then on a cinema
  screen with a high quality HD projector.




                  Jean VARRA   INA 2006          31
              Comparing results
 The objective of this comparison was
 to determine the most suitable quality
 /cost ratio.
  – A HD telecine transfer prices at least 3 to 4 times more
    than a SD telecine and a up conversion 3 to 4 times less
    than a HD telecine transfer.

Particular attention was paid to :
  – Subjective resolution
  – Noise in picture
  – Artefacts in movements

                    Jean VARRA   INA 2006                  32
        Comparing processes

 In almost all cases, 35 mm films were
  excellent quality and HD telecine gave far
  more better results compared to up-converted
  pictures, either on monitor or cinema screen.




                Jean VARRA   INA 2006        33
           Comparing processes

 16 mm film, was a more complex case to
  deal with :
 16 mm tele recordings:
    A new HD telecine did not provide significant improvements
     compared to up converted pictures.
 Reversal 16 mm :
    very little differences were noticed between the two processes.
 16 mm negative and positive film
    very little differences beween the two ways on a HD monitor but
     The new TC transfer appeared better on cinema screen.
    Note that academic 16 mm has an aspect ratio of 1;33 (4/3) and
     may require to be resized.

                          Jean VARRA   INA 2006                        34
       A temporary conclusion...

When using film clips for HDTV broadcasting and
publishing, in many cases, up conversion should be
acceptable provided up-converters go on improving.
 When using excerpts for cinema screening, a HD
telecine should be preferred for 35 mm and 16 mm film
according to their original quality.
 When using full programmes for broadcasting or
publishing, a HD telecine should be preferred.


                     Jean VARRA   INA 2006              35
                   Other questions
                    to deal with...
 What about resizing and respect of original frame?
 What about audio quality?
 Who will perform up conversion ? Live during
  broadcasting? The archives?




 And many other questions we’ll discover soon…...



                        Jean VARRA   INA 2006          36
Thank you for your attention




     Sources: INA formation
         Jean VARRA   INA 2006   37

				
DOCUMENT INFO