Rec. Itu-r br. 1575




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Rec. ITU-R BR.1575

RECOMMENDATION ITU-R BR.1575

Guide to the selection of digital video tape recording formats for studio production in the standard definition television (SDTV) environment


based on production requirements

(Question ITU-R 239/11)

(2002)

The ITU Radiocommunication Assembly,



considering

a) that digital video tape recording (VTR) formats for programme production are selected based on user requirements such as performance and operational requirements;

b) that Recommendation ITU-R BR.657 – Digital television tape recording, standards for the international exchange of television programmes on magnetic tape, describes user requirements for digital television tape recorders, and is the basis for the standardization of D-1 format;

c) that Recommendation ITU-R BR.1292 – Engineering guidelines for video recording in SDTV production and post-production chains, recommends engineering guidelines for television post-production;

d) that Recommendation ITU-R BR.1356 – User requirements for application of compression in television production, lists user requirements for application of compression in television production, for bit rates up to 50 Mbit/s in particular;

e) that Recommendation ITU-R BR.1376 – Compression families for use in recording and networked SDTV production, recommends compression based on intra-frame coding at a data rate close to 50 Mbit/s for mainstream applications which require high margin of quality overhead for post-production;

f) that Recommendation ITU-R BR.1376 specifies the two compression families which meet the requirements in considering e) above:

– DV-based 50 Mbit/s 4:2:2 intra-frame;

– MPEG 2 4:2:2P@ML 50 Mbit/s intra-frame;

g) that the two categories of programme production in standard definition television (SDTV) environment, the “high-end” and the “mainstream”, are identified based on the user’s requirements in Appendix 3 of Recommendation ITU-R BR.1376,



recommends

1 that for digital VTRs for studio production and post-production for SDTV, one of the following families of recorders should preferably be used according to required margin of quality overhead:

– uncompressed or loss-less compression recorders suitable for high-end production which requires highest margin of quality overhead for intensive post-production;

– slightly compressed recorders suitable for high-end production which requires higher margin of quality headroom for post-production;

– recorders at around 50 Mbit/s employing intra-frame coding, such as DV based 4:2:2 or MPEG-2 4:2:2P@ML suitable for mainstream production which requires modest margin of quality overhead for post-production.

NOTE 1 – Digital VTRs for SDTV program production that use compression below 50 Mbit/s will be covered in a separate Recommendation.

APPENDIX 1



Features and specifications of digital tape recording formats
for SDTV production

(Informative)

Tables 1 (SDTV digital VTR for 525/59.94) and 2 (SDTV digital VTR for 625/50) provide the major features and specifications of the commercially available tape-based storage devices for SDTV high-end and mainstream production.

TABLE 1


SDTV Digital VTR for 525/59.94


Category

High-end

Mainstream

Manufacture specification

D1

D5

Digital
BETACAM

DVCPRO 50

D-9
(Digital-S)

D10
(MPEG IMX)

Sampling
frequency

Video (MHz)

13.5

13.5/18

13.5

Audio (kHz)

48

Quantization

Video (bits)

8

10/8

10

8

Audio (bits)

20

16

24/16

Number of AES 3 channels(1)

2

2/4

Raster structure

Number of Y samples

720

720/960

720

Recorded lines

500

510

512

480

512

Y/C sampling

4:2:2

Compression (video)

Coding scheme

Uncompressed

Intra field

DCT


Intra frame
DCT

Intra frame
DCT

DV-based

MPEG-2(2) 4:2:2P@ML

Video rate (Mbit/s)

173

235

90

50

ECC

Video


Inner

64, 60

95, 87

178, 164

85, 77

162, 150

Outer

32, 30

128, 120

106, 96

149, 138

60, 46

Redundancy (%)

14

16

20

19

41

ECC

Audio


Inner

64, 60

95, 87

178, 164

85, 77

117, 105

Outer

10, 7

16, 8

10, 5

14, 9

18, 8

Redundancy (%)

105

118

117

72

152

Channel coding

S-NRZ

8-14

S-NRZI

24-25

I-NRZI


S-NRZI

Total rate (Mbit/s)

225.3

300.6

128

84

99

97

Number of recording RF channels

4

2

Drum diameter (mm)

75.0

76.0

81.4

21.7

62.0

81.4

Drum rotation (rps)

150

90

89.91

149.85

75

59.94

Number of tracks (/field)

10

12

6

20/Frame

10/Frame

8/Frame

Tape speed (mm/s)

286.6

167.228

96.7

67.640

57.737

64.5

Track pitch (m)

45.0

20.0

21.7

18

20

21.7

Minimum wavelength (m)

0.9

0.64

0.69

0.49

0.587

0.56

Width of tape (mm)

19.01

12.65

6.35

12.65

Media substance

Oxide

Metal particle

Tape Hc (kA/m)

68

143

125

184

143

120

Cassette size (mm)

S: 172  109

M: 254  150

L: 366  206


S: 161  98

M: 212  124

L: 296  167


S: 156  96

L: 254  145



M: 97.5  64.5

L: 125  78



188  104

S: 156  96

L: 254  145



Recording time (min)

13/41/94

23/63/124

40/124

33/92

124

60/184

(1) An AES 3 channel may carry two linear pulse code modulation audio channels or it may carry data as indicated by Status Channel bit 1.

(2) See Appendix 2.

TABLE 2


SDTV Digital VTR for 625/50


Category

High-end

Mainstream

Manufacture specification

D1

D5

Digital
BETACAM

DVCPRO 50

D-9
(Digital-S)

D10
(MPEG IMX)

Sampling
frequency

Video (MHz)

13.5

13.5/18

13.5

Audio (kHz)

48

Quantization

Video (bits)

8

10/8

10

8

Audio (bits)

20

16

24/16

Number of AES 3 channels

2

2/4

Raster structure

Number of Y samples

720

720/960

720

Recorded lines

600

608

608

576

608

Y/C sampling

4:2:2

Compression (video)

Coding scheme

Uncompressed

Intra field

DCT


Intra frame
DCT

Intra frame
DCT

DV-based

MPEG-2(1) 4:2:2P@ML

Video rate (Mbit/s)

173

233

89

50

ECC

Video


Inner

64, 60

86, 78

178, 164

85, 77

162, 150

Outer

32, 30

128, 120

126, 114

149, 138

64, 54

Redundancy (%)

14

18

20

19

28

ECC

Audio


Inner

64, 60

86, 78

178, 164

85, 77

137, 125

Outer

10, 7

16, 8

18, 9

14, 9

18, 8

Redundancy (%)

105

121

117

72

147

Channel coding

S-NRZ

8-14

S-NRZI

24-25

I-NRZI


S-NRZI

Total rate (Mbit/s)

225.3

303

126

84

99

88

Number of recording RF channels

4

2

Drum diameter (mm)

75.0

76.0

81.4

21.7

62.0

81.4

Drum rotation (rps)

150

100

75

150

75

50

Number of tracks (/field)

12

16

6

24/Frame

12/Frame

8/Frame

Tape speed (mm/s)

286.9

167.228

96.7

67.708

57.795

53.8

Track pitch (m)

45.0

18.0

26

18

20

21.7

Minimum wavelength (m)

0.9

0.70

0.59

0.49

0.587

0.56

Width of tape (mm)

19.01

12.65

6.35

12.65

Media substance

Oxide

Metal particle

Tape Hc (kA/m)

68

143

125

184

143

120

Cassette size (mm)

S: 172  109

M: 254  150

L: 366  206


S: 161  98

M: 212  124

L: 296  167


S: 156  96

L: 254  145



M: 97.5  64.5

L: 125  78



188  104

S: 156  96

L: 254  145



Recording time (min)

11/34/94

23/63/124

40/124

33/92

124

72/224

(1) See Appendix 2.

APPENDIX 2



Compression specifications of D10 MPEG IMX format

(Informative)


Introduction


The IMX-MPEG VTR is based upon a compliant MPEG elementary stream as its source of compressed data. MPEG 2 4:2:2P@ML is a very flexible standard. This contrasts with the unique requirements of a VTR.

In order to provide accurate editing, slow-motion and variable speed playback, and pictures in shuttle, a constrained bit stream is required. The following paragraphs define encoding parameters suitable for the Type D10-IMX recording format. The MPEG 2 4:2:2P@ML video elementary stream bit stream constrained to these parameters can be successfully decoded by a compliant MPEG 2 4:2:2 Profile@Main level decoder.


D-10 bit stream definition


This Appendix specifies the compression constraints and bit stream characteristics of an MPEG 2 4:2:2P@ML video elementary stream operating at bit rates up to 50 Mbit/s. The video compression format is fully compliant with the MPEG-2 video standard (ISO/IEC 13818-2: 2000) [4:2:2P@ML].

The video elementary stream bit stream shall comply with the syntax of SMPTE 328M – MPEG 2 video elementary stream editing information.

In order to provide accurate editing and playback in slow-motion and variable speed replay including pictures in shuttle, this clause defines encoding parameter specifications suitable for the Type D10 recording format capable of recording MPEG 2 4:2:2P@ML video elementary streams at bit rates up to 50 Mbit/s. The MPEG 2 4:2:2P@ML video elementary stream bit stream constrained to these parameter specifications is fully compliant with the MPEG 2 4:2:2P@ML video elementary stream syntax and can be successfully decoded by a compliant MPEG 2 4:2:2 Profile@Main level decoder.

General bit stream characteristics


Table 3

Basic bit stream constraints


Source format

SDTV 525/60/1.001 and 625/50

Bit rate

Up to 50 Mbit/s constrained bytes per GoP (CBG)

Group of pictures (GoP) structure

I-picture only

Maximum coded frame size

Up to 208 541 bytes net (30/1.001 I-frames/s)

Up to 250 000 bytes net (25 I-frames/s)

Table 4 indicates recommended operating points to simplify studio operations and to provide users with a tool to be used in designing systems.

TABLE 4

Optional operating points (bit rates)


D-10 profile

Bit rate
(Mbit/s)


Sequence header
bit rate value


Comments

Operating Point E

50

1E848h

To be used when compliant with EBU statement D84/85 1999

Operating point F

40

186A0h

May be used for interfaces to T3 telco circuits and other content production

Operating point G

30

124F8h

May be used for E3 telco interfaces, and non critical content material


MPEG compression parameter constraints


The following defined constraints shall apply.

The bit_rate_value in sequence_header shall be set with a value up to 50 Mbit/s.

The sequence_extension parameter shall be set with the following value:

- sequence_extension: bit_rate_extension = 0h


Video buffering verifier (VBV) delay constraint


The VBV delay parameter shall be constrained to a 1-frame delay for each GoP by defining the following values:

 525/60 systems 

- picture_header: vbv_delay = 0BBBh

 625/50 systems 

- picture_header: vbv_delay = 0E10h

MPEG 2 4:2:2 Profile@Main Level


The sequence_extension parameters shall be constrained to the following values:

- sequence_extension: profile_and_level_indication = 85h (MPEG 2 4:2:2P@ML)

- sequence_extension: chroma_format = 2h (MPEG 2 4:2:2P@ML)

All I-picture encoding


The picture_header parameter shall be constrained to the following values:

- picture_header: temporal_reference = 0h (1 picture in a GoP)

- picture_header: picture_coding_type = 1h (I-picture only)

Picture structure is frame picture only


The picture_coding_extension parameter shall be set to constrain the picture coding to frame pictures only by constraining to the following value:

- picture_coding_extension: picture_structure = 3h (frame picture)


Frame frequency


The sequence_header parameters shall be constrained to the following values:

# 525/60 systems

- sequence_header: frame_rate_code = 4h (30/1.001 Hz)



# 625/50 systems

- sequence_header: frame_rate_code = 3h (25 Hz)


Picture coding parameter constraints


The picture coding constraints shall be defined as follows:

- picture_coding_extension(): intra_dc_precision = 2h (10 bit DC)

- picture_coding_extension(): frame_pred_frame_dct = 0h (field/frame adaptive)

- picture_coding_extension(): q_scale_type = 1h (non-linear quantizer)

- picture_coding_extension(): intra_vlc_format = 1h (use intra-VLC table)

- picture_coding_extension(): alternate_scan = 0h (zig-zag scan)

- picture_coding_extension(): top_field_first = 1h (top field first only)

- picture_coding_extension(): repeat_first_field = 0h (no repeat first field)

- picture_coding_extension(): progressive_frame = 0h (interlace frames only)

- sequence_extension(): progressive_sequence = 0h (interlace frames only)


Slice structure


All slices shall contain only one macroblock. Each macroblock shall have a slice header as a sync-code. In case of any errors occurring during transmission/recording the error propagation will be less than one macroblock. The slice structure syntax shall be as follows:

slice(){ No.of bits Mnemonic

slice_start_code 32 bslbf

if (vertical_size > 2800)

slice_vertical_position_extension 3 uimsbf

if (){

if (scalable_mode == "data partitioning")

priority_breakpoint 7 uimsbf

}

quantiser_scale_code 5 uimsbf



if (nextbits() == '1'){

intra_slice_flag 1 bslbf

intra_slice 1 uimsbf

reserved_bits 7 uimsbf

while (nextbits() == '1'){

extra_bit_slice ( with the value '1' ) 1 uimsbf

extra_information_slice 8 uimsbf

}

}



extra_bit_slice ( with the value '0' ) 1 uimsbf

macroblock()

next_start_code()

}

Sequence_header and sequence_extension


The sequence_header and sequence_extension shall be present for every picture [as per SMPTE 328M], specified as follows.

video_sequence(){ No.of bits Mnemonic

next_start_code()

sequence_header()

if (nextbits() == extension_start_code){

sequence_extension()

do {

extension_and_user_data(0)



if (nextbits() == group_start_code){

group_of_picture_header()

extension_and_user_data(1)

}

picture_header()



picture_coding_extension()

extension_and_data(2)

picture_data()

if (nextbits() != sequence_end_code){

sequence_header()

sequence_extension()

}

} while (nextbits() != sequence_end_code)



} else {

( ISO/IEC 11172-2 )



}

sequence_end_code 32 bslbf


}


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