Home About Us Laboratory Services Forensic Science Communications Back Issues July 2006 technical Research and Technology - Forensic Science...

Research and Technology - Forensic Science Communications - July 2006

Table 3: An example of the representative video, audio, and control-track times, lengths, and frames for a 20.00-second overrecording with the following characteristics: (1) the underlying recording is at SP speed (2) the overrecording is at EP speed, and (3) the underlying recording and overrecording VCRs have hi-fi audio heads, but the overrecording unit does not have a flying erase head. The distance from the full-track erase head to the video-recording head has been designated as 80.00 mm, the frame numbers have been rounded to the nearest whole number, all lengths are in mm, and all times are in seconds.

 

Playback Video Sequence

Hi-Fi Audio

Linear Audio

Control Track

Segment

Time

Length

     Time     

      Length     

  Frames  

 

 

 

OU

7.19

80.00

0–7.19

0–80.00

1–216

Yes

Yes

Yes

OP

8.69

96.67

7.19–15.88

80.00–176.67

217–476

Yes

Yes

Yes

O

4.12

45.81

15.88–20.00

176.67–222.40

477–599

Yes

Yes

Yes

E

7.19

80.00

20.00–27.19

222.40–302.40

600–815

No

No

No

UNP

8.69

96.67

27.19–35.88

302.40–398.99

816–1075

No

No

No

UN

7.13

79.25

35.88–43.01

398.70–478.27

1076–1289

No

No

No