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Research and Technology - Forensic Science Communications - July 2006

Table 4: An example of the representative video, audio, and control-track times, lengths, and frames for a 2.00-second overrecording with the following characteristics: (1) the underlying recording is at SP speed, (2) the overrecording is at SP speed, and (3) the underlying and overrecording VCRs have flying erase and hi-fi audio heads. 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 

 

 

 

O

2.00

66.70

0.00–2.00

0.00–66.70

0–60

Yes

Yes

Yes

U

0.40

13.30

2.00–2.40

66.70–80.00

61–72

Yes

Yes

Yes

E–UP

2.00

66.70

2.40–4.40

80.00–146.70

73–132

No

Yes

Yes

UP–E

2.89

96.30

4.40–7.29

146.70–243.00

133–218

No

Yes

Yes

U

0.38

12.54

7.29–7.67

243.00–255.54

219–230

Yes

Yes

Yes

UN

2.00

66.70

7.67–9.67

255.54–322.24

231–290

Yes

No

No