Digital video signal reproducing apparatus with high-speed play mode

Abstract

Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in 2 m tracks (m is an integer greater than 1), in which a pair of rotary heads having respectively different azimuth angles scan traces across the magnetic tape, such traces substantially coinciding with the tracks when the magnetic tape is transported at a speed equal to the recording speed. The magnetic tape is transported at a high speed equal to (m×n±1) times the recording speed, where n is an integer greater than 0,1=0.5 when the pair of heads are arranged as a double azimuth head assembly and 1=0.25 when the heads are angularly separated by 180°.

What is claimed is:  
     
       1. Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in 2 m tracks (m is an integer greater than 1) when said magnetic tape was transported at a first speed, comprising: a pair of rotary heads having respectively different azimuth angles for scanning traces across said magnetic tape, said heads being constructed either as a double azimuth head assembly or as a pair of heads angularly separated by 180°, said traces substantially coinciding with said tracks when said magnetic tape is transported at said first speed; and tape transport means for transporting said magnetic tape at a second speed equal to (m×n±1) times said first speed, where n is an integer other than zero, 1=0.5 when said pair of heads comprise said double azimuth head assembly and 1=0.25 when said heads are angularly separated by 180°. 
     
     
       2. The apparatus of  claim 1  wherein n is a positive number when said tape transport means transports said magnetic tape in a forward direction and n is a negative number when said tape transport means transports said magnetic tape in a reverse direction. 
     
     
       3. The apparatus of  claim 1  wherein said digital video signals are NTSC video signals and m=5. 
     
     
       4. The apparatus of  claim 1  wherein said digital video signals are PAL video signals and m=6. 
     
     
       5. The apparatus of  claim 1 Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in  2  m tracks ( m is an integer greater than  1   )  when said magnetic tape was transported at a first speed, comprising: a pair of rotary heads having respectively different azimuth angles for scanning traces across said magnetic tape, said traces substantially coinciding with said tracks when said magnetic tape is transported at said first speed; and a tape transporter for transporting said magnetic tape at a second speed equal to  ( m×n± 1   )  times said first speed, where n is an integer other than zero, and  1  has a predetermined value depending upon the configuration of the heads,  wherein n is an odd integer when  and 1=0.25. 
     
     
       6. The apparatus of  claim 1  wherein the frame of digital video signals recorded in said 2 m tracks are orthogonally transformed video signals encoded in variable length code. 
     
     
       7. The apparatus of  claim 6  wherein said variable length code is a two-dimension Huffman code. 
     
     
       8. The apparatus of  claim 6  wherein the orthogonally transformed video signals of a frame are shuffled. 
     
     
       9. Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in 2 m tracks (m is an integer greater than 1) when said magnetic tape was transported at a first speed, each frame having been divided into blocks of picture elements and the blocks of a frame having been recorded in shuffled form with respect to each other , said apparatus exhibiting a data read-out rate and comprising: a pair of rotary heads angularly separated from each other by 180° and admitting of respectively different azimuth angles; and tape transport means for transporting said magnetic tape at a second speed equal to (m×n±1) times said first speed, where n is an odd integer, 1=0.25 when said apparatus exhibits a data read-out rate determined to be at least 50% and 1=0.125 when said apparatus exhibits a data read-out rate determined to be less than 50%. 
     
     
       10. The apparatus of  claim 9  wherein n is a positive number when said tape transport means transports said magnetic tape in a forward direction and n is a negative number when said tape transport means transports said magnetic tape in a reverse direction. 
     
     
       11. The apparatus of  claim 9  wherein said digital video signals are NTSC signals and m=5. 
     
     
       12. The apparatus of  claim 9  wherein said digital video signals are PAL signals and m=6. 
     
     
       13. The apparatus of  claim 9  wherein the frame of digital video signals recorded in said 2 m tracks are orthogonally transformed video signals encoded in variable length code. 
     
     
       14. The apparatus of  claim 13  wherein said variable length code is a two-dimension Huffman code. 
     
     
       15. Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in 2 m tracks (m is an integer greater than 1) when said magnetic tape was transported at a recording speed, each frame having been divided into blocks of picture elements and the blocks of a frame having been recorded in shuffled form with respect to each other, said apparatus exhibiting a data read-out rate and comprising: a pair of rotary magnetic heads disposed in a double azimuth head assembly and admitting of respectively different azimuth angles; and tape transport means for transporting said magnetic tape at a fast playback speed equal to (m×n±1) times said recording speed, where n is an integer other than zero, 1=0.5 when said apparatus exhibits a data read-out rate determined to be at least 50% and 1=0.25 when said apparatus exhibits data read-out rate determined to be less than 50%. 
     
     
       16. The apparatus of  claim 15  wherein n is a positive number when said tape transport means transports said magnetic tape in a forward direction and n is a negative number when said transport means transports said magnetic tape in a reverse direction. 
     
     
       17. The apparatus of  claim 15  wherein said digital video signals are NTSC signals and m=5. 
     
     
       18. The apparatus of  claim 15  wherein said digital video signals are PAL signals and m=6. 
     
     
       19. The apparatus of  claim 15  wherein the frame of digital video signals recorded in said 2 m tracks are orthogonally transformed video signals encoded in variable length code. 
     
     
       20. The apparatus of  claim 19  wherein said variable length code is a two-dimension Huffman code. 
     
     
       21. Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in  2  m tracks ( m is an integer greater than  1   )  when said magnetic tape was transported at a first speed, comprising: a pair of rotary heads having respectively different azimuth angles for scanning traces across said magnetic tape, said traces substantially coinciding with said tracks when said magnetic tape is transported at said first speed; and a tape transporter for transporting said magnetic tape at a second speed equal to  ( m×n± 1   )  times said first speed, where n is an integer other than zero, and  1  has a predetermined value depending upon the configuration of the heads, wherein the value of  1  is either  0 . 25  or  0 . 50 .   
     
     
       22. Apparatus for reproducing digital video signals from a magnetic tape, wherein a frame of digital video signals had been recorded in  2  m tracks ( m is an integer greater than  1   )  when said magnetic tape was transported at a recording speed, each frame having been divided into blocks of picture elements, said apparatus exhibiting a data read - out rate and comprising: a pair of rotary magnetic heads having respectively different azimuth angles; and a tape transporter for transporting said magnetic tape at a fast playback speed equal to  ( m×n± 1   )  times said recording speed, where n is an integer other than zero, and  1  is a value depending upon a data read - out rate, wherein the value of  1  is either  0 . 25  or  0 . 50 .