Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-10-02
2001-11-13
Garber, Wendy R. (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06317556
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for recording a first and a second digital information signal in slant tracks on a magnetic record carrier, the apparatus comprising input means for receiving the first and second digital information signal, signal processing means for processing the first and second digital signal into first and second trick play signals, respectively, suitable for recording in the tracks, writing, means for writing at a recording speed of the record carrier, the first and second trick play signals so as to obtain first and second trick play segments, respectively, located at specific positions in said tracks, the writing means comprising at least a first and a second write head located on a rotatable head drum, the first head having a gap with a first azimuth angle and the second head having a gap with a second azimuth angle which is different from the first azimuth angle, the first digital information signal being meant for enabling a replay in a reproduction apparatus at a trick play reproduction speed which equals n
1
times the recording speed, the second digital information signal being meant for enabling a replay in said reproduction apparatus at a trick play reproduction speed which equals n
2
times the recording speed, where n
1
and n
2
are integers unequal to each other and unequal to 0 and 1.
2. Description of the Related Art
Such a recording apparatus is known from WO 95/28,061, corresponding to U.S. Pat. No. 5,751,889. document D4 in the list of related documents. The known apparatus takes the form of a digital video recorder for recording a digital video signal. The digital video signal may be in the form of an MPEG encoded video signal, in which packets of information of the digital video signal are included in the serial data stream of the MPEG encoded video signal. In addition to such MPEG encoded video signal, a trick play signal can be recorded in the tracks on the record carrier. Such trick play signal can be the same video signal, but reproduced at a record carrier (trick play) speed which is other than the nominal reproduction speed. Generally, a separate datastream is recorded on the record carrier for enabling the reproduction at such trick play speed. The trick play signal can be derived from the MPEG encoded video signal, e.g., by selecting I-frames from the MPEG encoded video signal.
This trick play signal, however, need not necessarily be a trick play signal that has a relationship with the MPEG-encoded video signal, but can be a completely different signal. But, in the same way as the MPEG-encoded digital video signal, the serial datastream of the trick play signal comprises packets of information of the trick play signal.
The document mentioned above describes the recording of segments of information of a plurality of trick play signals in the tracks on a record carrier. The segments of a specific trick play signal have a specific position in the tracks in order to enable reproduction of the trick play signal at its corresponding trick play reproduction speed.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved recording apparatus for recording a plurality of trick play signals in accordance with a specific format on the record carrier.
The recording apparatus in accordance with the invention is characterized in that the first and second trick play signals comprise sync blocks of information of the first and second digital information signals, respectively, and that the writing means are adapted to write the sync blocks of the first trick play signal into a plurality of the first trick play segments and to write the sync blocks of the second trick play signal into a plurality of the second trick play segments, the sync blocks in the trick play segments comprising a first and a second sync block sequence number, the first sync block sequence number in a sync block having a relationship with the position of the sync block in a track, and the second sync block sequence number having no such relationship with the position of the sync block in said track.
The invention is based on the recognition that a specific sync block numbering of the sync blocks in the trick play segments is required. An important feature in this respect is that the trick play signals can comprise (so defined ‘original’) sync blocks having information of the trick play signal stored in them. The number of ‘original’ sync blocks read during one revolution of the head drum in a trick play reproduction mode is generally less than m
1
. Those sync blocks are numbered from a certain start count value m
0
, which is preferably zero, up to a first count value. Other sync blocks in the trick play segments can be in the form of sync blocks comprising parity information or sync blocks being repetitions of ‘original’ sync blocks. Those sync blocks are numbered as well, with the specific feature that the sync blocks comprising parity information and read during the said one revolution have sync block numbers starting with said first count value up to a final count value which is equal to m
0
+m
1
−1. In the situation where repetitions are present, an ‘original’ sync block and its repetition have the same sync block number.
The numbering of the parity sync blocks enables a later (different) choice to be made for the error correction encoding carried out on the trick play signal in question upon recording. Another error correction encoding will lead to more or less sync blocks comprising parity information to be stored on the record carrier. As the sync blocks of parity information have sync block numbers that run from the first count value and up, the parity sync blocks do not interfere with the ‘original’ sync blocks, so that a reproduction on the basis of the original sync blocks only is still possible, even in a reproduction apparatus having another error correction decoding than originally defined.
Further, the sync block numbers for the trick play sync blocks are in addition to ‘normal’ sync block numbers that identify the position of the sync blocks in a track on the record carrier. The presently defined sync block numbers are not related to such positions, so that there is a freedom of storing the sync blocks are other positions in the record carrier, without interfering with the trick play reproduction in question.
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Chieu Po-lin
Garber Wendy R.
Goodman Edward W.
U.S. Philips Corporation
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