Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-02-17
2003-04-22
Boccio, Vincent (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C704S201000
Reexamination Certificate
active
06553183
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video and/or audio recording apparatus, and more specifically relates to a digital video and/or audio recording apparatus for recording video and/or audio data to a recording device.
2. Description of the Background Art
Conventionally, digital audio recording devices for recording music and other audio data include the Digital Audio Tape (DAT) recorder, and, more recently, audio recording devices using the Mini Disc (MD) recording medium. Audio recorders using the CD-R (Compact Disc-Recordable) medium have also been developed and are currently available.
Digital video recording devices for recording movies and other moving picture data (including the associated audio data) include recording devices using the Digital Video Cassette (DVC) medium. Video recorders using the DVD-RAM (Digital Versatile Disc-RAM) medium are also being developed.
Audio recording devices using semiconductor memory are also used in answering machines and similar devices, while video recording devices for recording still picture similarly using semiconductor memory are used in digital cameras.
Such conventional video and/or audio recording devices record the video and/or audio data to a recording medium having a finite capacity, which varies depending upon the device. A problem with such devices, therefore, is that when the recording medium becomes filled to capacity while recording is in progress, an interruption occurs in video and/or audio reproduction.
This problem is addressed in many such devices by, for example, enabling the user to select a “standard” or “long play” mode to change the total recordable time of the medium. This causes the recording device to change the compression rate used for video and/or audio encoding according to the user-selected recording mode and the writing speed to the physical media, thus changing the effective recording time.
Even with this method, however, there is no change in the fact that the maximum recording time is predetermined, and the above-described problem is not truly resolved.
Japanese Patent Laying-Open No. 6-259099 (1994) teaches an audio recording apparatus for hierarchically coding and recording audio data to semiconductor memory.
FIG. 24
is a block diagram showing the major parts in a conventional audio recording apparatus as taught in the above-noted Patent Application Publication (referred to below as the conventional audio recording apparatus). As will be known from FIG.
24
, this conventional audio recording apparatus comprises: a hierarchical encoder
240
for hierarchically encoding audio data supplied thereto; recording unit
242
for recording data output from the hierarchical encoder
240
to the semiconductor memory
241
, which is integral to the recording unit
242
; and a recording controller
244
having a recording management database
243
, which it uses for controlling the recording unit
242
.
The operation of the above-described conventional audio recording apparatus is described next below with reference to FIG.
24
.
The hierarchical encoder
240
first hierarchically codes audio data input thereto. That is, the hierarchical encoder
240
codes the audio data using an orthogonal transformation or subband coding method, divides it into a plurality of frequency bands, and hierarchizes the frequency bands (that is, assigns a priority level to the frequency bands) such that a low frequency band is assigned to a low hierarchical layer (a high priority level), and a high frequency band is assigned to a high hierarchical layer (a low priority level). Alternatively, frequency bands that are audibly difficult to discern are assigned to a high hierarchical layer for masking.
The recording unit
242
then records the data output from the hierarchical encoder
240
to the semiconductor memory
241
in which the data is divided into groups of blocks in each hierarchized layer.
The recording controller
244
monitors the recording unit
242
during this process to measure the amount of data recorded to the semiconductor memory
241
, detects where in the semiconductor memory
241
the data (code blocks) for each layer is stored, and generate to hold a recording management database
243
indicating this detected address information. The amount of data stored to the semiconductor memory
241
and the capacity of the semiconductor memory
241
are compared, and when the recorded data exceeds the available capacity, the recording controller
244
controls the recording unit
242
as follows.
When the data to be recorded exceeds the storage capacity of the semiconductor memory
241
, the recording controller
244
refers to the recording management database
243
described above and instructs the recording unit
242
to continue recording data output from the hierarchical encoder
240
by overwriting data to an address in the semiconductor memory
241
where data associated with a higher layer is recorded. As a result, output data from the hierarchical encoder
240
continues to be recorded to the semiconductor memory
241
while leaving intact the lower layer data that was recorded before the storage capacity of the semiconductor memory was exceeded.
It should be noted that audio data recorded as described above to the semiconductor memory
241
can be reproduced by again referring to the recording management database
243
stored by the recording controller
244
to first read and decode lower layer data recorded before the semiconductor memory storage capacity was exceeded, and then read and decode data recorded after the storage capacity was exceeded.
This is because lower layer data can be decoded with reference only to, that lower layer, but higher layer data must be decoded with reference to a lower layer. Therefore, even if a higher layer is lost due to data overwriting, the remaining lower layer data can still be decoded. (It should be noted, however, that the sound quality of the reproduced audio drops because of high frequency band elimination.)
As described above, the conventional audio recording apparatus hierarchically codes audio data supplied thereto for recording to semiconductor memory
241
. When the semiconductor memory
241
becomes full, audio data is recorded by overwriting previously recorded data from a high hierarchical layer. This method is referred to below as “hierarchical overwrite recording.” As a result, recording continues even when the semiconductor memory
241
becomes full, and there is, therefore, no interruption in the reproduced audio. Furthermore, if recording is completed before the semiconductor memory
241
is filled, high quality audio can be reproduced.
However, semiconductor memory
241
typically does not have enough capacity for practical use as a video and/or audio data recording medium. Applications for such conventional audio recording apparatuses are therefore limited to applications having a relatively short recording time and not requiring particularly high sound quality, including, for example, answering machines as noted above, recorders for language study practice (such as English conversation as a second language), and toys (such as a toy parrot) for mimicking a person's voice.
The present inventors therefore invented a method for realizing the above-noted hierarchical overwrite recording method using a large capacity, random access, disc-type recording medium (such as a floppy disk, fixed disk, MD, CD, or DVD; such media are below referred to as “recording disks”).
Using this method, it is possible to record video and/or audio data for a movie or music for which both a long recording time and high quality reproduction are required without the reproduced video and/or audio being interrupted when the recording disk becomes full during recording. In addition, if recording is completed before the recording disk is filled, recording can be completed so that the recorded video and/or audio data can be reproduced with high quality.
It should be further noted, however, that recording data to a disk gener
Boccio Vincent
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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