Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1997-05-30
2001-02-20
Tran, Thai (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C345S215000
Reexamination Certificate
active
06192183
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video editing scheme to be used in playbacking and editing coded video data.
2. Description of the Background Art
In conjunction with the standardization of the video coding scheme such as MPEG, a use of the coded video has been widening, and there is a demand for an editing apparatus which is capable of retrieving a desired scene from the video quickly, processing the coded video in a coded form efficiently, and changing a playback order of the video.
Conventionally, in order to retrieve a desired scene from the non-coded video such as video images, it has been necessary to repeatedly execute operations such as rewinding and fast forwarding operations, so that there has been a problem that a considerable amount of time is required for the scene retrieval. In view of this problem, there has been a proposition of a video editing apparatus as disclosed in Japanese Patent Application Laid Open No. 5-183862 (1993), which has a detection means for detecting images at which the scene is changed in the video, and an index information production means for producing a video index information in terms of icons obtained by reducing the images detected by the detection means. This video editing apparatus has already been developed for practical use. According to this proposition, the icons representing the scene changed images detected from the video are displayed in a form of multiple image field display, so that an outline of the video content can be comprehended without watching the video in a time order, and therefore it becomes possible to realize the scene retrieval efficiently.
This conventional video editing apparatus is designed to handle the non-coded video such as video images, and when this conventional video editing apparatus is directly applied to handle the coded video, the following problems arise.
FIG. 1
shows one exemplary apparatus configuration in which the above described conventional video editing apparatus is directly applied to the coded video.
In
FIG. 1
, a portion enclosed by a solid line represents a general configuration of a conventional apparatus for playbacking the coded video in which a coded video control unit
22
reads out the coded video data stored in a coded video storage unit
21
and supply the coded video data to a decoding unit
23
which decodes the coded video data. The decoded video data are then supplied to and displayed at a display unit
24
. Here, the decoding unit
23
is usually implemented in a form of dedicated hardware.
Also, in
FIG. 1
, a portion enclosed by a dashed line represents the above described conventional video editing apparatus in which a scene change detection means
25
detects images at which the scene is changed in the video, an index production means
26
produces a video index information in terms of icons obtained by reducing the images detected by the scene change detection means
25
, and a display means
27
displays these icons in a form of multiple image field display.
FIG. 1
shows one exemplary configuration for realizing the above described conventional video editing apparatus in combination with an apparatus for playbacking the coded video, in which the decoded video data are taken from the decoding unit
23
of the playback apparatus and entered into the above described conventional video editing apparatus.
However, the decoding unit
23
is usually implemented in a form of dedicated hardware as already mentioned above, so that it is not easy to read out and process the decoded video data by means of software. Even if it is possible, there still remains a problem that an amount of data for the decoded video data is very large so that the data transfer (such as a data transfer using an internal bus of a computer) requires a considerable amount of time.
FIG. 2
shows another exemplary apparatus configuration in which the above described conventional video editing apparatus is directly applied to the coded video.
In
FIG. 2
, the scene change detection means is provided in a form of coded video data scene change detection means
28
which can detect a scene change directly from the coded video data. Such a coded video data scheme change detection means can be realized by using the known configuration as disclosed in Japanese Patent Application No. 6-22304 (1994). Then, the coded video control unit
22
reads out the coded video data stored in the coded video storage unit
21
and supply the coded video data directly to the coded video data scene change detection means
28
(before supplying the coded video data to the decoding unit
23
), so that an index production means
29
produces the index information according to the scene changes detected by the coded video data scene change detection means
28
.
This configuration of
FIG. 2
has a problem in that the index production means
29
is required to carry out the decoding processing in order to produce the icons in forms of the reduced images, so that a considerable amount of time is required for the index production processing.
In addition, there is another conventionally encountered problem that it is not easy to edit the coded video. This problem stems from the fact that it is not easy to segment the coded video data at arbitrary positions and change an order of segments. Because of this problem, it has conventionally been customary to carry out the editing on an original tape and then the edited video is coded, so as not to require the editing on the coded video,
This problem regarding a difficulty of editing the coded video will now be described in further detail for an exemplary case of using the MPEG coding scheme.
In the MPEG coding scheme, the image sequence is coded by using a combination of an intra-field coded picture (I picture) in which the image is compressed by removing the redundancy within each image field, an inter-field forward direction predictively coded picture (P picture) which utilizes a correlation between an image of interest and a past image, and an inter-field bidirectional predictively coded picture (B picture) which utilizes a correlation among an image of interest, a past image, and a future image, as shown in FIG.
3
. In
FIG. 3
, a picture
31
is an I picture which is coded within an image field, so that it is possible to reproduce an image from the data of this picture
31
alone. On the other hand, a picture
32
is a B picture from which an image cannot be reproduced until its past picture
31
and its future picture
33
are decoded. Consequently, in the MPEG coded video, it is only possible to segment the video at a position of the I picture. If the video is segmented at a position of the B picture
32
, for instance, it would become impossible to decode the B picture
32
because data of the I picture
31
would become unavailable.
In other words, in order to segment the video at a portion other than that of the I picture, it would be necessary to reconstruct the coded data by repeatedly executing the decoding processing and the coding processing, and because of that, there has been problems that it would require a considerable amount of time and an image quality would be degraded.
For the same reason, in the MPEG, a position from which the video playback can be started is limited to a position of the I picture (or a top of a packet containing the sequence header that stores parameters necessary for the decoding, strictly speaking). The above described conventional video editing apparatus does not account for this limitation at all, so that when the above described conventional video editing apparatus is directly used to handle the coded video, there is a problem that the decoding unit would not operate properly at a time of the video playback, that is, the playbacked images would be temporarily disturbed until the I picture is displayed. In addition, Japanese Patent Application Laid Open No. 5-183862 mentioned above does not have any teaching directed to a specific editing operation such as a change of playback orders.
Thus
Hamada Hiroshi
Niikura Yasuhiro
Taniguchi Yukinobu
Tonomura Yoshinobu
Banner & Witcoff , Ltd.
Nippon Telegraph and Telephone Corporation
Tran Thai
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