U.S. patent application number 14/224197 was filed with the patent office on 2017-07-06 for method and apparatus for composition of subtitles.
The applicant listed for this patent is THOMSON LICENSING. Invention is credited to Dirk GANDOLPH, Jobst HOERENTRUP, Ralf OSTERMANN, Hartmut PETERS, Harald SCHILLER.
Application Number | 20170195618 14/224197 |
Document ID | / |
Family ID | 43605449 |
Filed Date | 2017-07-06 |
United States Patent
Application |
20170195618 |
Kind Code |
A9 |
GANDOLPH; Dirk ; et
al. |
July 6, 2017 |
METHOD AND APPARATUS FOR COMPOSITION OF SUBTITLES
Abstract
Embodiments of the invention include a subtitling format
encompassing elements of enhanced syntax and semantic to provide
improved animation capabilities. The disclosed elements improve
subtitle performance without stressing the available subtitle
bitrate. This will become essential for authoring content of
high-end HDTV subtitles in pre-recorded format, which can be
broadcast or stored on high capacity optical media, e.g. the
Blue-ray Disc. Embodiments of the invention include abilities for
improved authoring possibilities for the content production to
animate subtitles. For subtitles that are separate from AV
material, a method includes using one or more superimposed subtitle
layers, and displaying only a selected part of the transferred
subtitles at a time. Further, colors of a selected part of the
displayed subtitles may be modified, e.g. highlighted.
Inventors: |
GANDOLPH; Dirk; (Ronnenberg,
DE) ; HOERENTRUP; Jobst; (Wennigsen, DE) ;
OSTERMANN; Ralf; (Hannover, DE) ; PETERS;
Hartmut; (Barsinghausen, DE) ; SCHILLER; Harald;
(Hannover, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THOMSON LICENSING |
Issy de Moulineaux |
|
FR |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20150281634 A1 |
October 1, 2015 |
|
|
Family ID: |
43605449 |
Appl. No.: |
14/224197 |
Filed: |
March 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12800418 |
May 14, 2010 |
8737810 |
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14224197 |
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10535106 |
May 16, 2005 |
7852411 |
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PCT/EP03/12261 |
Nov 3, 2003 |
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12800418 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 5/85 20130101; H04N
21/4312 20130101; H04N 9/8233 20130101; G11B 27/036 20130101; G11B
27/32 20130101; G11B 27/10 20130101; H04N 21/4884 20130101; G11B
27/19 20130101; H04N 5/278 20130101; H04N 21/8126 20130101; G11B
27/034 20130101 |
International
Class: |
H04N 5/85 20060101
H04N005/85; G11B 27/034 20060101 G11B027/034 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2002 |
EP |
02025474.4 |
Claims
1. Apparatus for composition of subtitles for audio/video
presentations, wherein data streams containing video, audio and
subtitle information are transferred from a storage medium, the
apparatus comprising: a processor for retrieving from said storage
medium subtitle layer data, wherein the subtitle layer data contain
graphic subtitle elements and data for a first color look-up table;
the processor extracting from said retrieved subtitle layer data
subtitle display region information for defining a subtitle display
region and subtitle display region cropping information, for
cropping the display region, the subtitle display region cropping
information comprising a parameter for horizontal position of the
cropped subtitle display region, a parameter for vertical position
of the cropped subtitle display region, a parameter for width of
the cropped subtitle display region, and a parameter for height of
the cropped subtitle display region; and a renderer for enabling
automatic cropping of rectangular parts of the subtitle elements to
be displayed in the cropped subtitle display region; wherein the
cropped parts of the subtitle elements to be displayed are defined
by said subtitle display region cropping information; and wherein
said first color look-up table is to be used within said cropped
parts of the subtitle elements.
Description
CROSS RELATED APPLICATIONS
[0001] This application is a Continuation of co-pending U.S.
application Ser. No. 12/800,418, herein incorporated by reference
in its entirety, which is a Continuation-In-Part of U.S.
application Ser. No. 10/535,106, filed May 16, 2005, herein
incorporated by reference in its entirety.
[0002] This application claims benefit of U.S. application Ser. No.
12/800,418, filed May 14, 2010, which claims the benefit, under 35
U.S.C. .sctn.365 of International Application PCT/EP03/12261, filed
Nov. 3, 2003, which was published in accordance with PCT Article
21(2) on Jun. 3, 2004 in English and which claims the benefit of
European patent application No. 02025474.4, filed Nov. 15,
2002.
FIELD OF THE INVENTION
[0003] The invention relates to a method and to an apparatus for
composition of subtitles for audio/video presentations, which can
be used e.g. for HDTV subtitles in pre-recorded formats like the
so-called Blue-ray Disc.
BACKGROUND OF THE INVENTION
[0004] The technique of subtitling for Audio-Visual (AV) material
has been used beginning with the first celluloid cinema movies and
further until the recent digital media appeared. The main target of
subtitling has been the support of handicapped people or small
ethnographic language groups. Therefore subtitling often aims at
the presentation of text information even when having been encoded
as graphic data like pixel maps. Therefore pre-produced AV material
for broadcasting (Closed Caption, Teletext, DVB-Subtitle etc.) and
movie discs (DVD Sub-Picture etc.) primarily are optimized for
subtitles representing simple static textual information. However,
progress in PC software development for presentation and animation
of textual information induces a corresponding demand for
possibilities and features within the digital subtitling technique
used for pre-recording and broadcasting. Using straightforward
approaches without any special precautions, these increased
requirements for subtitling would consume a too big portion of the
limited overall bandwidth. The conflicting requirements for a `full
feature` subtitle encompassing karaoke all through genuine
animations are on one hand the coding efficiency and on the other
hand the full control for any subtitle author.
[0005] For today's state of the art of digitally subtitling AV
material with separate subtitling information two main approaches
exist: Subtitling can be based on either pixel data or on character
data. In both cases, subtitling schemes comprise a general
framework, which for instance deals with the synchronization of
subtitling elements along the AV time axis.
Character Data Based Subtitling
[0006] In the character-based subtitling approach, e.g. in the
teletext system ETS 300 706 of European analog or digital TV,
strings are described by sequences of letter codes, e.g. ASCII or
UNICODE, which intrinsically allows for a very efficient encoding.
But from character strings alone, subtitling cannot be converted
into a graphical representation to be overlaid over video. For
this, the intended character set, font and some font parameters,
most notably the font size, must either be coded explicitly within
the subtitling bitstream or an implicit assumption must be made
about them within a suitably defined subtitling context. Also, any
subtitling in this approach is confined to what can be expressed
with the letters and symbols of the specific font(s) in use. The
DVB Subtitling specification ETS 300 743, in its mode of "character
objects", constitutes another state-of-the-art example of
character-based subtitling.
Pixel Data Based Subtitling
[0007] In the pixel-based subtitling approach, subtitling frames
are conveyed directly in the form of graphical representations by
describing them as (typically rectangular) regions of pixel values
on the AV screen. Whenever anything is meant to be visible in the
subtitling plane superimposed onto video, its pixel values must be
encoded and provided in the subtitling bitstream, together with
appropriate synchronization info, and hence for the full feature
animation of subtitles all pixel changed must be transported.
Obviously, when removing any limitations inherent with full feature
animations of teletext, the pixel-based approach carries the
penalty of a considerably increased bandwidth for the subtitling
data. Examples of pixel-based subtitling schemes can be found in
DVD's sub-picture concept "DVD Specification for Read-Only disc",
Part 3: Video, as well as in the "pixel object" concept of DVB
Subtitling, specified in ETS 300 743.
SUMMARY OF THE INVENTION
[0008] Embodiments of the invention include a subtitling format
encompassing elements of enhanced syntax and semantic to provide
improved animation capabilities. The disclosed embodiments improve
subtitle performance without stressing the available subtitle
bitrate. This will become essential for authoring content of
high-end HDTV subtitles in pre-recorded format, which can be
broadcast or pressed on high capacity optical media, e.g. the
Blue-ray Disc. The invention includes abilities for improved
authoring possibilities for the content production to animate
subtitles.
[0009] Introduced by the disclosure are elements of syntax and
semantic describing the color change for parts of graphics to
display. This can be used for highlight effects in applications
like for example karaoke, avoiding the repeated transfer of pixel
data.
[0010] Other disclosed elements of syntax and semantic facilitate
the ability of cropping parts of the subtitles before displaying
them. By using the technique of subsequently transferred cropping
parameters for an object to display, a bit saving animation of
subtitles becomes available. Such cropping parameter can be used
for example to generate text changes by wiping boxes, blinds,
scrolling, wipes, checker boxes, etc.
[0011] Furthermore the disclosed elements can be used to provide
interactivity on textual and graphical information. Especially the
positioning and/or color settings of subtitles can be manipulated
based upon user request.
DRAWINGS
[0012] Exemplary embodiments of the invention are described with
reference to the accompanying drawings and tables, which show:
[0013] FIG. 1: segment_type values for enhanced PCS and RCS;
[0014] FIG. 2: Enhanced page composition segment;
[0015] FIG. 3: Enhanced region composition segment;
[0016] FIG. 4: Example for the definition of a subtitle region and
its location within a page;
[0017] FIG. 5: Example for definition of a region sub-CLUT and
region cropping;
[0018] FIG. 6: Resulting display example;
[0019] FIG. 7: Interactive usage of subtitles;
[0020] FIG. 8: Video and Graphics Planes;
[0021] FIG. 9: Video and Graphics Mixing and Switching.
EXEMPLARY EMBODIMENTS OF THE INVENTION
[0022] The invention can preferably be embodied based on the syntax
and semantic of the DVB subtitle specification (DVB-ST). To provide
improved capabilities for the manipulation of graphic subtitle
elements, the semantics of DVB-ST's page composition segment (PCS)
and region composition segment (RCS) are expanded.
[0023] DVB_ST uses page composition segments (PCS) to describe the
positions of one or more rectangular regions on the display screen.
The region composition segments (RCS) are used to define the size
of any such rectangular area and identifies the color-lookup-table
(CLUT) used within.
[0024] Embodiments of the proposed invention keeps backward
compatibility with DVB-ST by using different segment_types for the
enhanced PCS and RCS elements, as listed in FIG. 1 showing segment
type values according to DVB-ST, with additional values for
enhanced PCS and enhanced RCS. It would also be possible to choose
other values instead. Another approach for keeping backward
compatibility would be to keep the existing segment_types and
increase the version_number of the specification, e.g. by
incrementing the subtitle_stream_id in the PES_data_field
structure.
[0025] FIG. 2. shows the data structure of an enhanced page
composition segment (PCS), containing a region_cropping section and
a region_sub_CLUT section. FIG. 3 shows the data structure of an
enhanced region composition segment (RCS), containing an identifier
sub_CLUT_id for a sub-color-look-up-table. With respect to original
DVB-ST, all structures shown are expanded. In the tables the
additional entries are lines 15-28 in FIG. 2 and line 16 in FIG.
3.
[0026] The enhanced PCS shown in FIG. 2 carries optional
information about the region cropping and optional information
about the region_sub-CLUT for every region listed. The two values
of region_cropping and region_sub_CLUT indicate if such optional
information is available for the current region in process.
Therefore cropping and sub-CLUT may be defined separately for every
region. While region_cropping is used as a flag, as indicated by
"if region cropping==0x01", the region_sub_CLUT shows the value how
many sub-CLUT positions are described. This is done to provide
different alternatives within the stream. Alternative sub-CLUT
positions can be used to define different menu button positions for
the display screen. Only one of them--the first one as a
default--is active and the user can change the position to navigate
through the different predefined positions pressing the remote for
example.
[0027] The enhanced RCS shown in FIG. 3 carries the sub_CLUT_id
identifying the family of CLUTs that applies to this region. This
is done to re-use CLUTs for different regions and different region
sub_CLUTs as well.
[0028] The enhanced PCS and enhanced RCS elements provide the
ability that subtitles can be manipulated independent from the
encoding method i.e. independent from whether they are encoded as
character data or pixel data.
[0029] The enhanced PCS and RCS can be used to perform many
different animation effects for subtitles. Those could be wiping
boxes, blinds, scrolling, wipes, checker boxes, etc. The following
figures show an application example for karaoke. FIG. 4 shows the
definition of a region R containing lyrics of a song displayed for
karaoke. The letters of the subtitle may be encoded as pixel data
or as character data as well. The region_vertical_address RVA and
the region_horizontal_address RHA define the location of the
subtitle within the frame, or page PG, to display.
[0030] FIG. 5 depicts in the upper part region cropping, and in the
lower part the location of the region sub-CLUT. Region cropping
defines which part of the region is effectively displayed. This is
achieved by four parameters RHC, RVC, RCH, RCW indicating the start
coordinates and the size of the fragment to display.
Region_horizontal_cropping RHC specifies the horizontal address of
the top left pixel of this cropping, region_vertical_cropping RVC
specifies the vertical address of the top line of this cropping,
region_cropping_width RCW specifies the horizontal length of this
cropping, and region_cropping_height RCH specifies the vertical
length of this cropping, wherein cropping means that part of the
subtitles that is visible on a display.
[0031] The region sub-CLUT location shown in the lower part of FIG.
5 defines which part of the region has to be displayed using a
color-look-up-table (CLUT) different from the region CLUT. This is
achieved by four parameters SCHA, SCVA, SCH, SCW indicating the
start coordinates and the size of the sub-region used by the
sub-CLUT. All coordinate parameters are to be understood relative
to the region the sub-CLUT belongs to. sub_CLUT_horizontal_address
SCHA specifies the horizontal address of the top left pixel of this
sub-CLUT, sub_CLUT_vertical_address SCVA specifies the vertical
address of the top line of this sub-CLUT, sub_CLUT_width SCW
specifies the horizontal length of this sub-CLUT and
sub_CLUT_height SCH specifies the vertical length of this
sub-CLUT.
[0032] Picking up all parameters defined with the previous figures
results in the displayed subtitle as depicted in FIG. 6. The
subtitle is not depicted in whole on the display but only the
cropped part of it. Furthermore the sub-CLUT was used to provide a
highlight HT, so that the user knows what to sing in the
moment.
[0033] As the enhanced PCS are sent within MPEG packet elementary
stream (PES) packets labeled by presentation time stamps (PTS), any
effect can be synchronized to the AV.
[0034] Another idea of the invention is the superseding of subtitle
animation parameters by the user. This offers a way to realize
interactive subtitles. The enhanced PCS parameters are transferred
as a default, and the user may change them via a remote control for
example. Thus the user is able to move, crop or highlight the
subtitle.
[0035] This could be an advantage for a user defined repositioning
of a subtitling text, so that the user can subjectively minimize
the annoyance by the subtitle text placement on top of the motion
video. Also the color of the subtitles could be set according to
users preferences. FIG. 7 shows a block diagram for interactive
subtitle modifications. The default parameters DD read from a disc
D are superseded by superseding data SD being generated upon the
user action UA and processed by a processor P.
[0036] Another application for overriding subtitle animation
parameters like position, cropping rectangle, CLUTs and sub-CLUTs
is the realization of some very basic sort of interactive gaming.
The subtitle may carry pixel data of an animated character. This
character is subsequently moved on the display screen driven by
either user interaction, programmatic control or both.
[0037] The overriding of subtitle animation parameters can be
implemented in at least two ways. The first option is that the
overriding parameters SD replace the parameters DD send in the
bitstream. The second option is that the overriding parameters SD
are used as an offset that is added to or subtracted from the
subtitle animation parameters DD send in the bitstream.
[0038] The enhanced PCS and RCS provide a lot more of animation
capabilities not explained. Following is a non-exhaustive list of
examples: wiping boxes, blinds, scrolling, wipes, checker boxes in
details.
[0039] Exemplary video and graphics planes are shown in FIG. 8 in
an exemplary, schematic manner. A background is provided by either
an MPEG-2 video layer MVL or a still picture layer SPL. They are
mutually exclusive, which means that not both of them need to be
held in a buffer at a time. The next two layers comprise a subtitle
layer SL and an AV sync type graphics layer AVSGL. These two layers
are in this example interchangeable, meaning that either the
subtitle layer SL or the AV sync type graphics layer AVSGL may have
priority over the other. The front layer is a non-AV sync graphics
layer NAVSGL, containing graphics that need not be synchronized
with the AV content, such as e.g. menus or other on-screen
displays. The inventive method can preferably be used for the
subtitle layer SL, the AV sync graphics layer AVSGL and/or the
Non-AV sync graphics layer NAVSGL.
[0040] FIG. 9 shows relevant components of an apparatus for video
and graphics mixing and switching. Data comprising either still
picture data or MPEG-2 video data, further data for subtitles, data
for animations and data for non-AV sync graphics such as menu
buttons, are retrieved from a disc D. Additionally or
alternatively, data for subtitles, animations and/or non-AV sync
graphics can be received from a network NW, e.g. internet. A
processing unit CPU processes the non-AV sync graphics data and
sends the resulting data to a rendering device for non-AV sync
graphics RNAVG.
[0041] The apparatus contains a still picture decoder SPDec and an
MPEG-2 video decoder MVDec, but since only one of them is used at a
time, a switch s1 can select which data shall be used for further
processing. Moreover, two identical decoders AVSGDec1,AVSGDec2 are
used for decoding subtitle and animation data. The outputs of these
two decoders AVSGDec1, AVSGDec2 may be switched by independent
switches s2,s3 to either a mixer MX, or for preprocessing to a
mixer and scaler MXS, which outputs its resulting data to said
mixer MX. These two units MX, MXS are used to perform the
superimposing of its various input data, thus controlling the
display order of the layers. The mixer MX has inputs for a front
layer f2, a middle front layer mf, a middle back layer mb and a
background layer b2. The front layer f2 may be unused, if the
corresponding switch s3 is in a position to connect the second AV
sync graphics decoder AVSGDec2 to the mixer and scaler MXS. This
unit MXS has inputs for front layer f1, middle layer m and
background layer b. It superimposes these data correspondingly and
sends the resulting picture data to the background input b2 of the
mixer MX. Thus, these data represent e.g. a frame comprising up to
three layers of picture and subtitles, which can be scaled and
moved together within the final picture. The background input b1 of
the mixer and scaler MXS is connected to the switch s1 mentioned
above, so that the background can be generated from a still picture
or an MPEG-2 video.
[0042] The output of the first AV sync graphics decoder AVSGDec1 is
connected to a second switch s2, which may switch it to the middle
layer input m of the mixer and scaler MXS or to the middle back
layer input mb of the mixer MX. The output of the second AV sync
graphics decoder AVSGDec2 is connected to a third switch s3, which
may switch it to the front layer input f1 of the mixer and scaler
MXS or to the middle front layer input mf of the mixer MX.
[0043] Depending on the positions of the second and third switch
s2,s3, either the output of the first or the second AV sync
graphics decoder AVSGDec1,AVSGD2 may have priority over the other,
as described above. For having the data from the first decoder
AVSGDec1 in the foreground, the second switch s2 may route the
subtitle data to the middle back input mb of the mixer MX, while
the third switch s3 routes the animation graphics data to the front
input f1 of the mixer and scaler MXS, so that it ends up at the
background input b2 of the mixer MX. Otherwise, for having the data
from the second decoder AVSGDec2 in the foreground, the switches
s2,s3 may route their outputs to the same unit, either the mixer
and scaler MXS or the mixer MX, as shown in FIG. 9.
* * * * *