Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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REPRESENTATION GROUPING FOR HTTP STREAMING
BACKGROUND
1. Technical Field.
[0001] The present disclosure relates generally to hypertext transfer
protocol (HTTP)
streaming of media content and, more particularly, to the grouping of
representations of media
content.
2. Related Art.
[0002] The background description provided herein is for the purpose of
generally
presenting the context of the disclosure. Work of the presently named
inventors, to the extent
it is described in this background section, as well as aspects of the
description that may not
otherwise qualify as prior art at the time of filing, are neither expressly
nor impliedly admitted
as prior art against the present disclosure.
[0003] The 3rd Generation Partnership Project (3GPP) has developed a
feature known
as HTTP Streaming, whereby mobile telephones, personal digital assistants,
handheld or
laptop computers, desktop computers, set-top boxes, network appliances, and
similar
devices can receive streaming media content via the hypertext transfer
protocol (HTTP).
Any device that can receive HTTP Streaming data will be referred to herein as
a client (or
client device). Content that might be provided to such client devices via HTTP
can include
streaming video, streaming audio, and other multimedia content such as timed
text. In
some cases, the content is prepared and then stored on a standard web server
for later
streaming via HTTP. In other cases, live or nearly live streaming might be
used, whereby
content is placed on a web server at or near the time the content is created.
In either case,
clients can use standard web browsing technology to receive the streamed
content at any
desired time.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0001] For a more complete understanding of this disclosure, reference is
now made to the
following brief description, taken in connection with the accompanying
drawings and detailed
description, wherein like reference numerals represent like parts.
[0002] FIG. 1 is a system architecture for adaptive HTTP streaming in
accordance to the
present disclosure;
[0003] FIG. 2 is a table illustrating an exemplary grouping of
representation of media
content in accordance with the present disclosure;
[0004] FIG. 3 is an excerpt of XML schema of an MPD that describes an
exemplary
representation in accordance with the present disclosure; and
[0005] FIG. 4 illustrates a processor and related components suitable for
implementing the
implementations of the present disclosure.
DETAILED DESCRIPTION
[0006] It should be understood at the outset that although illustrative
implementations of one
or more embodiments of the present disclosure are provided below, the
disclosed devices,
systems and/or methods may be implemented using any number of techniques,
whether currently
known or in existence. The components in the figures are not necessarily to
scale, emphasis
instead being placed upon illustrating the principles of the disclosed
technology. Moreover, in
the figures, like referenced numerals designate corresponding parts or
elements throughout the
different views. The following description is merely exemplary in nature and
is in no way
intended to limit the disclosure, its application, or uses. As used herein,
the term "module" refers
to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a
processor (shared,
dedicated, or group) and memory that executes one or more software or firmware
programs
stored in the memory, a combinational logical circuit, and/or other suitable
components that
provide the described functionality. Herein, the phrase "coupled with" is
defined to mean directly
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connected to or indirectly connected through one or more intermediate
components. Such
intermediate components may include both hardware and software based
components.
[0007] As noted in the background, client devices, also referred to herein
as clients, may
receive streaming media content via the hypertext transfer protocol (HTTP)
utilizing a feature
known as HTTP Streaming. Media content provided to a client by, for example, a
standard
HTTP server may include various media components such as streaming video,
streaming audio,
and/or other multimedia content (e.g., timed text). Each media component, or
alternatively, the
entire set of media components for a given media presentation may be offered
in several
alternative choices or formats that differ by encoding choice. For example,
the alternative
choices (i.e., encodings) of the media content or subsets of the media content
may differ by bit
rate, resolution, language, and/or codec.
[0008] By way of introduction, the apparatuses and/or methods described
herein are related
to adaptive HTTP streaming of media content to a client. The present
disclosure describes a
categorization, or assignment scheme of grouping alternative choices of the
media content or
subsets of the media content of a given media presentation, thereby improving
the efficiency in
which a client is informed of the alternative choices of media content
available for a given media
presentation.
[0009] Referring to FIG. 1, an exemplary system architecture for adaptive
HTTP streaming
that implements the apparatuses and method of the present disclosure is shown.
The system
architecture includes a content preparation phase 110, an HTTP streaming
server 120 (or simply
server 120), an HTTP cache 130, and the HTTP streaming client 140 (or simply
client 140). The
content preparation phase 110 prepares a media presentation for HTTP
streaming. The media
content of the media presentation is stored on an HTTP streaming server 120
and/or in the HTTP
cache 130. A media presentation is a structured collection of data that is
accessible to the client
140. The client 140 requests and downloads media data information to present a
streaming
service to a user of the client 140.
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[0010] The client 140 may utilize an HTTP GET request or a similar message
to request and
download the media presentation from the HTTP streaming server 120 and/or the
HTTP cache
130. In other words, the HTTP streaming server 120 and/or the HTTP cache 130
provide the
media presentation to the client 140 based on the receipt of a request. The
client 140 may then
present the media presentation to a user.
[0011] The media presentation may be described in an extensible markup
language (XML)
document, which in the 3GPP specifications is called a Media Presentation
Description (MPD).
The MPD contains metadata informing the client of the various formats in which
the media
content of the media presentation maybe encoded. In some implementation, the
MPD may be
provided (i.e., delivered or streamed) to the client from a server such as
server 120. As
mentioned above, each format of the media content may be encoded with a
distinct bit rate,
resolution, language, and/or codec. These various formats of the media content
(i.e., the media
presentation) are referred to as "representations." In other words, each
representation constitutes
one encoding choice among a possible plurality of encoding choices of the
media content or a
subset of the media content. The MPD contains a description of each available
representation of
the media presentation. During operation (i.e., during a streaming session),
the client 140 is
guided by the information in the MPD, namely, the client 140 may select one or
more
representations of the of the media presentation based on the information
provided in the MPD as
well as other information related to channel conditions (e.g., available
bandwidth). In addition,
the client 140 may select one or more representations of the of the media
presentation based on
capabilities or constraints of the client 140. For example, the client 140 may
select a particular
representation (or representations) of the media presentation based on screen
resolution, the
current channel bandwidth, the current channel reception conditions, the
language preference of
the user, and/or other parameters.
[0012] A given media presentation includes a sequence of one or more
periods. Each period
is indicative of a distinct period of time (i.e., time line) of the given
media presentation. A time
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line of a media presentation is defined by the concatenation of the respective
time line of each
constituent period. As such, periods within a given media presentation are
sequential and
generally non-overlapping. In other words, each period extends until the start
of the next period
within the media presentation. Each period of a given media presentation
contains one or more
representations of the same media content. In other words, each period
contains one or more
formats of the media content encoded with a distinct bit rate, resolution,
language, and/or codec,
etc. Furthermore, the timeline of each period is common amongst all
representations within that
period. The grouping scheme of various representations of the media content or
subsets of the
media content of a given media presentation will be discussed in more detail
below.
[0013] An MPD describing an entire media presentation may be provided to
the client 140,
and the client 140 may use the metadata in the MPD throughout the media
presentation (i.e.,
throughout the duration of the time line of the media presentation). In live
streaming scenarios,
the metadata
describing an entire media stream may not be known prior to commencement of a
streaming
session. Furthermore, parameters (e.g., channel conditions) related to the
streaming session may
change during the course of the session. For example, a client may move into
an area with poor
reception, and the data rate may slow down. In such a case, the client may
need to switch to a
representation with a lower bit rate. In another example, a client may choose
to switch the
display of the streamed media content from portrait to landscape mode, in
which case a different
representation may be required.
[0014] As such, in accordance with 3GPP HTTP Adaptive Streaming, each
representation
includes one or more downloadable portions of media and/or metadata referred
to as segments
whose locations are indicated in the MPD. With HTTP Streaming, the media
content may be
downloaded one segment at a time so that play-out of live content does not
fall too far behind
live encoding and so that a client can switch to a different content encoding
adaptively according
to channel conditions or other factors, as described above. A segment is
defined as a unit (i.e., a
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portion) that is uniquely referenced by a hypertext transfer protocol-uniform
resource locator
(HTTP-URL) or a combination of the HTTP-URL and a byte range included in the
MPD. In
other words, segments are addressable by a client based on the information in
metadata.
[0015] Furthermore, each representation either contains an initialisation
segment or each
media segment within the given representation is self-initialising. The
initialization segment
contains information for accessing the given representation and typically does
not contain any
media data. In other words, the initialization segment provides a client with
metadata that
describes the associated media content. In the present implementation, the
initialisation segment
includes a "ftyp" (i.e., a file-type) box, a "moov" (i.e., a movie) box, and
optionally a "pdin" box
as described in the ISO/IEC 14496-12 ISO Base Media File Format.
[0016] A representation contains one or more media components where each
media
component is an encoded version of a respective media type such as audio,
video, or timed text.
Media components are time-continuous across boundaries of consecutive media
segments within
a given representation. A media segment contains media components that are
either described
within the media segment or described by an initialisation segment of the
given representation.
In the present implementation, each media segment of a given representation
contains one or
more whole, self-contained movie fragments. A whole, self-contained movie
fragment includes
a "moor (i.e., a movie fragment) box and a "mdat" (i.e., media data) box. The
mdat box
contains the media samples that are referenced by track runs in the respective
movie fragment.
The moof box contains the metadata for the respective movie fragment.
[0017] Referring back to FIG. 1, the streaming client 140 may use of the
3GPP file format
and movie fragments. The 3GPP file format is based on the ISO/IEC 14496-12 ISO
Base Media
File Format. Media files, in accordance with the ISO Base Media File Format,
comprise of a
series of objects called boxes. Boxes can contain media data or metadata. In
non-fragmented
files, the moov box contains the codec information, timing information, and
location information
needed to play the media data. For fragmented media files provided via HTTP
Adaptive
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Streaming, the moov box simply contains codec information, and the timing
information and
location information is contained within the movie fragments (i.e., within one
or more media
segments) themselves. The use of fragmented files enables an encoder (not
shown) to write and
a client to receive the media one portion at a time. This minimizes startup
delay by including
metadata in the moof boxes of the media fragments as opposed to up front in
the moov box. In
HTTP Adaptive Streaming, the moov box may contains a description of the codecs
used for
encoding, but typically does not contain any specific information about the
media samples such
as timing, offsets, etc. Moof boxes contain references to the codecs listed in
the moov box.
[0018] As mentioned above, a representation contains one or more media
components where
each media component is an encoded version of a respective media type such as
audio, video, or
timed text. In some instances, it may be beneficial for purposes of efficiency
of streaming
service to store various media components of a given media presentation
separately on the server
120 such that the media components are streamed separately from the server
120. In this
configuration, each of the media components constitutes a distinct
representation. In this
manner, client 140 may selectively choose which media component(s) the client
140 wishes to
download (i.e., stream over HTTP) and which media component(s) the client 140
does not wish
to download from the server 120. For example, if channel conditions affecting
the streaming
session between the client 140 and the server120 deteriorate, the client 140
may elect to receive
an audio component of a media presentation and refrain from receiving a video
component of the
media presentation which typically requires significant channel bandwidth. If
each media
component (e.g., audio and video components) is stored in the same file (i.e.,
not stored
separately) at the server 120, the client 140 is limited to only receiving
both audio and video
components or neither regardless of channel conditions or any other operating
conditions
affecting the streaming session, thereby potentially resulting in a poor user
experience.
However, by storing each of the media components separately (i.e., in
respective files) at the
server 120, in the present example, the client 140 is required to provide
multiple requests (e.g.,
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HTTP GET requests) to separately retrieve the audio and video segments of the
media
presentation from the server 120. In contrast, if all the constituent media
components for a
particular representation are stored in a single file at the server 120, the
client 140 only needs to
provide a single request to retrieve the selected content.
[0019] The apparatuses and methods of the present disclosure provide a
flexible manner with
which to efficiently indicate to a client (e.g., client 140) how various
representations of the media
content are intended to be consumed (i.e., separately or in combination). As a
result, the ways in
which media components are stored (e.g., in separate files or in a common
file) at a server can be
left to the discretion of a content provider providing the media content. More
particularly, the
present disclosure describes a grouping or assignment scheme that indicates
whether a given
representation is an alternative choice of media content or whether the
representation is
alternative choice within a subset of the media content. In other words, the
present disclosure
describes a parameter, element, or other data (e.g., a "group attribute" in
the present
implementation) in metadata, sent by a server, that informs a client that a
given representation
includes an alternative encoding of every media component (e.g., audio, video,
and time text) of
the media content or that the representation simply constitutes an alternative
encoding of a single
media component (i.e., a subset) of the media content and may be combined with
other
representations.
[0020] Referring now to FIG. 2, an exemplary grouping of representations
within a given
period is shown. For the sake of simplicity and brevity, the present
disclosure will discusses the
various groupings of various encodings of audio, video, and/or time text media
types. Although
the present embodiment depicts four groups (also referred to herein as
"groupings") each having
three constituent representations, that a variable number of groups each
having a variable number
of representations is contemplated. Furthermore, those skilled in the art will
appreciate that the
group attributes (e.g., "0", "1", "2", and "3") referencing the respective
groups have been
arbitrarily assigned.
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[0021] As depicted in FIG. 2, the exemplary representations are assigned to
one of "Group
0", "Group 1", "Group 2", and "Group 3" (i.e., each exemplary representation
is assigned to a
group (or grouping) having a respective group attribute). In other words, each
representation
within a given group is associated with, characterized by, or identified by a
common group
attribute provided in metadata. In some implementations, each representation
within a given
group may be associated with or defined by a "parent element" (not shown). In
these
implementations, the group attribute (discussed above) would be attributed to
or assigned to the
parent element.
[0022] Representations within a respective group are alternatives to each
other (i.e., each
representation has a distinct encoding of a common set of media types(s)) of
the media content
available within a given period). For example, "Representation A",
"Representation B" and
"Representation C" of Group 0 each represent a unique, alternative encoding of
a combination of
audio, video, and subtitle components for the media content of the given
period. Whereas
"Representation G", "Representation H" and "Representation I" of Group 2 each
represent a
unique, alternative encoding of only the video component for the media content
of the given
period. In the present implementation, each representation within Group 0
represents a
"complete" representation such that that each representation contains all the
media components
available for the media content during that period. In other words, the
representations of Group 0
need not be combined by the client 140 with any other representation in order
to deliver all the
available media content for that period. As such, representations assigned to
Group 0 are
presented without any other representations from another group (i.e., any non-
zero group).
[0023] In contrast, in the present implementation, the respective
representations within
Group 1, Group 2, and Group 3 (i.e., the groups having a non-zero group
attribute) represent
"non-complete" alternative encodings within a respective subset (e.g., audio
only, video only,
subtitles only) of the media content for the given period. Since
representations from Groups 1, 2,
and 3 only provide an alternative encoding for a particular subset of the
media content, each of
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these representations is considered "non-complete." As such, representations
assigned to a non-
zero group may be presented in combination with representations from other non-
zero groups
(i.e., not including Group 0). Therefore, in order for the client 140 to
stream all the media content
for the given period, the client 140 selects/requests at most one
representation from each non-
zero group. For example, during an exemplary streaming session, the client 140
may select a
combination of Representation F from Group 1, Representation G from Group 2,
and
Representation K from Group 3 in order to stream all the media content for the
given period of
the media presentation. As such, in FIG. 2, the media content during a given
period is
represented by either one representation from Group 0, since the
representation is present (i.e.,
available), or a combination of at most one representation from each non-zero
group.
[0024] In the present implementation, the client 140 may select one
representation assigned
to Group 0 or the client 140 may select multiple representations, at most one
from each non-zero
group (e.g., Group 1, Group 2, and Group 3 based on information provided in
the metadata
and/or other information such as the bandwidth available during the streaming
session and/one or
more capabilities of the client 140. Once a media presentation has begun
streaming from the
server 120 to the client 140 based on the selected representation(s), the
client 140 continuously
consumes media content by requesting media segments or parts of media segments
of the
respective representations. As previously mentioned, a client may elect to
switch to different
representation(s) during the course of the streaming session taking in to
account (i.e.,
consideration) any updated MPD information the client may have received from
the server 120
and/or any updated information characterizing an environment of the device 140
(e.g., a change
in the available bandwidth). In other words, the client 140 may begin
streaming segments from a
representation or a set of representations that differ from that
representation or set of
representations utilized prior to the switch. In one example, the client 140
may elect to switch
from Representation A to Representation C within Group 0. In another example,
the client 140
may elect to switch from Representation D of Group 1, Representation H of
Group 2, and
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Representation L of Group 3 to Representation F of Group 1, Representation G
of Group 2, and
Representation J of Group 3. In yet another example, the client 140 may elect
to switch from
Representation B of Group 0 to Representation D of Group 1 and Representation
G of Group 2
(i.e., the client 140 may wish not to further receive the subtitles media
component).
[0025] Referring now to FIG. 3, an excerpt of XML schema of an MPD that
describes an
exemplary representation is illustrated. Within the description of the
representation, at 200, is a
description of the group attribute for the exemplary representation.
[0026] The content preparation phase 110, the HTTP streaming server 120,
the HTTP cache
130, and the HTTP streaming client 140 described above may include a
processing component
that is capable of executing instructions related to the actions described
above. FIG. 4 illustrates
an example of a system 1300 that includes a processing component, processor
1310, suitable for
implementing one or more implementations disclosed herein. In addition to the
processor 1310
(which may be referred to as a central processor unit or CPU), the system 1300
might include
network connectivity devices 1320, random access memory (RAM) 1330, read only
memory
(ROM) 1340, secondary storage 1350, and input/output (I/0) devices 1360. These
components
(also referred to herein as modules) might communicate with one another via a
bus 1370. In
some cases, some of these components may not be present or may be combined in
various
combinations with one another or with other components not shown. These
components might
be located in a single physical entity or in more than one physical entity.
Any actions described
herein as being taken by the processor 1310 might be taken by the processor
1310 alone or by the
processor 1310 in conjunction with one or more components shown or not shown
in the drawing,
such as a digital signal processor (DSP) 1380. Although the DSP 1380 is shown
as a separate
component, the DSP 1380 might be incorporated into the processor 1310.
[0027] The processor 1310 executes instructions, codes, computer programs,
or scripts that it
might access from the network connectivity devices 1320, RAM 1330, ROM 1340,
or secondary
storage 1350 (which might include various disk-based systems such as hard
disk, floppy disk, or
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optical disk). While only one CPU 1310 is shown, multiple processors may be
present. Thus,
while instructions may be discussed as being executed by a processor, the
instructions may be
executed simultaneously, serially, or otherwise by one or multiple processors.
The processor
1310 may be implemented as one or more CPU chips.
[0028] The network connectivity devices 1320 may take the form of modems,
modem
banks, Ethernet devices, universal serial bus (USB) interface devices, serial
interfaces, token ring
devices, fiber distributed data interface (FDDI) devices, wireless local area
network (WLAN)
devices, radio transceiver devices such as code division multiple access
(CDMA) devices, global
system for mobile communications (GSM) radio transceiver devices, worldwide
interoperability
for microwave access (WiMAX) devices, and/or other well-known devices for
connecting to
networks. These network connectivity devices 1320 may enable the processor
1310 to
communicate with the Internet or one or more telecommunications networks or
other networks
from which the processor 1310 might receive information or to which the
processor 1310 might
output information. The network connectivity devices 1320 might also include
one or more
transceiver components 1325 capable of transmitting and/or receiving data
wirelessly.
[0029] The RAM 1330 might be used to store volatile data and perhaps to
store instructions
that are executed by the processor 1310. The ROM 1340 is a non-volatile memory
device that
typically has a smaller memory capacity than the memory capacity of the
secondary storage
1350. ROM 1340 might be used to store instructions and perhaps data that are
read during
execution of the instructions. Access to both RAM 1330 and ROM 1340 is
typically faster than
to secondary storage 1350. The secondary storage 1350 is typically comprised
of one or more
disk drives or tape drives and might be used for non-volatile storage of data
or as an over-flow
data storage device if RAM 1330 is not large enough to hold all working data.
Secondary
storage 1350 may be used to store programs that are loaded into RAM 1330 when
such programs
are selected for execution.
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[0030] The
I/0 devices 1360 may include liquid crystal displays (LCDs), touch screen
displays, keyboards, keypads, switches, dials, mice, track balls, voice
recognizers, card readers,
paper tape readers, printers, video monitors, or other well-known input/output
devices. Also, the
transceiver 1325 might be considered to be a component of the I/O devices 1360
instead of or in
addition to being a component of the network connectivity devices 1320.
[0031] The
following are incorporated herein by reference for all purposes: 3GPP
Technical
Specification (TS) 26.234, 3GPP TS 26.244, ISO/IEC 14496-12, Internet
Engineering Task
Force (IETF) Request for Comments (RFC) 5874, and IETF RFC 5261.
[0032] All of
the discussion above, regardless of the particular implementation being
described, is exemplary in nature, rather than limiting. Although specific
components of the
present disclosure are described, methods, systems, and articles of
manufacture consistent with
the present disclosure may include additional or different components. For
example,
components of present disclosure may be implemented by one or more of: control
logic,
hardware, a microprocessor, microcontroller, application specific integrated
circuit (ASIC),
discrete logic, or a combination of circuits and/or logic. Further, although
selected aspects,
features, or components of the implementations are depicted as hardware or
software, all or part
of the apparatuses and methods consistent with the present disclosure may be
stored on,
distributed across, or read from machine-readable media, for example,
secondary storage devices
such as hard disks, floppy disks, and CD-ROMs; a signal received from a
network; or other
forms of ROM or RAM either currently known or later developed. Any act or
combination of
acts may be stored as instructions in computer readable storage medium.
Memories may be
DRAM, SRAM, Flash or any other type of memory. Programs may be parts of a
single program,
separate programs, or distributed across several memories and processors.
[0033] The
processing capability of the system may be distributed among multiple
system components, such as among multiple processors and memories, optionally
including
multiple distributed processing systems. Parameters, databases, and other data
structures may be
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separately stored and managed, may be incorporated into a single memory or
database, may be
logically and physically organized in many different ways, and may implemented
in many ways,
including data structures such as linked lists, hash tables, or implicit
storage mechanisms.
Programs and rule sets may be parts of a single program or rule set, separate
programs or rule
sets, or distributed across several memories and processors.
It is intended that the foregoing detailed description be understood as an
illustration of
selected forms that the invention can take and not as a definition of the
invention. It is only the
following claims, including all equivalents, that are intended to define the
scope of this
disclosure.
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