The present invention generally relates to communications systems and, more particularly, to wireless systems, e.g., terrestrial broadcast, cellular, Wireless-Fidelity (Wi-Fi), satellite, etc.
Today, mobile devices are everywhere—from MP3 players to personal digital assistants to cellular telephones to mobile televisions (TVs). Unfortunately, a mobile device typically has limitations on computational resources and/or power. In this regard, an Internet Protocol (IP) Datacast over Digital Video Broadcasting—Handheld (DVB-H) system is an end-to-end broadcast system for delivery of any type of file and service using IP-based mechanisms that is optimized for such devices. For example, see ETSI EN 302 304 V1.1.1 (2004-11) “Digital Video Broadcasting (DVB); Transmission System for Handheld Terminals (DVB-H)”; ETSI EN 300 468 V1.7.1 (2006-05) “Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems”; ETSI TS 102 472 V1.1.1 (2006-06) “Digital Video Broadcasting (DVB); IP Datacast over DVB-H: Content Delivery Protocols”; ETSI EN 301 1924 V1.4.1 (2004-06), “Digital Video Broadcasting (DVB); DVB specification for data broadcasting” and ETSI TS 102 471 V1.1.1 (2006-04) “Digital Video Broadcasting (DVB); IP Datacast over DVB-H: Electronic Service Guide (ESG)”. An example of an IP Datacast over DVB-H system as known in the art is shown in
In particular, in a DVB-H system data is transmitted in bursts as a series of discrete packets. These time slices of data can be used to separate different services offered on a physical broadcast channel. This allows a battery powered receiver to conserve power by only turning its radio on for those time intervals when relevant data is available. This is illustrated in
The amount of time, or length, of a time slicing cycle for a given service is a function of system design and can vary. This interval dictates the average time needed for a receiver to begin receiving data for a service. According to the DVB-H Project Office, present technology allows for an interval of two to four seconds between bursts resulting in an average service acquisition time of one to two seconds.
However, depending on the specific data offered by a service, further complications may exist that can add to the time required for the service to be fully available at the receiver for a user. In particular, the receiver may have to receive initialization data before the receiver can process the received data stream. For example, video coding schemes that require an initial Intra-frame (I-frame) be received and decoded by the receiver before subsequent predicted frames (P-frames) can be decoded can add delay. As such, when the receiver initially turns on, or even during a channel change, the receiver may have to wait for the data burst that conveys that first I-frame—thus, making the user wait for the service. Another example is the video standard H.264 (ITU-T Recommendation H.264 and ISO/IEC 14496-10 (MPEG-4 part 10) Advanced Video Coding, October 2004), which requires parameter sets be first received and passed to the decoder before any video frames can be decoded. Again, when the receiver initially turns on, or switches to a new channel, the receiver will have to wait for the particular data burst conveying the parameter sets. And, as a final example, synchronization data may be required in order to synchronize multiple streams of data. For example, a service may consist of an audio stream and a video stream, both transmitted as separate RTP (Real-Time Protocol) streams (e.g., see H. Schulzrinne, S. Casner, R. Frederick, V. Jacobson, “RFC 1889—RTP: A Transport Protocol for Real-Time Applications,” IETF, January 1996). Synchronization of these streams requires that the receiver receive RTCP (Real-Time Control Protocol) sender reports in order to determine a common reference clock for the separate RTP streams. Without these RTCP sender reports, the receiver will be unable to properly synchronize the video and the audio together—thus, again adding delay while the receiver waits for the RTCP sender reports.
As described above, a receiver may have to wait for initialization data before being able to fully present a service—thus increasing service acquisition time. In fact, a receiver may have to wait for multiple data bursts before finally receiving a data burst conveying the required initialization data. Therefore, and in accordance with the principles of the invention, an apparatus encodes a signal for providing an encoded signal having associated initialization data; and transmits the encoded signal, wherein the transmitted signal occurs in bursts for conveying the encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein the initialization data is sent in a burst and repeated in every following burst until new initialization data is received for transmission.
In an illustrative embodiment of the invention, an apparatus provides a service that includes video. In particular, the apparatus encodes a signal for providing an MPEG-2 encoded signal having associated initialization data such as I-frames; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the MPEG-2 encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one I-frame is conveyed in a burst and repeated in every following burst until a new I-frame is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys an MPEG-2 encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one I-frame, from every received burst, and discards a recovered I-frame that has been repeated from a previously received burst. As a result, the apparatus can fully utilize the MPEG-2 encoded video within each burst thus facilitating faster channel acquisition and recovery from errors.
In another illustrative embodiment of the invention, an apparatus provides a service that includes video. In particular, the apparatus encodes a signal for providing an H.264 encoded signal having associated initialization data such as parameter sets; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the H.264 encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one parameter set is conveyed in a burst and repeated in every following burst until a new parameter set is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys an H.264 encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one parameter set, from every received burst, and discards a recovered parameter set that has been repeated from a previously received burst. As a result, the apparatus can fully utilize the H.264 encoded video within each burst thus facilitating faster channel acquisition and recovery from errors.
In another illustrative embodiment of the invention, an apparatus provides a service that includes video and audio, which are transmitted as separate RTP streams. In particular, the apparatus encodes a signal for providing separate RTP streams for video and audio, the video and audio streams having associated initialization data such as RTCP sender reports; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the video and audio streams, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one RTCP sender report is conveyed in a burst and repeated in every following burst until a new RTCP sender report is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys separate video and audio RTP streams, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one RTCP sender report, from every received burst, and discards a recovered RTCP sender report that has been repeated from a previously received burst. As a result, the apparatus can fully utilize the separate RTP streams within each burst thus facilitating faster channel acquisition and recovery from errors.
In another illustrative embodiment of the invention, an apparatus provides a service that includes video. In particular, the apparatus encodes a signal in accordance with RObust Header Compression (ROHC) (RFC 3095) for providing an ROHC encoded signal having associated initialization data such as periodic initialization and refresh (IR) packets; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the ROHC encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one IR packet is conveyed in a burst and repeated in every following burst until a new IR packet is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys an ROHC encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one IR packet, from every received burst, and discards a recovered IR packet that has been repeated from a previously received burst. As a result, the apparatus can fully utilize the ROHC encoded video within each burst thus facilitating faster channel acquisition and recovery from errors.
In view of the above, and as will be apparent from reading the detailed description, other embodiments and features are also possible and fall within the principles of the invention.
Other than the inventive concept, the elements shown in the figures are well known and will not be described in detail. For example, other than the inventive concept, familiarity with Discrete Multitone (DMT) transmission (also referred to as Orthogonal Frequency Division Multiplexing (OFDM) or Coded Orthogonal Frequency Division Multiplexing (COFDM)) is assumed and not described herein. Also, familiarity with television broadcasting, receivers and video encoding is assumed and is not described in detail herein. For example, other than the inventive concept, familiarity with current and proposed recommendations for TV standards such as NTSC (National Television Systems Committee), PAL (Phase Alternation Lines), SECAM (SEquential Couleur Avec Memoire) and ATSC (Advanced Television Systems Committee) (ATSC), Chinese Digital Television System (GB) 20600-2006 and DVB-H is assumed. Likewise, other than the inventive concept, other transmission concepts such as eight-level vestigial sideband (8-VSB), Quadrature Amplitude Modulation (QAM), and receiver components such as a radio-frequency (RF) front-end (such as a low noise block, tuners, down converters, etc.), demodulators, correlators, leak integrators and squarers is assumed. Further, other than the inventive concept, familiarity with protocols such as the File Delivery over Unidirectional Transport (FLUTE) protocol, Asynchronous Layered Coding (ALC) protocol, Internet protocol (IP) and Internet Protocol Encapsulator (IPE), is assumed and not described herein. Similarly, other than the inventive concept, formatting and encoding methods (such as Moving Picture Expert Group (MPEG)-2 Systems Standard (ISO/IEC 13818-1)) for generating transport bit streams are well-known and not described herein. It should also be noted that the inventive concept may be implemented using conventional programming techniques, which, as such, will not be described herein. Finally, like-numbers on the figures represent similar elements.
As noted earlier, when a receiver initially turns on, or even during a channel change or even if just changing services within the same channel, the receiver may have to additionally wait for that data burst that conveys the required initialization data before being able to process any received data. As a result, the user has to wait an additional amount of time before being able to access a service or program. This is further illustrated in
Turning now to
With regards to the need of additional bandwidth for repeating initialization data in every burst this may be addressed in a number of ways. First, data sources such as video and audio encoders may support the ability to control the output bitrate of the encoder. Thus, the bandwidth of the content data may be reduced, e.g., by reducing the bitrate of the encoded video, in order to accommodate the bandwidth required for repeating the initialization data. Alternatively, the “on-time” for a burst may be increased to provide the required bandwidth, thus slightly increasing the duration of a time slicing cycle. Finally, it should also be noted that initialization data tends to be very small and may fit within the portion of a time slice typically used for padding in existing systems. In fact, a feedback mechanism can be used between a time slicing unit and an encoder so that the time slicing unit may report to the encoder the amount of remaining space in the time slice available after the initialization data so that the encoding bitrate may be adjusted to compensate for the presence of the initialization data.
An illustrative flow chart in accordance with the principles of the invention for use in a transmitter is shown in
Turning now to
Referring now to
Turning now to
The elements shown in
As noted earlier, a feedback mechanism can be used to alter the bit rate provided by encoder 205 in order to account for the size of the repeated initialization data in every data burst. This is illustrated in
Referring now to
In view of the above, and in accordance with the principles of the invention, faster channel, or service, acquisition is achieved by repeating initialization data in every data burst. It should be noted that although the inventive concept was illustrated in the context of an MPEG-2 encoded signal, the inventive concept is not so limited and is applicable to other types of encoding or transmission schemed that require initialization.
For example, in another illustrative embodiment of the invention, an apparatus provides a service that includes video. In particular, the apparatus encodes a signal for providing an H.264 encoded signal having associated initialization data such as parameter sets; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the H.264 encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one parameter set is conveyed in a burst and repeated in every following burst until a new parameter set is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys an H.264 encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one parameter set, from every received burst, and discards a recovered parameter set that has been repeated from a previously received burst. As a result, the apparatus can fully utilize the H.264 encoded video within each burst thus facilitating faster channel acquisition and recovery from errors.
In another illustrative embodiment of the invention, an apparatus provides a service that includes video and audio, which are transmitted as separate RTP streams. In particular, the apparatus encodes a signal for providing separate RTP streams for video and audio, the video and audio streams having associated initialization data such as RTCP sender reports; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the video and audio streams, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one RTCP sender report is conveyed in a burst and repeated in every following burst until a new RTCP sender report is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys separate video and audio RTP streams, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one RTCP sender report, from every received burst, and discards a recovered RTCP sender report that has been repeated from a previously received burst. As a result, the apparatus can fully utilize the separate RTP streams within each burst thus facilitating faster channel acquisition and recovery from errors.
In another illustrative embodiment of the invention, an apparatus provides a service that includes video. In particular, the apparatus encodes a signal in accordance with RObust Header Compression (ROHC) (RFC 3095) for providing an ROHC encoded signal having associated initialization data such as periodic initialization and refresh (IR) packets; and transmits the signal, wherein the transmitted signal occurs in bursts for conveying the ROHC encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time, and wherein at least one IR packet is conveyed in a burst and repeated in every following burst until a new IR packet is received for transmission.
In another illustrative embodiment of the invention, an apparatus receives a signal, wherein the signal occurs in bursts and conveys an ROHC encoded signal, wherein each burst has a duration and occurs in a time slicing cycle, each time slicing cycle comprising at least the burst duration and an off-time; recovers initialization data, e.g., at least one IR packet, from every received burst, and discards a recovered IR packet that has been repeated from a previously received burst: As a result, the apparatus can fully utilize the ROHC encoded video within each burst thus facilitating faster channel acquisition and recovery from errors.
In view of the above, the foregoing merely illustrates the principles of the invention and it will thus be appreciated that those skilled in the art will be able to devise numerous alternative arrangements which, although not explicitly described herein, embody the principles of the invention and are within its spirit and scope. For example, although illustrated in the context of separate functional elements, these functional elements may be embodied in one, or more, integrated circuits (ICs). Similarly, although shown as separate elements, any or all of the elements may be implemented in a stored-program-controlled processor, e.g., a digital signal processor, which executes associated software, e.g., corresponding to one, or more, of the steps shown in, e.g.,
This application claims the benefit of U.S. Provisional Application No. 61/001,484, filed Oct. 31, 2007.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US08/12219 | 10/28/2008 | WO | 00 | 4/8/2010 |
Number | Date | Country | |
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61001484 | Oct 2007 | US |