WO2012110906A1

WO2012110906A1 - Video stream receiver with buffer

Info

Publication number: WO2012110906A1
Application number: PCT/IB2012/050461
Authority: WO
Inventors: Wouter Anne Van Der Beek; Willem Franciscus Johannes HOOGENSTRAATEN; Peter WENDRICH
Original assignee: TP Vision Holding BV
Current assignee: TP Vision Holding BV
Priority date: 2011-02-14
Filing date: 2012-02-01
Publication date: 2012-08-23
Anticipated expiration: 2013-08-14

Abstract

Receivers (1) for receiving live video streams comprise buffers (12) for buffering the live video streams, and controllers (20) for detecting first levels (31) of fill rates oft he buffers (12) and for in response to level detections regulating output speeds of the buffers (12). The output speed has a first value for the fill rate being at or above the first level (31) and has a second value smaller than the first value for the fill rate being below the first level (31). The controller (20) may further detect a second level (32) of the fill rate lower than the first level (31), whereby the output speed has a third value smaller than the second value for the fill rate being below the second level (32). The first value may be a normal output speed and the third value may be zero. The second value may be 0.01-0.99 of the normal output speed, preferably0.50-0.99 of the normal output speed.

Description

Video stream receiver with buffer

FIELD OF THE INVENTION

The invention relates to a receiver for receiving a video stream. The invention further relates to a method, to a computer program product and to a medium.

Examples of such a receiver are (parts of) set top boxes and tuner boxes and other kinds of intermediate devices, and (parts of) televisions and display devices and other kinds of destination devices.

BACKGROUND OF THE INVENTION

US 2010 / 0050124 discloses a digital living network client device with thumbnail creation. Audio and video content may be stored within a home network and accessed by devices within the home network, such as a digital living network alliance network, for rendering and viewing. Users of devices within a home network may browse for audio and video content that is available within the home network. Thumbnail images associated with items of audio and video content may be displayed for the user to assist with selection of a desired item of audio and video content.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a receiver for receiving a video stream, which receiver is arranged for zapping or surfing or hopping through video streams in a user friendly way.

Further objects of the invention are to provide a method, a computer program product and a medium.

According to a first aspect, a receiver for receiving a video stream is provided, the receiver comprising

a buffer for buffering the video stream from a moment in time, a start of the video stream being situated before the moment in time, and

a controller for detecting a first level of a fill rate of the buffer and for in response to a level detection regulating an output speed of the buffer, the output speed having a first value for the fill rate of the buffer being at or above the first level and the output speed having a second value for the fill rate of the buffer being below the first level, the second value being smaller than the first value.

The buffer is arranged for buffering a video stream from a moment in time, whereby a start of the video stream is situated before the moment in time. This is for example the case for a video stream in the form of a live stream or a stream of broadcast content. The controller is arranged for detecting a first level of a fill rate or a fullness of the buffer. The controller is further arranged for in response to a level detection regulating an output speed of the buffer. This output speed of the buffer is regulated such that it has a first value for the fill rate of the buffer being at or above the first level and such that it has a second value smaller than the first value for the fill rate of the buffer being below the first level.

When a buffer starts buffering a video stream, usually it will take some time to collect a minimal amount of video data that is sufficient to start video production. By temporarily reducing an output speed of the buffer until a first level of a fill rate of the buffer has been reached, this first level of the fill rate of the buffer will be reached more quickly, whereby a small delay will be introduced between the video stream and the video production. The fact that the first level of the fill rate of the buffer is reached more quickly will increase a user friendliness much, owing to the fact that faster zapping or surfing or hopping has become possible. The small delay may thereby be hardly noticed by a user. The temporarily reduced output speed of the buffer will result in a temporarily reduced playback video speed of the receiver, but during the zapping or surfing or hopping this will not be a problem either.

The controller may regulate the output speed of the buffer directly, by directly controlling or instructing the buffer, or indirectly, by controlling or instructing a video producing unit that retrieves the video data from the buffer.

A buffer has an input speed and an output speed. An input speed of a buffer is a speed at which data is inputted into the buffer. An output speed of a buffer is a speed at which data is outputted from the buffer.

US 2009 / 0089445 discloses client controlled adaptive streaming and describes in general how to keep a level of a fullness of a buffer constant. This is done by increasing an output speed for a too high level and by decreasing an output speed for a too low level. This could also be done, in case an input speed is reduced for example due to a network situation, by decreasing an output speed in response to a detection of a reduction of the input speed. US 2009 / 0089445 does not deal with buffering a video stream from a moment in time, which video stream has been started before this moment in time. An embodiment of the receiver is defined by the controller being arranged for detecting a second level of the fill rate of the buffer, the second level of the fill rate of the buffer being lower than the first level of the fill rate of the buffer, the output speed having a third value for the fill rate of the buffer being below the second level, the third value being smaller than the second value. This embodiment introduces reduced output speeds in dependence of levels of the fill rate of the buffer. More levels and more output speeds are not to be excluded.

An embodiment of the receiver is defined by the first value of the output speed being a normal output speed and the third value of the output speed being zero. This embodiment introduces a buffer that up to the second level of the fill rate of the buffer is filled most quickly owing to the fact that up to the second level of the fill rate of the buffer the output speed is zero.

An embodiment of the receiver is defined by the second value of the output speed being 0.01-0.99 of the normal output speed, preferably 0.50-0.99 of the normal output speed. Further preferably, the second value of the output speed may be 0.90-0.99 of the normal output speed.

An embodiment of the receiver is defined by the controller being further arranged for detecting first video information in the video stream and for in response to a video detection of the first video information activating said regulating. This embodiment introduces an output speed regulation that can be activated and deactivated in dependence of the first video information present in the video stream. For first kinds of video streams, the output speed regulation may be activated, and for second kinds of video streams, the output speed regulation may be deactivated.

An embodiment of the receiver is defined by the first video information indicating that at least one of a pausing mode, a fast forward mode, a fast reverse mode and a seeking mode is not allowed. When one or more modes including a pausing mode, a fast forward mode, a fast reverse mode or a seeking mode are not allowed, the video stream may be a live stream or a stream with broadcast content, in which case the output speed regulation should be activated.

An embodiment of the receiver is defined by the controller being further arranged for detecting second video information in the video stream, the second video information indicating a particular frame that does neither require a preceding frame nor a following frame for constructing a picture, and the controller being further arranged for detecting a third level of the fill rate of the buffer, the third level of the fill rate of the buffer being lower than the second level of the fill rate of the buffer, and the particular frame being present in the buffer when being filled up to the third level of the fill rate of the buffer.

Certain video streams comprise frames, such as I-frames that do neither require a preceding frame nor a following frame for constructing a picture, P-frames that need data from a previous frame for constructing a picture, and B-frames that need data from a previous and a following frame for constructing a picture.

WO 2008 / 055712 discloses a provision of internet protocol television multicasts and describes the above-defined frames. WO 2008 / 055712 does not deal with levels of a fill rate of a buffer.

An embodiment of the receiver is defined by the controller being further arranged for in response to a video detection of the second video information controlling a provision of the particular frame to a display for being displayed, and the controller being further arranged for deactivating a video production when the fill rate of the buffer is up to the second level and activating the video production when the fill rate of the buffer is above the second level. This embodiment introduces support for a user who is zapping or surfing or hopping through video streams by presenting an at first non-moving picture to this user. This picture is constructed from the particular frame that, as described before, does neither require a preceding frame nor a following frame for this construction. This embodiment further introduces a video production that can be activated and deactivated in dependence of the level of the fill rate of the buffer. As long as an output speed of a buffer is zero, a video production could be deactivated.

An embodiment of the receiver is defined by the controller being further arranged for reducing or deactivating or correcting an audio production when the fill rate of the buffer is below the first level and restoring or activating the audio production when the fill rate of the buffer is at or above the first level. This embodiment introduces, for a video stream that comprises video data as well as audio data, an audio production that can be restored or activated and that can be reduced or deactivated or corrected in dependence of the level of the fill rate of the buffer. For an output speed lower than a normal output speed of a buffer, an audio production may become disturbing to a user, owing to the fact that the temporarily reduced output speed of the buffer may result in a temporarily reduced playback audio speed of the receiver. In that case, (a volume of) an audio production may be reduced or deactivated, and/or a pitch of the audio production may be corrected.

An embodiment of the receiver is defined by the receiver being a universal plug and play device for receiving the video stream from a digital living network alliance server, the receiver comprising an interface for transmitting a hypertext transfer protocol command or a real time streaming protocol command to the digital living network alliance server.

An embodiment of the receiver is defined by the video stream being one out of several live streams or one out of several streams of broadcast content.

An embodiment of the receiver is defined by the receiver being arranged for zapping or surfing or hopping through the several live streams or the several streams of broadcast content.

According to a second aspect, a method is provided for receiving a video stream via a receiver comprising a buffer for buffering the video stream from a moment in time, a start of the video stream being situated before the moment in time, the method comprising

a step of detecting a first level of a fill rate of the buffer and in response to a level detection regulating an output speed of the buffer, the output speed having a first value for the fill rate of the buffer being at or above the first level and the output speed having a second value for the fill rate of the buffer being below the first level, the second value being smaller than the first value.

According to a third aspect, a computer program product is provided for performing the step of the method as defined above.

According to a fourth aspect, a medium is provided for storing and comprising the computer program product as defined above.

An insight could be that a first level of a fill rate of a buffer has to be reached as quickly as possible to allow faster zapping or surfing or hopping through video streams at moments in time, whereby starts of the video streams are situated before these moments in time.

A basic idea could be that an output speed of a buffer is to be regulated such that it has a first value for a fill rate of the buffer being at or above a first level and such that it has a second value smaller than the first value for the fill rate of the buffer being below the first level.

A problem to provide a receiver for receiving a video stream, which receiver is arranged for zapping or surfing or hopping through video streams in a user friendly way, has been solved.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Figure 1 shows a receiver,

Figure 2 shows a buffer with levels of a fill rate,

Figure 3 shows a receiver in the form of a set to box, and

Figure 4 shows a receiver as a part of a television.

DETAILED DESCRIPTION OF EMBODIMENTS

In the Fig. 1, a receiver 1 is shown. Examples of such a receiver 1 are set top boxes and tuner boxes and parts thereof, and televisions and display devices and parts thereof. The receiver 1 comprises an interface 11 for receiving a video stream from a server. The receiver 1 may for example be a universal plug and play device and the server may for example be a digital living network alliance server. The interface 11 may further be used for transmitting a hypertext transfer protocol command or a real time streaming protocol command to the digital living network alliance server. The video stream may for example be one out of several live streams or one out of several streams of broadcast content. The receiver 1 may for example be arranged for zapping or surfing or hopping through the several live streams or the several streams of broadcast content.

A data output of the interface 11 is coupled to a data input of a buffer 12, and a data output of the buffer 12 is coupled to a data input of a demultiplexer 13. A video data output of the demultiplexer 13 is coupled to a data input of a video decoder 14, and a data output of the video decoder 14 is coupled to a data input of a video processor 15. An audio data output of the demultiplexer 13 is coupled to a data input of an audio decoder 16, and a data output of the audio decoder 16 is coupled to a data input of an audio processor 17. Data outputs of the video processor 15 and the audio processor 17 are to be coupled to a television or a display device or a display-loudspeaker-combination not shown here.

The receiver 1 further comprises a controller 20 comprising a level detector 21, a regulator 22, a video detector 23 and a controlling processor 24 including a memory. The controlling processor 24 controls a bidirectional bus system that couples control inputs / outputs of the interface 11 and the buffer 12 and the demultiplexer 13 and the video decoder 14 and the video processor 15 and the audio decoder 16 and the audio processor 17 and the level detector 21 and the regulator 22 and the video detector 23 with each other. In the Fig. 2, a buffer 12 with levels of a fill rate is shown. The buffer 12 has a first level 31 of a fill rate, a second level 32 of the fill rate, and a third level 33 of the fill rate. The first level 31 is of the three levels 31-33 the highest level and may for example be equal to a 100% fill rate, the second level 32 is a lower level and the third level 33 is of the three levels 31-33 the lowest level and may for example be equal to a fill rate > 0%.

The receiver 1 functions as follows. The buffer 12 buffers the video stream from a certain moment in time, whereby a start of the video stream is situated before the certain moment in time. This is for example true for a video stream in the form of a live stream or a stream of broadcast content. The level detector 21 detects whether the first level 31 of the fill rate of the buffer 12 has been reached, and for example informs the controlling processor 24. The regulator 22, in response to a level detection, and for example in response to an instruction from the controlling processor 24, regulates an output speed of the buffer 12. This output speed has a first value for the fill rate of the buffer 12 being at or above the first level 31 and this output speed has a second and smaller value for the fill rate of the buffer 12 being below the first level 31.

So, at the certain moment in time, the buffer 12 is empty and starts buffering. Until the first level 31 of the fill rate of the buffer 12 has been reached, the output speed of the buffer 12 has the second value smaller than the first value. As soon as the first level 31 of the fill rate of the buffer 12 has been reached, the output speed of the buffer 12 is increased to the first value.

When the buffer 12 starts buffering the video stream, usually it will take some time to collect a minimal amount of video data that is sufficient to start video production. By temporarily reducing the output speed of the buffer 12 until the first level 31 of a fill rate of the buffer 12 has been reached, this first level 31 of the fill rate of the buffer 12 will be reached more quickly, whereby a small delay will be introduced between the video stream and the video production. The fact that the first level 31 of the fill rate of the buffer 12 is reached more quickly will increase a user friendliness much, owing to the fact that faster zapping or surfing or hopping has become possible. The small delay may thereby be hardly noticed by a user. The temporarily reduced output speed of the buffer 12 will result in a temporarily reduced playback video speed of the video decoder 14 and/or the video processor 15, but during the zapping or surfing or hopping this will not be a problem either.

The regulator 22 may regulate the output speed of the buffer 12 directly, by directly controlling or instructing the buffer 12 for example via the controlling processor 24, or indirectly, by controlling or instructing the video decoder 14 and/or the video processor 15 for example via the controlling processor 24, which video decoder 14 and/or video processor 15 retrieve the video data from the buffer 12 via the demultiplexer 13.

Preferably, the level detector 21 may be arranged for detecting a second level 32 of the fill rate of the buffer 12, which second level 32 of the fill rate of the buffer 12 is lower than the first level 31 of the fill rate of the buffer 12. The output speed has a third value smaller than the second value for the fill rate of the buffer 12 being below the second level 32. The first value of the output speed is for example a normal output speed and the third value of the output speed is for example zero. The second value of the output speed is for example 0.01-0.99 of the normal output speed, preferably 0.50-0.99 of the normal output speed, further preferably 0.90-0.99 of the normal output speed.

Preferably, the video detector 23 is used for detecting first video information in the video stream and for in response to a video detection of the first video information activating the regulator 22. This could for example be realized by letting the video detector 23 inform the controlling processor 24 and by sending an instruction from the controlling processor 24 to the regulator 22. The first video information indicates for example that at least one of a pausing mode, a fast forward mode, a fast reverse mode and a seeking mode is not allowed. When one or more modes including a pausing mode, a fast forward mode, a fast reverse mode or a seeking mode are not allowed, the video stream may be a live stream or a stream with broadcast content. In that case, the regulator 22 should advantageously be activated. For other kinds of video streams, such as video streams from a storage medium, the regulator 22 could be deactivated.

Preferably, the video detector 23 is further used for detecting second video information in the video stream. This second video information indicates a particular frame that does neither require a preceding frame nor a following frame for constructing a picture. The level detector 21 should then be arranged for detecting the third level 33 of the fill rate of the buffer 12, which third level 33 of the fill rate of the buffer 12 is lower than the second level 32 of the fill rate of the buffer 12. The third level 33 is chosen such that the particular frame will be present in the buffer 12 when being filled up to this third level 33 of the fill rate of the buffer 12.

Preferably, the video detector 23 is further used for in response to a video detection of the second video information controlling a provision of the particular frame to a display for being displayed. This could for example be realized by letting the video detector 23 inform the controlling processor 24 that in response retrieves the particular frame and supplies it to the display. The level detector 21 should then be arranged for deactivating the video decoder 14 and/or the video processor 15 when the fill rate of the buffer 12 is up to the second level 32 and activating the video decoder 14 and/or the video processor 15 when the fill rate of the buffer 12 is at or above the second level 32. This could for example be realized by letting the level detector 21 inform the controlling processor 24 that in response sends an instruction to the video decoder 14 and/or the video processor 15. This way, a user who is zapping or surfing or hopping through video streams is supported by getting a presentation of an at first non-moving picture. This picture is constructed from the particular frame that, as described before, does neither require a preceding frame nor a following frame for this construction.

Preferably, the level detector 21 is further arranged for reducing or deactivating or correcting the audio decoder 16 and/or the audio processor 17 when the fill rate of the buffer 12 is below the first level 31 and restoring or activating the audio production when the fill rate of the buffer 12 is at or above the first level 31. This could for example be realized by letting the level detector 21 inform the controlling processor 24 that in response sends an instruction to the audio decoder 16 and/or the audio processor 17. This way, for a video stream that comprises video data as well as audio data, the audio production can be restored or activated and can be reduced or deactivated or corrected in dependence of the level of the fill rate of the buffer 12. For an output speed lower than a normal output speed of the buffer 12, an audio production may become disturbing to a user, owing to the fact that the temporarily reduced output speed of the buffer 12 may result in a temporarily reduced playback audio speed of the audio decoder 16 and/or the audio processor 17. In that case, (a volume of) an audio production may be reduced or deactivated, and/or a pitch of the audio production may be corrected.

In the Fig. 3, a receiver 1 in the form of a set to box is shown, that is coupled via a video coupling and an audio coupling to a television 2.

In the Fig. 4, a receiver 1 is shown as a part of a television 2. The television 2 further comprises a display-loudspeaker-combination 3 coupled to the receiver 1 via a video coupling and an audio coupling.

Alternative structures are not to be excluded. For example, the bidirectional bus system could be replaced by two unidirectional bus systems whereby each control input / output is to be replaced by a control input and a control output. For example, each bus system could be replaced by a switch having a terminal per control input / output or a terminal per control input and per control output. For example, the level detector 21 could be replaced by a level detection function in the controlling processor 24 possibly in the form of software in its memory, the regulator 22 could be replaced by a regulation function in the controlling processor 24 possibly in the form of software in its memory, and the video detector 23 could be replaced by a video detection function in the controlling processor 24 possibly in the form of software in its memory.

Other levels and more kinds of levels are not to be excluded. Other output speeds and more output speeds are not to be excluded. Other receivers than universal plug and play devices are not to be excluded. Other servers than digital living network alliance server are not to be excluded. Other commands than hypertext transfer protocol commands and real time streaming protocol commands are not to be excluded. The controller may have any embodiment suitable for level detection, output speed regulation, video detection, video production (de)activation and audio production (de)activation etc.

Summarizing, receivers 1 for receiving live video streams comprise buffers 12 for buffering the live video streams, and controllers 20 for detecting first levels 31 of fill rates of the buffers 12 and for in response to level detections regulating output speeds of the buffers 12. The output speed has a first value for the fill rate being at or above the first level 31 and has a second value smaller than the first value for the fill rate being below the first level 31. The controller 20 may further detect a second level 32 of the fill rate lower than the first level 31 , whereby the output speed has a third value smaller than the second value for the fill rate being below the second level 32. The first value may be a normal output speed and the third value may be zero. The second value may be 0.01-0.99 of the normal output speed, preferably 0.50-0.99 of the normal output speed.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A receiver (1) for receiving a video stream, the receiver (1) comprising

a buffer (12) for buffering the video stream from a moment in time, a start of the video stream being situated before the moment in time, and

a controller (20) for detecting a first level (31) of a fill rate of the buffer (12) and for in response to a level detection regulating an output speed of the buffer (12), the output speed having a first value for the fill rate of the buffer (12) being at or above the first level (31) and the output speed having a second value for the fill rate of the buffer (12) being below the first level (31), the second value being smaller than the first value.

2. The receiver (1) as defined in the claim 1, the controller (20) being arranged for detecting a second level (32) of the fill rate of the buffer (12), the second level (32) of the fill rate of the buffer (12) being lower than the first level (31) of the fill rate of the buffer (12), the output speed having a third value for the fill rate of the buffer (12) being below the second level (32), the third value being smaller than the second value.

3. The receiver (1) as defined in the claim 2, the first value of the output speed being a normal output speed and the third value of the output speed being zero.

4. The receiver (1) as defined in the claim 3, the second value of the output speed being 0.01-0.99 of the normal output speed, preferably 0.50-0.99 of the normal output speed.

5. The receiver (1) as defined in the claim 2, the controller (20) being further arranged for detecting first video information in the video stream and for in response to a video detection of the first video information activating said regulating.

6. The receiver (1) as defined in the claim 5, the first video information indicating that at least one of a pausing mode, a fast forward mode, a fast reverse mode and a seeking mode is not allowed.

7. The receiver (1) as defined in the claim 5, the controller (20) being further arranged for detecting second video information in the video stream, the second video information indicating a particular frame that does neither require a preceding frame nor a following frame for constructing a picture, and the controller (20) being further arranged for detecting a third level (33) of the fill rate of the buffer (12), the third level (33) of the fill rate of the buffer (12) being lower than the second level (32) of the fill rate of the buffer (12), and the particular frame being present in the buffer (12) when being filled up to the third level (33) of the fill rate of the buffer (12).

8. The receiver (1) as defined in the claim 7, the controller (20) being further arranged for in response to a video detection of the second video information controlling a provision of the particular frame to a display for being displayed, and the controller (20) being further arranged for deactivating a video production when the fill rate of the buffer (12) is up to the second level (32) and activating the video production when the fill rate of the buffer (12) is above the second level (32).

9. The receiver (1) as defined in the claim 7, the controller (20) being further arranged for reducing or deactivating or correcting an audio production when the fill rate of the buffer (12) is below the first level (31) and restoring or activating the audio production when the fill rate of the buffer (12) is at or above the first level (31).

10. The receiver (1) as defined in the claim 1, the receiver (1) being a universal plug and play device for receiving the video stream from a digital living network alliance server, the receiver (1) comprising an interface (11) for transmitting a hypertext transfer protocol command or a real time streaming protocol command to the digital living network alliance server.

11. The receiver (1) as defined in the claim 1 , the video stream being one out of several live streams or one out of several streams of broadcast content.

12. The receiver (1) as defined in the claim 11, the receiver (1) being arranged for zapping or surfing or hopping through the several live streams or the several streams of broadcast content.

13. A method for receiving a video stream via a receiver (1) comprising a buffer (12) for buffering the video stream from a moment in time, a start of the video stream being situated before the moment in time, the method comprising

a step of detecting a first level (31) of a fill rate of the buffer (12) and in response to a level detection regulating an output speed of the buffer (12), the output speed having a first value for the fill rate of the buffer (12) being at or above the first level (31) and the output speed having a second value for the fill rate of the buffer (12) being below the first level (31), the second value being smaller than the first value.

14. A computer program product for performing the step of the method as defined in claim 13.

15. A medium for storing and comprising the computer program product as defined in claim 14.