WO2013017165A1

WO2013017165A1 - Shaping media traffic based on manifest file in http adaptive streaming

Info

Publication number: WO2013017165A1
Application number: PCT/EP2011/063300
Authority: WO
Inventors: Hans Bystrom; Paul Stallard
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2011-08-02
Filing date: 2011-08-02
Publication date: 2013-02-07

Abstract

There is provided a method in a communications network. The method comprises receiving a description file, said description file sent from a media provider to a device via the communications network. The description file describes media available for streaming from the media provider to the device. The method further comprises editing the description file to remove from the description file a reference to at least one version of media available for streaming. The method further still comprises sending the edited description file to the device.

Description

SHAPING MEDIA TRAFFIC BASED ON MANIFEST FILE IN HTTP ADAPTIVE

STREAMING

Technical field

The present application relates to a method in a communications network, a proxy in a communications network, and a computer-readable medium. The present application relates to media streaming in general, and more

particularly adaptive bitrate streaming. Examples are described in the context of HTTP Adaptive Bitrate Streaming. Background

HTTP Adaptive Bitrate Streaming (also known as Adaptive HTTP Streaming) is a technique used in streaming media over computer networks. While in the past most video streaming technologies utilized streaming protocols such as Real Time Streaming Protocol (RTSP) and Real-time Transport Protocol

(RTP), today's adaptive streaming technologies are almost exclusively based on HTTP and designed to work efficiently over large distributed HTTP

networks such as the Internet.

HTTP Adaptive Bitrate Streaming works by detecting both the available

bandwidth in a connection to a device and the processing capacity of the device. This information is then used to select the quality of a media stream to be streamed to the device. This requires the media stream to be available for streaming in multiple versions at multiple bit rates. The media playing client in the device switches between streaming the different versions

depending on available resources. HTTP Adaptive Bitrate Streaming is

generally accepted to provide media streaming with limited stalling, and fast start time, thus providing a good user experience with both devices using a high capacity connection and those using low capacity connections. Adaptive bitrate streaming is described in US patent number US 7,818,444 awarded to Move Networks, Inc. and which is incorporated herein by

reference. A problem with HTTP Adaptive Bitrate Streaming is that it relies on the media playing client in the device to request the best available stream from a media server. This is done Over-The-Top (OTT) and so does not involve any signaling with the communications network. That is, the communications network merely provides the connection to the device. As a result, HTTP Adaptive Bitrate Streaming may fill all available bandwidth in the connection to the device, which may impact upon other devices and services competing for the same network bandwidth. This is in particular a problem for wireless communications networks, but can also affect wired communications networks such as networks providing home broadband (often operated by Internet Service Providers).

Thus, there is a need for communications network operators to find ways to limit or control HTTP Adaptive Bitrate Streaming.

Products have been developed to address this problem. The "Vantrix

Bandwidth Optimizer" allows optimization of video streaming across all network conditions, as described in Vantrix Corporation's international patent application having publication number WO 2010/130023. The video encoding rate is modified on the fly, on each individual video session, by opening, decoding and then re-encoding each stream to a frame rate or bitrate most suitable for the network conditions at that particular point in time. As the quality of the connection deteriorates, Adaptive Streaming lowers the media encoding rate in real time and then smoothly increases it when conditions improve.

A disadvantage with solutions like Vantrix Bandwidth Optimizer is that it requires decoding and re-encoding of the video. These steps are

computationally intensive, requiring significant processor resources and limiting the scalability of this solution.

There is a need for an improved method and apparatus for shaping of media streaming traffic. Summary

Adaptive Bitrate Streaming works using a description file, sometimes referred to as a manifest, sent from the media server to the device in response to a request for a particular media sent from the device to the media server. The description file contains descriptions of each version of the particular media available for streaming from the media server. Both the request for media and the description file are carried by the communications network. A media playing client in the device reviews the content of the description file and selects a version for streaming.

According to the method and apparatus described herein, the communications network is able to influence the version selection made by the device by modifying the description file. As the description file is sent from the media server to the device via the communications network, the communications network intercepts this file and edits it. The description file is parsed by the communications network and references to undesirable versions of the media, (e.g. the high bitrate versions) are deleted from the description file. Because references to undesirable versions are removed from the description file, the device is not able to select these versions for streaming. The communications network is thus provided with a mechanism for influencing the bandwidth used for streaming media. This influence may be the determining of the maximum bitrate the device can use. An advantage of this approach is that no video decoding or re-encoding is required. Accordingly, there is provided a method in a communications network. The method comprises receiving a description file, said description file sent from a media provider to a device via the communications network. The description file describes media available for streaming from the media provider to the device. The method further comprises editing the description file to remove from the description file a reference to at least one version of media available for streaming. The method further comprises sending the edited description file to the device. By allowing the communications network to modify the description file, the communications network is able to control how much network bandwidth is used for media streaming. This means that the communications network can ensure that as many devices as possible can obtain a good communication service.

The media available for streaming may comprise at least two different versions of a piece of content. The different versions may comprise at least two different bitrate versions. The different versions may comprise at least two different formats. The description file may comprise a manifest of media available for streaming from the media provider to the device. The description file may be a manifest file. The manifest file may be for adaptive streaming.

A description of at least the highest bit rate version may be removed from the description file. At least one description of versions of the media in a particular format may be removed from the description file. The media format may be defined by a codec and/or a container. The particular format may be unsuitable for the device. The particular format may be an inefficient use of bandwidth or exceed the bandwidth available for delivery to the device. The particular format may not be in line with network provider policies.

The editing of the description file may comprise removing from the description file the references having a bit rate greater than a threshold value. The threshold value may be determined based upon at least one of a measure of available communications network bandwidth; the capabilities of the device; and a quality of service associated with the device. The measure of available communications network bandwidth may be provided by: a policy controller measuring available capacity; and/or a subscriber management system determining the device's subscription tier.

The processing power of the device and the screen resolution of the device may be used to determine which references are removed from the description file. The capabilities of the device may be determined using IMEI

(International Mobile Equipment Identity) or TAC (Type Allocation Code) from the communications network, or by using UAProf (User Agent Profile) form a browser in the device. The quality of service may be associated with the device may be determined by a subscription tier of a subscription associated with the device.

The description file may be a manifest for HTTP adaptive bitrate streaming. The description file may be sent by the media provider to the device in response to a media request sent from the device to the media provider via the communications network.

The method may further comprise receiving a selection message from the device, the selection message sent towards the media provider and indicating a selection of a version of the media indicated in the edited description file. There is further provided a proxy in a communications network. The proxy is arranged to receive a description file, said description file sent from a media provider to a device via the communications network. The description file describes media available for streaming from the media provider to the device. The proxy is further arranged to edit the description file to remove from the description file a reference to at least one version of media available for streaming. The proxy is further arranged to send the edited description file to the device.

By allowing a proxy in the communications network to modify the description file, the communications network is able to control how much network bandwidth is used for media streaming. This means that the communications network can ensure that as many devices as possible can obtain a good communication service. The proxy may be a node in the communications network.

A description of at least the highest bit rate version of the media may be removed from the description file. The proxy may be arranged to edit the description file by removing from the description file the references having a bit rate greater than a threshold value. The proxy may be further arranged to determine the threshold value based upon at least one of: a measure of available communications network bandwidth; the capabilities of the device; and a quality of service associated with the device.

The description file may be a manifest for HTTP adaptive bitrate streaming. The description file may be sent by the media provider to the device in response to a media request sent from the device to the media provider via the wireless communications network.

The proxy may be further arranged to receive a selection message from the device, the selection message sent towards the media provider and indicating a selection of a version of the media indicated in the edited description file.

The communications network may be a wireless communications network. The device may be a wireless communications device.

There is further provided a computer-readable medium, carrying instructions, which, when executed by computer logic, causes said computer logic to carry out any of the methods defined herein.

Brief description of the drawings

Methods and apparatus for shaping media streaming traffic will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a signaling diagram illustrating the initiation of HTTP Adaptive Bitrate Streaming according to a known method;

Figure 2 shows a signaling diagram illustrating the initiation of HTTP Adaptive Bitrate Streaming according to the method disclosed herein;

Figure 3 illustrates a manifest before editing and the same manifest after editing;

Figure 4 illustrates an application of the method described herein to a wireless communications network; Figure 5 is a flow diagram illustrating a method disclosed herein; and Figure 6 is a flow diagram illustrating an alternative method disclosed herein. Detailed description

Figure 1 shows a signaling diagram illustrating the initiation of HTTP Adaptive Bitrate Streaming according to a known method. A device 1 10 communicates via a communications network 120 with a media provider 130. At 101 and 102, the device 1 10 sends a media request to the media provider 130 via the communications network 120. In reply, at 103 and 105, the media provider 130 sends a manifest to the device 1 10 via the communications network 120. The manifest is a text description of the media content files associated with the requested media. Depending on implementation the manifest may be a separate file, or inserted in a defined section of the video content asset file. The device 1 10 uses the information in the manifest to learn what bitrate versions are available and how it can obtain them. The device 1 10 selects a version from the manifest and sends this version selection to the media provider, again via the communications network 120, at 106 and 107. Upon receipt of the version selection, the media provider 130 begins delivery of the selected media version, via the communications network 120, at 108 and 109.

Figure 2 shows a signaling diagram illustrating the initiation of HTTP Adaptive Bitrate Streaming according to the method disclosed herein. This method is very similar to that of Figure 1 , except that here a proxy is placed in the communications network 120, which handles the communications between the device 1 10 and the media provider 130. The proxy is a transparent proxy with content inspection and modification capabilities.

As shown in Figure 2, a media request is sent from the device 1 10 to the media provider 130 at 101 and 102. At 103 the media provider 130 sends a manifest towards the device 1 10, in response to the media request. This manifest is sent 103 via the communications network 120 and is intercepted by the proxy therein. In the proxy, at 204 the manifest is parsed and, in this example, the

information that relates to the media versions whose bitrates exceed the desired limit of the network provider is removed. At 205, the edited manifest is then delivered by the communications network 120 to the device 1 10.

Version selection (106, 107) and media delivery (108, 109) proceed as described above in relation to figure 1 .

In this way, the high bitrate versions of the media become invisible to the device 1 10, and so are not used. This means that the bandwidth consumed by the media stream is limited by the communications network. Furthermore, this is done without media decoding or re-encoding. Parsing and modification of the text information in the manifest can be implemented much more efficiently in comparison with video decoding and re-encoding. Figure 3 illustrates how a manifest is edited, showing a logical illustration of a manifest before editing 340 and a logical illustration of the same manifest after editing 350. Manifest 340 relates to particular media 310. According to the known method illustrated in Figure 1 , manifest 340 would be sent to a device 1 10 by a media provider 130 in response to a request for media 310.

Manifest 340 comprises a description of the different versions of media 310 that are available from the media provider 130. In this example, four versions are available: version 31 1 encoded at a bitrate of 4 Mbps (megabits per second), version 312 encoded at 3 Mbps, version 313 encoded at 2 Mbps, and version 314 encoded at 1 .5 Mbps. Descriptions of each of these four versions are contained in manifest 340.

In practice, it is likely that each version of the media will comprise a plurality of segments, each of which must be downloaded, decoded and played by the media playing client in the device 1 10 in sequence. In such a situation, the manifest comprises a list of references to each segment of each version, such that once the media playing client has selected a version of the media it can request the appropriate segments of the media version in the appropriate sequence, i.e. starting at the beginning. Further, live content may be streamed using adaptive streaming. The main principles of the adaptive streaming are the same, but with live content the content provider frequently sends updated manifest files describing the new chunks as they are created. The entire manifest for the live stream cannot exist when streaming begins as the chunks do not yet exist, and further the total number of chunks may be unknown or even infinite. The manifest editing described above may be applied to such live streaming. For the application of the method disclosed herein to live streaming, the manifest is edited each time an updated manifest is sent from the media provider 130 to the device 1 10. This means that where the manifest is edited according to the network conditions, then a current manifest may be edited differently to a preceding manifest if the network conditions have changed since the preceding manifest was edited. As shown in figure 3, an edit operation 304 is performed on manifest 340 to create manifest 350. In this example, the communications network has set a threshold bitrate for media streaming at 3.2 Mbps, and so references to versions of media with a bitrate greater than this are removed from the manifest by the editing operation 304. Therefore, manifest 350 resulting from the editing operation 304 has had references to version 31 1 removed, because version 31 1 has an encode bitrate of 4 Mbps, which is greater than the 3.2 Mbps threshold value.

Figure 4 illustrates an application of the method described herein to a wireless communications network. A wireless communications device 410

communicates with a media provider 430 via a wireless communications network 420 (which includes a proxy 425) and the internet 435. The wireless communications network 420 provides a connection between the wireless communications device 410 and the internet 435. The media provider 430 is connected to the internet 435. When the wireless communications network 420 is providing communications services to a large number of devices, the bandwidth available to each device is limited. However, when adaptive bitrate media streaming is negotiated between the device 410 and the media provider 430 in the conventional way, the status of the wireless communications network 420 is not taken into account. This can impact negatively on services other than media streaming that are provided by the communications network. By applying the method disclosed herein, the wireless communications network 420 is able to limit the bandwidth any one device 410 takes up for media streaming, ensuring, for example: that bandwidth is evenly distributed between devices connected to it; that certain subscribers are given higher bitrate services; or that media streaming does not negatively impact other services carried by the network such as voice over IP.

Figure 5 is a flow diagram illustrating a method disclosed herein and performed in a proxy of a communications network 120. At 510 a description file is received. The description file is sent from a media provider 130 to a device 1 10 via the communications network 120. The description file describes media available for streaming from the media provider 130 to the device 1 10. At 530 the description file is edited to remove from the

description file a reference to at least one version of media available for streaming. At 540 the edited description file is sent to the device 1 10.

Figure 6 is a flow diagram illustrating an alternative method disclosed herein and also performed in a proxy of a communications network 120. At 610 a description file is received. The description file is sent from a media provider 130 to a device 1 10 via the communications network 120. The description file describes media available for streaming from the media provider 130 to the device 1 10. At 620 a threshold bitrate is determined based upon at least one measure of available communications network bandwidth. The measure of available communications network bandwidth is provided by a policy controller measuring available network capacity. At 630 the description file is edited to remove from the description file references to media versions having a bitrate greater than a threshold value. At 640 the edited description file is sent to the device 1 10. Because parsing and modification of the text information in the manifest can be implemented much more efficiently in comparison with video decoding and re-encoding, the method and apparatus disclosed herein provides a simple and cost efficient way for a communications network to perform shaping of media streaming traffic. Further, any content version sent to the user is one that is made available by the content provider, and so must be acceptable to the content provider. Further still, the disclosed method can operate with encrypted media streams, provided the manifest file is not encrypted. In the above example the policy controller provides a measure of available communications network bandwidth. In alternatives, the policy controller may receive a measure of available communications network bandwidth from another node in the communications network. In a further alternative, an available network bandwidth measurement is made by the proxy 425, and the proxy 425 makes a determination of the threshold bitrate.

Further, the threshold bitrate for a device may be determined by factors other than the available communications network bandwidth. For example, factors affecting the threshold bitrate may include: the subscription type of an account associated with the device; the status of an account associated with the device; whether the device is roaming; time of day; and/or geographic location.

A media playing client in the device 1 10 selects which media version to stream from the media provider 130. The media playing client should take into account the capabilities of the device when making this selection. For example, the media playing client should select a version of the media having a pixel resolution less than or equal to the number of pixels on the display of the device 1 10. Streaming media having a pixel resolution greater than that which will be displayed is a waste of bandwidth. However, media playing clients have been identified which do not appropriately take such

considerations into account. Such media player clients may simply select the highest bitrate version the communication connection can support. Such a poor selection not only results in a waste of network bandwidth, but also can impact upon the operation of the device 1 10. Streaming a higher bandwidth version of media than is needed will take more processing for both receipt of the communication, for decoding and for downsampling. This results in increased power consumption, and reduced battery life for a battery powered device. The editing of the description file as described herein may be used to remove references to such inappropriate choices, forcing the client to select an appropriate version. For example, in order to most effectively use available battery power in a wireless communications device, a desirable traffic pattern for media streaming over a wireless communications network is to use continuous bursts of data with durations of 10 seconds or more, with idle periods in between. To achieve this, the available bandwidth needs to be significantly higher than media bitrate. It is common for adaptive bitrate streaming algorithms in existing media playing clients to not consider this trade off. Such clients simply try to use the highest bitrate possible. So in the case of a smartphone connecting to a content provider with high bitrates available (e.g. intended for playback on a living room TV), the media playing client will select the highest bitrate media version even if this is far more than is needed on the small smartphone screen. This may result in the radio bearer of the smartphone being continuously active and so the battery will be drained quickly. Accordingly, the shaping of media streaming traffic as disclosed herein may also be advantageous to the user of a smartphone in addition to the benefit to the operator of a wireless communications network.

Different media versions available from a streaming server may be encoded using different codecs. Some codecs are more efficient than others. The editing of the description file (or manifest) described herein may take this into account. The editing operation may include removing references to media versions encoded using one or more inefficient codecs, leaving references to media versions that will provide an improved balance between media quality and bandwidth usage. It will be apparent to the skilled person that the exact order and content of the actions carried out in the method described herein may be altered according to the requirements of a particular set of execution parameters. Accordingly, the order in which actions are described and/or claimed is not to be construed as a strict limitation on order in which actions are to be performed.

While examples have been given in the context of HTTP Adaptive Streaming, these examples are not intended to be the limit of streaming system to which the disclosed method and apparatus may be applied. The principles disclosed herein can be applied to any streaming system which uses a description file. For example, this method and apparatus may be applied to Apple™ HTTP Live Streaming, and Microsoft™ Smooth Streaming.

Further, while examples have been given in the context of a particular communications network, these examples are not intended to be the limit of the communications networks to which the disclosed method and apparatus may be applied. The principles disclosed herein can be applied to any communications network which carries media using adaptive bitrate streaming.

Claims

1 . A method in a communications network, the method comprising:

receiving a description file, said description file sent from a media provider to a device via the communications network, said description file describing media available for streaming from the media provider to the device;

editing the description file to remove from the description file a reference to at least one version of media available for streaming; and

sending the edited description file to the device.

2. The method of claim 1 , wherein a description of at least the highest bit rate version is removed from the description file.

3. The method of claim 1 , wherein the editing of the description file comprises removing from the description file the references having a bit rate greater than a threshold value.

4. The method of claim 3, further comprising determining the threshold value based upon at least one of a measure of available communications network bandwidth; the capabilities of the device; and a quality of service associated with the device.

5. The method of any preceding claim, wherein the description file is a manifest for HTTP adaptive bitrate streaming.

6. The method of any preceding claim, wherein the description file is sent by the media provider to the device in response to a media request sent from the device to the media provider via the communications network.

7. The method of any preceding claim, further comprising receiving a selection message from the device, the selection message sent towards the media provider and indicating a selection of a version of the media indicated in the edited description file.

8. The method of any preceding claim wherein the communications network is a wireless communications network and the device is a wireless communications device.

9. A proxy in a communications network, the proxy arranged to:

receive a description file, said description file sent from a media provider to a device via the communications network, said description file describing media available for streaming from the media provider to the device;

edit the description file to remove from the description file a reference to at least one version of media available for streaming; and

send the edited description file to the device.

10. The proxy of claim 9, wherein a description of at least the highest bit rate version of the media is removed from the description file.

1 1 . The proxy of claim 9, wherein the proxy is arranged to edit the description file by removing from the description file the references having a bit rate greater than a threshold value.

12. The proxy of claim 1 1 , further arranged to determine the threshold value based upon at least one of: a measure of available communications network bandwidth; the capabilities of the device; and a quality of service associated with the device.

13. The proxy of any of claims 9 to 12, wherein the description file is a manifest for HTTP adaptive bitrate streaming.

14. The proxy of any of claims 9 to 13, wherein the description file is sent by the media provider to the device in response to a media request sent from the device to the media provider via the communications network.

15. The proxy of any of claims 9 to 14, the proxy further arranged to receive a selection message from the device, the selection message sent towards the media provider and indicating a selection of a version of the media indicated in the edited description file.

16. The proxy of any of claims 9 to 15, wherein the communications network is a wireless communications network and the device is a wireless communications device.

17. A computer-readable medium, carrying instructions, which, when executed by computer logic, causes said computer logic to carry out any of the methods defined by claims 1 to 8.