WEARABLE CAMERA AND METHOD FOR OPTIMIZING POWER CONSUMPTION IN A WEARABLE CAMERA - Patent application

Abstract

To provide a wearable camera and a method for power consumption optimization in the wearable camera.SOLUTION: A method for power consumption optimization in a wearable camera 100 comprises the steps of: monitoring bitrate of a video stream captured by the wearable camera 100; upon the bitrate being above a first bitrate threshold, activating a movement sensor 130 of the wearable camera 100; upon activation of the movement sensor 130, analyzing whether the activation of the movement sensor 130 is beneficial for reducing the bitrate; and in a case activation of the movement sensor 130 is beneficial for reducing the bitrate, keeping the movement sensor 130 active and performing image stabilization on the basis of movement data from the movement sensor 130, otherwise, deactivating the movement sensor 130.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to optimizing power consumption in wearable cameras. [Background technology]

[0002] Wearable cameras are used, for example, by police officers to capture video and other data during patrols and incidents. Such cameras can also be called body worn cameras (BWCs). Wearable cameras are typically battery powered. Thus, there is a limit to the power available for wearable cameras. Therefore, optimizing power consumption in wearable cameras is desirable. Summary of the Invention

[0003] It is an object of the present invention to facilitate battery power conservation in a wearable camera.It is a further object of the present invention to facilitate bitrate conservation for video streams generated by a wearable camera.

[0004] According to a first aspect, a method for power consumption optimization in a wearable camera is provided. The method includes: monitoring a bit rate of a video stream captured by the wearable camera; activating a motion sensor of the wearable camera when the bit rate exceeds a first bit rate threshold; analyzing whether activation of the motion sensor is favorable to reduce the bit rate when the motion sensor is activated; and if activation of the motion sensor is favorable to reduce the bit rate, keeping the motion sensor active and performing image stabilization based on motion data from the motion sensor, otherwise stopping the motion sensor.

[0005] Power consumption in the wearable camera can be saved by only putting the motion sensor of the wearable camera into active mode when the motion data measured by the motion sensor is needed for other functions of the wearable camera, such as image stabilization. Thus, the operation time of the wearable camera can be extended. Similarly, optimization of power consumption with respect to the bit rate of the video stream can be provided. Thus, battery power can be used in a bit rate optimization manner. If bit rate savings are available when activating the motion sensor, the motion sensor can be kept active to provide motion data to perform bit rate savings, image stabilization.

[0006] The method may further include activating image stabilization of the video stream based on the motion data from the motion sensor. Analyzing whether activation of the motion sensor is advantageous to reduce the bit rate may include analyzing the bit rate of the video stream after image stabilization of the video stream is activated. Activation of the motion sensor may be advantageous to reduce the bit rate if the bit rate of the video stream after image stabilization of the video stream is lower than a second bit rate threshold. The second threshold may be ≦90% of the first bit rate threshold. Depending on the scene and the pattern of motion, an acceptable saving in bit rate due to image stabilization based on the motion data may be about 10%-50%. Thus, if image stabilization reduces the bit rate of the video stream by a value greater than 10%, activation of the motion sensor is advantageous and the motion sensor and image stabilization should be kept active. Otherwise, activation of the motion sensor is not advantageous and power consumption may be saved by stopping the motion sensor and / or image stabilization. Keeping the motion sensor and image stabilization active may provide an optimization of bit rate usage versus battery power usage. Thus, battery power can be used to reduce the bit rate of the video stream.

[0007] The first bit rate threshold can be dependent on a current state of charge of the wearable camera's battery. The second bit rate threshold can be dependent on a current state of charge of the wearable camera's battery. Thus, the first and / or second bit rate thresholds can be dynamically set such that if the battery's state of charge gets too low, the remaining state of charge is not spent on activating the motion sensor and possibly image stabilization as well.

[0008] The first bit rate threshold may be dependent on the available storage space in the local data storage of the wearable camera. The second bit rate threshold may be dependent on the available storage space in the local data storage of the wearable camera. Thus, the first and / or second bit rate threshold may be dynamically set so that when the recording of the video stream takes up an unexpectedly large amount of space, for example due to a large amount of noise, the available storage space may be saved by more easily activating the image stabilization based on the motion data.

[0009] Analyzing whether activation of the motion sensor is advantageous to reduce the bit rate can include analyzing motion data from the motion sensor. Activation of the motion sensor can be advantageous to reduce the bit rate if the motion data indicates that the wearable camera is shaking. The shaking of the wearable camera can be due to a person wearing the wearable camera taking a deep breath, for example, after running. By shaking the wearable camera, in this context, it is meant that the wearable camera is vibrating. For the wearable camera to shake, the vibration is preferably periodic. Furthermore, for the wearable camera to shake, the vibration preferably has an amplitude that exceeds a shaking threshold. Typically, if the wearable camera shakes, activation of image stabilization based on the motion data will reduce the bit rate, and therefore the motion sensor and image stabilization should be kept active to reduce the bit rate. Otherwise, activation of the motion sensor is not advantageous and power consumption can be saved by stopping the motion sensor and / or image stabilization. Keeping the motion sensor and image stabilization active can provide an optimization of bit rate usage versus battery power usage. Thus, battery power can be used to reduce the bit rate of the video stream.

[0010] Alternatively or in combination, activation of the motion sensor may be advantageous to reduce the bit rate when the motion data indicates that the wearable camera is co-located. By the wearable camera is co-located, in this context, it is meant that the wearable camera is not moving in a main direction. Motion in a main direction may be, for example, that the person wearing the wearable camera is walking or running. According to the inventor's experience, in the case of motion in a main direction, image stabilization is not as effective, and the motion sensor and likewise the image stabilization may be stopped to save battery power.

[0011] The method may further include keeping the motion sensor and image stabilization of the video stream active for a predetermined period of time before again performing the step of analyzing whether activation of the motion sensor is advantageous to reduce the bit rate. Thus, processing power may be conserved by having to perform the step of analyzing less frequently.

[0012] The method can include keeping the motion sensor and image stabilization of the video stream active until the motion data indicates a steady wearable camera. In this context, a steady wearable camera means that the motion data indicates that the motion of the wearable camera, typically vibration motion, is below a threshold. Thus, the wearable camera is no longer shaking. In the case of a steady camera, the motion sensor and image stabilization can be stopped since image stabilization will not provide bitrate reduction. Stopping the motion sensor and image stabilization will induce battery power conservation.

[0013] The method may include storing the video stream in local data storage of the wearable camera.The method may include transmitting the video stream from the wearable camera.

[0014] According to a second aspect, a non-transitory computer-readable recording medium is provided. The non-transitory computer-readable recording medium has instructions, possibly in the form of computer-readable program code, stored thereon, which are configured to perform the method of the first aspect when executed on a device having processing capabilities. The device having processing capabilities can be a wearable camera, for example a body-worn camera or a dash cam.

[0015] The above-mentioned features of the method according to the first aspect also apply to the second aspect, where applicable, and in order to avoid undue repetition, reference is made thereto.

[0016] According to a third aspect, a wearable camera is provided. The wearable camera includes an image sensor configured to capture image data; an encoder configured to encode the image data into a video stream; a motion sensor configured to measure motion data of the wearable camera, the motion sensor configured to be set to an active mode or an inactive mode; a battery configured to power the wearable camera; and a circuit. The circuit is configured to perform a bit rate monitoring function configured to monitor a bit rate of the video stream, an image stabilization function configured to image stabilize the image data based on the motion data from the motion sensor, a sensor mode setting function configured to set the motion sensor to an active mode when the bit rate exceeds a first bit rate threshold, and an analysis function configured to analyze whether activation of the motion sensor is advantageous to reduce the bit rate when the motion sensor is activated. The analysis function is further configured to instruct the sensor mode setting function to keep the motion sensor in the active mode and instruct the image stabilization function to perform image stabilization if activation of the motion sensor is advantageous to reduce the bit rate, and to instruct the sensor mode setting function to set the motion sensor to an inactive mode otherwise.

[0017] The analysis function may be configured to analyze whether activation of the motion sensor is advantageous for reducing the bit rate by analyzing a bit rate of the video stream after image stabilization by the image stabilization function. Activation of the motion sensor may be advantageous for reducing the bit rate if the bit rate of the video stream after image stabilization is lower than a second bit rate threshold. The second threshold may be ≦90% of the first bit rate threshold.

[0018] The analysis function can be configured to analyze whether activation of a motion sensor is advantageous to reduce the bit rate by analyzing the motion data. Activation of a motion sensor can be advantageous to reduce the bit rate if the motion data indicates that the wearable camera is shaking and / or that the wearable camera is located in the same place.

[0019] The wearable camera may further comprise a local data storage configured to store the video stream.The wearable camera may further comprise a transmitter configured to wirelessly transmit the video stream.

[0020] Furthermore, the above-mentioned features of the method according to the first aspect also apply to the third aspect, where applicable. In order to avoid undue repetition, reference is made thereto.

[0021] Further scope of applicability of the present disclosure will become apparent from the detailed description set forth hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

[0022] Thus, it is understood that the invention is not limited to the specific component parts of the described device or the specific operations of the described method, since such devices and methods may vary. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It should be noted that, as used in this specification and the appended claims, the articles "a," "an," "the," "said" are intended to mean that there are one or more of an element, unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" can include several devices and the like. Furthermore, the words "comprising," "including," "containing," and similar words do not exclude other elements or steps.

[0023] The above and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which: The drawings should not be considered limiting; instead, the drawings are used to illustrate and understand.

[0024] As shown in the figures, the sizes of layers and regions may be exaggerated for illustrative purposes, and thus are provided to illustrate the overall structure, with like reference numbers referring to like elements throughout. [Brief description of the drawings]

[0025] [Figure 1] 1 shows a schematic block diagram of a wearable camera. [Diagram 2] 1 is a block scheme of a method for optimizing power consumption in a wearable camera. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the invention to those skilled in the art.

[0027] FIG. 1 shows a wearable camera 100. The wearable camera 100 may be a body-worn camera BWC. The wearable camera 100 may be a dash cam. The wearable camera 100 may be used, for example, by police officers to capture video and possibly other data during patrols and incidents. The captured data may then be required as evidence, for example, when investigating crimes and prosecuting suspected perpetrators. To store the captured data, a data management system external to the wearable camera 100, such as a video management system or an evidence management system, may be used. Such data management systems generally provide storage of the captured data as well as viewing of the captured data in real time or as playback of recorded data. Typically, the wearable camera 100 is battery powered and has a limited bit rate. The limited bit rate is due to local data storage limitations for the data management system and / or bandwidth limitations for wireless connections. The wearable camera 100 includes an image sensor 110, an encoder 120, a motion sensor 130, a battery 140, circuitry 150, and memory 160.

[0028] Battery 140 is configured to power wearable camera 100, i.e., components of the wearable camera that require power. Battery 140 may be a rechargeable battery.

[0029] The image sensor 110 is configured to capture image data. The image data may be, for example, image frame data. Image sensors and the capture of image data are well known to those skilled in the art and will not be discussed in greater detail in this disclosure.

[0030] The encoder 120 is configured to encode the image data captured by the image sensor 110 into a video stream, and sometimes the video stream provided by the encoder 120 is referred to as an encoded video stream. Typically, the video encoder 120 is configured to encode some of the image frames of the video stream as key frames and some of the image frames of the video stream as delta frames. A key frame is an encoded video frame that does not require information from other encoded video frames to be decoded. Thus, a key frame is encoded based on information from an image frame of the video data to which the key frame is set to correspond. Typically, similarities within an image frame are used to encode an image frame into a key frame. In video encoding, a key frame is also known as an intra frame, often called an I frame. The image frames of the video stream between two key frames are encoded as delta frames. Typically, a delta frame only contains the changes that occur from one frame to the next. Thus, a delta frame typically contains less data than a key frame. In video encoding, a delta frame is also known as an inter frame, often called a P frame or a B frame. P frames point to the previous frame for data reference. Therefore, the content of the previous frame must be known to decode the P frame. B frames can point to both the previous and forward frames for data reference. Therefore, the content of both the previous and forward frames must be known to decode the B frame.

[0031] Wearable camera 100 may further comprise local data storage 170. Local data storage 170 may be configured to store the video stream. The local data storage typically has a limited data storage capacity. Local data storage 170 may be any type of local data storage suitable for storing the video stream. For example, local data storage 170 may be in the form of an SD card reader and an SD card. Another example of local data storage 170 may be in the form of a flash memory, e.g., a NAND flash.

[0032] In order to transmit video data, e.g., a video stream, stored locally on wearable camera 100 to a data management system, wearable camera 100 can be configured to be docked into a docking station. When docked into the docking station, the locally stored video data can be transmitted from wearable camera 100 to the data management system. Additionally, when docked into the docking station, the battery of wearable camera 100 can be charged.

[0033] The wearable camera 100 may further comprise a transmitter 180. The transmitter 180 may be configured to wirelessly transmit the video stream to the data management system. The transmitter 180 may be configured to continuously transmit the captured video stream to the data management system. The wireless transmission is typically limited by the bandwidth available for wireless transmission.

[0034] The motion sensor 130 is configured to measure motion data of the wearable device. The motion sensor 130 may comprise a gyroscope and / or an accelerometer. The gyroscope is configured to measure the motion data in the form of orientation and / or angular velocity of the wearable camera 100. The accelerometer is configured to measure the motion data in the form of acceleration (or velocity rate) of the wearable camera 100 in its own instantaneous still frame. The motion sensor 130 is configured to sample the motion data as a function of time. The motion sensor 130 can be set to an active mode or an inactive mode. Thus, at a particular moment, the motion sensor 130 is active or inactive. In the active mode, the motion sensor 130 is measuring motion data. In the active mode, the motion sensor 130 is consuming power from the battery 140. In the inactive mode, the motion sensor 130 is not measuring motion data. In the inactive mode, the motion sensor 130 is consuming no power or very limited power from the battery 140. Thus, in the active mode, the motion sensor 130 draws significantly more power from the battery 140 than in the inactive mode.

[0035] Circuitry 150 is configured to implement the overall functionality of wearable camera 100. Circuitry 150 may include a processor 152, such as a central processing unit (CPU), a microcontroller, or a microprocessor. Processor 152 is configured to execute program code stored in memory 160 to implement the functionality of wearable camera 100.

[0036] The memory 160 can be one or more of a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, a random access memory (RAM), or other suitable devices. In a typical arrangement, the memory 160 can include non-volatile memory for long-term data storage and volatile memory that serves as system memory for the circuit 150. The memory 160 can exchange data with the circuit 150 through a data bus. There can also be associated control lines and an address bus between the memory 160 and the circuit 150.

[0037] The functionality of wearable camera 100 may be embodied in executable logic routines (e.g., lines of code, software programs, etc.) stored on a non-transitory computer-readable medium (e.g., memory 160) of wearable camera 100 and executed by circuitry 150 (e.g., using processor 152). Furthermore, the functionality of wearable camera 100 may be a standalone software application or form part of a software application that performs further tasks related to wearable camera 100. The described functionality may be considered as the way in which a processing unit of circuitry 150, e.g., processor 152, is configured to execute it. Similarly, while the described functionality may be implemented in software, such functionality may also be performed by dedicated hardware or firmware, or some combination of hardware, firmware, and / or software.

[0038] The circuit 150 may be configured to perform a bitrate monitoring function 421. The bitrate monitoring function 421 is configured to monitor the bitrate of the video stream encoded by the encoder 120.

[0039] The circuit 150 can be configured to perform an image stabilization function 422. The image stabilization function 422 is configured to image stabilize the video data captured by the wearable camera 100 based on the motion data from the motion sensor 130 in the active mode. Thus, the image stabilization function 422 relies on the motion data from the motion sensor 130 as input data for performing the image stabilization. The image stabilization function 422 can be set to an active mode or an inactive mode. Thus, at a particular moment, the image stabilization function 422 is active or inactive. In the active mode, the image stabilization function 422 is performing image stabilization of the video data captured by the wearable camera 100. In the active mode, the image stabilization function 422 is consuming power from the battery 140. In the inactive mode, the image stabilization function 422 is not performing image stabilization of the video data captured by the wearable camera 100. In the inactive mode, the image stabilization function 422 is consuming no power or very limited power from the battery 140. Thus, in the active mode, the image stabilization function 422 consumes significantly more power from the battery 140 than in the inactive mode.

[0040] The circuit 150 can be configured to execute a sensor mode setting function 423. The sensor mode setting function 423 is configured to set the motion sensor 130 to an active mode or an inactive mode. In particular, the sensor mode setting function 423 can be configured to set the motion sensor 130 to an active mode when the bit rate exceeds a first bit rate threshold. The first bit rate threshold can be a preset threshold. The first bit rate threshold can be dependent on the current charge state of the wearable camera 100 battery 140. Thus, the first bit rate threshold can be dynamically set so that if the charge state of the battery 140 becomes too low, the remaining charge state is not spent on activating the motion sensor and possibly image stabilization as well. Alternatively, the first bit rate threshold can be dependent on the available storage space in the local data storage 170. Thus, the first bit rate threshold can be dynamically set so that if the recording of the video stream takes up an unexpectedly large space, for example due to a large noise, the available storage space can be saved by more easily activating the image stabilization based on the motion data.

[0041] The circuit 150 can be configured to perform an analysis function 424. The analysis function 424 is configured to analyze whether activation of the motion sensor 130 is advantageous for reducing the bit rate. Thus, the analysis function 424 is configured to be performed when the motion sensor 130 is activated. The analysis function 424 can be configured to analyze whether activation of the motion sensor 130 is advantageous for reducing the bit rate in various ways.

[0042] The analysis function 424 may be configured to analyze whether activation of the motion sensor 130 is advantageous to reduce the bit rate by analyzing the bit rate of the video stream after the image stabilization by the image stabilization function 422 is performed, and thus analyzes the bit rate of the video stream after the image stabilization by the image stabilization function 422 is activated. Activation of the motion sensor 130 may be advantageous to reduce the bit rate if the bit rate of the video stream after the image stabilization of the video stream is lower than a second bit rate threshold. The second threshold may be ≦90% of the first bit rate threshold. Depending on the scene and the pattern of the motion, an acceptable saving in bit rate due to the image stabilization based on the motion data may be about 10%-50%. Thus, if the image stabilization by the image stabilization function 422 reduces the bit rate of the video stream by a value larger than 10%, activation of the motion sensor 130 is advantageous and the motion sensor 130 and the image stabilization function 422 should be kept active. Otherwise, activation of the motion sensor 130 is not advantageous and power consumption can be conserved by disabling the motion sensor 130 and / or the image stabilization function 422 .

[0043] Alternatively or in combination, the analysis function 424 can be configured to analyze whether activation of the motion sensor 130 is advantageous to reduce the bit rate by analyzing the motion data. Activation of the motion sensor 130 can be advantageous to reduce the bit rate if the motion data indicates that the wearable camera 100 is shaking. The shaking of the wearable camera 100 can be due to the person wearing the wearable camera 100 taking a deep breath, for example, after running. By the wearable camera 100 is shaking, in this context, it is meant that the wearable camera 100 is vibrating. For the wearable camera 100 to be shaking, the vibration is preferably periodic. Furthermore, for the wearable camera 100 to be shaking, the vibration preferably has an amplitude that exceeds the shaking threshold. Typically, when the wearable camera 100 is shaking, activation of the image stabilization based on the motion data reduces the bit rate, and therefore the motion sensor 100 and the image stabilization function 422 should be kept active to reduce the bit rate. Otherwise, activation of the motion sensor 130 is not advantageous and power consumption can be conserved by disabling the motion sensor 130 and / or the image stabilization function 422 .

[0044] Alternatively or in combination, the analysis function 424 can be configured to analyze whether activation of the motion sensor 130 is advantageous to reduce the bit rate by analyzing the motion data. Activation of the motion sensor 130 can be advantageous to reduce the bit rate when the motion data indicates that the wearable camera 100 is located in the same place. By the wearable camera 100 being located in the same place, in this context, it means that the wearable camera 100 is not moving in the main direction. Movement in the main direction can be, for example, that the person wearing the wearable camera 100 is walking or running. According to the inventor's experience, in the case of movement in the main direction, image stabilization is not so effective, and the motion sensor 130 and likewise the image stabilization function 422 can be stopped to save battery power.

[0045] The analysis function 424 can be further configured to instruct the sensor mode setting function 423 to keep the motion sensor 130 and typically as well as the image stabilization function 422 active if activation of the motion sensor 130 is advantageous for reducing the bit rate. Otherwise, the analysis function 424 can be further configured to instruct the sensor mode setting function 423 to set the motion sensor 130 and typically as well as the image stabilization function 422 to an inactive mode. The analysis function 424 can actively instruct the sensor mode setting function 423 to keep the motion sensor 130 and typically as well as the image stabilization function 423 active. Alternatively, the analysis function 424 can passively instruct the sensor mode setting function 423 to keep the motion sensor 130 and typically as well as the image stabilization function 422 active, i.e., the command to keep the motion sensor 130 and typically as well as the image stabilization function 422 active can be in a form in which the command is not sent to the sensor mode setting function 423. Thus, the motion sensor 130 and typically the image stabilization function 422 as well will be in active mode until the set sensor mode function 423 tells it otherwise.

[0046] The analysis function 424 can be configured to keep the motion sensor 130, and typically also the image stabilization function 422, active for a predetermined period of time before performing a new analysis of whether activation of the motion sensor 130 is advantageous to reduce the bit rate. The period of time can be on the order of minutes. Alternatively or in combination, the analysis function 424 can be configured to keep the motion sensor 130, and typically also the image stabilization function 422, active until the motion data indicates a stable wearable camera. In this context, a stable wearable camera 100 means that the motion data indicates that the motion, typically vibration motion, of the wearable camera 100 is below a threshold value.

[0047] In relation to Fig. 2, a method 200 for power consumption optimization in a wearable camera 100 is discussed. The method 200 is based on an insight made by the inventor that power consumption in the wearable camera 100 can be saved by only putting the motion sensor 130 of the wearable camera 100 into active mode when motion data measured by the motion sensor 130 is needed for other functions of the wearable camera, such as image stabilization. Thus, the method can save power consumption, and therefore possibly battery life as well, in the wearable camera 100. This can be performed at the same time as performing bit rate optimization. Thus, the method allows the use of motion data from the motion sensor 130 when the bit rate of the video stream captured by the wearable camera 100 is reduced. Thus, the use of storage space in the local data storage 170 and / or the use of bandwidth used to transmit the captured video stream can be optimized.

[0048] Some of all steps of the method 200 may be performed by the above-mentioned functions of the wearable camera 100. The method includes the following steps: The steps may be performed in any suitable order.

[0049] The bit rate of the video stream captured by the wearable camera 100 is monitored S202. If the bit rate exceeds a first bit rate threshold, the motion sensor 130 of the wearable camera 100 is activated S204. If the motion sensor 130 is activated, it is analyzed S206 whether activation of the motion sensor 130 is advantageous to reduce the bit rate. If activation of the motion sensor 130 is advantageous to reduce the bit rate, the motion sensor 130 is kept active S208 and image stabilization is performed S210 based on the motion data from the motion sensor 130, otherwise the motion sensor 130 is stopped S212.

[0050] The method may include activating S205 image stabilization of the video stream based on the motion data from the motion sensor 130. If this step is performed, the S210 step of performing image stabilization based on the motion data from the motion sensor 130 is said to be keeping image stabilization based on the motion data from the motion sensor 130 active.

[0051] The step S206 of analyzing whether activation of the motion sensor 130 is favorable for reducing the bit rate may include analyzing the bit rate of the video stream after image stabilization of the video stream is activated. In such a case, activation of the motion sensor 130 is favorable for reducing the bit rate if the bit rate of the video stream after image stabilization of the video stream is lower than a second bit rate threshold. As mentioned above, the second threshold is preferably ≦90% of the first bit rate threshold. Furthermore, as also mentioned above, the first bit rate threshold and / or the second bit rate threshold may depend on the current charge state of the battery 140 of the wearable camera 10. Furthermore, as also mentioned above, the first bit rate threshold and / or the second bit rate threshold may depend on the available storage space in the local data storage 170 of the wearable camera 100.

[0052] The S206 step of analyzing whether activation of motion sensor 130 is advantageous for reducing bit rate may include analyzing motion data from motion sensor 130. In such a case, activation of motion sensor 130 may be advantageous for reducing bit rate if the motion data indicates that wearable camera 100 is shaking, where shaking of wearable camera 100 is discussed above in connection with analysis function 424. Further, in such a case, activation of motion sensor 130 may be advantageous for reducing bit rate if the motion data indicates that wearable camera 100 is co-located, where co-location of wearable camera 100 is discussed above in connection with analysis function 424.

[0053] The method may further include keeping the motion sensor 130 and image stabilization of the video stream active for a predetermined period of time before again performing step S206 of analyzing whether activation of the motion sensor 130 is advantageous to reduce bit rate.

[0054] The method may further include keeping the motion sensor 130 and image stabilization of the video stream active until the motion data indicates a stable wearable camera 100. Stabilization of wearable cameras is discussed above.

[0055] The method may further include storing the video stream in local data storage 170 of the wearable camera 100. The method may further include wirelessly transmitting the video stream from the wearable camera 100.

[0056] Those skilled in the art will recognize that the present invention is in no way limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0057] For example, the wearable camera 100 can be used by police officers. During patrol, the police officers can use the wearable camera 100 for continuous recording. However, continuous recording requires a large amount of local data storage 170, and most of the time the captured data will not be of much interest. Therefore, it is usually preferable to record only on demand. Therefore, the wearable camera 100 can be equipped with an activation button that allows the police officers to easily activate and deactivate it when desired.

[0058] Further, the wearable camera 100 may include a video buffer. The video buffer is configured to buffer the video data. When the wearable camera 100 activates recording, the video data in the video buffer may be added to the video stream. By doing so, events occurring before activation may be recorded as part of the video stream. The video buffer may be configured to buffer the video data for a period of up to one or several minutes before the wearable camera 100 activates recording. The video data buffered in the video buffer may be stored without image stabilization of the video stream based on motion data being performed. Thus, the motion sensor 130 does not need to be active until the wearable camera 100 activates recording. Using the video data from the video buffer, image stabilization of the buffered video data may be performed as a post-processing using features shown in the video stream.

[0059] Additionally, 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.

Claims

1. A method for power consumption optimization in a wearable camera (100), comprising: Monitoring (S202) a bit rate of a video stream captured by the wearable camera; activating (S204) a motion sensor (130) of the wearable camera when the bit rate exceeds a first bit rate threshold, and activating (S205) image stabilization of the video stream based on motion data from the motion sensor; If the motion sensor (130) and the image stabilization are activated, analyzing (S206) whether activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate; and keeping the motion sensor (130) active (S208) and performing image stabilization based on motion data from the motion sensor (130) (S210) if activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate, otherwise deactivating the motion sensor (130) (S212). A method comprising:

2. 2. The method of claim 1, wherein analyzing whether activation of the motion sensor (130) and the image stabilization is favorable for reducing the bit rate (S206) comprises analyzing the bit rate of the video stream after image stabilization of the video stream is activated, and activation of the motion sensor (130) is favorable for reducing the bit rate if the bit rate of the video stream after image stabilization of the video stream is lower than a second bit rate threshold, the second bit rate threshold being less than or equal to 90% of the first bit rate threshold.

3. The method of claim 2 , wherein the first bitrate threshold and / or the second bitrate threshold depend on a current state of charge of a battery (140) of the wearable camera.

4. The method of claim 2 or 3, wherein the first bitrate threshold and / or the second bitrate threshold depend on available storage space in a local data storage (170) of the wearable camera.

5. 5. The method of claim 1, wherein analyzing (S206) whether activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate includes analyzing motion data from the motion sensor (130), and activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate if the motion data indicates that the wearable camera (100) is shaking.

6. The method of any one of claims 1 to 5, wherein analyzing (S206) whether activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate includes analyzing motion data from the motion sensor (130), and activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate when the motion data indicates that the wearable camera (100) is located at the same location.

7. 7. The method of claim 1, further comprising keeping the motion sensor (130) and image stabilization of the video stream active for a predetermined period of time before performing again the step of analyzing whether activation of the motion sensor (130) and image stabilization is advantageous to reduce the bit rate.

8. The method of claim 1 , further comprising keeping the motion sensor (130) and image stabilization of the video stream active until the motion data indicates a stable wearable camera (100).

9. The method of any one of claims 1 to 8, further comprising storing the video stream in a local data storage (170) of the wearable camera (100) and / or transmitting the video stream from the wearable camera (100).

10. 10. A non-transitory computer readable storage medium having instructions stored thereon that, when executed on a device having processing capability, are for implementing the method of any one of claims 1 to 9.

11. A wearable camera, an image sensor (110) configured to capture image data; an encoder (120) configured to encode the image data into a video stream; a motion sensor (130) configured to measure motion data of the wearable camera, the motion sensor (130) being configured to be set in an active mode or an inactive mode; a battery (140) configured to power the wearable camera; and a circuit (150) comprising: a bitrate monitoring function (421) configured to monitor the bitrate of said video stream; an image stabilization function (422) configured to image stabilize the image data based on motion data from the motion sensor (130); a mode setting function (423) configured to set the motion sensor (130) and the image stabilization to the active mode when the bit rate exceeds a first bit rate threshold; and an analysis function (424) configured, when the motion sensor (130) and the image stabilization are activated, to analyze whether activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate; configured to run The analysis function (424) is further configured to instruct the mode setting function (423) to keep the motion sensor (130) in the active mode and instruct the image stabilization function (422) to perform image stabilization if operation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate, and to instruct the mode setting function (423) to set the motion sensor (130) to the inactive mode otherwise.

12. 12. The wearable camera of claim 11, wherein the analysis function (424) is configured to analyze whether activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate by analyzing the bit rate of the video stream after image stabilization by the image stabilization function (422), and activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate if the bit rate of the video stream after image stabilization is lower than a second bit rate threshold, and the second bit rate threshold is less than or equal to 90% of the first bit rate threshold.

13. The wearable camera of claim 11 or 12, wherein the analysis function (424) is configured to analyze whether activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate by analyzing the motion data, and activation of the motion sensor (130) and the image stabilization is advantageous for reducing the bit rate when the motion data indicates that the wearable camera is shaking and / or the wearable camera is located in the same place.

14. A wearable camera as described in claim 12 or claim 13 when claim 12 is cited, wherein the first bit rate threshold and / or the second bit rate threshold depend on a current charge state of the wearable camera's battery (140) and / or available storage space in the wearable camera's local data storage (170).

15. 15. The wearable camera of claim 11, further comprising a local data storage (170) configured to store the video stream and / or a transmitter (180) configured to wirelessly transmit the video stream.

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