vDelay: A Tool to Measure Capture-to-Display Latency and Frame Rate

Boyacı, Ömer; Forte, Andrea; Baset, Salman; Schulzrinne, Henning

doi:10.1109/ism.2009.46

Cited by 37 publications

(25 citation statements)

References 2 publications

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“…From the above experiments, we can conclude that the longer camera exposure time causes the overlapped timestamp problem and more overlapping problems appear on Cellphone2 than on PC according to equation (2). A shorter timestamp refresh interval and/or a longer camera exposure time will make the overlapped timestamp problem worse.…”

Section: B) Relationship Between the Maximum Number Of Overlapped Timmentioning

confidence: 88%

“…However, the fast readability and greater storage capacity compared with the standard barcodes make the QR-code increasingly popular. For error-resiliency, Boyaci et al [2] used an european article number (EAN)-8 barcode because of its checksum mechanism. The EAN-8 barcode with a checksum can allow to detect whether the timestamp is contaminated, and refuse to read the barcode if it is damaged or distorted.…”

Section: B) Timestamp Representationsmentioning

confidence: 99%

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Capture-to-display delay measurement for visual communication applications

Chen

Wei

Song

et al. 2015

SIP

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We propose a method to measure the capture-to-display delay (CDD) I . I N T R O D U C T I O NEnd-to-end delay is an important concern for two-way visual communication applications. Video codec manufacturers need to measure the end-to-end delay of a video codec system in order to develop low-delay video codecs. Network service providers need to make sure the end-toend delay of a visual communication application is within the application requirement. A simple and general tool for measuring the end-to-end delay of a visual communication system is invaluable for applications related to two-way visual communications. Figure 1 shows an example of a mobile video chat system. Video captured by the camera is compressed by a video encoder. The encoder usually contains an encoder buffer to smooth the video bit-rate as described in [1]. The video bitstream is then packetized and transmitted over the network. At the decoder side, the video is decoded and displayed. The decoder usually contains a decoder buffer to smooth out the network jitter and to buffer the bit-stream before the video decoding. The encoder and decoder buffers can result in a relatively long delay. The end-to-end delay in this example, is the latency from frame capturing at the encoder side to the frame display at the decoder side, which we call capture-to-display delay (CDD), including the whole chain of video encoding, encoder buffering, packetization, The traditional way to measure the latency is by using timestamps. A timestamp is a code representing the global time. It can be generated by a counter driven by a network clock commonly available to both the encoder and the decoder. To measure the time delay between two points A and B, a timestamp is inserted at point A, retrieved at the point B, and compared with the global time at point B. For example, for the visual communication system shown in Fig. 1, to measure the end-to-end delay of the network part, timestamps are generated from the network clock and inserted at the network interface point in the encoder side. These timestamps are retrieved at the network interface point at the decoder side to compare with the global time. Similarly, to measure the CDD, we can insert timestamps at the video capture point, and observe the timestamps relative to the global time at the display point. As long as a network clock is available and the encoder clock and the decoder clock are synchronized, the delay can be calculated. However, in order to do this, we need to be able to modify the hardware or software to insert the timestamps, and retrieve the timestamps at the desired points. In many situations including our application scenario, cellphone video codecs are implemented in hardware and software by the developers. Thus, we cannot modify the video encoder and decoder to insert or retrieve the timestamps. Also, usually the encoder clock and the decoder clock are not synchronized. These make the measuring of the CDD particularly challenging.Boyaci et al.[2] presented a tool to measure the CDD of a video chat...

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Section: B) Relationship Between the Maximum Number Of Overlapped Timmentioning

confidence: 88%

Section: B) Timestamp Representationsmentioning

confidence: 99%

Capture-to-display delay measurement for visual communication applications

Chen

Wei

Song

et al. 2015

SIP

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show abstract

“…Despite the advantages of continuous lighting and low electromagnetic emission of a LCD (liquid crystal display), these monitors have problems with time and accurate presentation of color, milliseconds apart (sometimes even 10ms) 27 . Where as the refresh rate determines the speed at which an image is displayed on an LCD monitor, and usually starts at 60Hz in modern monitors, that means it can take up to 16.6 ms for certain color appears in an LCD monitor coupledwith the fact that the update time of a pixel for an new pixel is usually 5ms 28 . This makes us look with concern for the difference shown in the colorchange of the stimulus, suggesting that new tests can be conducted to determine differences in parameterization of other colors, as well as other types of monitors, keyboards and operational systems.…”

Section: Discussionmentioning

confidence: 99%

Validity of Software for Measurement of Total Reaction Time With Simple Stimulus -Trt_s 2012

Crocetta

Viana

Silva

et al. 2014

J. Hum. Growth Dev.

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Objective: Determine the validity of the TRT_S 2012 software in to assess the total reaction time (TRT) with a simple visual stimulus (TRTSimple) and mental fatigue from TRT (TRTFatigue). Methods: Three types of validation were applied: a) concurrent, for determining the correlation between the TRT_S 2012 Software and Vienna Test System (VTS), b) content of a sample of adults, and c)mechanical, using a robot that performs a mechanic motion to respond to a light stimulus.The study included 216 young adults, college students aged 17 -45 years (x = 24.0 ± 6.0) and a robot. Descriptive and inferential statistics were used for performance on TRT obtained by young adults and robot in two software. Results: The intra-class correlation in the adults TRT showed strong correlation between VTS and TRTSimple (R = .72). Identification of the proposed initial stimulus in TRTFatigue presented intermediate correlation with VTS (R = .56) and the final stimulus presented low correlation with VTS (R=.35).The robot TRT showed standard deviation ranging .5 ms (on average) between the highest and lowest.The standard error of the mean ranged from .23 to .28 and the distributions were homogeneous between 8.2 to 9.7%. Conclusion: The results confirmed the validity of the software TRT_S 2012 . It is a reliable cognitive test that can be applied to young adults for measuring the TRT with simple visual stimuli and for evaluating the influence of mental fatigue from the TRT. however, the delays caused by the computer resources used should be considered and measured with a resource like the robot. We conclude that the TRT_S 2012 software is valid for assessing the TRT and cognitive fatigue in healthy adults.Key words: reaction time, mental fatigue, software.

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“…A user centric measurement is presented in [14] enabling video delay measurements using QR codes, which was also further developed in [15] where audio measurements were added and thereby enabling synchronization measurements. A capture-to-display latency and frame rate estimation was presented in [2] where barcodes were used in a JAVA application running on the sender device. These methods enable measurements but in a limited range of scenarios.…”

Section: Related Workmentioning

confidence: 99%

A robust method for estimating synchronization and delay of audio and video for communication services

Rossholm

Lövström

2014

Multimed Tools Appl

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PostprintThis is the accepted version of a paper published in Multimedia tools and applications. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination. Abstract One of the main contributions to the quality of experience in streaming services or in two-way communication of audio and video applications is synchronization. This has been shown in several studies and experiments but methods to measure synchronization are less frequent, especially for situations without internal access to the application and independent of platform and device. In this paper we present a method for measuring synchronization skewness as well as delay for audio and video. The solution incorporates audio and video reference streams, where audio and video frames are marked with frame numbers which are decoded on the receiver side to enable calculation of synchronization and delay. The method has been verified in a two-way communication application in a transparent network with and without inserting known delays, as well as in a network with 5 and 10 % packet loss levels. The method can be used for both streaming and two-way communication services, both with and without access to the internal structures, and enables measurements of applications running on e.g. smartphones, tablets, and laptops under various conditions.

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vDelay: A Tool to Measure Capture-to-Display Latency and Frame Rate

Cited by 37 publications

References 2 publications

Capture-to-display delay measurement for visual communication applications

Capture-to-display delay measurement for visual communication applications

Validity of Software for Measurement of Total Reaction Time With Simple Stimulus -Trt_s 2012

A robust method for estimating synchronization and delay of audio and video for communication services

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