Manual - Video Telephony

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A Rohde & Schwarz Company

Video Telephony SettingsManual

June 2012

SwissQual License AG Allmendweg 8 CH-4528 Zuchwil Switzerland

t +41 32 686 65 65 f +41 32 686 65 66 e [email protected]

Part Number: 16-070-200709-3


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SwissQual has made every effort to ensure that eventual instructions contained in the document are adequate and freeof errors and omissions. SwissQual will, if necessary, explain issues which may not be covered by the documents.SwissQuals liability for any errors in the documents is limited to the correction of errors and the aforementioned advisoryservices.

Copyright 2000 - 2012 SwissQual AG. All rights reserved.

No part of this publication may be copied, distributed, transmitted, transcribed, stored in a retrieval system, or translated

into any human or computer language without the prior written permission of SwissQual AG.Confidential materials.

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Video Telephony Settings Manual

2000 - 2012 SwissQual AG

Contents |CONFIDENTIAL MATERIALS

ii

Contents

1 Introduction .......................................................................................................................................... 1

Overview ................................................................................................................................................ 1

Enabling 3G on a Mobile Phone ............................................................................................................ 1

Example ............................................................................................................................................ 1

Forcing Into a Video Call ....................................................................................................................... 2

Supported Call Options and Voices Tests ....................................................................................... 2

2 Phone-to -Phone Video Telephony Setti ngs ...................................................................................... 3

Speech Samples and Recording Time .................................................................................................. 3

Voice Test Results ................................................................................................................................. 4

Capturing a Video Call With a Camera .................................................................................................. 4

3 Usin g the H.324M Video Stack fo r Video Telephon y ....................................................................... 5

Defining a Video Stack Job ................................................................................................................... 5

Results and Restrictions ........................................................................................................................ 6

Viewing Results in Real Time........................................................................................................... 6

Voice Transmission .......................................................................................................................... 7

Video Transmission .......................................................................................................................... 7

Lip Synchronization .......................................................................................................................... 7

Audio and Video Connect Trigger Points ......................................................................................... 7 Restrictions ....................................................................................................................................... 8

Asynchronous Link to the Phone With the V.80 Protocol ................................................................ 8

4 Video Telephon y t o Video Stack or to Respo nder ........................................................................... 9

Phone to Stack Option ........................................................................................................................... 9

Phone to Responder Option ................................................................................................................ 10

FiguresFigure 1-1 Overview of the components in a CS64K video call ........................................................................ 1

Figure 2-1 Phone to Phone test option in TestManager .................................................................................... 3

Figure 2-2 Record Hangover setting for Video Telephony ................................................................................ 3

Figure 3-1 Video Stack options in Test Manager .............................................................................................. 6

Figure 3-2 Record HO setting in Test Manager ................................................................................................ 6

Figure 3-3 Example schematic of the serial link from the Host PC to the phone .............................................. 8

Figure 4-1 Phone to Video Stack option in Test Manager ................................................................................. 9

Figure 4-2 Phone to Responder option in Test Manager ................................................................................ 10

Figure 4-3 Temporal structure for an audio-video clip that is used in responder mode. ................................. 11


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Chapter 1 | IntroductionCONFIDENTIAL MATERIALS

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Network mode , and then select Dual mode or UMTS .

Forcing Into a Video Call

Diversity automatically sets up video calls. By default, if the receiving end is not available to answer the videocall (phone and network dependent), the video call fails, and the voice call is not established.

Supported Call Options and Voices Tests

SpeechWideband

No Videocall x x x x x x x x x x

Phone to Phone x x x x x x x x x x (VMonCam)* (VMonCam)*Stack to Stack(half-duplex & full-duplex) x x x x x x VQuad VQuad

Phone to Stack x (x)* x x x (VMonCam)*

Phone to Responder x x x x (VMonCam)*

* Not recommended** SQuadv3 and SQuad08 are supported

B side AEC RTT

Call setup Direction of A/V Intrusive Voice tests Video testsNoise

SuppressionSpeechP.862Speech** A sideCall opti on

Downlink(B->A)

Uplink(A->B)MTCMOC


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Chapter 2 | Phone-to-Phone Video Telephony SettingsCONFIDENTIAL MATERIALS

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2 Phone-to-Phone Video Telephony Settings

This chapter describes the phone-to-phone video telephony settings in TestManager.To view the available video settings for a job in TestManager 1. Click Tasks in the Navigation pane, click Jobs , and then click Add J ob s .

2. On the General tab for the job, click Video settings , and then click Phone to Phone .

Figure 2-1 Phone to Phone test option in TestManager

Speech Samples and Recording Time

The signal delay in video calls can be higher than in common voice calls. For best results in Listening Quality(Speech test type) measurements in video calls, you might need to increase the Record Hang-Over (HO)time up to 5000 ms.

Figure 2-2 Record Hangover setting for Video Telephony


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Chapter 2 | Phone-to-Phone Video Telephony SettingsCONFIDENTIAL MATERIALS

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Voice Test Results

In addition to pure call statistics for CS64K video calls, you can also perform all of the common SwissQualvoice channel tests. These test can have a very strong and variable delay in the voice channel due to thelength of time that is required to load the video signal as well as the forced synchronization between thedelayed video and voice signals.

The variable delay in the transmission of fast moving pictures is more than 0.5 s, even during speech activity.For this reason, the results that you obtain for Listening Quality are significantly lower for moving picturesthan the near voice call quality results for fixed images and muted or covered cameras.

The signal delay that is obtained with SQUAD-RTT is a measure of latency. Due to the varying delay, theresults might differ from test to test. In each case, video calls have a much higher latency, even if video hasnot been transmitted.

The SQUAD-AEC echo measurement might also lead to incorrect results. The strong variable delay alsoresults in an echo having different delays that SQUAD-AEC handles as different echoes.

Note: Some of these different echoes are not powerful enough to be detected by the algorithm.

Capturing a Video Call With a Camera

Video telephony measurements are performed in a Diversity MCM where a video camera captures thedisplay of a mobile phone during a video call. The camera transmits the video from the handset display to thehost computer, which also records the audio channel of the video call. The captured video is evaluated byVMonCam on the PC, which is the SwissQual no-reference algorithm for video quality analysis.

Important: Video capture is not the best method to measure the quality of a video call. Vehicleacceleration and low quality roads during a drive test as well as a darkened handset displaywhen the MCM cover is closed can negatively affect the video capture results. For morereliable information on video quality, consider time to first picture and freezing.


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Chapter 3 | Using the H.324M Video Stack for Video TelephonyCONFIDENTIAL MATERIALS

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3 Using the H.324M Video Stack for VideoTelephony

The 3G 324M stack, which is normally part of the terminal software, enables the video telephony serviceover CS64K channels. This stack integrates the audio and video data multiplexer, the H.245 protocol, andalso controls the audio and video encoders and decoders.

Video stack mode bypasses the phone internal stack and runs these software components on the host PCMinstead. This mode gives you complete control of the contents that you want to transmit in a video telephonyconnection. This level of control is required when you want to transmit and evaluate predefined voice andvideo clips as 'intrusive' or 'full-reference' quality measurements.

In video stack mode, a fixed video clip of head and shoulders is transmitted. If you want, you can combinethis clip with a voice clip that is in a supported format. The quality of the video clip is evaluated by theSwissQual VQuad test, which is a full-reference video quality model. The quality of the voice clip is evaluatedwith SQuad-LQ or optionally with ITU-T P.862.

Defining a Video Stack Job

This section describe how to create video stack to video stack intrusive jobs in TestManager that includespeech and speech-P.862 tests. You can create intrusive jobs that support MOC and MTC and can be runduring uplink and downlink. You can only run these jobs on Nokia phones that support video calls. For moreinformation, see the Diversity and QualiPoc - Supported Devices.pdf document.

Note: TestManager supports both FTP and DTMF job transfers. For a DTMF job transfer, theconfiguration call is always established as a normal voice call. The switch into video stackmode occurs after the configuration is finished and before the first measurement starts.

To configure a video st ack measurement in TestManager 1. In TestManager, click Tasks in the Navigation panel.

2. Click Jobs and click Add J ob .

3. In the Details area for the job, click Video settin gs , and then select a video stack option.

Note: For a common voice call test, that is, without the video stack option, select No VideoCall .

Stack to Stack (half duplex): Video clip is transmitted in the same direction as the voice clip andstuffing blue frames are sent in the opposite direction.

Stack to Stack (full duplex): Video clip is transmitted simultaneously in both directions while thevoice clip remains half-duplex, that is, the clip is only transmitted in one direction.

In video stack mode, you can only use speech or speech-P.862 intrusive tests. Although you cannotchange the default video clip, you can use any of the available speech reference samples.


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Figure 3-1 Video Stack options in Test Manager

4. On the General tab in the Details area, enter 12500 in the Record HO box.

Important: Due to improvements in the VQuad algorithm, 12500 ms are sufficient for R97 andabove.

Figure 3-2 Record HO setting in Test Manager

The high Record HO value provides Diversity with enough time to record the complete signal. For example,when the signal delay is long, the PCM requires more time than usual to complete the high performancevideo evaluation. However, the high Record HO value also decreases the number of video telephony

evaluations that can be performed. For example, in a 90 s call, a PCM only has time to complete four evaluations.

Results and Restrictions

This section describes the results and restrictions for video telephony.

Viewing Results in Real TimeIn video stack mode, the SQuad-LQ evaluation runs as the main application. To monitor the SQuad-LQ andVQuad results in real time, use the Diversity NQView software.

Important: Due to limited system resources, you cannot watch the video results in real time onthe Video tab for the VoiceEngine. Similarly, do not use Remote Desktop to observe the


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VoiceEngine during a measurement.

Voice TransmissionThe default codec for the audio channel is AMR-FR (12.2 kbit/s). If you assume that a transmission isundistorted, you can expect SQuad-LQ values greater than 3.7. However, you can select any of the speechreference samples that were installed by SwissQual.

Video TransmissionFor the video transmission, a 6-second fixed head-and-shoulders video clip with a corresponding speech clipis used. The voice and video clips are transmitted and recorded synchronously. If the speech clip is nottransmitted, blue frames are fed into the video channel.

Note: There is no content dependency between the speech and the video clips. The video clipis only a typical example that is interlaced with two meaningful sentences.

The video signal is encoded with the ITU-T H.263 codec and has a fixed frame rate of 5 fps. The use of thiscodec, combined with the restricted transmission capacity, leads to a strong degradation of the video quality,even in perfect radio conditions.

Lip SynchronizationThe term LipSync describes the de-synchronization that can occur between the video and the audio signalsin a transmission. This condition is easy to observe when the source of the sound effect is visible in thevideo, for example, a speaker's face, a musician, or a smoking gun. The following situations can cause de-synchronization during video streaming: Separate transmission of the audio and video signal De-multiplexing and re-multiplexing of the audio and video signals Player decodes the audio signal faster that the video signal Different buffering mechanisms

In CS64K video telephony, the audio and video data is multiplexed according to the 3G 342 M standard. Toavoid de-synchronization during transmission, the SwissQual video telephony solution uses the 3G 324 Mstack to feed the multiplexer directly with pre-encoded audio and video signals. The receiving end consists of a decoder and a simple player, which does not require buffering or other intelligence. As a result, de-synchronization is eliminated and the LipSync value is assumed to be 0 ms.

Audio and Video Connect Trigger Point sThe following trigger points occur when you make a video call: Physical channel opens: After this plain CS64K data connection opens, the protocols of the two stacks

start to exchange information. Logical channels open: Transmit the encoded audio and video signals

The 3G 342 M uses the time between these two trigger points, which is normally a few seconds, for protocolexchange and acknowledgements. Diversity uses these trigger points to track the call progress with respectto call success as well as to calculate channel setup durations.

Due to the fixed correspondence of the signals, the audio and video logical channels open synchronously(see Lip Synchronization on page 7). As a result, the 3G 324 M stack interprets the opening of these twochannels as a single trigger point.

Due to the amount of time that is required to decode a video frame, the first video image does notimmediately appear. SwissQual uses a fixed frame rate of 5 fps to ensure that this image is captured at least200 ms after the audio and video channels open. However, in reality, this value depends on the frame rate


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and the transmission delay.

RestrictionsVideo coding and evaluation consumes a significant amount of power, particularly in a Diversity PCM. Toreduce the power load on the PCM, you need to observe the following rules during an active measurement: Do not switch any of the debug or log files Do not remotely log in to a PCM, for example, with Remote Desktop Connection Do not start background activities such as file copying or virus scanning

You can only use the SwissQual video telephony solution with the following mobile phones: Nokia 6630 Nokia 6680 Nokia N80 Nokia N95 Nokia N6120/6121

Asynchronous Link to the Phone With the V.80 ProtocolThe serial link from the video stack components on the host PC to the phone is the most crucial part of theSwissQual video telephony solution. This link remains asynchronous even when a video call is in asynchronous 64 kbit/s mode. Since Windows cannot adequately support the serial link with a constant datarate in real time, the serial link uses the V.80 protocol instead. This protocol uses additional cachingmechanisms to manage the variations that can arise in the data rate.

Figure 3-3 Example schematic of the serial link from the Host PC to the phone


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Chapter 4 | Video Telephony to Video Stack or to Responder CONFIDENTIAL MATERIALS

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4 Video Telephony to Video Stack or to Responder

If you want, you can use a mixed configuration approach to video telephony. This approach involves thefollowing video stack options: Phone to Video Stack: Mobile phone with an internal video stack calls a Diversity system that runs the

video stack on a host PC. The stack sends out the common video clip and the voice clip that youspecified in the speech test. Transmission is only supported in the video stack to phone direction, that is,video stack always sends and phone always receives.

Phone to Responder: Mobile phone calls a responder station, which plays a video clip. The currentsolution only requires that the B-side answers the call.

Phone to Stack Option

For the Phone to Stack option, the phone is the A-side, the video stack is the B-side, and the audioconnection is through the headset connector.

Note: The voice sample and the call window timings of the B-side can be the same as anormal video stack.

The Phone to Stack option is restricted to MOC calls in downlink transmission, that is, from B to A as well asSpeech and Speech-P.862 tests.

Note: The MOC:MTC value on the Timings tab for the an MOC call in 1.0.

Set the video stack as the B-side device and the mobile phone as the A-side device.

Figure 4-1 Phone to Video Stack option in Test Manager

If you also want to evaluate the video signal on the A-side, you need to install a camera to capture thedisplay of the A-side device.

Note: Diversity automatically enables camera capturing when you connect a camera to thesystem.

To allow sufficient time to evaluate the video signal, you need to enter a Record HO value of 12500 ms.However, if the camera is disabled or you just want to evaluate the voice signal at the A-side, use the default


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Record HO value of 3000 ms.

Phone to Responder Option

For the Phone to Responder option, the phone is the A-side device and uses the internal video option toreceive and to display the video signal. The audio connection for the phone is through the headsetconnector. The B-side acts a responder station that plays a combined audio and video signal from memorywhen the call is established. The Diversity system is responsible for the establishing and ending the call.

The Phone to Responder option is restricted to MOC calls in downlink transmission, that is, from B to A aswell as Speech and Speech-P.862 tests.

Note: The MOC:MTC value on the Timings tab for the an MOC call in 1.0.

Figure 4-2 Phone to Responder option in Test Manager

The responder cannot be controlled by the signal that is played. As a result, this signal must exactly matchthe timings of the test and the test files of the calling A-side. That is, the signal must include thesynchronization sequence at the beginning of the transmission as well as all voice and video clips that the

job expects.

If you also want to evaluate the video signal on the A-side, you need to install a camera to capture thedisplay of the A-side device.

Note: Diversity automatically enables camera capturing when you connect a camera to thesystem.

In Figure 4-3, a common example for a pre-defined video clip, a sufficient time slot for evaluating the videosignal has already been allotted for the clip generation by the responder.


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Video track

Audio track

Sync sequence

Voice clips (6s)

Video clips (6s)

12.5s 12.5s 12.5s4.5s

Blue frames aslimitter

Figure 4-3 Temporal structure for an audio-video clip that is used in responder mode.

The pre-defi ned clip matches the exact structure between the sync sequence and the successive clips. Inthis series, Diversity analyses every second clip, where the clip length is 6 s and the RecordHO is 18500ms .However, the frequency of clips in the signal is higher and can be equipped for high seed analysis, which,similar to the QualComm FFA phone, can be configured to avoid muting during long silence intervals.

Important: You can only use this option in conjunction with a QualComm FFA QPT6800phone, which uses a packet switched connection and a SIP VoIP client on the phone for videotelephony. This video telephony client allows the playback of pre-stored video files.

If you want to emulate the Phone to Responder option in the Phone to Phone option, you need to add thefollowing entry to the Windows registry:

To emulate the phone to responder option1. On the Start menu, click Run , type regedit in the Open box, and then click OK .

2. In the console tree of the Registry Editor , go to the following location:HKEY_LOCAL_MACHINE\SOFTWARE\SwissQual\NetQual\NQMP\

3. In the right-pane, right-click ConfigCallMOCOnly , and then click Modify .

4. In the Value Data box, type 0 , and then click OK .

Important: SwissQual reserves the right to modify this functionality.

Documents

Manual - Video Telephony