1、 International Telecommunication Union ITU-T P.1201.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2012) SERIES P: TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Models and tools for quality assessment of streamed media Parametric non-intrusive assessment of audiovisual media stream
2、ing quality Lower resolution application area Recommendation ITU-T P.1201.1 ITU-T P-SERIES RECOMMENDATIONS TERMINALS AND SUBJECTIVE AND OBJECTIVE ASSESSMENT METHODS Vocabulary and effects of transmission parameters on customer opinion of transmission quality Series P.10 Voice terminal characteristic
3、s Series P.30 P.300 Reference systems Series P.40 Objective measuring apparatus Series P.50 P.500 Objective electro-acoustical measurements Series P.60 Measurements related to speech loudness Series P.70 Methods for objective and subjective assessment of speech quality Series P.80 P.800 Audiovisual
4、quality in multimedia services Series P.900 Transmission performance and QoS aspects of IP end-points Series P.1000 Communications involving vehicles Series P.1100 Models and tools for quality assessment of streamed media Series P.1200Telemeeting assessment Series P.1300 Statistical analysis, evalua
5、tion and reporting guidelines of quality measurements Series P.1400 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T P.1201.1 (10/2012) i Recommendation ITU-T P.1201.1 Parametric non-intrusive assessment of audiovisual media streaming quality Lower resolution applic
6、ation area Summary Recommendation ITU-T P.1201.1 specifies the algorithmic model for the lower resolution (LR) application area of Recommendation ITU-T P.1201. The ITU-T P.1201 series of Recommendations specifies models for monitoring the audio, video and audiovisual quality of IP-based video servic
7、es based on packet-header information. The lower resolution application area of the ITU-T P.1201.1 part of ITU-T P.1201 can be applied to the monitoring of performance and quality of experience (QoE) of video services such as mobile TV. The algorithm for the higher resolution (HR) case is specified
8、in ITU-T P.1201.2. See ITU-T P.1201 for details and respective application ranges and limitations of use. This Recommendation includes an electronic attachment for testing compliance. History Edition Recommendation Approval Study Group 1.0 ITU-T P.1201.1 2012-10-14 12 ii Rec. ITU-T P.1201.1 (10/2012
9、) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for st
10、udying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study gr
11、oups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with
12、 ISO and IEC. NOTE In this Recommendation, the expression Administration is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisio
13、ns (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words shall or some other obligatory language such as must and the negative equivalents are used to express requirements. The use of such wor
14、ds does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position con
15、cerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by pate
16、nts, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2013 All rights reserved. No part of this publi
17、cation may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T P.1201.1 (10/2012) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Conventions 2 6 Model description . 2 6.1 Parameter extraction modules 3
18、 6.2 Aggregation of basic parameters into audio and video parameters 12 6.3 Aggregation of basic parameters into quality estimation model 27 6.4 Quality estimation modules 31 7 Model compliance 40 Electronic attachment: Test vectors for testing compliance. Rec. ITU-T P.1201.1 (10/2012) 1 Recommendat
19、ion ITU-T P.1201.1 Parametric non-intrusive assessment of audiovisual media streaming quality Lower resolution application area 1 Scope Recommendation ITU-T P.1201.11describes an algorithmic model (ITU-T P.1201-LR: Parametric non-intrusive assessment of audiovisual media streaming quality Lower reso
20、lution application area) for monitoring the audio, video and audiovisual quality of IP-based video services based on packet-header information. ITU-T P.1201.1 addresses the lower resolution (LR) application area, including services such as mobile TV. The ITU-T P.1201-LR model is a no-reference (i.e.
21、, non-intrusive) model which operates by analysing packet header information. Further input information on more general aspects of the stream, such as the video resolution, which may not be available from packet header information, is provided to the algorithm out-of-band, for example in the form of
22、 stream-specific side information. As output, the model provides individual estimates of audio, video and audiovisual quality in terms of the five-point absolute category rating (ACR) mean opinion score (MOS) scale. This Recommendation is to be used with media payload (audio, video) encapsulated in
23、RTP/UDP/IP packets. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references ar
24、e subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a doc
25、ument within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.264 Recommendation ITU-T H.264 (2011), Advanced video coding for generic audiovisual services. ITU-T P.1201 Recommendation ITU-T P.1201 (2012), Parametric non-intrusive assessment of
26、 audiovisual media streaming quality. IETF RFC 3267 IETF RFC 3267 (2002), Real-Time Transport Protocol (RTP) Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol
27、for Real-Time Applications. IETF RFC 3640 IETF RFC 3640 (2003), RTP Payload Format for Transport of MPEG-4 Elementary Streams. IETF RFC 3984 IETF RFC 3984 (2005), RTP Payload Format for H.264 Video. IETF RFC 4352 IETF RFC 4352 (2006), RTP Payload Format for the Extended Adaptive Multi-Rate Wideband
28、(AMR-WB+) Audio Codec. IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. _ 1This Recommendation includes an electronic attachment for testing compliance. 2 Rec. ITU-T P.1201.1 (10/2012) 3 Definitions None. 4 Abbreviations and acronyms This Recommendation uses the following abbre
29、viations and acronyms: ACR Absolute Category Rating HR Higher Resolution HVGA Half Video Graphics Array IP Internet Protocol LR Lower Resolution MOS Mean Opinion Score P-E Parameter Extraction QCIF Quarter Common Intermediate Format QVGA Quarter Video Graphics Array RTP Real-time Transport Protocol
30、SDP Session Description Protocol UDP User Datagram Protocol 5 Conventions None. 6 Model description Figure 6-1 shows a block diagram for the ITU-T P.1201.1 model. The model takes packet headers and side information (e.g., encoder and decoder (codec), client behaviour, etc.) as input. The streams may
31、 be encrypted or unencrypted. The parameter extraction modules (P-E) extract audio and video-related parameters and output them to parameter calculation modules that consist of modules calculating basic parameters and modules calculating input parameters of quality estimation modules. Finally, quali
32、ty estimation modules output audio, video and audiovisual MOSs at predetermined time intervals (e.g., 10 seconds) upon request of the performance monitoring system. The model details are described in the following clauses. Note that a prefix is added to the name of parameters (i.e., A_ for audio par
33、ameters, V_ for video parameters, AV_ for audiovisual parameters, and no suffix for rebuffering parameters). Rec. ITU-T P.1201.1 (10/2012) 3 Figure 6-1 Block diagram for the ITU-T P.1201.1 model 6.1 Parameter extraction modules 6.1.1 Parameter extraction module for audio The parameter extraction mod
34、ule for audio consists of three parts on the basis of input information: 1) the side information, 2) RTP timestamp, and 3) RTP sequence number and payload, as shown in Figure 6-2. Figure 6-2 Parameter extraction module for audio Packet headerinformationRTP headerUDP headerIP headerVideo quality esti
35、mation moduleAudiovisual quality estimation moduleAudio quality estimation moduleP-E-RP-E-AP-E-VVideoMOSAudiovisualMOSAudio MOSSide information about codec, client behavior etc.Available to allmodulesP-E-VParameter calculation module for audioParameter calculation module for videoP-E-RP-E-AParameter
36、 extractionmodule for audioParameter extractionmodule for rebufferingDefined InterfaceParameter extractionmodule for videoKey:Parameter extraction module for audioBasic audio parameter extraction module from side informationBasic audio parameter extraction module from RTP timestampBasic audio parame
37、ter extraction from RTP sequence number and payloadaudioCodecaudioFrameLengthA_CRA_MTA_TSmA_NTSA_RPA_PLLkA_PLEFA_receivedBytesiA_lostBytesjSide informationAudio RTP timestampAudio RTP sequence number and payload4 Rec. ITU-T P.1201.1 (10/2012) 1) Basic audio parameter extraction module from side info
38、rmation The basic audio parameter extraction module from side information extracts the payload type (audioRTPPayloadType), destination port number (audioDestPort), audio codec (audioCodec) and audio frame length (audioFrameLength) in milliseconds from side information (e.g., pre file). The payload t
39、ype (audioRTPPayloadType), destination port number (audioDestPort) and audio codec (audioCodec) may also be extracted from the session description protocol (SDP), as defined in IETF RFC 4566, if SDP is available. The audio frame length (audioFrameLength) value can also be parsed from the audio eleme
40、ntary stream directly if the stream is not encrypted. If the audio RTP timestamp clock rate (A_CR) is not input by the side information or SDP, the module calculates the audio RTP timestamp clock rate (A_CR) using audio frame length (audioFrameLength) as follows: LengthaudioFrameA_CR3101024 = (6-1)
41、Note that in AMR-NB and AMR-WB+, this step is not needed because the RTP timestamp clock rate (A_CR) is 8000 or 72000, respectively, as defined in IETF RFC 4867 and IETF RFC 4352. The inputs and outputs of the basic audio parameter extraction module from side information are listed in Tables 6-1 and
42、 6-2. Table 6-1 Inputs for the basic audio parameter extraction module from side information Input parameter Data type Example value Input from audioRTPPayloadType int 97 Side info. (e.g., pre file), or SDP if available audioDestPort int 1234 Side info. (e.g., pre file), or SDP if available audioCod
43、ec char AAC-LC Side info. (e.g., pre file), or SDP if available audioFrameLength double 21.33 Side info. (e.g., pre file) Table 6-2 Outputs of the basic audio parameter extraction module from side information Output parameter Data type Example value Output to audioCodec Char AAC-LC Audio quality est
44、imation module audioFrameLength double 21.33 Audio parameter calculation module A_CR double 48000.00 Basic audio parameter extraction module from RTP timestamp Basic audio parameter calculation module Note that in the following modules audio RTP packets should be identified by the given audioRTPPayl
45、oadType and/or audioDestPort. 2) Basic audio parameter extraction module from RTP timestamp The basic audio parameter extraction module from RTP timestamp extracts audio RTP timestamp (A_TS) for the start and end of the audio stream (A_TSs and A_TSe) within predetermined time intervals (e.g., 10 sec
46、onds). The module calculates the minimum value of the difference between consecutive audio RTP packets (A_TSm) when the difference between consecutive audio RTP packets is greater than 0. The measurement time for audio (A_MT) is calculated as follows: Rec. ITU-T P.1201.1 (10/2012) 5 IF (A_TSe A_TSs)
47、 THEN A_CRA_TSmA_TSsA_TSeA_MT+= (6-2) ELSE A_CRA_TSmA_TSsA_TSeA_MT+=4294967296(6-3) ENDIF The module counts the number of different RTP timestamp (A_NTS) that is incremented by one when the audio RTP timestamp changes. The inputs and outputs of the basic audio parameter extraction module from RTP ti
48、mestamp is shown in Tables 6-3 and 6-4. Table 6-3 Inputs for the basic audio parameter extraction module from RTP timestamp Input parameter Data type Example value Input from A_CR double 48000.00 Basic audio parameter extraction module from side information A_TS int 0-4294967295 Packet (e.g., PCAP)
49、Table 6-4 Output of the basic audio parameter extraction module from RTP timestamp Output parameter Data type Example value Output to A_MT double 10.06776 Audio quality estimation module A_TSm int 1024 Basic audio parameter calculation module A_NTS int 472 Basic audio parameter calculation module 3) Basic audio parameter extraction module from RTP sequence number and payload The basic audio parameter extraction module from RTP sequence number and payload extracts the packet-loss length (A_PLLk) per pack
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