a 3dtv broadcasting scheme for high-quality stereoscopic content over a hybrid network

IEEE TRANSACTIONS ON BROADCASTING, VOL. 59, NO. 2, JUNE 2013 281

A 3DTV Broadcasting Scheme for High-QualityStereoscopic Content Over a Hybrid Network

Jangwon Lee, Kugjin Yun, and Kyuheon Kim

Abstract—Various methods are used to provide three-dimensional television (3DTV) services over a terrestrial broad-casting network. However, these services cannot provide high-quality 3D content to consumers. It is because current terrestrialbroadcast networks are allocated with limited bandwidths totransmit 3D content while 3D content requires larger bandwidthcompared to that of 2D content. To overcome this limitation,this paper proposes a hybrid 3DTV broadcasting system, whichutilizes both a terrestrial broadcast network and a broadbandnetwork. In the proposed system, two elementary streams of leftand right views for a stereoscopic video service are transmit-ted over a terrestrial broadcasting network and a broadbandnetwork, respectively. In addition, the proposed system suggestsa new mechanism for synchronization between these two ele-mentary streams. The proposed scheme can provide high-quality3DTV service regardless of bandwidth of the terrestrial broadcastnetwork while maintaining backward compatibility with a 2DDTV broadcasting service.

Index Terms—3DTV broadcasting, bandwidth limitation, hy-brid network, high-quality 3DTV service.

I. Introduction

ADVANCES in 3D digital technologies enable consumersto enjoy the 3D visual experience on electronic devices at

home. The interest in 3D broadcasting services using a digitalTV (DTV) system has increased in recent years. Consequently,the volume of 3DTV products on the market has expandeddramatically, and broadcasters have begun to explore thepossibility of delivering 3D content to homes. In addition,many international and industrial standard bodies, such asMoving Picture Experts Group (MPEG), Society of MotionPicture and Television Engineers (SMPTE) and Digital VideoBroadcasting (DVB) have developed specific standards forthe compression, storage, and transmission of 3DTV content[1]–[4].

In this circumstance, many research and development inindustrial and academic fields have focused on 3DTV broad-casting schemes for stereoscopic content over the legacy DTV

Manuscript received September 6, 2012; revised January 3, 2013; acceptedJanuary 8, 2013. Date of publication May 1, 2013; date of current versionMay 20, 2013. This work was supported in part by the Ministry of KnowledgeEconomy, Korea, under the Information Technology Research Center SupportProgram (NIPA-2012-H0301-12-1006) and supervised by the National ITIndustry Promotion Agency. This paper was recommended by AssociateEditor Y. Wu.

The authors are with the Department of Information and Electron-ics Engineering, Kyung Hee University, Yongin, Korea (e-mail: [email protected]; [email protected]; [email protected]).

Color versions of one or more of the figures in this paper are availableonline at http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TBC.2013.2256678

channel [5]–[11]. However, by using these schemes 3DTVservices are limited in terms of the quality of 3DTV contentbecause of the limitation in bandwidth of the legacy DTVchannel. These schemes transmit stereoscopic content withinthe capacity of the DTV channel by reducing their resolutionor Signal-to-Noise Ratio (SNR), which causes the degradationof quality in 3DTV content compared to 2D one.

Nowadays, TVs have are evolving into hybrid TVs, whichuse both broadcast and broadband networks, and thus enablevarious interactive rich media services based on TV and web-based content [12]–[14]. These hybrid TV services are notonly richer in terms of content, but also more powerful interms of transmission bandwidth than the legacy DTV services[15], [16]. The capacity of the current broadband network issufficient to provide high quality video streaming services.Thus, if both broadcasting and broadband networks are usedfor the same hybrid 3DTV program, it is expected that 3DTVservices with higher qualities can be realized. Therefore,this paper proposes a new 3DTV broadcasting scheme overhybrid networks to overcome the current bandwidth limita-tions and to maintain 2D DTV services, regardless of 3DTVservices.

Stereoscopic content is composed of left and right viewsequences, which are independently encoded into two el-ementary streams. In the proposed scheme, one stream isdownloaded as a file over a broadband network in advance ofthe designated viewing time. The other stream is transmittedin real time over a broadcast network, and then the twostreams are linked for the display of one program. However,it is difficult to combine the streams from two independentnetworks into one program due to different delays causedby disparate encoding times and transmission environments.Therefore, the proposed hybrid 3DTV broadcasting schemesuggests a new synchronization mechanism between left andright view streams from broadcast and broadband networks.Furthermore, this mechanism provides the frame accuratesynchronization required for precise display of each pair ofleft and right view frames of the stereoscopic content.

This paper is organized as follows. In Section II, the hybrid3DTV broadcasting system is conceptually introduced bycomparing it to the current 3DTV broadcasting system. Theproposed hybrid 3DTV broadcasting scheme is explained inSection III, and it is experimentally verified in Section IV.Finally, Section V provides an analysis of the proposed hybrid3DTV broadcasting scheme with recommendations for futurework on this topic.

0018-9316/$31.00 c© 2013 IEEE

282 IEEE TRANSACTIONS ON BROADCASTING, VOL. 59, NO. 2, JUNE 2013

Fig. 1. Conceptual diagram of current 3DTV broadcasting services, (a) Frame compatible method, (b) Dual stream method.

II. Hybrid 3DTV Broadcasting Service

A. Current 3DTV Broadcasting Service

There are two representative schemes for current 3DTVbroadcasting services based on a legacy DTV channel: theframe compatible method and the dual stream method.

1) Frame Compatible Method: Fig. 1 (a) shows a concep-tual diagram of the frame compatible method. This methoduses a frame compatible stereoscopic video sequence, which isa compound of one of two images for left and right views [5].In this broadcasting system, the compound image sequence isencoded into an MPEG-2 video stream [17] with 17.5 Mbps,and then transmitted in MPEG-2 Transport Stream (TS) [18]in the same manner as a legacy 2D DTV system. Thus, thismethod provides stable and fully compatible functionalities interms of both media compression and delivery with a current2D DTV service system.

However, this compound image sequence causes a loss inquality caused by the half resolution of the individual left andright view sequences in a single compound sequence. In thecase of using frame compatible images of the side-by-side typeas shown in Fig. 1 (a), for example, the horizontal resolutionsof original left and right view images are reduced by half. Inaddition, the broadcasting services provided by this methodhave the problem of showing a compound image sequence forlegacy 2D DTV users. In order to prevent this problem, it isnecessary to allocate a separate TV channel for this 3DTVservice.

2) Dual Stream Method: The dual stream method wasdeveloped in order to counter the previously explained dis-advantages of the frame compatible method, such as the lossof resolution and the lack of 2D DTV compatibility. As shownin Fig. 1 (b), 2D base and 3D auxiliary video sequences forindividual left and right views with full resolution are usedin this method, in which two sequences are independently

encoded with MPEG-2 video and MPEG-4 Advanced VideoCoding (AVC) [19]. The two encoded streams are multiplexedinto one TS, and then transmitted within the DTV channel. Inthis method, most legacy 2D DTVs do not have a problem inhandling the 3DTV signal since legacy 2D DTVs discard the3D auxiliary video stream, and then decode and play only the2D base video stream, which is fully compatible with legacyDTV ones [6], [7].

However, in this method the 3DTV services also havelimitations on quality since the two streams are transmittedwithin the legacy DTV channel capacity of 19.4 Mbps. Cur-rent DTV broadcasting systems allocate mostly below the17.5 Mbps for video streaming. Thus, both streams of left andright views are also allocated within 17.5 Mbps. Generally, anMPEG-2 video stream of 12∼13 Mbps for the 2D base videosequence and an MPEG-4 AVC stream of 5–6 Mbps for the 3Dauxiliary video sequence are used in this method [6]. Thus, thequality of content in this method is lower than in the legacyDTV service, which uses a single stream wholly allocated in17.5 Mbps.

B. Concept of Hybrid 3DTV Broadcasting Service

This paper proposes a new 3DTV broadcasting service thatadopts a hybrid network. As shown in Fig. 2, the design ofthis method is based on the dual stream method previouslyexplained in Subsection II-A.2. However, the 3D auxiliaryvideo stream is transmitted separately as the files over abroadband network in advance of the broadcasting time. Thus,the 2D video stream can be allocated fully in 17.5 Mbps of abroadcasting signal.

As explained in Section I, both 2D base and 3D auxiliaryvideo streams must be synchronized to achieve a 3D displayin a hybrid 3DTV receiver. This paper proposes a newsynchronization mechanism by constructing a “timed-indexstream” that carries the timeline of the 3D auxiliary video

LEE et al.: 3DTV BROADCASTING SCHEME FOR HIGH-QUALITY STEREOSCOPIC CONTENT OVER A HYBRID NETWORK 283

Fig. 2. Conceptual diagram of the hybrid 3DTV broadcasting service.

Fig. 3. MPEG-2 TS timing model.

stream in the file. The timed-index stream is composed ofthe successive timed-index, where each timed-index containsa specific frame number of a 3D auxiliary video stream in thefile. The timed-index stream is synchronized and multiplexedwith a 2D base video stream by the legacy MPEG-2 TSmultiplexer. Therefore, the hybrid 3DTV receiver can processboth 2D base and 3D auxiliary video streams in a MPEG-2TS synchronized manner, even though the 3D auxiliary videostream is transmitted outside the MPEG-2 TS.

Since the timed-index stream is ignored, and only the 2Dbase stream is decoded in legacy 2D DTVs, 2D compatibleservices are also possible through the proposed hybrid 3DTVbroadcasting scheme. In addition, the timed-index streamdoes not influence the bandwidth allocation of the 2D basevideo stream in the MPEG-2 TS. It is because each timedindex is realized by a simple data structure with a smalldata size.

III. Hybrid 3DTV Broadcasting Scheme

A. Service Signaling Method

As explained in Subsection II-B, 3D auxiliary video filesfor a hybrid 3DTV program are delivered in advance ofthe designated service time of the hybrid 3DTV program.The delivered files are stored in the local storage of thehybrid 3DTV receiver, and should be played on time inthe program. Thus, the signal of the hybrid 3DTV programon air must include information for hybrid 3DTV servicesignaling, which describes the linked files of the program. Thispaper proposes a descriptor as shown in Table I, where thefile−linkage−service−descriptor() is used to identify the files

TABLE I

Syntax of File Linkage Service Descriptor

Syntax No. of Bitsfile−linkage−service−descriptor(){descriptor−tag 8descriptor−length 8

linkage−file−count 8for(i=1; i<linkage−file−count; i++){

file−ID 8linkage−file−name−length 8linkage−file−name Variable

}}

linked with the hybrid 3DTV program. In this descriptor, thelinkage−file−count means a count of the files linked with thecurrent hybrid 3DTV program. The file−ID is a unique identi-fier of the linkage file, and the linkage files are referenced withthis field from the linksge−file−timed−index(), which is ex-plained in the next subsection. The linkage−file−name−lengthdescribes the byte length of the following linkage−file−name,which identifies each file name including a path in a localstorage of a hybrid 3DTV receiver. As shown in Table I, thelinkage files are repeated the same number of times as thelinkage−file−count. Thus, it is possible to support multiplefiles for one hybrid 3DTV program, which enables flexible andefficient file editing and management. For example, individualfiles contain a divided time slot of the program with a longduration, and thus a receiver can handle only one of the filesfor the current time slot.

This file−linkage−service−descriptor() is located in Pro-gram Specific Information (PSI) tables of MPEG-2 TS, suchas Program Map Table (PMT). Since PSI tables are first parsedduring the MPEG-2 TS demultiplexing process, the proposeddescriptor located in PMT can signal the start of the hybrid3DTV service and provide service information, such as adirectory of the files used in the hybrid 3DTV program. A 2DDTV or a hybrid 3DTV receiver without the files describedin this descriptor displays only a 2D base video stream. Thus,the proposed hybrid 3DTV broadcasting scheme can providecompatible service for all users.


Fig. 4. ISO base media file structure.

B. Synchronization Method

In order to display left and right streams that are sep-arately transmitted over broadcast and broadband networks,it is essential to provide a mechanism for synchronizationbetween those two streams. Moreover, this synchronizationmechanism should guarantee reliable accuracy to a framelevel since individual pairs of stereoscopic left and right viewframes should be displayed at the same time. Therefore, thispaper proposes the synchronization mechanism for hybrid3DTV based on the MPEG-2 TS timing model shown in Fig.3. This approach enables the proper design of an accuratesynchronization mechanism with minimum modification of theexisting system.

As shown in Fig. 3, MPEG-2 TS offers the system timeclock (STC) based timing model for synchronization betweenvideo and audio signals. The program clock reference (PCR)is the sampled value of a program’s system clock with afrequency of 27 MHz. The PCR fields are carried in theTS packet headers and periodically transmitted to a receiver.Through the PCR transmission, the receiver periodically re-constructs the transmitter’s clock. The decoding time stamp(DTS) and presentation time stamp (PTS) of individual pack-etized elementary stream (PES) packets are set according tothe transmitter’s clock, so the receivers can decode and renderaudio and video streams at the appointed time [18].

The 3D auxiliary file is constructed as a specific fileformat. The ISO base media file format [20] is considereda representative file format specification, and thus is used asa base structure for the various derived files, such as the MP4[21]. As shown in Fig. 4, the ISO base media file format isbroadly composed of two parts: the movie (moov) box and themedia data (mdat) box. The mdat box contains all samples,where each sample is an encoded frame of the audio or videostreams. The moov box provides a directory of all samplescontained in the mdat box. In this box, the stbl box providesall information on individual samples, such as a data locationand timing. Thus, a receiver can access any specific frame inthe file when the frame number is provided.

Therefore, this paper proposes a newly defined “timed-index” structure to describe the specific file and the framenumber, as shown in Table II. As shown in Table II, thelinkage−file−timed−index() contains an index of a specific

TABLE II

Syntax of Linkage File Timed-index

Syntax No. of Bitslinkage−file−timed−index(){

linkage−flag 1reserved 7if(linkage−flag){

file−ID 8frame−number 32

}}

frame in a linked file, which is one of the files listed inthe file−linkage−service−descriptor() explained in Table I.The linkage−flag indicates whether an index exists in thisstructure or not. When this field is set to 0, a hybrid 3DTVreceiver displays only a 2D base video frame in the 2D modewithout the linkage of a 3D auxiliary video frame. Thus,the proposed broadcasting scheme enables a flexible 3DTVbroadcasting scenario, such as a 3DTV program composedof sequentially mixed 2D and 3D video streams [6][7]. Thefile−ID appoints one of the linkage files that are listed in thefile−linkage−service−descriptor(). The frame−number is aninteger that indicates a specific frame in the appointed file.The frames in the file are sequentially numbered from 0 bythe order of decoding time of each frame.

The timed-index structures for successive frames of a 3Dauxiliary stream converge in the timed-index stream. Thisstream is synchronized and multiplexed in one TS with a 2Dbase video stream, as in the case of audio and video streamsshown in Fig. 3.

C. Transmission Method

This section explains the overall procedure in the proposedhybrid 3DTV broadcasting system for transmitting the hybrid3DTV signal, which contains the service descriptor and thetimed-index stream explained in the previous subsections. Thesystem is broadly composed of two parts: a 2D base TSmultiplexer and a 3D auxiliary file server for broadcastingand a broadband network, respectively.

As shown in Fig. 5, the 3D auxiliary video sequence isencoded by an AVC decoder and constructed as a specific file,such as MP4. The file manager creates a list of the generatedfiles, including their broadcasting program date, their time andlocation in a server, and their path and name in a receiver.This file list can be provided to receivers with a web service,as the Electronic Program Guide (EPG) does. When usersselect the program they want to watch in 3D view, the receiverdownloads the linkage files via the file location in the server.The downloaded files are stored with the appointed file pathand name that are provided in the file list. Thus, a receivercan obtain the linkage files of the program in advance of thedesignated service time.

When the hybrid 3DTV program begins to be broad-casted, the section generator encodes a PSI section such asa PMT containing the service signaling information suggestedin subsection II-A. For example, as shown in Fig. 5, the


Fig. 5. Block diagram of 2D base TS multiplexer and 3D auxiliary file server.

file−linkage−service−descriptor() in the PMT describes theinitial information of hybrid 3DTV broadcasting, where thetwo files are used for the hybrid 3DTV program. This de-scriptor contains the linkage−file−name, which is the sameas the file path and name in the file list provided by thefile manager. The second loop describes individual streaminformation, including both the 2D base video and the timed-index stream. Since the 2D base video is defined by thesame type as a legacy 2DTV video stream, this paper definesthe 0 × 02 value as the stream−type for the MPEG-2 videostream. This paper also defines the value of the stream−typefor the timed-index stream as 0x06, which is defined for PESpackets containing private data in MPEG-2 TS specification.These interoperable definitions of stream−type enable multi-plexing schemes that are compatible with current broadcastingsystems. However, other streams, excluding the timed-indexstream, could have the stream−type of 0×06 in a program. Inthis case, the timed-index stream can be uniquely identified bythe existence of the file−linkage−service−descriptor() in theinner loop.

The 2D base video sequence is encoded by a MPEG-2 videoencoder, and the timed-index generator encodes the timed-index stream by the method suggested in subsection II-Awith the index information, which is received from the filegenerator. The index information contains the decoding andpresentation time of all frames that are provided with stts andctts boxes in the ISO base media file format, as shown in Fig.4. Using this information, the timed-index generator createssequential timed-indices in the decoding order of the frames.

Fig. 6. Example of DTS and PTS decision in the case of “IPPP. . . ” and“IBBP. . . ” prediction structures.

The PES packetizer gives the timing information to 2D basevideo and timed-index streams by recording DTS and PTS ineach PES packet header. In this procedure, one 2D base videoframe and one timed-index are paired in decoding order, andthey have same DTS, as shown in Fig. 6. If the decoding orderand the presentation orders of 2D base and 3D auxiliary videostreams are the same, the pairs will also have the same PTS.Otherwise, there is a gap between the PTS of the pairs. Fig. 6shows the case of “IPPP. . . ” and “IBBP. . . ,” the structuresused for 2D base and 3D auxiliary video streams, respectively.The gap in PTS is caused by different decoding delays in thetwo streams. Each decoding delay is equal to the number ofhierarchy levels minus 1 [22]. The gap of the PTS (�T h) instreams for hybrid broadcasting can be defined as in (1), where


Fig. 7. Hybrid T-STD model.

�T f denotes the frame interval of two streams, and decodingdelays of the 2D base and 3D auxiliary video streams aredenoted by �tdbase and �tdaux, respectively.

�Th = (�tdaux − �tdbase) × �Tf (1)

As shown in Fig. 6, �tdbase and �tdaux are 0 and 1,respectively, since the number of hierarchy levels of “IPPP. . . ”and “IBBP. . . ” are 1 and 2, respectively. Thus, there is �Th ofone frame duration in this case. If the 2D base and 3D auxiliaryvideo streams have the same prediction structures as in thecurrent 3DTV service [23], then �Th is equal to 0. The PTSgaps between the 2D video and the timed-index stream shouldbe considered in a receiver, as explained in the next subsection.After the PES packetizing procedure, both the 2D base videostream and the timed-index stream are multiplexed into oneMPEG-2 TS, which also contains the service descriptor andtimed-index stream explained in Subsections III-A and B,respectively.

D. Hybrid Transport System Target Decoder (Hybrid T-STD)Model

The T-STD is a conceptual model for modeling the decodingprocess during the construction or verification of MPEG-2 TS[18]. Based on this MPEG-2 T-STD model, this paper proposesa new hybrid T-STD model for a stable decoding process andsynchronization management of decoders and buffers linkedto both broadcasting and broadband networks.

As shown in Fig. 7, the proposed hybrid T-STD is composedof both legacy T-STD components for a 2D base video streamand newly designed buffers and decoders for both a timed-index stream and 3D auxiliary files. The file buffer denotedby FBaux is filled with 3D auxiliary file data from the storage.An access unit of the timed-index stream, denoted Aidx(j), isdecoded by the timed-index decoder (Didx) at tdbase(j), whichis the decoding time of Aidx(j). At the same time, a decoded

timed-index denoted idx(j) is sent to FBaux, and an access unitof the 3D auxiliary file (Aaux(j)) is extracted by using idx(j).The extracted Aaux(j) is transferred to the decoder (Daux) attdidx(j), which is the decoding time of idx(j). If the 2D baseor 3D auxiliary video streams need re-ordering according tothe use of B-frame pictures, the decoded frames are transferredto individual re-ordering buffers, which are denoted Obase andOaux, respectively. The re-ordering buffers output the decodedframes Pbase(k) and Paux(k) at the individual presentationtimes tpbase(k) and tpidx(k), respectively. If the streams do notneed re-ordering, the decoders directly output the decodedframes at tpbase(k) and tpidx(k). As explained in Subsection III-C., there is a gap of �T h between tpbase(k) and tpidx(k) whenthe 2D base and 3D auxiliary video streams have differentprediction structures. The hybrid buffer (HBbase) removes thegap by keeping Pbase(k) during �T h. Thus, the minimum sizeof the hybrid buffer (HBSmin) can be defined as in (2), wherethe bitrate of Pbase(k) is denoted by PSbase.

HBSmin = �Th × PSbase (2)

HBbase outputs Pbase(k) at tpbase(k) + �T h, which is equalto tpidx(k). When the 2D base and 3D auxiliary video streamshave the same prediction structures as described in SubsectionIII-C, the two streams can be synchronized without practicalHBbase, since tpbase(k) is equal to tpidx(k). Therefore, in allcases, the frames of the stereoscopic video pair in both the2D base and 3D auxiliary video can be displayed at the sametime.

IV. Experimental Result

This section presents the experimental results of a labo-ratory test for verifying the feasibility and conformance ofthe proposed hybrid 3DTV broadcasting scheme. As shownin Fig. 8, a test-bed was developed for various experimen-tal broadcasting services, which includes both the proposed


TABLE III

Experimental Service Configuration

Servicetype

Stereoscopic videosequences

Codec Bit rate /Resolution

Encapsulation

Framecompatible

Side-by-side MPEG-2video

17.5 Mbps /1920*1080

MPEG-2 TS

Dualstream

2D base video(left)

MPEG-2video

12.5 Mbps /1920*1080

MPEG-2 TS

3D auxiliary video(right)

MPEG-4AVC

5.0 Mbps /1920*1080

Hybrid3DTV

2D base video(left)

MPEG-2video

17.5 Mbps /1920*1080

MPEG-2 TS

3D auxiliary video(right)

MPEG-4AVC

10.0 Mbps /1920*1080

MP4 file

hybrid 3DTV broadcasting scheme and the current 3DTVbroadcasting schemes, such as the frame compatible anddual stream method. The test-bed is composed of severalsubsystems, such as the TS multiplexer (TS MUX), the TSpumper, the file generator, the file server, and three kinds ofreceivers, including 2D DTV, 3DTV, and hybrid 3DTV.

The TS MUX is a software platform that performs proce-dures for the legacy MPEG-2 TS generation, such as MPEG-2 video encoding, PES packetizing, and TS multiplexing. Toimplement dual stream method service explained in SubsectionII-A.2), the AVC encoder is also embedded in this subsystem[7]. Moreover, the TS MUX supports the proposed hybrid3DTV broadcasting scheme, which includes the service signal-ing method by inserting the file−linkage−service−descriptor()in the PMT section, as explained in Subsection III-A. Thesynchronization method is implemented by constructing thetimed-index stream as explained in Subsection III-B. Withthis service signaling and synchronization information, theTS MUX generates the MPEG-2 TS for the hybrid 3DTVbroadcasting service, as explained in Subsection III-C. TheTS pumper transmits the generated MPEG-2 TS for the legacy3DTV or hybrid 3DTV to the receivers though a digital videobroadcasting asynchronous serial interface (DVB ASI) cable.

The 3D auxiliary file for the hybrid 3DTV service isgenerated with its timed-index by the file generator, as shownin Fig. 8. The timed-index is packetized and multiplexed intoone MPEG-2 TS with the 2D base video stream by the TSMUX, and the file is delivered to the hybrid 3DTV receiverfrom the file server, where the server and the receiver areindividually connected to the Internet by the Gigabit Ethernet(GbE), as shown in Fig. 8.

The receivers perform TS demultiplexing, PES depacketiz-ing, decoding, and the displaying process. In particular, thedesign of the hybrid 3DTV receiver is based on the hybrid T-STD model explained in Subsection III-D for the conformancetest of the proposed hybrid 3DTV broadcasting scheme. The3DTV receiver is designed according to the frame compatibleand dual stream method introduced in Subsection II-A. The2D DTV receiver is a general MPEG-2 TS player that candecode the current 2D DTV signals only.

As shown in Fig. 8, the TS MUX and the file generatorconstruct three different types of services for the same content:frame compatible, dual stream and the proposed hybrid meth-ods. Table III also shows the configuration for these services.

TABLE IV

Comparison Results of PSNR

Service typePSNR (dB)

Left video Right videoFrame compatible 35.52 35.72Dual stream 37.39 37.87Hybrid 3DTV 39.46 39.67

First, the frame compatible service contains a side-by-sidetype of stereoscopic video stream, which is encoded withMPEG-2 video of 17.5 Mbps, as specified in Subsection II-A.1. The second service is built by the dual stream methodas explained in Subsection II-A.2 where left and right videosequences are encoded with MPEG-2 video of 12.5 Mbps andMPEG-4 AVC of 5.0 Mbps, respectively. The final service isconstructed by complying with the hybrid 3DTV broadcastingscheme proposed in this paper. It contains the MPEG-2 videostream of 17.5 Mbps for left video sequence and the timed-index stream for hybrid synchronization. This service containsa 3D auxiliary video file in the MP4 file format, which includesa right video stream of 10.0 Mbps. In particular, in order toverify the synchronization method proposed in Subsection III-B, the frame numbers are marked at the top left corner ofall frames in both left and right sequences, as shown in Fig.8. All video sequences in these three services have the sameresolution of 1920*1080 and durations of 1133 seconds.

The images on the 3DTV and hybrid 3DTV receivers inFig. 8 are captured from the polarized 3D display. As shownin these images, the hybrid 3DTV service on the hybrid 3DTVreceiver shows more clear pictures than the frame compatibleand dual streaming services in the 3DTV receiver.

Table IV shows the comparison results of Peek Signal-to-Noise Ratio (PNSR) between the streams of the threeservices. The PSNR of the left video stream in the hybrid3DTV service is higher than that of the frame compatible anddual stream services by 3.94 and 2.07 dB, respectively. Theright video stream of the hybrid 3DTV has 3.95 and 1.80higher PSNR than that of frame compatible and dual streamservices, respectively. These results show objective qualitiesof the 3DTV content are naturally increased by the expansionof the allocated bit-rate for the stereoscopic video streams.

In order to verify synchronization of the 2D base and 3Dauxiliary video streams, the frame numbers are marked in allframes, as shown in Fig. 8. The marked frame numbers ofthe left and right video sequences exactly correspond overall stereoscopic video pairs in the test content. According tothis result, the proposed synchronization method is accuratelyperformed with streams separately transmitted by hybrid net-works.

Moreover, the left video streams in the hybrid 3DTV serviceas well as in the dual stream service are displayed in the 2DDTV receiver in 2D mode, while the frame compatible videostream is displayed as it is in the side-by-side type. Moreover,as the results show in Table IV, through the proposed broad-casting scheme it is feasible to offer 2D-compatible servicewith a higher quality than the service offered by the currentdual stream method.


Fig. 8. Experimental test-bed configuration and results.

In the above experiments, the file for the hybrid serviceis transferred by an HTTP file downloading scheme over IP,where the download time is 77.32 seconds in an averagedownload rate of 17.47 Mbps. Furthermore, the bandwidth forthe timed-index stream is 4.5 Kbps and is thus a negligibleamount of bandwidth in the 19.4 Mbps bandwidth of the wholeMPEG-2 TS.

V. Conclusion

This paper proposed a new scheme to broadcast 3DTV overa hybrid network. In order to maintain compatibility with alegacy 2D DTV receiver, the design of this scheme is based onthe stereoscopic dual stream method. In addition, the schemeprovides a way to overcome the bandwidth limitation of thecurrent 3DTV broadcasting service by using a hybrid networkthat is widely adopted by current smart TVs. This schemeincludes a new service signaling method, a synchronizationmethod between individually transmitted streams, a transmis-sion method with a newly designed timed-index stream and 3Dauxiliary files, and a hybrid T-STD model for the modeling ofa practical hybrid 3DTV receiver.

The proposed scheme would make possible a 3DTV broad-casting service with higher quality than the terrestrial 3DTVbroadcasting services that are currently available. Furthermore,the proposed technology can support not only 3DTV servicebased on stereoscopic content, but also many more kinds ofcontent and applications, such as scalable video coding (SVC)and multiview video coding (MVC) [19] content services thatneed an accurate synchronization mechanism to broadcast overa hybrid network.

References

[1] Text of ISO/IEC 13818-1:2007/AMD 7 Signaling of Stereoscopic Videoin MPEG-2 Systems, document N12462, ISO/IEC JTC1/SC29/WG11,San Jose, CA, USA, Feb. 2012.

[2] Text of ISO/IEC 13818-2:2000/DAM 4 Frame Packing Arrangement Sig-naling for 3D Content, document N11794, ISO/IEC JTC1/SC29/WG11,Daegu, Korea, Jan. 2011.

[3] Stereoscopic 3D Full Resolution Contribution Link Based on MPEG-2TS, SMPTE ST 2063-2012, SMPTE, 2012.

[4] Frame Compatible Plano-Stereoscopic 3DTV (DVB-3DTV), DVB docu-ment A154, DVB, Feb. 2011.

[5] A. Vetro, A. M. Tourapis, K. Muller, and T. Chen, “3D-TV contentsstorage and transmission,” IEEE Trans. Broadcast., vol. 57, no. 2,pp. 384–394, Jun. 2011.

[6] N. Hur, H. Lee, G. Lee, S. Lee, A. Gotchev, and S. Park, “3DTVbroadcasting and distribution systems,” IEEE Trans. Broadcast., vol. 57,no. 2, pp. 395–407, Jun. 2011.

[7] K. Yun, K. Kim, N. Hur, S. Lee, and G. Park, “Efficient multiplexingscheme of stereoscopic video sequences for digital broadcasting ser-vices,” ETRI J., vol. 32, no. 6, pp. 961–964, Dec. 2010.

[8] N. Hur, G. Lee, W. You, J. Lee, and C. Ahn, “An HDTV-compatible3DTV broadcasting system,” ETRI J., vol. 26, no. 2, pp. 71–82,Apr. 2004.

[9] G. B. Akar, A. M. Tekalp, C. Fehn, and M. R. Civanlar, “Transportmethod in 3DTV: A survey,” IEEE Trans. Circuits Syst. Video Technol.,vol. 17, no. 11, pp. 1622–1630, Nov. 2007.

[10] A. M. Tekalp, E. Kurutepe, and M. R. Civanlar, “3DTV overIP,” IEEE Signal Process. Mag., vol. 24, no. 6, pp. 77–87,Nov. 2007.

[11] T. Schierl and S. Narasimhan, “Transport and storage systems for 3-Dvideo using mPEG-2 systems, RTP, and ISO File Format,” Proc. IEEE,vol. 99, no. 4, pp. 671–683, Apr. 2011.

[12] D. Lee, M. Lee, and D. Kang, “OHTV (open hybrid TV) serviceplatform based on terrestrial DTV,” in Proc. 12th Int. Conf. AdvancedCommun. Technol., Feb. 2010, pp. 399–402.

[13] TTA, Standard for Terrestrial Open Hybrid TV, TTAI.OT-07.0002, Dec.2010.

[14] Open IPTV Forum (OIPF). OIPF Release 2 Specification Volume1—Overview [V2.1]—[2011-06-21] [Online]. Available: http://www.openiptvforum.org/specifications.html


[15] K. Merkel, “Hybrid broadcast broadband TV, the new way to a com-prehensive TV experience,” in Proc. 14th ITG CEMT, Mar. 2011, pp.1–4.

[16] ETSI, Hybrid Broadcast Broadband TV, version 1.1.1, ETSI TS 102796, Jun. 2010.

[17] ISO/IEC, Information Technology—Generic Coding of Moving Picturesand Associated Audio Information: Video, ISO/IEC 13818-2:2000 sec-ond edition, Dec. 2000.

[18] ISO/IEC, Information Technology—Generic Coding of Moving Picturesand Associated Audio Information: Systems, ISO/IEC 13818-1:2007third edition, Oct. 2007.

[19] ISO/IEC, Information Technology—Coding of Audio-Visual Objects—Part 10: Advanced Video Coding, ISO/IEC 14496-10:2009 fifth edition,May 2009.

[20] ISO/IEC, Information Technology—Coding of Audio-Visual Objects—Part 12: ISO Base Media File Format, ISO/IEC 14496-12:2008 thirdedition, Oct. 2008.

[21] ISO/IEC, Information Technology—Coding of Audio-Visual Objects—Part 14: MP4 File Format, ISO/IEC 14496-14:2003 first edition, Nov.2003.

[22] H. Schwarz, D. Marpe, and T. Wiegand, “Analysis of hierarchical Bpictures and MCTF,” in Proc. IEEE Int. Conf. Multimedia Expo, Jul.2006

[23] TTA, Transmission and Reception for Terrestrial 3DTV Broadcasting—Part 1: Legacy Channel, TTAK.KO-07.0100, Dec. 2010.

Jangwon Lee received the B.S. and M.S. degrees inelectronics engineering from Kyung Hee University,Seoul, Korea, in 2007 and 2009, respectively. He iscurrently pursuing the Ph.D. degree in electronicsengineering with Kyung Hee University, Korea. Hiscurrent research interests include MPEG systemsand digital broadcasting technologies.

Kujin Yun received the B.S. and M.S. degrees incomputer engineering from the Chunbuk NationalUniversity of Korea, Cheongju, Korea, in 1999 and2001, respectively. He has been pursuing the Ph.D.degree in electronics engineering at Kyung HeeUniversity, Seoul, Korea, since 2011. He joinedthe Electronics and Telecommunications ResearchInstitute in 2001 and is currently with the Broad-casting System Research Group. His current researchinterests include the 3DTV broadcasting and MPEG-2/4 systems.

Kyuheon Kim received the B.S. degree in electronicengineering from Hanyang University, Seoul, Korea,in 1989, and the M.Phil. and Ph.D. degrees inelectrical and electronic engineering from the Uni-versity of Newcastle upon Tyne, U.K., in 1996. From1996 to 1997, he was with Sheffield University,U.K., as a Research Fellow. From 1997 to 2006, hewas with the Electronics and TelecommunicationsResearch Institute, Korea, as the Head of InteractiveMedia Research Team, where he standardized anddeveloped T-DMB specification, and conducted a

Head of Korean delegates for MPEG standard body from 2001 to 2005. Since2006, he has conducted research at Kyung Hee University, Seoul, Korea.He has published numerous technical papers. His current research interestsinclude interactive media processing, digital signal processing, and digitalbroadcasting technologies. Dr. Kim was a recipient of the Ministry Awardfrom the Ministry of Information and Communication in 2003 and the PrimeMinister Award in 2005.

a 3dtv broadcasting scheme for high-quality stereoscopic content over a hybrid network

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