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A Software-Only Video Production Switcher for the Internet Mbone

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A Software-Only Video Production Switcher for the Internet Mbone A Software-Only Video Pro duction Switcher for the Internet MBone Tina Wong Ketan Mayer-Patel David Simpson Lawrence A. Rowe Computer Science Division University of California, Berkeley ftwong,kpatel,davesimp,[email protected] ABSTRACT single camera that mainly fo cuses on the sp eaker, and o ccasionally pans to show other materials such In this pap er, we describ e the design and imple- as slides on the overhead pro jector, a demo running mentation of a software video pro duction switcher, onaworkstation, or memb ers of the lo cal audience. vps, that improves the quality of MBone broad- This single camera approach is the most common casts. vps is mo deled after the broadcast televi- con guration seen in low-budget, small-scale broad- sion industry's studio pro duction switcher. It pro- casts on the MBone. vides sp ecial e ects pro cessing to incorp orate audi- We are working on to ols to improve the quality ence discussions, add titles and other information, and simplify the pro duction and control of MBone and integrate stored videos into the presentation. broadcasts. This pap er describ es the design and vps is structured to work with other MBone con- implementation of a software-only videoproduction ferencing to ols. The ultimate goal is to automate switcher vps that can b e used to improve the the pro duction of MBone broadcasts. quality of an MBone broadcast. vps is mo deled after a studio production switcher [9] used in the 1 INTRODUCTION broadcast television industry. A studio pro duction switcher is a custom-designed hardware device that Live programs are pro duced and broadcast world- provides an array of real-time editing and sp ecial ef- wide on the Internet MBone using IP Multicast [1] fects functions. A director can select one of several and the MBone [2] conferencing to ols e.g., vic [8], picture sources e.g., cameras, videotap es, and still vat [7], wb [3], sdr [5] etc.. Some examples are image displays to b e the output. Other sources are the NASA Space Shuttle Missions, conference pre- generated by the device by applying sp ecial e ects sentations e.g., Sixth International WWW Confer- pro cessing to one or more streams such as inserting ence, and livemusic p erformances. These broad- titles into a picture, sup erimp osing one picture on casts usually have audiences ranging from tens to another, chroma-keying, and wiping or fading from hundreds of viewers distributed world-wide. one picture to another. Wehave broadcast the weekly Berkeley Multime- vps will enhance the quality of an MBone broad- dia and Graphics Seminar on the MBone since early cast by providing e ects available in a hardware 1995. The seminar is pro duced using the LBL/UCB switcher. Sp eci call y,wewant to display lo cal and MBone to ols vic and vat to capture and transmit remote audience discussions and feedback, add ti- video and audio streams, resp ectively. The shared tles and credits, integrate stored analog and dig- whiteb oard to ol wb is used to distribute p ostscript ital videos into the presentation, and incorp orate slides. A second wb is used by the broadcast direc- sp ecial e ects to improve the visual images and tor hereafter, director to communicate with par- retain audience attention. Ultimately, our goal is ticipants in order to debug problems with the trans- to automate the pro duction pro cess byintegrating mission and monitor video and audio quality.We vps with a broadcast management system [13] that are also testing a o or control to ol qb [6] to facili- maintains ro om, equipment and broadcast con gu- tate question asking. The current broadcast uses a rations, observes eventschedules, and launches and monitors the MBone to ols required to pro duce a T. Wong is supp orted by a GAANN fellowship. 2 production drawing tool switcher INTERNET wb vps MBONE video capture STUDIO vic rtpgw MBONE video transcoding vat qb mbr audio capture floor control recording tool Figure 1: vps in an MBone Broadcast. broadcast. Figure 1 shows how vps ts into the current system. It is organized as follows. Section context of a typical MBone broadcast. The Stu- 2 presents an example of vps in use. Section 3 de- dio MBone is a lo cal domain network connecting scrib es the vps software architecture. The imple- the pro cesses required to pro duce the broadcast. It mentation of vps is describ ed in section 4. Section can supp ort high data rates e.g., 5 to 30 Mbs and 5 talks ab out future work and section 6 summarizes go o d quality video streams e.g., MJPEG video. the pap er. The public MBone is the Internet and it runs at a considerably lower sp eed. 2 AN EXAMPLE SCENARIO A hardware pro duction switcher is a highly de- We describ e how vps can improve the qualityofan velop ed technology that could b e used in an MBone MBone broadcast by illustrating its use through an broadcast. However, this solution has several limi- example scenario. tations. First, video sources must b e converted to a Before b eginning the scenario, we rst describ e switch-sp eci c analog format b efore b eing passed to the two GUI interfaces to vps: the director's con- the switcher and converted back to a digital format sole and the speaker's console, shown in Figures 2 and encapsulated as RTP data [11] after pro cessing and 3, resp ectively. The director's console pro duces so that it can b e sent to the MBone. vps avoids the content of the broadcast. The main window of these conversions by op erating on video streams in this console has an editor area at the top and a pre- the RTP representation. Second, a hardware sys- view area at the b ottom. The director uses the edi- tem is not extensible. vps is designed in a mo dular tor area to cho ose a sp eci c e ect editor and to con- manner to allow new e ects to b e added to the sys- gure the parameters of that e ect. The preview tem. Third, vps can b e controlled by other soft- area shows thumbnails of video sources including ware to automate decisions by a director through the results of applying an e ect. The director can reactive software heuristic technologies. Finally, click onathumbnail to see more information ab out a hardware switcher has only one user interface. that video. The output window of the director's vps can b e op erated by many GUIs ranging from console shows the current video b eing broadcast. a simple interface designed for a sp eaker to a so- This window also describ es the broadcast multicast phisticated interface designed for a skilled director. session, if applicable. The sp eaker's console allows Moreover, interfaces can b e customized for di erent the sp eaker to incorp orate stored videos into the users. lecture. It has a preview area similar to the direc- This pap er describ es the design of vps including tor's console. The sp eaker clicks on a thumbnail the GUI interface and the implementation of the 3 Figure 2: The Director's Console. to select and and bring up a VCR-like player to remote lo cations also have digital cameras attached playback a video. to their workstations, and the sp eaker has several The following shows how vps can b e used in this videos to accompany her lecture. The director uses 1 scenario. Supp ose a seminar is b eing conducted on these videos to pro duce the content of the broad- the Berkeley campus. Students on campus attend cast. He previews them in the preview area of the the seminar in the lecture ro om, and remote viewers director's console. He also monitors the broadcast join in virtually bywatching the broadcast on the with the output window. New video sources can b e MBone. added at any time during the broadcast. For ex- ample, a remote viewer who joins late can still b e a vps source and part of the lecture broadcast. Beginning a Lecture A short time b efore the lecture starts, the direc- tor switches from a still image that identi es the program to a picture showing the sp eaker. He uses the cut editor of the director's console to select this picture and switch sources. He then uses the subti- tle editor to insert the seminar title and the sp eaker name onto the picture. After a minute or so, the di- Figure 3: The Sp eaker's Console. rector removes the titles by switching to the original picture. Figure 4 shows screen shots that illustrates the op ening of the lecture. Viewing Sources and Monitoring the Broadcast 1 Supp ose there are two cameras in the seminar ro om: These videos might b e stored on a video le server or replayed on a VCR. one fo cusing on the sp eaker and one facing the au- dience. Supp ose further that participants at several 4 Figure 4: Pro ducing Op ening Phase of Lecture. Playing Stored Video Incorp orating Audience Discussions At some p oint in the lecture, the sp eaker wants A lo cal audience memb er raises his hand to notify to show a video. She uses the sp eaker's console the sp eaker that he has a question. A few remote to select and play the video.
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