DOCSLIB.ORG

Synchronization and Smpte Time Code

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Synchronization and Smpte Time Code Synchronization and SMPTe Time Code n film and video two different media, visual and auditory, must be experienced together. In order to create sound that works seamlessly with visuals, you need I. two playback systems-one strictly for audio and another strictly for video. These two systems must be capable of playing back together in perfect time. The process of · making two or more distinct audio or visual systems play back together is called synchronization. Synchronization is a basic principle of working with audio for video and film. Any alter­ ation of the audio must be done in the conteJKt of the visual image. It wouldn't be pos­ sible to establish and control the relationship between the two media without synchronization. A thorough mastery of the concepts and practices of synchronization will become invaluable as you get deeper and deeper into audio post-production. This chapter is devoted to synchronization theory, techniques, and real-world practices that you will use every day when creating sound for films and video. Synchronization Basics As I said, synchronization is the process of keeping two or more audio or visual systems running at the same speed and with the same relationship to each other. Keeping audio in sync with video means playing both together from the same point without either one moving faster or slower than the other. It is crucial to do this with a high degree of accuracy and repeatability, as every single edit and mix move you perform must be matched up with a certain action on-screen. Two things are necessary for accurate sync. The first is a positional reference, or the "where-in-time." The second is a playback rate, or "how fast." I like to use the analogy of cars on a two-lane highway. The positional references are the mile markers on the side of the highway that tell you where on the road you are. The playback rate is the speed of the car, for instance 65 mph. If you know what mile marker you're at and how fast you're traveling, it's easy to get another car moving along in sync with your car. Think of the audio as one car and the video as a second car in the next lane. If either car speeds up or slows down, the two cars will no longer be in sync. The drivers of 43 44 Pro Tools for Video, Film, and Multimedia, Second Edition Chapter 3 Synchronization and SMPTE Time Code 45 these two cars must be in constant communication with one another In order to maintain the correct speed and position. With Pro Tools and digital audio, this COlTl.II1U­ nication is handled in two ways-one for positional information and the other forr speed reference. Digital audio is based on a sampling frequency that determines how often the analog audio is digitally sampled and turned into numeric information. The source of thi ~ s sam­ pling frequency is referred to as the digital clock and is required for proper operat ion of any digital audio device. If the sampling frequency or clock speed is changed, the speed at which audio is played back will change accordingly. If the clock speed increas es, digital audio will play back faster and higher in pitch. If the clock speed slows, aud io will play back slower and lower in pitch. Thus, the sampling frequency can control t he speed of the audio. This is how the speed reference for synchronization is communiicated when using Pro Tools. Positional Reference You must assign unique numbers to each segment of audio and video in a projrect in order to know exactly where you are at any given point in either medium. For instance, Figure 3.1 An SMPTE readout displaying 1 hour, 11 minutes, 45 seconds, and 24 frames. bars and beat numbers can be used to identify locations in a piece of music. In wisua l systems, each frame of film or video must be given a unique number. This is aCiCOlTI­ Several standard frame rates for film and video are commonly used. They are as follows: plished through the use of SMPTE (Society of Motion Picture and Television Engirneers) time code. • 24 frames per second for film Every frame of film or video in an AV project may have a specific SMPTE time code • 25 frames per second for European or PAL video number assigned to it. SMPTE time code is the standard method by which you get ]posi­ • 29.97 frames per second for NTSC color video tional references in audio, film, and video (see Figure 3.1). SMPTE time code represents time in an eight-digit number with colons separating each time value for hours, minlUtes, • 30 frames per second for audio only or old B&W television seconds, and frames (OOh:OOm:OOs:OOf). A frame of SMPTE can be as small as 1/60t h of • 23.976 frames per second for HD video that converts to NTSC video a second or as large as 1I24th of a second, depending on how fast the film or vidreo is moving. I'll discuss the different frame rates in more depth in just a bit. For now, Ulllder­ • 59.94 frames per second for HD video that converts to NTSC video (29.97 x 2) stand that SMPTE time code numbers are positional references-they tell you where (often mistakenly referred to as 60fps) you are in a soundtrack or film. • 60 frames per second for HD video at its highest standard speed Playback Rate In digital audio, the rate at which sound is played back is not measured in frames but in The second thing you need to know to achieve accurate synchronization is how fast the samples. Each sample of audio is a unit of information, or slice of time, much in the frames are moving. In my highway analogy, this relates to the speed of the two cars. In same way that each frame of film or video is a single snapshot of time, although an film and video, the playback rate is the frame rate. In digital audio, the playback rate is audio sample is exponentially smaller in duration. The rate at which samples are played the sample rate or sampling frequency. The speed relationship between the audio and back (the sample rate) is usually expressed in kilohertz (abbreviated kHz); multiplying video must remain the same in order to be in sync. Otherwise, the audio will either slip the kilohertz number by 1,000 results in the number of samples per second-for exam­ ahead of or behind the video. ple, 44.1kHz represents a rate of 44,100 samples per second. Chapter 3 Synchronizatio~ and SMPTE Time Code 47 46 Pro Tools for Video, Film, and Multimedia, Second Edition There are several sample rates commonly used in audio production. They are as follows: the edge of the film, placing notes and then numbers to help the editing process. This evolved into the use of "feet and frames" as a mtasuring tool. Each second of film • 44.1kHz: The standard music sample rate. This is used to create the commercial contains 24 individual frames. A foot-long piece Gf 35mm film has 15 frames in it. music CDs people buy everyday. Using feet and frames with edge numbers made com]> licated editing much more feasible. This was the first time code, and it was used while editing film on machines similar to • 48kHz: The video and film standard. Professional digital video formats such as Sony's Digital Betacam use this sample rate. the one shown in Figure 3.2. • 88.2kHz: Hi-res music sample rate for audio CDs. Easily converts to 44.1kHz. • 96kHz: Hi-res sample rate for music and video; it is a multiple of 48kHz and is easier to convert. • 192kHz: Super hi-res sample rate for demanding recordings such as orchestral, jazz, and archival recordings. Currently impractical for film and video due to large file sizes, but may be used in the near future. To sum up, in order to synchronize audio and video, you must know the positional information, in the form of SMPTE time code and playback speed. Audio and video must start from the same position and play back at the same rate in order to maintain perfect sync. This might sound simple, but as you will see, it can get quite complicated once you consider all the variations in SMPTE formats and playback rates. Origin and History of Time Code In order to better understand the variety of SMPTE formats, let's take a look at how time code developed and eventually turned into the SMPTE format. Film In the early days of film, scenes were filmed from beginning to end with one camera and in one complete take. Film scenes paralleled the way plays on stage were viewed. The . only editing that would take place would be to cut all the scenes together in the correct Figure 3.2 A Moviola machine that is still used to edit fil ll1 and magnetic audio film together using order. The high-speed edits and rapid-fire cuts that are the norm today were simply not the system of feet and frames for counting. used in early film. Gradually, as filmmakers began to explore the new medium, new techniques of filming caught on. Soon, scenes were filmed in multiple takes using different camera angles, in NTSC versus PAL order to capture the action in new and exciting ways. These new filming techniques With the advent of television and then videotape lecording, new editing systems devel­ made the editing process much more complicated, as each scene had multiple edits oped that allowed video to be edited from multiple-source tapes onto a final master throughout.
Load more

Recommended publications
  • Shadow Telecinetelecine
    ShadowShadow TelecineTelecine HighHigh performanceperformance SolidSolid StateState DigitalDigital FilmFilm ImagingImaging TechnologyTechnology Table of contents • Introduction • Simplicity • New Scanner Design • All Digital Platform • The Film Look • Graphical Control Panel • Film Handling • Main Features • Six Sector Color Processor • Cost of ownership • Summary SHADOWSHADOTelecine W Telecine Introduction The Film Transfer market is changing const- lantly. There are a host of new DTV formats required for the North American Market and a growing trend towards data scanning as opposed to video transfer for high end compositing work. Most content today will see some form of downstream compression, so quiet, stable images are still of paramount importance. With the demand growing there is a requirement for a reliable, cost effective solution to address these applications. The Shadow Telecine uses the signal proce- sing concept of the Spirit DataCine and leve- rages technology and feature of this flagship product. This is combined with a CCD scan- ner witch fulfils the requirements for both economical as well as picture fidelity. The The Film Transfer market is evolving rapidly. There are a result is a very high performance producthost allof new DTV formats required for the North American the features required for today’s digital Marketappli- and a growing trend towards data scanning as cation but at a greatly reduced cost. opposed to video transfer for high end compositing work. Most content today will see some form of downstream Unlike other Telecine solutions availablecompression, in so quiet, stable images are still of paramount importance. With the demand growing there is a this class, the Shadow Telecine is requirementnot a for a reliable, cost effective solution to re-manufactured older analog Telecine,address nor these applications.
    [Show full text]
  • Problems on Video Coding
    Problems on Video Coding Guan-Ju Peng Graduate Institute of Electronics Engineering, National Taiwan University 1 Problem 1 How to display digital video designed for TV industry on a computer screen with best quality? .. Hint: computer display is 4:3, 1280x1024, 72 Hz, pro- gressive. Supposing the digital TV display is 4:3 640x480, 30Hz, Interlaced. The problem becomes how to convert the video signal from 4:3 640x480, 60Hz, Interlaced to 4:3, 1280x1024, 72 Hz, progressive. First, we convert the video stream from interlaced video to progressive signal by a suitable de-interlacing algorithm. Thus, we introduce the de-interlacing algorithms ¯rst in the following. 1.1 De-Interlacing Generally speaking, there are three kinds of methods to perform de-interlacing. 1.1.1 Field Combination Deinterlacing ² Weaving is done by adding consecutive ¯elds together. This is ¯ne when the image hasn't changed between ¯elds, but any change will result in artifacts known as "combing", when the pixels in one frame do not line up with the pixels in the other, forming a jagged edge. This technique retains full vertical resolution at the expense of half the temporal resolution. ² Blending is done by blending, or averaging consecutive ¯elds to be displayed as one frame. Combing is avoided because both of the images are on top of each other. This instead leaves an artifact known as ghosting. The image loses vertical resolution and 1 temporal resolution. This is often combined with a vertical resize so that the output has no numerical loss in vertical resolution. The problem with this is that there is a quality loss, because the image has been downsized then upsized.
    [Show full text]
  • ASPECT RATIO Aspect Ratios Are One of the More Confusing Parts of Video
    ASPECT RATIO Aspect ratios are one of the more confusing parts of video, although they used to be simple. That's because television and movie content was all about the same size, 4:3 (also known as 1.33:1, meaning that the picture is 1.33 times as long as it is high). The Academy Standard before 1952 was 1.37:1, so there was virtually no problem showing movies on TV. However, as TV began to cut into Hollywood's take at the theater, the quest was on to differentiate theater offerings in ways that could not be seen on TV. Thus, innovations such as widescreen film, Technicolor, and even 3-D were born. Widescreen film was one of the innovations that survived and has since dominated the cinema. Today, you tend to find films in one of two widescreen aspect ratios: 1. Academy Standard (or "Flat"), which has an aspect ratio of 1.85:1 2. Anamorphic Scope (or "Scope"), which has an aspect ratio of 2.35:1. Scope is also called Panavision or CinemaScope. HDTV is specified at a 16:9, or 1.78:1, aspect ratio.If your television isn't widescreen and you want to watch a widescreen film, you have a problem. The most common approach in the past has been what's called Pan and Scan. For each frame o a film, a decision is made as to what constitutes the action area. That part of the film frame is retained, and the rest is lost.. This can often leave out the best parts of a picture.
    [Show full text]
  • A R R I T E C H N I C a L N O T E
    A R R I T E C H N I C A L N O T E P - 1013 USA TV Ground Glass Markings Summary This note describes the frame outlines relevant to shooting film for television in the USA. The Important Frame Outlines to Know Both the markings on the ground glass and telecine calibration films are based on international standards that assure that an object framed in a given spot through the viewfinder will appear on that same spot in telecine. When shooting for television, one should be familiar with the following frame lines: Camera Aperture TV Transmission TV Safe Action TV Safe Title (not shown on most ground glasses) Please note that the frame outlines pictured above are for a Super 35 ground glass, and will be slightly different for other formats. Also note that TV Safe Title is usually not shown on most ground glasses. Full Aperture Corresponds to the full amount of negative film exposed. Caution: most ground glasses will permit viewing outside of this area, but anything outside of this area will not be recorded on film. This outline is usually found on ground glasses, but not in telecine. TV Transmission The full video image that is transmitted over the air. Sometimes also called “TV Scanned”. TV Safe Action Since most TV sets crop part of the TV Transmission image, a marking inside of TV Transmission has been defined. Objects that are within the TV Safe Action lines will be visible on most TV sets. This marking is sometimes referred to as “The Pumpkin”.
    [Show full text]
  • Spirit 4K® High-Performance Film Scanner with Bones and Datacine®
    Product Data Sheet Spirit 4K® High-Performance Film Scanner with Bones and DataCine® Spirit 4K Film Scanner/Bones Combination Digital intermediate production – the motion picture workflow in which film is handled only once for scan- ning and then processed with a high-resolution digital clone that can be down-sampled to the appropriate out- put resolution – demands the highest resolution and the highest precision scanning. While 2K resolution is widely accepted for digital post production, there are situations when even a higher re- solution is required, such as for digital effects. As the cost of storage continues to fall and ultra-high resolu- tion display devices are introduced, 4K postproduction workflows are becoming viable and affordable. The combination of the Spirit 4K high-performance film scanner and Bones system is ahead of its time, offe- ring you the choice of 2K scanning in real time (up to 30 frames per second) and 4K scanning at up to 7.5 fps depending on the selected packing format and the receiving system’s capability. In addition, the internal spatial processor of the Spirit 4K system lets you scan in 4K and output in 2K. This oversampling mode eli- minates picture artifacts and captures the full dynamic range of film with 16-bit signal processing. And in either The Spirit 4K® from DFT Digital Film Technology is 2K or 4K scanning modes, the Spirit 4K scanner offers a high-performance, high-speed Film Scanner and unrivalled image detail, capturing that indefinable film DataCine® solution for Digital Intermediate, Commer- look to perfection. cial, Telecine, Restoration, and Archiving applications.
    [Show full text]
  • 24P and Panasonic AG-DVX100 and AJ-SDX900 Camcorder Support in Vegas and DVD Architect Software
    ® 24p and Panasonic AG-DVX100 and AJ-SDX900 camcorder support in Vegas and DVD Architect Software Revision 3, Updated 05.27.04 The information contained in this document is subject to change without notice and does not represent a commitment on the part of Sony Pictures Digital Media Software and Services. The software described in this manual is provided under the terms of a license agreement or nondisclosure agreement. The software license agreement specifies the terms and conditions for its lawful use. Sound Forge, ACID, Vegas, DVD Architect, Vegas+DVD, Acoustic Mirror, Wave Hammer, XFX, and Perfect Clarity Audio are trademarks or registered trademarks of Sony Pictures Digital Inc. or its affiliates in the United States and other countries. All other trademarks or registered trademarks are the property of their respective owners in the United States and other countries. Copyright © 2004 Sony Pictures Digital Inc. This document can be reproduced for noncommercial reference or personal/private use only and may not be resold. Any reproduction in excess of 15 copies or electronic transmission requires the written permission of Sony Pictures Digital Inc. Table of Contents What is covered in this document? Background ................................................................................................................................................................. 3 Vegas ..........................................................................................................................................................................
    [Show full text]
  • Cinematography
    CINEMATOGRAPHY ESSENTIAL CONCEPTS • The filmmaker controls the cinematographic qualities of the shot – not only what is filmed but also how it is filmed • Cinematographic qualities involve three factors: 1. the photographic aspects of the shot 2. the framing of the shot 3. the duration of the shot In other words, cinematography is affected by choices in: 1. Photographic aspects of the shot 2. Framing 3. Duration of the shot 1. Photographic image • The study of the photographic image includes: A. Range of tonalities B. Speed of motion C. Perspective 1.A: Tonalities of the photographic image The range of tonalities include: I. Contrast – black & white; color It can be controlled with lighting, filters, film stock, laboratory processing, postproduction II. Exposure – how much light passes through the camera lens Image too dark, underexposed; or too bright, overexposed Exposure can be controlled with filters 1.A. Tonality - cont Tonality can be changed after filming: Tinting – dipping developed film in dye Dark areas remain black & gray; light areas pick up color Toning - dipping during developing of positive print Dark areas colored light area; white/faintly colored 1.A. Tonality - cont • Photochemically – based filmmaking can have the tonality fixed. Done by color timer or grader in the laboratory • Digital grading used today. A scanner converts film to digital files, creating a digital intermediate (DI). DI is adjusted with software and scanned back onto negative 1.B.: Speed of motion • Depends on the relation between the rate at which
    [Show full text]
  • 185 for Presentation July 8, 1971, NATIONAL CABLE TELEVISION
    185 For presentation July 8, 1971, NATIONAL CABLE TELEVISION ASSOCIATION, Washington, D. C. TELECINE SYSTEMS FOR THE CATV ORIGINATION CENTER by Kenneth K. Kaylor Phil ips Broadcast Equipment Corp. Although 11 1 ive'' programming is considered a necessary part of the program origination services of a community-oriented CATV system, tele- cine facilities will hold the key to success or failure of such an operation from an economic standpoint. The word 11 tele-cine11 was developed during the early days of television broadcasting to define those facil i- ties devoted to the video reproduction of the various film media. Since the original commercial telecine television camera was an 11 iconoscope11 camera which had a very large sensitive surface (about 11 11 3 x 4 ), a film projector was focused onto the sensor by using a standard projection lens as shown in Fig. 1. This technique was quite simple and optical alignment was very easy. E1 im i nat i ng the 11 Shutte r Bar" effect In the case of motion picture film, the theatre projector had to be modified in order to prevent a "shutter bar" effect caused by the 186 difference in frame rates between television and motion picture stan­ dards. Standard sound motion picture film operates at 24 frames per second while the U. S. standard for television scanning is 30 frames per second. The intermittent mechanism had to be modified so that the 1ength of time between "pu 11 -downs" a 1 te rnates between 1/20 and 1/30 second. The average of these two fractions is 1/24 second, or the time demanded by the standard 24-frame-per-second motion picture projection rate.
    [Show full text]
  • Glossary of Digital Video Terms
    Glossary of Digital Video Terms 24P: 24 frame per second, progressive scan. This has been the frame rate of motion picture film since talkies arrived. It is also one of the rates allowed for transmission in the DVB and ATSC television standards – so they can handle film without needing any frame-rate change (3:2 pull-down for 60 fields-per-second systems or running film at 25fps for 50 Hz systems). It is now accepted as a part of television production formats – usually associated with high definition 1080 lines, progressive scan. A major attraction is a relatively easy path from this to all major television formats as well as offering direct electronic support for motion picture film and D-cinema. 24Psf: 24 frame per second, progressive segmented frame. A 24P system in which each frame is segmented – recorded as odd lines followed by even lines. Unlike normal television, the odd and even lines are from the same snapshot in time – exactly as film is shown today on 625/50 TV systems. This way the signal is more compatible (than normal progressive) for use with video systems, e.g. VTRs, SDTI or HD-SDI connections, mixers/switchers etc., which may also handle interlaced scans. It can also easily be viewed without the need to process the pictures to reduce 24-frame flicker. 3:2 pull-down: Method used to map the 24 fps of film onto the 30 fps (60 fields) of 525-line TV, so that one film frame occupies three TV fields, the next two, etc. It means the two fields of every other TV frame come from different film frames making operations such as rotoscoping impossible, and requiring care in editing.
    [Show full text]
  • EBU Tech 3315-2006 Archiving: Experiences with TK Transfer to Digital
    EBU – TECH 3315 Archiving: Experiences with telecine transfer of film to digital formats Source: P/HDTP Status: Report Geneva April 2006 1 Page intentionally left blank. This document is paginated for recto-verso printing Tech 3315 Archiving: Experiences with telecine transfer of film to digital formats Contents Introduction ......................................................................................................... 5 Decisions on Scanning Format .................................................................................... 5 Scanning tests ....................................................................................................... 6 The Results .......................................................................................................... 7 Observations of the influence of elements of film by specialists ........................................ 7 Observations on the results of the formal evaluations .................................................... 7 Overall conclusions .............................................................................................. 7 APPENDIX : Details of the Tests and Results ................................................................... 9 3 Archiving: Experiences with telecine transfer of film to digital formats Tech 3315 Page intentionally left blank. This document is paginated for recto-verso printing 4 Tech 3315 Archiving: Experiences with telecine transfer of film to digital formats Archiving: Experience with telecine transfer of film to digital formats
    [Show full text]
  • IQMCC30 3G/HD/SD-SDI Motion Compensated Frame Rate Converter and Motion Adaptive Up, Down, Cross Converter
    User Instruction Manual IQMCC30 3G/HD/SD-SDI Motion Compensated Frame Rate Converter and Motion Adaptive Up, Down, Cross Converter www.s-a-m.com IQMCC30 Information and Notices Information and Notices Copyright and Disclaimer Copyright protection claimed includes all forms and matters of copyrightable material and information now allowed by statutory or judicial law or hereinafter granted, including without limitation, material generated from the software programs which are displayed on the screen such as icons, screen display looks etc. Information in this manual and software are subject to change without notice and does not represent a commitment on the part of SAM. The software described in this manual is furnished under a license agreement and can not be reproduced or copied in any manner without prior agreement with SAM, or their authorized agents. Reproduction or disassembly of embedded computer programs or algorithms prohibited. No part of this publication can be transmitted or reproduced in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage and retrieval system, without permission being granted, in writing, by the publishers or their authorized agents. SAM operates a policy of continuous improvement and development. SAM reserves the right to make changes and improvements to any of the products described in this document without prior notice. Contact Details Customer Support For details of our Regional Customer Support Offices, please visit the SAM website and navigate to Support/Customer Support Contacts. www.s-a-m.com/support/contact-support/ Customers with a support contract should call their personalized number, which can be found in their contract, and be ready to provide their contract number and details.
    [Show full text]
  • Standard 3:2 Pulldown, Explained by Arri
    A R R I T E C H N I C A L N O T E P - 1008 What is 3:2 Pulldown? July 20, 2000 Summary This note describes the 3:2 Pulldown process used in US Telecines to transfer 24 fps film to 29.97 fps video. Overview The 3:2 Pulldown process is a method to map the 24 frames per second (fps) that are captured during film production onto the 29.97 fps of a 525 line TV system, like the one used in the United States. This note concerns itself only with the 3:2 Pulldown process as used in the United States. Why 24 fps Film? Even though in the early days of film production many different fps rates were experimented with, most footage was captured at 18 fps as a compromise between flicker and raw stock cost. This changed when sound was introduced: To achieve reasonable sound quality the magnetic audio recorder had to move faster than 18 fps. 24 fps was adopted for the audio recorder and for the film camera. This has remained the speed of choice in the United States. Why 29.97 fps Video? The fps of video playback in the US was originally 30 fps. This speed was chosen to make a possible hum bar stationary in the picture, thus making it less objectionable. When color was introduced, the color information was superimposed over the B/W signal to ensure that the television broadcast could still be viewed on the old B/W sets. To make this work, the playback frequency had to be changed from 30 fps to 29.97 fps.
    [Show full text]