视频传输是如何实现的? (2011)
How were video transfers made? (2011)

原始链接: https://www.film-tech.com/ubb/f12/t000972.html

这个论坛讨论详细介绍了胶片视频转录的发展历程。最初,将胶片转录到 VHS 或电视等格式依赖于“胶片链”——通过投影机和摄像机系统放映胶片以创建视频信号。常用的母带格式包括 2 英寸 Quad、1 英寸 C 型、Beta SP,以及后来的数字格式,如 D1、D2 和 Digi-Beta。 早期的系统需要特定的胶片速度和快门类型才能与电视标准(NTSC 或 PAL)同步。后来,飞行光点扫描仪提供了更温和的胶片处理和色彩校正功能。在 90 年代中期,典型的流程是将胶片转录到 Beta SP,然后复制到 1 英寸 C 型以进行 VHS 复制。 如今,该过程主要为数字化的。胶片逐帧或连续地使用“数据电影机”系统扫描,提供更高的精度和稳定性。软件工具可以校正图像问题并允许进行广泛的后期制作处理,从而产生更高质量的数字母带——这是与过去实时模拟方法相比的重大转变。 这也解释了为什么较旧的模拟格式即使分辨率较低,也可能具有独特的“胶片感”外观。

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原文

Author Topic: How were/are video transfers made?
Aaron Garman
Phenomenal Film Handler

Posts: 1470
From: Toledo, OH USA
Registered: Mar 2003
 - posted 07-29-2011 09:48 PM      Profile for Aaron Garman   Email Aaron Garman   Send New Private Message       Edit/Delete Post 
So I think I understand modern transfers: there is a master digital file that is then compressed for Blu-ray/DVD/etc. and then loaded onto the disc in the respective file format. That master digital file of course comes from many a different source, but I'd guess many from a 2K workflow.

My real question is how did it work before digital editing, digital tape, etc? How did they get the film (whether from a OCN, release print, etc.) onto say VHS, LaserDisc, or even television? And what format were those master tapes in? I'd imagine even some early DVDs had some sort of master tape before all digital workflows became popular.

Sorry for the novice questions, but I'm trying to understand that despite formats like Blu-ray having so much better resolution and clarity, that some of my old LaserDiscs have a more natural, analog, film-like look despite lower resolution and video noise.

AJG


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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99
 - posted 07-30-2011 07:54 AM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
The earliest system (used from the beginning of television through the 1980s and, to some extent, still) was a "film chain." This typically consisted of one or more 16mm or 35mm film projectors set up to project into a multiplexer (mirror device) that directed the images to a film-chain camera. The output of the camera would then be broadcast on the air or recorded to tape. 2" Quad and 1" C-type would have been common in the 1970s through the 1980s, with 1", Beta SP, D1, D2, and Digi-Beta becoming more common in the 1990s. D1, D2, and Digi-Beta are all digital formats; the others are analog.

Film-chain projectors in NTSC-land have fast-pulldown intermittents and 5-bladed shutters in order to sync properly with 59.94 Hz interlaced video. In PAL-land, the film is run at 25fps for the same reason.

Every TV station had a 16mm film-chain setup through the mid-1980s, at least. (Some may still have the equipment.)

I believe that flying-spot scanners like the Rank and Bosch were a 1970s and 1980s invention. Unlike film chain equipment, they are gentler on film and allow transfers from negative material, as well as scene-to-scene color correction. These are still used widely today, although frame-by-frame scanning has become more common, at least for big-budget feature films.

In 1995, I was involved with a project where the recommended process (which we followed) was a Rank film transfer to Beta SP, then a dub to 1" C-type for use as a master for low-volume VHS duplication (about 100 copies). Beta SP was considered to be of higher quality, but 1" was considered to be less prone to dropouts. The duplication process involved a playback deck, a distribution amp, and a rack of high-end VHS VCRs. High-volume VHS duplication is/was an entirely different process, which I don't know enough about to explain here.


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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001
 - posted 07-30-2011 10:18 AM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
Today most movies shot on film go through the digital intermediate process and no longer use traditional telecine systems that dub the film image to analog or digital tape in real time. These days the image is digitally scanned and then processed with a variety of software tools.

Current film scanners don't have as many of the technical problems that are inherent to traditional telecine systems. Some use the term "datacine" for these types of systems. Film scanners either carefully scan each film frame one frame at a time or pull the film through in continouous motion. Either way the systems are built to hold the images in a far more steady, more tightly focused manner. The software systems can correct a variety of problems, including movement of the film image. Some of that image-steadying technology has found its way into more mainstream applications like Adobe After Effects (the new warp stabilizer feature). You get a far more precise, more dynamic looking video master with the current crop of film scanning and post production image processing tools.

Here's some links to PDFs about certain film scanners currently in use.

Spirit 4K PDF

Northlight PDF

ARRISCAN PDF


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