Preparing for Video Capture into PFClean

2 Sep, 2016 | KNOWLEDGE BASE, PFCLEAN

In this blog we will be covering some useful information to help you start capturing video media from a tape deck straight into PFClean. This will include system requirements for different tape formats, preparing your system for tape capture and some tips to help you along the way.

The workstation from our workstation build guide is a great way to start capturing tapes in PFClean as it is able to ingest all SD, HD and rarer 2K video formats as uncompressed AVIs directly into PFClean. If you’re modifying your own system or just want to check to make sure your system is on spec here are some general rules for system preparation to follow.

01. Storage

The table below will give you a good indication of the write speed your drive must achieve for a given format and the approximate storage a 90 minute feature will require. It is important to note that drive write speeds are not linear and will fluctuate over time with buffering and heat. As a rule, 30% head room on top of the data rate must be allowed for stable tape capture and avoidance of dropped frames. For example, to capture PAL 50i with a data rate of 30 MB/s a drive write speed of 40 MB/s must be achieved.

A drive’s performance can deteriorate as it fills up, so it is important to monitor your storage and not take it too close to maximum capacity. Generally it is advised not to take your storage within 10% of maximum capacity especially in the case of a multi disk array such as RAID.

When using HDD rather than SSDs it is important to check that the drives are in an active state (spinning) before committing to a capture. Most mechanical drives will fall into a sleep state after a given amount of time and will not be up to full write speed until they have spooled up. SSDs will always be better than HDDs at capturing but can be very expensive when dealing with multiple TBs of captures.

VIDEO FORMATDATA RATE MB/s
(approximate)
REQUIRED DRIVE WRITE SPEED MB/s
(approximate)
STORAGE (90min feature)
(approximate)
PAL 50i/25p 8bit3040156.4 GB
PAL 50i/25p 10bit3748195.5 GB
NTSC 60i/30p 8bit30.540158.4 GB
NTSC 60i/30p 10bit37.549198 GB
NTSC 60i/23.98p 8bit30.540126.6 GB
NTSC 60i/23.98p 10bit37.549158.2 GB
HD PAL 50i/25p 8bit148.3193782.1 GB
HD PAL 50i/25p 10bit185.4241977.6 GB
HD NTSC 60i/30p 8bit178231938.5 GB
HD NTSC 60i/30p 10bit222.52891.15 TB
HD 24p 8bit142.3185751 GB
HD 24p 10bit178231938.6 GB
HD 23.98p 8bit142.2185750.8 GB
HD 23.98p 10bit177.8231938 GB

02. Capture Card

When installing a capture card it is important to check which is the appropriate slot to install it into on your motherboard. In the case of the card we have selected for our workstation build, the Blackmagic Design Decklink Studio 4K requires a 4 lane PCIe generation 1 socket. Some cards will require 8 and 16 lanes and not every socket on motherboards will be compatible so it is important to consult your motherboard manual before installation. Common problems with cards not working are insufficient bandwidth and/or power. In order to remote control the VTR from PFClean a 9-pin remote cable is required to be connected from the deck to the workstation and the appropriate switch engaged on the VTR. The cards will have their own software for engaging the digital input/outputs and analogue input/outputs so it’s important to check which is selected for your given tape source. For the new thunderbolt based Mac Pro, the Blackmagic UltraStudio 4k will provide both analogue and digital inputs for capturing in PFClean.

03. Signal Purity

There are a plethora of inline hardware scalers, de-noising and image enhancement systems available such as the Teranex, but better results can be achieved with a greater degree of control inside of PFClean.

With any kind of restoration, signal purity from the source is of utmost importance and will always achieve the best restoration results. Trying to work with material that already has layers of interpolation from inline hardware can be problematic, especially when trying to unpick problems that they often create. Working with the source directly inside of PFClean enables you to make the kind of decisions and adjustments that are just not possible post-capture using inline equipment. Additionally it gives you the opportunity to make multiple versions for archiving and delivery from the one capture, saving you time and limiting the amount of stress on the tape.  

Purity of the capture becomes hugely important when dealing with a tape that has deteriorated so badly it has required baking. Quite often only a few opportunities to capture the tape at its best can be made post-baking, making PFClean’s integrated workflow the highest quality and the most delicate way to handle precious archive material.

04. Physical Inspection

When handling any legacy tape format it is imperative that a physical inspection must be undertaken before ingesting it, as damage can be caused to the VTR and the media. This is physically easier on formats such as 1” and 2” where the tape is exposed outside of its chassis. The main things to look out for when performing the inspection are warping, wrinkling and stretching of the tape along with excess moisture oxidisation along the edges due to poor binder adhesion/loss of backing (sticky-shed syndrome). Continuous squealing of tape can be a sure sign there is a problem developing and must be attended to before further damage is caused.

05. Time Base Corrector

Older analogue video formats such as domestic VHS have a very weak unstable signal and may require the use of a Time Base Corrector in order to successfully capture the tape into PFClean. A Time Base Corrector will buffer the video signal and slowly release it at a steady rate, allowing domestic analogue formats to sync with professional broadcast equipment such as a capture card.

06. All is Not Lost

Sometimes the tape capture is out of your hands and despite the condition of some tapes, all is not lost, many common tape faults can be fixed in near real time inside of PFClean’s powerful new Telerack toolset. Deeper problems that require a great deal attention can also be fixed using PFClean’s trusted effects in the Workbench.

Related Posts

0 Comments

Submit a Comment

Your email address will not be published. Required fields are marked *

Share This

Share This Post On: