Editing Acorn Archimedes (section)

=== Full-motion video ===

With the introduction of CD-ROM and the broader adoption of multimedia, Acorn announced a [[full-motion video]] system called Acorn Replay in early 1992, supporting simultaneous audio and video at up to 25 frames per second in the RISC OS desktop or in "a low resolution full screen mode". Unlike certain other full-motion video technologies, Replay offered the ability to read compressed video data from mass storage in real time and to maintain a constant frame rate, all on standard computing hardware without the need for dedicated video decoding hardware. The [[data compression|compression]] techniques employed by Replay reportedly offered "compression factors of between 25 and 40" on the source video data, with the software decompression requiring a computer with 2&nbsp;MB of RAM or more.<ref name="acornuser199203_replay">{{ cite magazine | url=https://archive.org/details/AcornUser116-Mar92/page/n10/mode/1up | title=Full Motion Video System for the Arc | magazine=Acorn User | date=March 1992 | access-date=29 October 2021 | pages=9 }}</ref>

Given a slower access medium such as CD-ROM or floppy disk, video could be played back at up to 12.5 frames per second, with up to 25 frames per second from a hard disk. One 800&nbsp;KB floppy disk could reportedly hold 12 seconds of video. In the introductory phase of the technology, support for Replay files was quickly introduced into hypermedia applications such as Genesis and Magpie, with software developers being the primary audience for the creation of content, largely due to the expense of the equipment required to capture and store large volumes of video data. Software developers would engage the services of a suitably equipped company to convert source material to digital form, with the Replay software then used to process the video frame by frame, employing image compression techniques and "a form of [[Delta encoding|Delta compression]]", ultimately producing a movie file.<ref name="acornuser199204_replay">{{ cite magazine | url=https://archive.org/details/AcornUser117-Apr92/page/n104/mode/1up | title=Action Replay | magazine=Acorn User | date=April 1992 | access-date=29 October 2021 | last1=James | first1=Paul | pages=103 }}</ref>

Acorn's introduction of Replay prompted comparisons with Apple's [[QuickTime]] system which was already broadly available to users of Macintosh systems. Replay's advantages included the efficiency of the solution on existing hardware, with even an entry-level A3000 upgraded to 2&nbsp;MB of RAM being able to handle 2&nbsp;MB of data per second to achieve the advertised 12.5 frames per second playback. In contrast, a Macintosh system with 2&nbsp;MB of RAM was reportedly unable to sustain smooth video playback, although audio playback was unaffected by the dropped video frames, whereas a 4&nbsp;MB system could achieve 15 frames per second from a CD-ROM drive, although such a system was more expensive than Acorn's ARM3-based systems that could more readily achieve higher frame rates. QuickTime was also reported as only able to play video smoothly at 1/16th of the size of the screen, also favouring 32,000 colour display modes that were available on Macintosh systems with 68020 or faster processors. One disadvantage of Replay on the Acorn systems was the limitation of playback to 256 colours imposed by the built-in video system.<ref name="acornuser199207_replay">{{ cite magazine | url=https://archive.org/details/AcornUser120-Jul92/page/n108/mode/1up | title=Action Replay | magazine=Acorn User | date=July 1992 | access-date=29 October 2021 | last1=Drage | first1=Chris | pages=107–109 }}</ref>

Educational software and resources providers saw the potential of Replay to deliver interactive video at a more affordable price than existing [[Laservision]] content, although it was noted that, at that time, Laservision still provided "the best quality, full-screen, moving image to date". Opportunities were perceived for making compilations of video clips available on CD-ROM for multimedia authoring purposes, although educational developers felt that the true value of the technology would be realised by making video like other forms of information, permitting its use in different contexts and works and thus offering children "control over the media". Educators also looked forward to more accessible authoring possibilities, with children being able to record, edit and incorporate their own video into their projects. However, the expense associated with handling video data, with the storage of one minute of video estimated at 60&nbsp;MB, combined with the expense of commercial video digitisation, estimated at £100 per minute of video, meant that such possibilities would remain inaccessible for most users at that time. Indications that this situation would change were present in the QuickTime market, with it already supporting the creation of short movies in conjunction with video digitiser cards and editing tools such as [[Adobe Premiere]].<ref name="acornuser199207_replay" />

Support for video authoring on the desktop emerged in 1993 with the Replay DIY product from Irlam Instruments: a single-width podule suitable for A540 and A5000 computers with 2&nbsp;MB of RAM or more, these being the only models available at the time with the necessary performance. The podule accepted analogue video input from video cameras, recorders and laserdisc players, allowing the video to be previewed in a window on the desktop. While recording, no preview would be shown, and the hardware would digitise the audio and video input, transfer the data to the computer's memory, and this would then be sent straight to a hard disk. At its introduction, the video quality was limited to "normal Arm2 Replay, that is 256-colour, 160x128 pixels at 12.5 frames per second", although an upgrade to capture 25 frames per second was anticipated. Uncompressed video occupied around 21&nbsp;MB per minute, but processing of such video using the provided Acorn Replay compression software would bring the size of the resulting video down to around 4 or 5&nbsp;MB per minute. Compression was, however, relatively slow, since the compression scheme was asymmetric, meaning that decompression was fast enough to facilitate playback in real time, but compression could take "a few minutes for every few seconds of video". Nevertheless, the possibilities of video capture were predicted to "generate and maintain immense interest in the classroom, or even at home", and the digitiser's low cost (at £250 plus VAT) together with low-cost editing software such as Uniqueway's Empire (at £50 plus VAT) was regarded as surprising, possibly in light of the high cost of services previously needed to achieve similar results.<ref name="acornuser199304_replay">{{ cite magazine | url=https://archive.org/details/AcornUser129-Apr93/page/n23/mode/1up | title=Four of a Kind | magazine=Acorn User | date=April 1993 | access-date=29 October 2021 | last1=Bell | first1=Graham | pages=22–23 }}</ref>

Further developments in the video authoring domain were brought to the platform by [[Square Enix Europe#Eidos Interactive|Eidos]], who had developed an "offline non-linear editing system" around the Archimedes in 1989, involving the digitisation of source video and its storage on hard disks or magneto-optical media for use with editing software. Such software would be used to produce an "edit schedule list" based on editing operations performed on the digitised, "offline" video, and these editing details would subsequently be applied in an "online" editing session involving the source video, this typically residing on "linear" media such as tape. To support the more convenient offline editing environment, a highly efficient symmetric compression scheme known as ESCaPE (Eidos Software Compression and Playback Engine) had been devised, offering movie sizes of around 1.5&nbsp;MB per minute. To remedy the time-consuming process of using Acorn's Replay compression software with the Replay DIY product, this being a consequence of the "Moving Lines" compression scheme emphasised by Replay at that time, Eidos introduced its own compression software for Replay DIY based on ESCaPE and given the same name. Together with the Eidoscope software, based on Eidos' professional Optima software, it was claimed that "no other computer platform has anything to match in terms of convenience and sheer usability" and that these developments would "encourage a lot more Archimedes users to have a go at making movies".<ref name="acornusr199308_eidos">{{ cite magazine | url=https://archive.org/details/AcornUser133-Aug93/page/n30/mode/1up | title=The cutting edge | magazine=Acorn User | date=August 1993 | access-date=29 October 2021 | last1=Burley | first1=Ian | pages=29–31 }}</ref> In 1995, Computer Concepts offered a bundle featuring Eidoscope and the company's Eagle M2 "multimedia card" which featured audio and video capture, improved audio playback, and MIDI ports. Aimed at non-professional applications, Eidoscope was limited to editing movies up to a resolution of {{nowrap|160 x 128}} and did not support [[Timecode|time codes]].<ref name="archimedean1995_i11">{{ cite magazine | url=https://archive.org/details/Archimedean_Issue_11_1995_Computer_Concepts_GB/page/n11/mode/2up | title=Pearls on film? | magazine=The Archimedean | publisher=Computer Concepts | date=1995 | issue=11 | pages=11–12 }}</ref>