Video editing on a RiscPCBy Peter Noble. Published: 18th Oct 2005, 13:22:42 | Permalink | Printable
Smile, you're on cameraLiving in New Zealand, RISC OS user Peter Noble uses his RiscPC and Videodesk to edit film and produce presentations and videos for friends and family. Here, he talks us through how he typically puts together a short video.
I first became interested in video editing after my wedding in 1999. I've always had an interest in photography, but after visiting the person who put together my wedding video, my interest was raised. The person was using an Apple Power Mac 9600 with a 300MHz G3 processor, 128GB disk and lots of memory. I believe he was using Radius to do the editing and was also using Digital Video (DV). He had an expensive setup, but as an Acorn user for over 10 years, at that point I was interested in what my StrongARM powered RiscPC could do. I did consider using a PC or Mac but in the end I decided to stick with Acorn as I love the simplicity of RISC OS.
After a bit of research, I tracked down some old Acorn User magazines with articles about Acorn video cards and, obviously, the Videodesk product. There were other packages around but none could achieve full screen video at PAL standard: 768 x 576 pixels. So Videodesk was it, and in 2000 I set about trying to buy a product that had a retail price of £999. I was lucky enough to get a second hand Videodesk card and software for £435. After upgrading my VRAM from 1 to 2MB and purchasing a brand new 30GB IDE drive, I was ready to start my journey. My machine had a massive 34MB of RAM including the VRAM and that is what I used for the first three projects. I now have finally upgraded to 128MB as the version of Videodesk that I use (1.08 beta version 1) has a slight memory leak problem.
As most people are aware, video editing is a rather memory hungry affair and Videodesk is no exception, but in a RISC OS fashion, it is possible to use it on a machine with only 34MB of RAM. With my increased system memory, it now uses about 70MB during the editing process.
What can Videodesk do?
First released in 1996, Videodesk is a non-linear video editing suite - which means it allows users to build up a video in an order other than what will appear in the final order of scenes. It is also a non-destructive video editing suite, and while most modern applications are non-destructive, back in the mid- to late-1990s, not all were. This means that when you do a fade or anything that changes the source material, a new piece of video is created for this effect, preserving the source data. In destructive video editing, the actual source material is altered, making it difficult to adjust effects or reuse sequences. It's very much like the difference between working with bitmap and vector graphics.
Videodesk records analogue video via a RCA or S-VHS input and then through the use of the chips on the accompanying expansion card, it converts that analogue signal into video data. This is recorded in MJPEG format, also known as 'motion JPEG'. The IDE interface on my machine can record video data to the hard disc at a rate of 1.2MB per second (plus sound), whereas SCSI is supposed to sustain 2MB per second (plus sound). DV requires considerably more. Essentially, a lot of disc space can be quickly consumed when handling video files. Videodesk can also record in Replay format, but only at much lower resolutions and Replay uses considerably more disc space in comparison.
Videodesk supports the use of multiple video and audio tracks, and is only really limited by the disc speed for playback. It also has a range of titles and basic effects, such as fade, blur, wipe and dissolve. Generally speaking, these effects are all that most people need unless one wants to enter into the world of movie type effects and motion tracking. Still pictures can also be digitised for use in video production.
Once the different video clips have been edited and placed in order, the final video can be then sent via the expansion card out to a video recorder - again via RCA or S-VHS. There is no option to output to a computer format like MPEG, but a video can be output as an entire group of MJPEGs and then converted if someone had software to do that.
Videodesk also has the feature of unlimited undo and redo; every save of the edit line contains all the moves from beginning to end so as long as there is disc space for this log of changes, the user can always get access to any previous editing work.
Making a movie
Once I have recorded the source video, I connect the camera via a S-VHS cable to the hardware card and set about bringing the video in. The first decision to make concerns the quality of the recording as every second of video is made up of 25 frames of images in the PAL standard of 768 x 576. Videodesk has an option to halve the vertical resolution and therefore decrease the amount of compression performed and therefore processor time spent on each frame. The frames are actually interlaced and made up of 2 fields, with one showing the even scan lines and the other field showing the odd scan lines. In the following project, I used this option, and also set the sound quality to 16bit stereo, sampled at 32kHz.
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Videodesk stops recording to a file once it hits the 2GB file size mark, so for any film that's over about 30 minutes in length, there will be a number of video clips that need to be stitched together. As this is not a DV system, the computer cannot control the video camera remotely, so there is a manual process of stopping and starting the source device. Videodesk does allow access to the timing information encoded onto video tape by the camera, so this helps align the recording once it is in the computer. For the short recording described below, I decided not to use this 'timecode' functionality.
The current project I'm working on for my brother is a short 4 minute 30 second video of a play he performed for his local church, held outside at a community fair. I captured the video in a number of different styles, including in black and white. This was to ensure I filmed a perfect run as once recorded, Videodesk can't alter the colour quality or brightness of the video, as opposed to something that can, such as Cineworks.
The total size of the project is quite small at only 1.6GB, as the largest I have put together was over three hours long and weighed in at 16GB. All the files are saved in a project directory. This directory is the only place that Videodesk will accept files from, so when I later add the audio tracks, I will copy the sampled .wav audio files into a new sub-directory in the project. Below are two screenshots, one from this current project after I had just finished bringing in the video, and the other from a previous, larger project, titled 'Hapua'.
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You can see the different movie files, each up to 1.5GB, and the imported still images for static pictures. The 'fxdata' directory at the top contains sub-directories used for storing all the special effects. The introduction of DVDburn from hubersn Software has finally encouraged me to backup the 'Hapua' project to something other then a hard disc.
Once a project is loaded, the user sees a screen showing clips of video, and here begins the process of planning how the piece will all come together. For this project, I hoped to add my standard credits at the beginning and also some still photos from the play during the closing credits. I also planned to add a track from a CD to go alongside the credits at the end.
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The story board for this project was planned as follows:
- Run Peter's standard introduction credits
- Run credits with background audio from the play
- Play flier with background audio for the play
- Fade to video of the play
- Fade out to credits of people in the play with still photos, backed by CD track
The most complex piece of work that I have put together so far was a farewell video of my parents leaving their house - the aforementioned Hapua project. The first four minutes of this film had over 60 cuts running through all the people who came to the event, which was a rather large job seeing as I had 90 minutes of source video to go through. For this shorter project, I will use just one scene, namely my brother's live play.
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In the scene window, I can move clips around, and also change the running order in the time-line editor. I can also add or move the audio around, linking it to and unlinking it from the video if I so wish. In this case, I uncoupled the audio and cut out some of the video as I want to have some audio running during the introduction credits without showing the video that the sound was recorded with.
I also added a fade to allow the black background introduction credits to fade into the black opening flier. My StrongARM processor performs the effects and saves the rendering at a rate of two frames per second, which is about a twelfth of real-time video. Interestingly, this is about 11 times faster then an ARM610 powered machine, which I tested just for fun. Another observation is that during editing, all the work is done on the ARM chip and not on the Videodesk graphics card, and from what I can tell, the hardware card is just sending video from the hard disc to the RCA and S-VHS outputs for viewing.
For previous films, I developed a standard credits clip that involves animated text moving in from a number of different areas of the view and crossing over. To achieve this requires four different titles being rendered from bottom to top to enable the cross-over effect.
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This short video also used another set of credits as it was obviously a joint film made with the help of my brother. All the credits were designed as static screens. I produced them first as drawfiles, using DrawWorks Millennium and ArtWorks, and later exported the graphics as spritefiles using Art2Spr. These were then dropped into Videodesk as static stills. This means that the credits for this project involved a large number of fades between the different static images. The picture below shows the whole project with all the fades visible - they are the green dots on the 'Effects 2' line. In Videodesk, using static pictures tends to be clearer than using the built-in titling functions.
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As I go through the editing process, Videodesk has the ability to view two different video tracks being edited frame by frame, and I can also view the edits and current sequence in real-time on an external monitor, as the application can't perform playback on the desktop without a RiscTV card or similar. I understand that Dave McEwen's Cineorama can play MJPEGs so it would be interesting to see how that would work on a RiscPC.
The final step is just tidying up the audio and adding the CD track. As you can see in the screenshot above, there is a fade in for the recorded audio and fade outs and fade in for the CD track. For the CD track, I ripped it from the CD only to be reminded by Videodesk that it would only accept 32khz 16bit stereo sound. After a slight panic, SoundCon came to the rescue to convert the audio to the required format, and the final audio was added with appropriate fade effects. With all the edits done, I sent the full video and audio package to a DVD recorder for safe keeping. And that's it: Another project complete, lots of fun, and although it was hard work in places, hopefully the audience will enjoy my efforts.
The future of video editing and RISC OS
Videodesk isn't developed or actively sold any more and I don't think that Irlam are around. My view is that we have the software, but it needs tweaking here and there, although Cineworks looks nice. It has more features than the Videodesk package and also seems easy to use.
What needs to happen is three things: A DV card for the Iyonix and support in Cineworks to read DV files. I would expect that the Iyonix would be fast enough to play full screen DV in full frame or missing every second frame, which probably does really not matter during the editing process. The final thing is for some suitable media authoring software that has the ability to transfer the DV files to a DVD. It is a huge undertaking, but it does seem to be the way to get video editing onto the leading hardware that we have.
Stay tuned for an example video produced by Peter on RISC OS, available from drobe.co.uk soon.
Videodesk from CJE Micros
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