Capturing/digitizing video or stills
- Use the Web interface to route the
relevant deck to moviola. Moviola only has digital input, not
composite. If it's a digital deck like the digibeta, then route directly by
middle-clicking the deck and left-clicking moviola. If it's not
digital, then you'll need to route through a transcoder like FS1 or
FS2: middle-click the deck, left-click a transcoder, then middle-click
that transcoder and left-click on the moviola item in the list on the
right (under Computers).
- If you're making a movie and if you don't already have a
directory on the
/nle directory on moviola, make yourself
one. That's a 30GB fast local disk array dedicated to video stuff. You
need to capture to a local disk to get high enough bandwidth, don't
even try using a NFS-mounted one.
- Start up the
capture program on moviola from your
/nle subdirectory. (It's also known as
- You can either capture movies or still frames. The movie icon is
the leftmost one on the bottom left (the little camera), the still
frame icon is the rightmost of those three (the face).
- In either case, you want to pick the Digital option under the
O2 Video Hardware item.
- If you're making a movie, select Tasks->Movie->Video
Production(JPEG) from the menus to create fullsize frames with
hardware JPEG compression. You can use the Show Tasks Settings under
the Tasks menu to customize the size and compression. I recommend that
you use JPEG compression if you want nice smooth motion. Using any of
the other (software) codecs or no compression at all will result in a
jerky movie. I also recommend using the popular QuickTime movie format
instead of the obscure SGI movie format, provided only for backward
- If you're grabbing a still frame decide on the size (full,
half, quarter) and format (SGI/RGB, TIFF, GIF, and JPEG/JFIF), either
by picking something preset from Tasks->Image or going totally custom
through Tasks->Show Task Settings.
- Decide what directory you'd like your saved files to be saved
into. Use the text input box on top of the browser area on the
right. Note that if you're saving movies, you should save onto
local disk to minimize chances of missing frames.
- The record button is the little red circle in the lower right. If
you're capturing a still image, just hit the button once. If
you're capturing a movie, you'll need to hit the record button
to start and the blue square stop button to finish. The screen
will freeze briefly after an image capture. After a movie
capture, more processing will happen, as shown by a dialog
- You can view saved images or movies from the browser on the right. If
you doubleclick on a movie file, it will automatically play on
the left. If you doubleclick on an image file, it will appear
on the left. To return to previewing the video input source,
hit the blue square stop button.
- You can change the default name if you want by clicking on the
text. If you just keep clicking the record button, the
- You can use the standard image processing tools on the SGI to
change your image files into another format. For example, "togif
image1.rgb image1.gif", or "sgitopnm < image1.rgb | pnmscale
-xysize 100 100 > smallimage1.ppm", or "convert image1.rgb
image1.jpg". You can always use xv if you want to convert
using a GUI.
- For simple video processing, you can use the movieconvert
program on the SGI. For more complex processing, use Adobe Premiere on the SGI or
Avid MCXpress on the PC.
- If you want frame-accurate control over the deck as you
capture, or want to set up many precise batch captures, use Adobe Premiere instead of
If you have already recorded an audio voiceover and you're sitting in
the video lab recording a live video segment, it's often really useful
to be able to hear the voiceover at the same time as you're running
your live screen capture, so you can get the timing right. (For
instance, you want to time it so that when you say the word "now" in
the phrase "and now we see the foobar lighting effect" you hit some
key that will have a visible result. I'm assuming you've already split
the voiceover into scene-sized chunks in your audio waveform editing
The reason this is nontrivial is that digitizing live video at the
highest possible quality takes all the CPU time and disk bandwidth on
moviola. So playing back the audio files from moviola is not a good
thing to do simultaneously with inbound video digitizing. And you
can't play back audio files from radiance since its CPU is in another
room and moreover it doesn't support audio playback. That leaves
crossbar as the only SGI in the room which can safely emit audio. But
crossbar is far enough away from moviola and the lab is loud enough
that simply using its builtin speaker isn't very helpful, so you need
to wire up its audio out into the audio in jacks on the IO panel and
routed it through the mixer board into the main lab speakers.
Copy the relevant audio files over to the /tmp disk on crossbar. (You
want them local to crossbar instead of playing off moviola's disks.)
Then you can rsh to crossbar from the console on moviola and start up
a soundplayer app that appears on the moviola console. It's safe to
have the soundplayer GUI on moviola's console: it's not going to cause
any resource contention, since the disk and CPU usage are all on
crossbar. Then the digitizing person can just click two buttons on
moviola's console in quick sucession (the soundplayer play button and
the digitizing record button) in order to start things going.
Moviola's troubleshooting section for exact
symptoms and how to fix.
If you're having trouble with dropped frames (i.e. things look jerky)
when capturing video:
- If when you try to use JPEG compression you have trouble or get
error messages, try reseating the video board. The connection has been
known to be flakey in the past, perhaps because moviola is in a
location where it gets kicked often. See
- Make sure you're using hardware JPEG compression. The software
codecs will definitely drop frames. Uncompressed video is the
worst of all, we definitely do not have enough bandwidth to
get a 14MB/sec stream onto disk.
- You can tell capture to abort if frames are dropped while
capturing a movie. It's a radio button under image in the Task
Settings panel. This is much easier than doing the whole
capture, and then eyeballing it.
- Make sure you're recording on to the local disk, not your
NFS-mounted home directory. Moviola has a
big local /nle partition just for video recording.
- You should turn off audio capture if you only care about video, since
it's on by default and takes up bandwidth. Pick the "Do not
record audio track" radio button under the Audio tab on the
Task Settings panel.
- All of the above suggestions are lossless. You should be able
to digitize fullsize video smoothly using the JPEG hardware.
If somehow you're still having trouble and are desperate, here
are some suggestions that will lower the quality of your
video, but at least in a manner of your own choosing:
- Reduce from fullsize frames to halfsize frames.
- Reduce the frame rate from 30 to 15, under the logic that it's
better to have lower temporal resolution than random
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Last modified: Fri Jan 28 15:17:32 PST 2000