oct 16
blender projects
what's coming next
- Thursday - meet in libraray media lab with Hilary
- see assignments page : nothing for Hendricks, then project proposal, then video
- video
- I've put up a bunch of links on the resources page; start reading
- (Note also that nearly all the technical terms in my explanations that follow, e.g. NTSC, have tasty wikipedia articles...)
- assignment(s) based on readings coming after Hendricks
video - background info, take 1
First you have to understand something about telvision and film.
NTSC (National Television System Committee) is the U.S. standard.
(Europe's is PAL, Asia's is SECAM)
29.97 frames per second
interlaced (that is, odd lines 1/60'th sec, even lines next 1/60)
(see http://en.wikipedia.org/wiki/Interlace )
based originally on 60Hz US electrical
(adjusted downward when color came out because of frequency beat patterns)
484 horizontal scan lines + 41 lines of other data
PAL, for comparison, based on 50Hz electricity, was 50fps interlaced
(which showed a bit of noticable flicker; now is usually 100fps)
and has 625 lines, which gives it a higher spatial resolution.
Film is typically
24 frames per second
progressive (that is, one image per frame)
How's it actually work? (the physics)
You can see this is going to be a mess
- lots of different spatial resolutions and timings. And it only gets worse.
In current practice, 640x480 video is about what a typical TV does.
Much smaller is aimed at a small screen, like an iPod.
Much bigger is heading towards "HD" (high definition)
Frame rates vary. Most common are 30p, 60i, 24p
23.976p - converts to NTSC easily
24p - cinematic film
25p - PAL, SECAM (europe and asia)
30p - common for modern camera capture; little flicker
50i - PAL (Eurpean TV)
60i - NTSC (U.S. TV)
file formats : containers vs codecs
containers :
.avi - microsoft's
.mov - apple's (quicktime)
.mp4 - standard MPEG4 container
.m4v - apple's iTunes store mpeg4 container
codecs :
MJPEG - Motion JPEG (i.e. one jpeg image per frame)
MPEG-1 - low bandwidth video CD
MPEG-2 - DVD's
MPEG-4 - Advanced Simple Coding;
common modern computer format
good compression; HD compatible
DivX, XviD, 3ivX, are all variations
H.264 - also called MPEG4 AVC
'Advanced Video Coding'
apple iPod uses it
more compute intensive than MPEG-4
RealVideo (.rm 'real media' container, or streamed)
WindowsMediaVideo (.wmv container)
Theora - open source
usually in .ogg container
usually with Vorbis audio
... and then most of these can be paired with a variety of audio ...
Video cameras, camcorders, and all that
my FujiFilm F10 digital camera does 640x480p30
stores up to about 18min on 1GB SD memory card
transfers to computer as foo.avi (container)
with MJPEG (motion jpeg - basically 60 .jpg's/sec)
JVC GR-X5U
'DV format SD mode' = 640x480i60
recorded onto miniDV tape
OK Jim, why do I need to know all this?
- If you're working with video at all, you need to understand what you have, what you want, and how to convert it - otherwise you're spitting into the wind. IMHO.
software (coming)
- players
- converters / burners
- editors
coming
- we'll see what time allows
- look at files on a DVD
- internet movie : what's really being played? Can I download it?
- Applications on Jim's Mac :
- QuickTime Player ($25 for editing extras - plays files)
- DVD Player (part of Mac OS - plays DVD's / VIDEO_TS folders)
- iMovie HD (simple import; extremely minimal editing; $ or with new Mac)
- Snapz Pro X ($ - video screen capture)
- FFmpeg - open source conversion tool; various versions
- Handbrake - DVD to MPEG4 etc
- MacTheRipper - DVD to disk (VIDEO_TS folder)
- Other editing applications
- wikipedia: List of video editing software
- Final Cut Pro - in library media lab
- open source
- I still haven't had complete success (e.g. stable, simple, strong) with these, but I'm still looking ...
- Avidemux - (mac, win, linux); see wikipedia:avidemux - installed on Mac OS X with DarwinPorts - so far I'm not amazed.
- Jahshaka (alpha release; unfinished)
- Cinelerra (linux - looks complicated, supposed to be powerful, wants big iron); see wikipedia:cinelerra
