[vorbis] Video codec

[Jelle Foks]

Jernej Simonèiè wrote:
> 
> ----- Izvorno sporoèilo -----
> Od: Chrissy and Raul <chrissyandraul at hotmail.com>
> |
> | I propose for Ogg internet media:
> |
> | Frame Rates:
> |
> | - 15 fps (half 30 fps)
> | - 24 fps (Film native rate.  I heard that in Europe 24 fps movie DVDs are
> | presented at 25fps which make them end sooner, good, more time for the
> | family, is this true?)
> 
> Yes it is true, PAL video standard has 25 FPS, and FILM 2 PAL conversion
> works by simply
> speeding up the movie for 4%.

I'd say that that is the best method to use anyway, because doubling a
field once every 24 fields would result in very annoying image shocking
st 2Hz.

> | - 30 fps
> 
> I'd add 25 (PAL) and 12.5 (half PAL) here. Also AFAIK NTSC video is 29.97
> FPS, and not 30 FPS.

To be exact, 30*1000/1001. The deviation from 30Hz originates from
analog NTSC modulation, where it was done to remove some interference
effects.

For internet video, which is displayed on computer monitors anyway, why
not use a (fraction of) the standardized VESA monitor frequencies? That
would make displaying a lot easier, and better. On a 70Hz monitor, you
get much smoother video from a 70/4=17.5fps video than form a 15fps
video, because you can display each frame at its exactly intended time,
and you can synchronize on the vertical retrace.

Of course, come to think of it, one reason not to do that is because
most cameras are NTSC, PAL, or film, so there is not much source
material at 17.5fps...

> |
> | Bitrates (based on actual experiments with video compression):
> |
> | SIF (320x240 resolution)

Note that SIF is 320x240 for NTSC, and 320x288 for PAL, both are 2304000
pixels per second.

> | - 512 Kbps including 96 Kbps audio
> | - 384 Kbps including 64 Kbps audio
> | - 256 Kbps including 56 Kbps audio
> |
> | QSIF (160x120 resolution)
> | TBA Some numbers available next week.

QSIF for PAL is 160x144.

> | I am using three scenes for the video compression experiments: hockey,
> | mongolian rock concert, mongolian flag and plaza.
> |
> | >
> | > > For now, I have not seen evidence of 128 Kbps media delivery at SIF
> | > > resolution and I think QSIF (160x120) resolution is only good for
> video
> | > > phones or media including one single talking head.
> | >
> | >Just a stir in the pot: How about moving parts of web sites competition
> | >to macromedia flash?
> |
> | Uh?
> |
> | RAUL LOPEZ
> |
> | >
> | >Jelle.
> | >
> 
> Jernej Simoncic, jernej.simoncic at guest.arnes.si
> http://www2.arnes.si/~sopjsimo/
> ICQ: 26266467
> 

Cya,

Jelle.

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.