isight&space;story

Screencasting&space;intro

This&space;is&space;a&space;screencasting&space;tutorial.

How&space;many&space;of&space;you&space;know&space;what&space;screencasting&space;is?

Screencasting&space;is&space;recording&space;your&space;computer's&space;screen&space;and&space;posting&space;that&space;online&space;as&space;a&space;demonstration&space;of&space;your&space;software,&space;or&space;your&space;arrangement&space;of&space;other&space;people's&space;software.&space;Screencasting&space;is&space;Screenshots+Podcasting&space;(in&space;a&space;very&space;loose&space;way).

We're&space;going&space;to&space;learn&space;how&space;to&space;do&space;that.&space;We're&space;going&space;to&space;learn&space;how&space;to&space;record&space;our&space;screens,&space;compress&space;the&space;results,&space;and&space;put&space;them&space;on&space;the&space;web.&space;I&space;hope&space;everyone&space;brought&space;something&space;they're&space;working&space;on&space;to&space;demo;&space;we're&space;going&space;to&space;compare&space;movies&space;later!

How&space;many&space;of&space;you&space;have&space;made&space;a&space;desktop&space;movie&space;before?&space;Ok,&space;I'll&space;talk&space;a&space;bit&space;by&space;way&space;of&space;introduction,&space;then&space;step&space;down&space;and&space;we'll&space;get&space;to&space;it.&space;By&space;the&space;end&space;of&space;this&space;tutorial,&space;you&space;should&space;all&space;be&space;able&space;to&space;make&space;a&space;screencast.

First&space;some&space;history.&space;Early&space;software&space;was&space;mostly&space;text&space;based,&space;so&space;you&space;usually&space;just&space;looked&space;at&space;the&space;features.&space;In&space;the&space;case&space;of&space;games,&space;there&space;was&space;likely&space;to&space;be&space;an&space;illustration&space;to&space;convey&space;intended&space;effect.&space;Free&space;software?&space;There&space;was&space;so&space;little&space;of&space;it,&space;you&space;saw&space;your&space;colleagues&space;using&space;it&space;first,&space;or&space;there&space;was&space;plent&space;of&space;time&space;to&space;download&space;it&space;and&space;try&space;it&space;yourself.

But&space;as&space;GUI&space;software&space;become&space;more&space;common,&space;and&space;more&space;pretty,&space;it&space;became&space;common&space;to&space;show&space;an&space;actual&space;photo&space;of&space;the&space;application&space;in&space;use&space;in&space;books&space;and&space;manuals,&space;and&space;later,&space;as&space;image&space;files&space;on&space;the&space;web.

These&space;are&space;called&space;screenshots,&space;and&space;really&space;got&space;going&space;around&space;the&space;linux&space;desktop&space;six&space;or&space;seven&space;years&space;ago.&space;Anyone&space;remember&space;themes.org?&space;It&space;was&space;a&space;massive&space;site&space;in&space;its&space;golden&space;age,&space;where&space;people&space;could&space;share&space;background&space;images,&space;toolkit&space;and&space;window&space;manager&space;themes&space;along&space;the&space;lines&space;of&space;sites&space;like&space;art.gnome.org,&space;and&space;of&space;course&space;screenshots&space;of&space;their&space;tricked&space;out&space;desktops&space;with&space;the&space;windows&space;artfully&space;arranged.

How&space;do&space;screenshots&space;work?&space;At&space;the&space;most&space;basic&space;level&space;you&space;just&space;dump&space;the&space;framebuffer&space;to&space;a&space;file.

Examples:&space;KSnapshot,&space;Gnome&space;screen&space;capture

import&space;-window&space;root&space;file.png&space;

xwdump

But&space;as&space;GUI&space;development&space;evolved,&space;interaction&space;design&space;became&space;more&space;important.&space;A&space;picture&space;isn't&space;worth&space;a&space;thousand&space;words&space;when&space;you're&space;explaining&space;how&space;to&space;use&space;a&space;complex&space;application,&space;so&space;showing&space;of&space;ease&space;of&space;use&space;improvements.

Moreover,&space;as&space;computers&space;have&space;become&space;faster,&space;the&space;development&space;of&space;eye&space;candy&space;has&space;turned&space;more&space;to&space;animations&space;and&space;subtle&space;motion&space;and&space;overlay&space;effects,&space;not&space;just&space;in&space;elegant&space;but&space;static&space;visuals.

And&space;that's&space;the&space;benefit&space;of&space;taking&space;not&space;just&space;a&space;single&space;image&space;but&space;a&space;movie.&space;A&space;movie&space;is&space;just&space;a&space;sequence&space;of&space;images,&space;played&space;back&space;quickly&space;enough&space;to&space;give&space;the&space;illusion&space;of&space;motion.&space;So&space;conceptually&space;you&space;make&space;a&space;screencast&space;just&space;by&space;takes&space;a&space;bunch&space;of&space;screenshots&space;quickly.

Unfortunately,&space;screenshot&space;apps&space;generally&space;aren't&space;fast&space;enough&space;to&space;make&space;a&space;smooth&space;movie.&space;If&space;you're&space;spending&space;4&space;hours&space;testing&space;a&space;linux&space;install&space;in&space;qemu,&space;then&space;grabbing&space;a&space;frame&space;every&space;six&space;seconds&space;isn't&space;bad,&space;but&space;for&space;normal&space;interactive&space;work&space;you&space;need&space;at&space;least&space;12&space;frames&space;every&space;second.

That's&space;where&space;screen&space;recording&space;applications&space;come&space;in.&space;They&space;focus&space;on&space;reducing&space;the&space;capture&space;overhead,&space;and&space;usually&space;also&space;help&space;you&space;encode&space;the&space;results&space;in&space;a&space;video&space;file.

A&space;note&space;on&space;formats:

A&space;video&space;made&space;of&space;a&space;sequence&space;of&space;individual&space;frames,&space;even&space;with&space;something&space;like&space;jpeg&space;compression,&space;is&space;generally&space;too&space;large&space;for&space;people&space;to&space;download.&space;So&space;you&space;need&space;to&space;use&space;a&space;compressed&space;video&space;format&space;that&space;takes&space;advantage&space;of&space;the&space;redundancy&space;between&space;successive&space;frames.

Unfortunately,&space;almost&space;all&space;video&space;compression&space;formats&space;are&space;patented,&space;including&space;mpeg&space;and&space;flash.&space;So&space;in&space;much&space;of&space;the&space;western&space;world,&space;it's&space;not&space;possible&space;to&space;create&space;them&space;with&space;free&space;software,&space;including&space;here&space;in&space;Australia.

I&space;work&space;with&space;the&space;Xiph.org&space;foundation,&space;trying&space;to&space;create&space;free&space;alternatives&space;for&space;digital&space;media,&space;so&space;I'm&space;not&space;going&space;to&space;tell&space;you&space;how&space;to&space;encode&space;your&space;video&space;in&space;mpeg&space;or&space;flash,&space;we're&space;going&space;to&space;focus&space;on&space;two&space;free&space;distribution&space;formats,&space;and&space;some&space;intermediates.

Animaged&space;GIF

gif&space;is&space;now&space;free,&space;the&space;last&space;LZW&space;patent&space;having&space;expired&space;in&space;2005.&space;It&space;has&space;the&space;advantage&space;that&space;every&space;web&space;browser&space;has&space;native&space;support&space;for&space;playback:&space;just&space;use&space;an&space;<img/>&space;tag.

The&space;disadvangates&space;are&space;that&space;the&space;compression&space;isn't&space;great,&space;and&space;it's&space;limited&space;to&space;256&space;colours,&space;so&space;the&space;subtle&space;shadings&space;of&space;todays&space;desktop&space;environments&space;will&space;end&space;up&space;dithered.

Ogg&space;Theora

This&space;is&space;a&space;free&space;video&space;format.&space;It&space;compresses&space;much&space;better&space;than&space;.gif&space;and&space;isn't&space;limited&space;by&space;the&space;colourspace.&space;However,&space;default&space;playback&space;support&space;is&space;only&space;common&space;in&space;Linux&space;installs&space;less&space;than&space;a&space;few&space;years&space;old.&space;People&space;on&space;other&space;platforms&space;will&space;probably&space;have&space;to&space;install&space;something.

The&space;counterpart&space;to&space;the&space;256&space;colour&space;issue&space;is&space;that&space;encoders&space;are&space;designed&space;for&space;photographic&space;images,&space;and&space;at&space;low&space;bitrates&space;you'll&space;get&space;blurring&space;and&space;popping&space;artefacts.

Tools

There&space;are&space;a&space;couple&space;of&space;screen&space;recorders.&space;I&space;suggest&space;you&space;pick&space;one,&space;and&space;keep&space;going&space;down&space;the&space;list&space;until&space;you&space;get&space;something&space;that&space;works:

Byzanz&space;(makes&space;gif,&space;uses&space;the&space;damage&space;extension&space;to&space;construct&space;small&space;animated&space;gif)

Istanbul&space;(makes&space;theora,&space;works&space;without&space;damage,&space;heavier&space;cpu&space;load)

xvidcap&space;(best&space;capture,&space;makes&space;mpeg,&space;and&space;a&space;bunch&space;of&space;files&space;we&space;can&space;encode&space;to&space;theora&space;by&space;hand)

vncrec&space;(need&space;patched&space;version&space;to&space;encode&space;theora

Now,&space;I&space;don't&space;know&space;it&space;all,&space;and&space;)typical&space;of&space;emerging&space;support&space;in&space;free&space;and&space;open&space;source&space;software,&space;there&space;are&space;several&space;different&space;screen&space;recording&space;programs,&space;and&space;they&space;all&space;only&space;sort&space;of&space;work.&space;So&space;you&space;may&space;have&space;to&space;try&space;a&space;few&space;things,&space;and&space;we'll&space;need&space;to&space;help&space;each&space;other&space;out.

In&space;fine&space;linux&space;tradition,&space;let's&space;all&space;try&space;and&space;get&space;one&space;of&space;the&space;above&space;installed,&space;and&space;try&space;recording&space;our&space;screens.&space;After&space;that&space;we'll&space;compare&space;and&space;critique&space;movies.

<go&space;help&space;people&space;get&space;the&space;software&space;running>

Ok,&space;sounds&space;like&space;a&space;lot&space;of&space;us&space;have&space;movies&space;going.&space;Now&space;that&space;we&space;have&space;the&space;technical&space;part&space;down,&space;we&space;move&space;in&space;to&space;&space;performance.&space;That's&space;what&space;you're&space;doing&space;with&space;you&space;make&space;a&space;screencast.&space;You're&space;performing&space;your&space;application&space;for&space;others.&space;Demonstrating&space;what's&space;cool,&space;Showing&space;people&space;how&space;it&space;works,&space;and&space;usually&space;trying&space;to&space;educate&space;and&space;impress&space;them.

And&space;what&space;is&space;performance&space;without&space;review&space;and&space;critique?&space;We're&space;going&space;to&space;break&space;into&space;small&space;groups&space;now,&space;of&space;around&space;four&space;people&space;each.&space;For&space;15&space;minutes,&space;take&space;turns&space;showing&space;the&space;other&space;people&space;the&space;recording&space;you've&space;made.&space;When&space;it's&space;not&space;your&space;turn,&space;think&space;about&space;what&space;you're&space;seeing.&space;Does&space;the&space;video&space;explain&space;the&space;application&space;well?&space;Can&space;you&space;see&space;what's&space;going&space;on?&space;Is&space;it&space;interesting&space;to&space;watch?&space;Try&space;to&space;be&space;constructive&space;and&space;point&space;out&space;things&space;you&space;thing&space;could&space;be&space;better.&space;Then&space;we'll&space;all&space;try&space;again&space;and&space;see&space;if&space;we&space;can&space;improve.