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Lol – Stupid strapped on all the way…

Before we can start working on games and all the fun stuff, it’s imperative that we’ve got solid fundamentals. Here in Week 2 of CUFDIG302A – Author Interactive Sequences we’re looking at conditional branching (i.e. if/and/or/not statements), flow control (i.e loops) and generating random numbers.

If you’ve not gone through the Week 1 slides, and you’re new to coding, then take a step back to and take it order – it’ll really help. Otherwise enjoy the notes!

The download link to the slides along with some legal gubbins regarding their use is after the jump, so if you fancy learning ActionScript – you’ll find the knowledge to start from near to absolute basics right here, and pretty soon we’ll be onto Symbols, Classes, Events, Object Orientation, Interaction, Sound, Collision Detection and all that other good stuff. We’ll even make a couple of flash games – which should be quite fun

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As I’m teaching the programming section of Certificate III in Media, CUFDIG302A – Author Interactive Sequences, I’m going to post up my slides as I go along so anyone who wants them can learn ActionScript 3.0 – but as well as just the coding side of things, it’s useful to get an overview of what Flash is, what it isn’t, and what a couple of the most commonly used tools do. So here’s a Flash CS4 & Drawing primer…

There’s a download link to the slides along with some legal gubbins regarding their use after the jump, so if you’re new to Flash and want a quick introduction, you’ll find the knowledge to start from absolute basics, learn the difference between raster and vector artwork, working with layers and drawing and grouping objects right here. This is just a quick primer, and is meant to tie in with the ActionScript slide series, where pretty soon we’ll be drawing things and then instantiating and manipulating them through our ActionScript code.

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One of the classes I’m teaching this year is (PDF link) CUFMEM07A – Apply Principles of Visual Design, and although a lot of it isn’t going to be of much use to people who don’t dig on design principles and elements, some well-explained Photoshop articles mightn’t hurt anyone who stumbles across the site, so I’ll make with the posting…

In this exercise, we’re starting from the beginning and creating selections from one image to combine with another, and we look at some feathering of selections to get rid of hard edges between contrasting visual elements. What you end up creating is shown below:

Very simple, very quick – useful if your Photoshop skills are a bit rusty, or if you’re just starting out.

You can find the document (in MS Word 2K3 format, so viewable in Open Office and MS Office 2K3 & 2K7) which steps through the process, with lovely, lovely screengrabs and the like here.

It’s easy enough to rip DVDs to .AVIs or .MKVs – you can just use nice, GUI-enabled tools like HandBrake. But what about when you want to transfer an AVI back to DVD format so it can be played on a standalone DVD player? Well, the Shetboy sent me his command-line technique a while back (which we can automate to some extent) – and I’ve got to say it works flawlessly.

1.) Get the Right Tools for the Job

If you’ve ever had a look at a video DVD on your PC, you’ll notice is has a bunch of .VOB files broken up into roughly 1GB sections which contain the pieces of your movie (if it’s a DVD of TV episodes you’re more likely to have a greater number of VOBs split up into one per episode on the disc). To deal with all the transcoding we’re going to do, we need the right tools. Some of these you’re likely to already have, others maybe not.

Package pre-requisites for transcoding:
mencoder, mplayer, libxvidcore, libxvidcore4, xvid4conf, xvidtune, ffmpeg, libavcodec0d, libmpeg*, w32codecs, transcode, mjpegtools, dvdauthor

You can install them all via the following command (where any you already have will just be skipped):

sudo apt-get install mencoder mplayer libxvidcore libxvidcore4 xvid4conf xvidtune ffmpeg libavcodec0d  w32codecs transcode mjpegtools dvdauthor libmpeg*

2.) Find Out Your .AVI’s Crop Area

To do a nice transcode, best results are gained by not transcoding any black bars in the avi. This step also helps in getting a perfect re-size every time without messing up the aspect ratio.

To do this run:

mplayer -vf cropdetect <file.avi>

An mplayer window will open and the avi will play. Press the right arrow about 10 times and leave it running for a few seconds. The reason for this is that different resolutions can sometimes be used for the intro to TV shows, or company logos and things, and we want the main feature being played. After it has been showing the body of the show for a few seconds kill the mplayer window.

Output from the above command will be shown in your console window, and should look something like this:

— A whole bunch of other stuff we don’t care about here —

Opening video filter: [cropdetect]
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg’s libavcodec codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg MPEG-4)
==========================================================================
alsa-init: using device default
alsa: 48000 Hz/2 channels/4 bpf/65536 bytes buffer/Signed 16 bit Little Endian
AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Starting playback…
VDec: vo config request – 624 x 352 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.77:1 – prescaling to correct movie aspect.
VO: [xv] 624×352 => 624×352 Planar YV12
[CROP] Crop area: X: 623..0 Y: 351..0 (-vf crop=-608:-336:618:346).
[CROP] Crop area: X: 623..0 Y: 351..0 (-vf crop=-608:-336:618:346). *** This is the crop-area of the pre-show company logos etc. – don’t use it! ***
[CROP] Crop area: X: 623..0 Y: 351..0 (-vf crop=-608:-336:618:346).
…
[CROP] Crop area: X: 0..623 Y: 0..351 (-vf crop=624:352:0:0).7 0
[CROP] Crop area: X: 0..623 Y: 0..351 (-vf crop=624:352:0:0).7 0
[CROP] Crop area: X: 0..623 Y: 0..351 (-vf crop=624:352:0:0).7 0 *** This is the crop-area of the main presentation which we’re going to use! ***
[CROP] Crop area: X: 0..623 Y: 0..351 (-vf crop=624:352:0:0).7 0
[CROP] Crop area: X: 0..623 Y: 0..351 (-vf crop=624:352:0:0).7 0
…

The last bunch of lines showing the crop area for the main presentation are what’s important here. We’ll use this info shortly.

3.) Transcode the Video File

We’ll be doing the transcoding using mencoder, which takes an un-holy number of parameters to do a great job.

An example of a command in the proper format is …

mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=dvd:tsaf -srate 48000 -ofps 25 \
-lavcopts vcodec=mpeg2video:vrc_buf_size=1835:keyint=15:vrc_maxrate=9800:vbitrate=4900:aspect=16/9:acodec=ac3:abitrate=192 \
-af lavcresample=48000 \
-vf crop=624:352:0:0,scale=720:576,expand=720:576,harddup \
-o ~/transcoded/ep01.mpg \ 
Star.Wars.The.Clone.Wars.S01E01.HDTV.XviD-0TV.avi

To figure out what’s going on so you can tweak the numbers appropriately, I’ve separated out the switches into a table to best explain how it works:

So, even though it looks like a bit of a nightmare, you only need to change a few things in the entire command:

1.) Choose your output fps by setting -ofps 25 for PAL or -ofps 23.95 for NTSC.
2.) Set whether we want to output in widescreen 16/9 or old-school 4/3 by setting -aspect=16/9 or -aspect=4/3
3.) Feed in the result of running our mplayer cropdetect so we end up with something like -vf crop 624:352:0:0,
4.) Feed in the result of running our scale calculation so we end up with something like scale=720:576,
5.) Give it an input source AVI and an output file to dump the transcoded MPEG to
6.) Optionally, only transcode a couple of minutes to make sure it’s all running alright. Once you’re happy with the transcode take out the -frames line and it’ll transcode the whole video file for you.

If you really want to dig into the switches more, you could always take a look at this page which shows how to use mencoder in significantly more detail.

4.) Generate the DVD

Now we’ve done the hard part and we’ve got a big ‘ol .mpg file of our avi, it’s time to generate the DVD structure. If you’re putting multiple mpegs to a DVD, keep the file limit to about 4.2GB otherwise it won’t fit on a single-sided DVD5. If you’ve got a DVD9 writer you might be alright up to about 8GB, but I don’t have one so I haven’t tested this.

Word of Warning: When you’re generating large MPEG files for DVDs do NOT work on a FAT32 file system – FAT32 has a 4GB file limit, and if you end up with a 4GB+ file, things are going to fail.

You need to run two commands to generate a DVD:

dvdauthor -t -o newfolder file1.mpg [file2.mpg] [file3.mpg] ...
dvdauthor -o newfolder -T

The first command instructs dvdauthor to make a title out of each file (think chapter so we can skip through them easily), and can take a while to run. The second command generates our table of contents and completes near instantly. Read more via the mighty man dvdauthor if you’re that way inclined…

So, an example of the command usage, assuming I’d created the dvdprep folder in my home folder, might be:

dvdauthor -o ~/dvdprep/starwars1 ~/transcoded/ep01.mpg ~/transcoded/ep02.mpg ~/transcoded/ep03.mpg ~/transcoded/ep04.mpg
dvdauthor -o ~/dvdprep/starwars1 -T

Important: In the above example ~/dvdprep MUST exist but the directory starwars1 MUST NOT!

With this done, the start of each new file can be jumped to within the DVD by hitting chapter next or previous on your DVD software or player. Before burning to disc you should check that it works ok by checking with a video player like VLC and select ‘Play DVD from Directory’ or similar.

5.) Burn the DVD!

That’s it! We’re done! Burn the DVD directory (i.e. the contents of ~/dvdprop/starwars1 now containing the AUDIO_TS and VIDEO_TS folders in his example) using Brasero, K3b or your burning software o’ choice. Whatever you use, make sure you burn the disc as a New Video DVD though!!

Happy transcoding!