HTML5TV

This is my attempt to finish my masters degree. I'm just kidding :-)

Actually, in 1997 I had idea to have masters degree on topic of video
delivery over Internet. I was few years too early to make it actually
work, but now-days we have all components needed to create good video
archive on the web.

I envision this as combination of two parts:

 * powerful editing suite running locally to annotate video
 * good web interface with sync between slides and video


SOURCE MATERIAL

I have some of my presentations in video with slides, but I also have
few of freely available presentations which would benefit from
audio-video slide annotation. So you are assumed to have two files:

 1. video file in Ogg Theora format
 2. pdf file with slides of presentation

all other meta-data should be stored in git under media/

If you have different file formats, go ahead and use ffmpeg2theora:

  http://v2v.cc/~j/ffmpeg2theora/

New Theora encoder 1.1 create videos that are better than anything I saw
on the web, oggz tool has chop support, so extracting part of video is
very easy and possible.


VIDEO EDITING

I really don't want to learn another set of tools. I like mplayer,
it works on all platforms I'm interested in (including EeePC and
PlayStation 3) and i all-ready know keyboard shortcuts for it.

So, I used it over it's slave protocol which is described on

  http://www.mplayerhq.hu/DOCS/tech/slave.txt

and available locally as docs/slave.txt which I used to implement new keyboard
commands:

  dpavlin@t61p:~/t61p/html5tv$ grep -A10 'keyboard' bin/mplayer.pl 

	# XXX keyboard shortcuts

	  $1 eq 'c'  ? repl
	: $1 eq ','  ? add_subtitle
	: $1 eq 'F1' ? prev_subtitle
	: $1 eq 'F2' ? move_subtitle( -0.3 )
	: $1 eq 'F3' ? move_subtitle( +0.3 )
	: $1 eq 'F4' ? next_subtitle
	: $1 eq 'F5' ? save_subtitles
	: $1 eq 'F9' ? add_subtitle
	: $1 eq 'F12' ? edit_subtitles
	: warn "CUSTOM $1\n"
	;

I used to work with semi-professional Sony U-matic video montage back in 1990
and have grown to love it's work flow which doesn't force you to click
all over the screen to do something useful.

In fact, with it, you need 3-5 times more time to finish material,
and with most video editing solutions available in open source,
I needed at least 10-20 times more time to do anything useful.


SUBTITLING

I decided to store subtitles in array-of-arrays in yaml with simple structure
of start,end,title. On every save, I need also to create .srt subtitle format
for mplayer and json data for web interface.

Effective subtitle editing requires preroll. This is feature from my U-matic days
because scopes (U-matic video recorders with magnetic tape) couldn't speed up
instantly, so they would rewind, start AND SHOW YOU FEW SECONDS BEFORE YOUR EDIT.

This is crucial part in implementing following work flow with mplayer:

  1. press i to record EDL point (start of subtitle)
  2. press i to end EDL (end of subtitle)
  3. press , to enter subtitle (usually you want to enter subtitle after end of sentence)
  4. preroll 3 seconds before subtitle and review it
  5. continue subtitling, goto 1

You can also use F9 to add subtitle (nicely located near i key) or F12 to enter vi
and make bulk subtitle changes (remove empty subtitles and so on).

SLIDES

Subtitles are least common denominator for meta data which I want to preserve.
However, to sync subtitles with slides, I have introduced magic syntax:

     [42] slide title

which triggers switch to slide 42.


HTML5 WEB INTERFACE

Web interface using HTML5 <video> tag based on work from BBC R&D TV

	http://open.bbc.co.uk/rad/demos/html5/rdtv/episode2/index.html

	http://www.bbc.co.uk/blogs/rad/2009/08/html5.html

Which in turn is based on jCarousel from

	http://sorgalla.com/projects/jcarousel/

I removed most of nice design, added support for slides and made it
scale to accomodate different resolutions of video materials. 


TRY IT OUT

Create media/conference-title/www file with source urls for video and presentation

	$ cd media/conference-title
	$ wget -nc -i www

	# set default video
	$ ln -s 20090704183304_dobrica.mts.ogv video.ogv

	# generate hires slide jpegs using ghostscript
	$ ./bin/slides-hires.sh media/conference-title/presentation.pdf

	# setup interface
	$ cd www 
	$ ln -sf ../media/conference-title media
	$ cd -

	# annotate some material
	$ ./bin/mplayer.pl

	# resize presentation and show montage preview
	$ ./bin/slides-resize.sh

You will probably want to run resize after you made first annotation in mplayer
because you will get visual overview of all available slides which is useful
when typing in slide markers [42] in subtitles.

When slide reisze finish, you might want to open http://localhost/html5tv/www/tv.html
in Firefox and check final result.