[LINK] downloading YouTube videos

[Craig Sanders]

On Sat, Jan 19, 2008 at 11:54:01AM +1100, andrew clarke wrote:
> On Sat, Jan 19, 2008 at 08:20:38AM +1100, Craig Sanders wrote:
> 
> > another reason this is relevant to Link is the disturbing fact that the
> > video is only available as a flash movie hosted on youtube. i.e. it's a
> > program that you have to run rather than just video data in a file which
> > can be played by any video player program (any player that has the right
> > video codecs, of course).
> 
> On FreeBSD there is no reliable way to execute Flash applets, so I use
> youtube-dl, a Python script for downloading YouTube movies, and the open
> source MPlayer to view them.  youtube-dl and MPlayer will also run under
> Windows.

yes, i use such tools (on linux).   they mostly work but are clumsy to
use....actually, the tools work OK but the content on youtube generally
isn't worth the bother.


> There are a few issues with using BitTorrent as a distribution system,
> which were encountered when podcasting began.  This isn't to say
> torrents can't be used, but it might explain why it's not used by sites
> such as YouTube.  Those that come to mind:

sure, it's not perfect.  streaming videos isn't, either.

> 1. With current-day torrent clients it's difficult to stream content,
> because seeders will usually share random segments of the stream, rather
> than sequential segments.  There is new software to work around this
> situation, eg. http://www.bittorrent.com/dna/streamingservices.html, but
> it's not in widespread use.

the client has some degree of control over the order that segments are
downloaded because the client is the one that requests segments from
seeds & peers (e.g. the azureus bittorrent client has an option to
download the first and last segments of a file first). of course, the
seed or peer can choose whether or not to accede to the request.

if a client were to request segments in sequential order, then that
would be similar to streaming, as long as the seeds/peers had the
segments being requested and were willing to give them as requested.

it could of course be improved, but the way BT works now is probably
adequate for small, personal sites.

it certainly can't be worse than the way streaming works now - i find
that, even on an 8Mbps ADSL link, streaming videos from the net is
often subject to annoying delays and pauses, so the output is jerky.
that's one of the reasons i prefer to download the entire file before
viewing it.


> 2. "Every downloader also becomes an uploader" - there are legal risks
> with this in terms of users unknowingly sharing copyrighted content
> where they are not legally permitted to.

not if we're talking about open content stuff like this pascal's wager
video.


> 3. Uploading data from corporate networks (or universities) can be a
> problem in terms of bandwidth consumption.  Most torrent clients have a
> way to limit the bandwidth they use, but it has to be configured
> manually by the user.

usually it's configured automatically based on your download bw, with an
option to change the upload bw limit manually if you want.

not every client has to upload, anyway. as long as there are sufficient
seeds and peers to cater for current 'demand' for the file(s), it will
work....and that will scale semi-automatically (assuming that at least
some of the downloaders are willing and able to upload too) as the more
downloaders there are, the more potential uploaders there are.

that was also the point of what i said about self-organising networks of
small publishers (e.g. "bloggers") assisting each other by agreeing to
help seed each others files.


craig

-- 
craig sanders <cas at taz.net.au>

"I use the word "Humanist" to mean someone who believes that man is just as
 much a natural phenomenon as an animal or a plant; that his body, mind or
 soul were not supernaturally created but are products of evolution, and that
 he is not under the control or guidance of any supernatural being, but has
 to rely on himself and his own powers."
            [Julian Huxley, "The Humanist Frame," 1961]