Clarence Risher wrote:
Tim Starling wrote:
I know, I've read the spec. But presumably it
is fairly rare for Ogg files
to consist of chained audio and video streams. Most Ogg files can be easily
categorised as either audio or video. It's not a problem that you can
construct a file which can't be, and it's not a problem that at present, it
may be difficult to automatically distinguish between the two.
I disagree. Almost every ogg file that contains video also contains
audio (the "normal" definition of a "video file" implicitly includes
audio). But not every, just almost. I have seen many scientific
publications, videos of experiments and such, with no audio.
I never said otherwise. I said that a file containing video should be ogv,
regardless of whether it contains audio.
[snip section that Simetrical answered]
Proper desktop systems have been doing the right thing
for ages now,
for example the Gnome file manager doohicky (nautilus) correctly shows
a thumbnail and movie strip views on video files, while it shows a
music icon on audio files.
Even Windows Vista can happily differentiate files with file magic...
Scanning
files for stream headers is slow, and you can't expect every
application to support it. Gnome does, Windows Vista does, but what about
the directory list module in Lighttpd? What about the unix ls command? What
about FTP clients, archivers and older desktop systems?
Why would any of those applications need to support it? File extensions
are archaic, a dying anachronism in today's world of file magic and/or
MIME types. Let them go.
These applications need to support it because they are responsible for
delivering information about the file to the user. File magic is slow and
unreliable.
[snip section that Nick answered]
And, to make a final inquiry... What players are you
people using that
can play OGG+(Vorbis/MP3/AAC/FLAC) but cant play OGG+(Theora/MPEG4)? I
have a half dozen media players installed on my machine, including
mplayer, xmms, totem, and xine, and every one of them can play every
media file I have, video, audio, or otherwise.
Maybe there is some player that can play audio but not video. Who knows? My
main concern is rapidly delivering information about the file to the user.
Imagine a world without extensions. You could name your files like this:
~/quantum/data/The_Matrix
~/movies/The_Matrix
~/soundtracks/The_Matrix
But it soon becomes obvious that this system is inadequate. You move your
files around a lot, by email, DCC, bittorrent, etc., and that directory
information is easily lost. People are complaining that they downloaded a
file from bittorrent called The_Matrix, looking for the movie, and they just
got a 10^6 x 10^6 Hamiltonian. So you decide to attach suffixes for
disambiguation:
~/quantum/data/The_Matrix_data
~/movies/The_Matrix_movie
~/movies/The_Matrix_soundtrack
Hmmm, but is the title "The Matrix movie" or "The Matrix" which is a
movie?
This is all very confusing. And "soundtrack" takes quite some time to type.
So let's use "." instead of "_" to separate the title from the
type, and
let's use a standard set of abbreviations.
~/quantum/data/The_Matrix.data
~/movies/The_Matrix.video
~/movies/The_Matrix.audio
Oh no, extensions! The anachronism returns! So why would anyone advocate
.ogv over .video? The container format probably matters about as much to the
user as the codec and encoding parameters. I can think of two reasons to
include the container format in the filename:
* Momentum, existing standards, support for legacy systems, etc.
* Branding. We all love open source and want to make sure everyone knows
that we're using it. There are lots of codec names which can also be used
for branding, such as Theora and Vorbis, but Ogg is the umbrella brand.
-- Tim Starling