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Contents
What Is It?
Licensing
Audio Quality
Features
Development
Current Affairs
Meta-FAQ
What Is It?
- What is Ogg Vorbis?
-
Ogg Vorbis is a new audio compression format. It is
roughly comparable to other formats used to store and play
digital music, such as MP3, VQF, AAC, and other digital
audio formats. It is different from these other formats
because it is completely free, open, and unpatented.
- What do all the names mean?
-
Vorbis is the name for the specific audio compression
scheme used to create Ogg Vorbis files. It is part of the
Ogg project, which is a blanket project designed to create a
fully open multimedia system. Right now, Ogg Vorbis is the
only functional part of the Ogg project which is anywhere
near completion.
- Where do the names come from? What does the logo
mean?
-
Xiph.org has a page
explaining the sources and meanings of the names and
logos.
- What
is the file extension for Ogg Vorbis?
-
Since it is part of the Ogg project, Vorbis files have
the extension .ogg.
- What is the MIME content type for an Ogg Vorbis
stream?
-
application/x-ogg
- Does Vorbis completely replace MP3, or is it just
a complementary codec?
-
Ogg Vorbis has been designed to completely replace all
proprietary, patented audio formats. That means that you can
encode all your music or audio content in Vorbis and never
look back.
- When will Ogg Vorbis be done?
-
There are stable reference implementations available now,
and the file format has been finished for some time. A
Vorbis file created today will still be compatible with
future decoders for years to come. The format has been
designed to be flexible, so that the developers can continue
to improve file size and sound quality without "breaking"
older encoders and players.
- I'm an artist. Why should I be interested?
-
There are a couple of reasons:
Although not all artists realize it, MP3 is what is known
as a "lossy" format. Thus, much of the sound data is removed
when MP3 files are created. This results in a file with
inferior sound quality to a CD. Vorbis is also a "lossy"
format, but uses superior acoustic models to reduce the
damage. Thus, music released in Vorbis will sound better
than a comparably sized MP3 file.
Also, artists should be concerned about licensing terms
for formats. If you decide to sell your music in MP3 format,
you are responsible for paying Fraunhofer a percentage of
each sale because you are using their patents. Vorbis is
patent and license-free, so you will never need to pay
anyone in order to sell, give away, or stream your own
music.
- I'm a
music fan. Why should I be interested?
-
For one, Vorbis provides a high-quality format for you to
listen to your music. For a given file size, Vorbis sounds
better than MP3, and is getting better as development
continues. Vorbis already enjoys widespread player support
and should be compatible with several major hardware players
soon. With Vorbis, you can listen to your music with higher
quality in less space. Also, using Vorbis means your player
and encoder choices aren't bound by licensing terms. Right
now, you can only choose from a few encoders to create your
MP3 files, because most companies won't or can't pay the
licensing terms for encoders. Using Vorbis lets you choose
from a wide variety of encoders.
- I'm a
developer. Why should I be interested?
-
If you develop hardware or software audio players, you
cannot distribute your work without being affected by
proprietary audio patent licensing terms. With Vorbis, you
can create hardware or software products to encode or decode
music files without restrictions, royalty payments, or
limits on distribution. Vorbis also provides a flexible,
high-quality format that is of great interest to all the
audio geeks out there. For more developer information,
please refer to our developer
site.
- I run a music company. Why should I be
interested?
-
Music companies should be very interested in the Ogg
Vorbis format. Other technologies require large financial
investments to get started, but Vorbis offers a unique
platform that is easily reachable for growing companies and
a money saver for established businesses. Because of its
wide player support and its open nature, your customers and
clients will not be plagued by incompatibilities and they
will appreciate the higher sound quality as
well.
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Licensing
- What licensing applies to the Ogg Vorbis format?
-
The Ogg Vorbis specification is in the public domain. It
is completely free for commercial or noncommercial use. That
means that commercial developers may independently write Ogg
Vorbis software which is compatible with the specification
for no charge and without restrictions of any kind. However,
developers that wish to use the open source software we have
written must adhere to certain rules.
- What licensing applies to the included Ogg Vorbis
software?
-
The bundled Ogg Vorbis utility software is released under
the terms of the GNU GPL, or GNU General Public License. The
details can be found at http://www.gnu.org/.
The libraries and SDKs are released under the more
business-friendly BSD license. Please note that developers
are still free to use the specification to independently
write closed-source implementations of Ogg Vorbis which are
not bound by these licenses.
- We
make commercial, closed source software. Can I use Ogg
Vorbis at all? What licensing do I need to pay?
-
Again, there are no licensing fees for ANY use of the Ogg
Vorbis specification. As a commercial developer, you are
free to create and sell (or give away) open or closed source
implementations of Vorbis encoders, decoders, or other
tools. However, if you use our software rather than writing
an independent implementation, you must respect the terms of
the license. Our libraries (available under the BSD license)
can be used whole or in part by closed source
applications.
- Are
there licensing fees for distributing, selling, or streaming
media in the Ogg Vorbis format like there are in other
formats, such as MP3?
-
No.
- If there aren't any licensing fees, how are you
going to make money off the format? Will you charge fees
later, after Vorbis becomes popular?
-
The benefits of a patent-free, license-free format
outweigh the concerns of making money directly from the
format. The Vorbis format will always be free and in the
public domain. Xiph.org is investigating a variety of models
for funding development, some of which may include licensing
non-free Vorbis-related programs and libraries to commercial
projects. One example of this is Tremor, the fixed-point
decoder for embedded systems. Nevertheless, the reference
encoder and decoder will always be open source and third
parties will always be free to modify or reimplement
them.
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Audio Quality
- I've heard that Vorbis is a "lossy" codec. What
does this mean?
-
There are two broad classes of compression algorithms:
lossless and lossy. Lossless compression algorithms produce
compressed data that can be decoded to output that is
identical to the original. Zip is a very common example of a
lossless compression format. FLAC is a lossless
compression format that is specifically designed for audio.
The other type of compression algorithm is called
lossy. This form of compression is very popular
with multimedia data, like pictures, movies, and sound.
Since these types of information are perceived by humans
with imperfect senses, the original data does not have to be
reproduced exactly. Some of the information in the original
file can actually be discarded because we wouldn't notice it
even if it was there. Lossy codecs can achieve much higher
compression than lossless codecs by intelligently discarding
unneeded information. In most cases, some loss of quality
can be tolerated, so even more data can be discarded,
further increasing compression. MP3, RealAudio, and Vorbis
all use lossy audio compression. This means that a Vorbis
file, for example, will decode to a WAV file that is
different than the original. The differences may or may not
be noticable, depending upon the quality selected during
compression.
- Does Ogg Vorbis sound better than MP3?
-
Yes, definitely. Naturally, we invite you to judge this
for yourself.
- Will Ogg Vorbis audio quality improve?
-
Yes. Vorbis has a flexible format which allows
significant tuning of sound quality and training of the
algorithms even after the file format is frozen. Vorbis
sounds very good today, and will continue to sound better
every day.
- Why is Ogg Vorbis better than the other "New MP3"
codecs that are available?
-
Vorbis sounds better. Vorbis is open, so you're free to
use it on your favorite platform. Vorbis doesn't have
intellectual property restrictions to get in the way. And
Vorbis doesn't just try to sound better, it tries to do
things fundamentally better in all the ways that it can.
- Can I convert my MP3 collection to the Ogg
Vorbis format?
-
You can convert any audio format to Ogg Vorbis. However,
converting from one lossy format, like MP3, to another lossy
format, like Vorbis, is generally a bad idea. Both MP3 and
Vorbis encoders achieve high compression ratios by throwing
away parts of the audio waveform that you probably won't
hear. However, the MP3 and Vorbis codecs are very different,
so they each will throw away different parts of the audio,
although there certainly is some overlap. Converting a MP3
to Vorbis involves decoding the MP3 file back to an
uncompressed format, like WAV, and recompressing it using
the Ogg Vorbis encoder. The decoded MP3 will be missing the
parts of the original audio that the MP3 encoder chose to
discard. The Ogg Vorbis encoder will then discard other
audio components when it compresses the data. At best, the
result will be an Ogg file that sounds the same as your
original MP3, but it is most likely that the resulting file
will sound worse than your original MP3. In no case will you
get a file that sounds better than the original MP3.
Since many music players can play both MP3 and
Ogg files, there is no reason that you should have to switch
all of your files to one format or the other. If you like
Ogg Vorbis, then we would encourage you to use it when you
encode from original, lossless audio sources (like CDs).
When encoding from originals, you will find that you can
make Ogg files that are both smaller and better quality than
MP3.
(If you must absolutely must convert from MP3 to Ogg,
there are several conversion scripts available on Freshmeat.)
- You're claiming that Vorbis has great audio quality.
Have you done any listening tests to back this up?
-
Over the last few public beta and prereleases, we've
fixed many of the outstanding bugs that affected audio
quality. After the 1.0 release, we're hoping to conduct
double blind listening tests with a variety of test samples
to fairly compare Vorbis with competing audio formats. Based
on informal listening tests by the developers and other
interested parties, we are confident that Vorbis will fare
well in these tests. These tests will be used to further
tune the format as development continues.
- I've heard some test samples that had audible
artifacts. Why did this happen?
-
While the Vorbis file format is standardized, the Vorbis
encoder has undergone several beta and prerelease testing
cycles. If the files you heard were encoded using an earlier
version encoder, they might contain serious audio quality
bugs that have already been fixed. Try re-encoding from the
source audio using the latest encoder. If you still think
you've got a bug that produces unreasonable artifacts,
please e-mail the vorbis-dev list with the details.
- What does the "Quality" setting mean?
-
Beginning with libvorbis 1.0rc3, audio quality is no
longer measured in kilobits per second, but on an arbitrary
scale of 0 to 10, called "quality." This change in
terminology was brought about by a tuning of the
variable-bitrate algorithm that produces better sound
quality for a given average bitrate, but which does not
adhere as strictly to that average as a target.
This new scale of measurement is not tied to a
quantifiable characteristic of the stream, like bitrate, so
it's a fairly subjective metric, but provides a more stable
basis of comparison to other codecs and is relatively
future-proof. As Segher Boessenkool <segher@xiph.org>
explained, "if you upgrade to a new vorbis encoder, and you
keep the same quality setting, you will get smaller files
which sound the same. If you keep the same nominal bitrate,
you get about the same size files, which sound somewhat
better." The former behavior is the aim of the quality
metric, so encoding to a target bitrate is now officially
deprecated for all uses except streaming over
bandwidth-critical connections.
For now, quality 0 is roughly equivalent to 64kbps
average, 5 is roughly 160kbps, and 10 gives about 400kbps.
Most people seeking very-near-CD-quality audio encode at a
quality of 5 or, for lossless stereo coupling, 6. The
default setting is quality 3, which at approximately 110kbps
gives a smaller filesize and significantly better fidelity
than .mp3 compression at 128kbps.
- How does Vorbis fare for speech compression?
-
It works well, but is generally not the optimal solution.
Vorbis is designed for the compression of music and general
purpose audio. Special purpose codecs can achieve much
greater compression of speech than Vorbis. Vorbis also tends
to have a latency that is too high for telephony, a common
use of speech codecs. Read the Speech
Coding and Compression FAQ for more details. Those
looking for an open-source, patent-free speech codec should
take a look at Speex.
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Features
- How
big are Ogg Vorbis files? How do they compare to MP3 files
at similar bitrates?
-
Two files encoded at the same bitrate, will always be the
same size, if they are both encoded with CBR (Constant
Bitrate). The current Vorbis encoder can encode files in VBR
(Variable Bitrate) which can produce smaller files with
better quality, since it doesn't have to waste data for
audio that is easy to encode. Files produced by the Vorbis
encoder at the default quality will be similar in size to
110kbps MP3 files, but will sound better.
- What is the maximum bitrate at which Vorbis can
be encoded?
-
Theoretically, there isn't one. Vorbis is tuned for
bitrates of 16kbps to 128kbps PER CHANNEL. But there's
nothing in the spec that says you can't encode a file at
512kbps or 8kbps. The current encoder supports the following
bitrates: 64-500kbps stereo and 32-256kbps mono (at 44.1kHz
sampling rate). Lower bitrates will be officially available
in future versions.
-
-
Yes, Vorbis includes a flexible,
complete comment field for song and artist info, as well
as other track data. The official encoder, oggenc, allows
you to enter comment info at encode-time. Other 3rd-party
encoding tools also let you enter or edit track data.
- How fast are the encoders/decoders?
-
Right now the encoder is about as fast as most commercial
audio encoders (and about twice as fast as beta 3), but not
nearly as fast as some others. Since we are using
unoptimized beta code, this is to be expected. As the vorbis
tools mature they will become faster. The decoding is
roughly the same complexity as MP3 decoding, and once the
Vorbis decoding tools are optimized, they should decode at
similar speeds. Decoding speed has increased 3-4x over the
first beta already, after the first stage of
optimization.
- Where's video?
-
If you're interested in our progress on a video codec,
check out Theora at http://www.theora.org. Theora's 1.0
release is scheduled for Summer of 2003.
- What about streaming in Ogg Vorbis format?
-
Streaming is an important component of Vorbis. The format
has been designed from the ground-up to be easily
streamable. The designers of Vorbis are working alongside
the creators of Icecast streaming media software to make
Icecast Vorbis-compatible. We are also working on player
support for streaming Ogg files. Streaming Ogg files from
the web will be supported by the player plugins at the 1.0
Vorbis release.
- What software and hardware support Ogg
Vorbis?
-
Ogg Vorbis encoding and/or playback is now native in a
wide variety of popular software. It's included in popular
players such as WinAmp, Sonique, FreeAmp for Windows, and
Unsanity Echo for MacOS. It's also supported in popular
audio applications such as CDex, Siren Jukebox, and
GoldWave. For a more complete list, refer to our software
page. Ogg Vorbis is not supported by any
publicly-available hardware yet, but portable playback is
possible for Sharp Zaurus owners by purchasing tkcPlayer
software from TheKompany.
- Can I bundle Vorbis and another media type
(like text lyrics or pictures) in the same file?
-
Yes. The Ogg container format was designed to allow
different media types to be multiplexed together. In the
future, Ogg movies will most likely consist of a Vorbis
audio track and a video track (using Tarkin, VP3 or some
other video codec) inside of a single Ogg file. Some
preliminary work has been done to put MNG and MIDI content
into Ogg files as well. Experimental code is available in
the ogg-tools module in the Xiph.org CVS
repository. Programmers working on such extensions can
discuss issues and questions on the vorbis-dev mailing
list.
- What other unique features does Ogg Vorbis
have?
-
Vorbis has a well defined comment header that is easy to
use and extensible and obviates the need for clunky hacks
like ID3 tags. Vorbis has bitrate scaling - a feature that
lets you adjust the bitrate of a Vorbis file or stream
without reencoding; just chop the packets up in the sizes
you want them. Vorbis files can be sliced and edited with
sample granularity. Vorbis has support for many channels,
not just 1 or 2. Vorbis files can be logically chained
together.
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Development
- How do I get started with Ogg Vorbis
development?
-
It is important to first become familiar with current
development efforts. The best ways to do this are:
- Download and compile the latest development code from
the Xiph.org CVS
repository. The important modules for Ogg Vorbis
development are ogg, vorbis, ao, and vorbis-tools. If you
are interested in working on putting other media types
into Ogg files, the ogg-tools module also has example
code.
- Subscribe to the vorbis user and
vorbis developer mailing lists.
- Talk to developers in IRC. They usually are hanging
around in #vorbis on irc.xiph.org. They can tell you more
about what projects would be interesting at the current
moment.
Once you have seen what others are doing, you will have a
better chance to find a project to work on.
- How do I contribute a bug-fix or enhancement of
the Xiph.org Ogg Vorbis libraries and tools?
-
If you want to contribute bug fixes or enhancements to
vorbis-tools, the preferred method is to generate a patch
against the latest CVS code. You can do
this by running the command "cvs diff -u >
mybugfix.patch" from the source code directory you checked
out from CVS.
Once you have a patch, you need to file a bug/enhancement
report on the Xiph.org
Bugzilla server. You can attach your patch to the bug
entry. If you consider the enhancement to be of general
interest or want comments from the developer community, you
are encouraged to post a message to the Vorbis development
mailing list describing the patch and linking to the bug
entry with your patch.
Please note that patches contributed under license terms
not compatible with the existing package license (BSD for
libogg and libvorbis, GPL for libao and vorbis-tools) will
generally not be accepted.
- Is it feasible to port the Vorbis
decoder/encoder to a platform without floating point support
(such as a StrongARM CPU)?
-
The reference implementations of the Vorbis decoder and
encoder provided on the vorbis.com
download page depend heavily on floating point hardware.
While this presents no problem for workstation-class CPUs
(like x86 and PowerPC), it means that embedded CPUs without
floating point support (as are often found in portable
devices) are at a severe disadvantage. There are two
possible ways to work around this problem:
- Emulate the floating point instructions -- Kernel
emulation of floating point instructions is too slow to
use for vorbis. There are userspace libraries which
provide floating point emulation that might be fast enough
for your hardware. Examples are MathLib
for PalmOS and the -msoft-float support in GCC.
- Change the vorbis library to use integer-only
instructions -- This is the more efficient solution, but
also requires more specialized knowledge to implement.
Several people seem to have attempted it or are working on
it now, but no free integer-based Vorbis decoder exists at
the moment. Xiph.org has an integer-based decoder library
available for licensing. Contact Emmett Plant for
details.
- Why doesn't the latest release version
compile properly on Linux-From-Scratch systems?
-
It's a bug in gcc-2.95. One workaround is to compile with
-march=i586 instead of the default -march=i686; real fixes
already exist in newer versions of gcc.
"Linux-From-Scratch" users encounter this bug most
frequently, since that distribution uses the lethal
combination of gcc-2.95 and -march=i686 by default, but it
may also affect other distributions like Gentoo or users who
choose their own compilers or optimizations.
- Why can't I compile the latest CVS on Red
Hat 7.3?
-
Red Hat 7.3 comes with two versions of autoconf. 2.13 is
the default; CVS will only compile with 2.53.
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Current Affairs
- Version 1.0 is out! What does that mean?
-
For several months, and through several beta and
prerelease versions, the reference Vorbis encoder and
auxiliary software have been undergoing extensive
bug-fixing, audio quality tuning, and listening tests in
order to make it the best quality possible. We are now ready
to offer Ogg Vorbis to the public in a complete, open, and
free software suite as an alternative to other more
restrictive or lower-quality music formats.
You are encouraged to download the software, encode your
favorite music, and compare its quality to other compression
schemes, and developers are encouraged to use the software
and format in their own projects.
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Meta-FAQ
- I have a question that isn't answered by
this FAQ. Where can I turn for help?
-
There are archived mailing lists for advocacy, user
discussion, and development at Xiph.org's mailing list
page, as well as an IRC channel #Vorbis on IRC network
OpenProjects.net.
- Where can discussions about and
contributions to this FAQ be made?
-
Xiph.org's mailing
list page also has subscription info and archives of the
Vorbis-FAQ mailing list. Contributions and discussion are
welcome there.
- How current is this FAQ?
-
It was updated on 2002-07-15 0310GMT.
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