This repository is a mirror of https://achurch.org/hg/libnogg/ (project page: https://achurch.org/libnogg/). Please do not open pull requests against this repository, as they will not be accepted.

Copyright (c) 2014-2026 Andrew Church <achurch@achurch.org>
See the file COPYING for conditions on use and redistribution.

Version: 1.18

libnogg is a library for decoding Ogg Vorbis audio streams, written with the aims of (1) improved code quality and robustness compared to the reference libogg and libvorbis libraries, and (2) improved performance compared to those libraries.

libnogg was originally developed from the public domain stb_vorbis decoder implementation, available as of this writing at https://github.com/nothings/stb.

libnogg is written in pure C99 (with some additional compiler- and architecture-specific code used to improve performance) and should compile with any standards-compliant compiler. The library does not rely on any external environmental services other than stdio for reading from file-based streams, and this specific functionality can be disabled for environments such as embedded systems in which stdio is unavailable or too expensive to include.

The included Makefile is written for GNU Make and supports building in POSIX-compatible environments (such as Linux, Mac OS X, and Windows using MinGW), using Clang, GCC, or the Intel C compiler (icc). With certain limitations, the Makefile can also be used to build native Windows objects with the Microsoft Visual C (MSVC) compiler; see under "Building" below.

On POSIX-compatible systems, libnogg can be built by simply running the make command (or gmake, if GNU Make is installed under that name on your system) in the top directory of the libnogg distribution. This will create shared and static library files in the top directory, which can then be installed on the system with make install (this may require elevated system privileges, such as with the sudo command).

Several configuration variables are available to control the build process or specify nonstandard paths for dependent libraries. These can be set on the make command line; for example, make ENABLE_ASSERT=1. See the "Configuration" section at the top of the Makefile file for details.

The Makefile also includes rules for building Windows libraries using Microsoft's Visual C/C++ compiler, with the following limitations:

• The build must be run under the Windows Subsystem for Linux (see https://learn.microsoft.com/en-us/windows/wsl/).
• The CC variable must point to the cl.exe compiler binary, and "cl.exe" must be in lowercase. If the compiler is installed in a pathname containing a space (such as "Program Files"), the value of CC must be quoted; for example: make CC=\''/mnt/c/.../cl.exe'\'
• The INCLUDE and LIB environment variables must be set as for an MSVC command prompt (see the vcvars32.bat and vcvars64.bat scripts included with MSVC).
• Only one of the shared or static library can be built in a single call to make. By default, the static library is built.
• Automatic dependency generation is not supported; changes to header files will not trigger rebuilds of source files which use them.
• Coverage analysis is not supported.
• Building of the nogg-benchmark tool has not been tested.

To build libnogg as part of a project in another build system, add the include/nogg.h header and all files in the libnogg distribution matching the wildcard src/*/*.c to the project. (It is recommended to use an actual wildcard, or a recursive reference to the directory src, if the build system supports such a feature; this allows the project to automatically pick up files added in subsequent updates to the library without any changes to the project configuration.) The libnogg source files should be configured to use the C99 language standard (or any later revision of the C standard, such as C11) if that is not the compiler's default.

The file tools/nogg-decode.c demonstrates how libnogg can be used to decode audio data from an Ogg Vorbis stream.

See the documentation in include/nogg.h for further details.

The following table shows decoding performance measured by running the nogg-benchmark tool on the files tests/data/thingy.ogg (monaural) and tests/data/sketch039.ogg (stereo), scaled so that the time taken by the reference decoder (libvorbis) is 1.0; thus, smaller values indicate better performance.

                         |    Time (monaural decode)
   Architecture (CPU)    | libvorbis | Tremor | libnogg
-------------------------+-----------+--------+---------
x86-64 (AMD Ryzen 3700X) |    1.00   |  1.19  |  0.44
ARM 32-bit (TI OMAP4460) |    1.00   |  0.70  |  0.61
ARM 64-bit (Apple A7)    |    1.00   |  1.31  |  0.78

                         |     Time (stereo decode)
   Architecture (CPU)    | libvorbis | Tremor | libnogg
-------------------------+-----------+--------+---------
x86-64 (AMD Ryzen 3700X) |    1.00   |  1.06  |  0.41
ARM 32-bit (TI OMAP4460) |    1.00   |  0.78  |  0.63
ARM 64-bit (Apple A7)    |    1.00   |  1.16  |  0.61

libnogg only decodes the first Ogg bitstream found in the input data. Interleaved and concatenated bitstreams with different bitstream IDs are properly detected but will be ignored during decoding.

libnogg does not support lossless deletion of samples from the beginning of the stream (negative initial sample position).

Please send any bug reports or suggestions directly to the author.