opusfile.library 1.0
====================
Plays Ogg Opus (.opus) files on classic AmigaOS. libopus 1.6.1 (decoder,
fixed point), libogg 1.3.6 and opusfile (master 2026-03-28) are linked
into one shared library that exports
* the opusfile API: open files, memory blocks or your own streams
(web radio), read 16-bit PCM, seek, tags, chained streams,
ReplayGain-style gain, album art tag parsing
* the raw libopus decoder API, single stream and multistream
(5.1 / 7.1), for applications that do their own container parsing
74 functions. Output is always 48 kHz, 16-bit signed, big endian.
* no FPU needed (integer-only codec)
* no ixemul, no other libraries, no C library in the application
required - only exec.library and dos.library
* reentrant, any number of tasks may decode at the same time
* brings its own decoding stack: the caller's 4 KB default stack is fine
* one build per CPU: 68000, 68020, 68030, 68040, 68060
* the 68020/030/040 builds use the 32x32->64 bit muls.l and have the
FFT butterflies in assembly; their output is bit-identical to a
64-bit PC build of libopus
Installation
------------
Copy the library for your CPU to LIBS:
CPU copy
68000 / 68010 Libs/68000/opusfile.library
68020 / 68030 Libs/68020/opusfile.library
68040 Libs/68040/opusfile.library
68060 Libs/68060/opusfile.library
68080 (Vampire) Libs/68040/opusfile.library
for example
Copy opusfile/Libs/68040/opusfile.library LIBS:
Do not use the 68040 build on a 68060: the 060 does not implement the
64-bit muls.l and would trap into 68060.library on every multiply.
Tools (68020+)
--------------
C/opus2raw file.opus [out.raw]
Shows stream information and tags; with a second argument decodes
to raw 16-bit big-endian stereo PCM, 48 kHz.
C/opbench file.opus [out.raw]
Decodes the file from memory and reports the speed as a real-time
factor.
Speed
-----
Measured on a 68080 (Vampire A1200, Kickstart 3.2), 68040 build:
CELT stereo 128 kbit/s 1.60x real time
CELT mono 64 kbit/s 2.75x
SILK (speech) 12 kbit/s 5.58x
Hybrid stereo 40 kbit/s 2.02x
5.1 surround 256 kbit/s 0.53x
Real 68020-68060 CPUs have not been measured. At their clock rates they
will not decode 48 kHz stereo music in real time; speech and low-rate
mono streams are more realistic there.
For programmers
---------------
SDK/ contains the include files (proto, clib, GCC inline, fd, lvo), the
SFD and the original opusfile.h/opus.h headers with
their documentation.
#include <proto/exec.h>
#include <proto/opusfile.h>
struct Library *OpusFileBase = OpenLibrary("opusfile.library", 1);
OggOpusFile *of = op_open_file("music.opus", &err);
while ((n = op_read_stereo(of, pcm, 11520)) > 0) { ... }
op_free(of);
CloseLibrary(OpusFileBase);
Differences from the original API:
* 64-bit values (op_pcm_total, op_pcm_seek, ...) are exported as _ptr
functions; <libraries/opusfile_compat.h> maps the original names, so
source code does not change
* opus_decoder_ctl()/opus_multistream_decoder_ctl() are exported as
...ctlA(); the compat header maps the usual OPUS_SET_xxx() calls
* op_fopen() reads through dos.library and returns an opaque stream
* not available: op_fdopen, op_freopen, the URL/HTTP functions (do the
networking yourself and use op_open_callbacks()), the float API, the
encoder
* callbacks (OpusFileCallbacks, decode callback) use the C calling
convention with arguments on the stack; small-data programs must
declare them __saveds, register-argument programs __stdargs
README.md has the details: callbacks and stacks, tasks vs. processes,
resource use, how the library was built and tested.
SDK/examples contains the sources of opus2raw and opbench.
Tested
------
* A1200 with Vampire 68080, Kickstart 3.2 (47.13): 68020, 68040 and
68060 builds load and expunge cleanly; six stream types incl. 5.1;
tags; called with a 4 KB stack; two decoders in parallel; no memory
leaks
* Vampire V4 Standalone, 68080, Kickstart 3.2: 68040 build
* decoder output compared bit by bit against PC builds of libopus
Not yet tested on real 68000-68060 hardware, with the 68000/68030 builds,
or on Kickstart 3.0/3.1.
Reports welcome.
History
-------
1.0 (11.10.2026) first release
License
-------
3-clause BSD, see COPYING (libopus, libogg, opusfile (c) Xiph.Org
Foundation and contributors; Amiga glue (c) 2026 Matthias Muench).
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