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author | Vignesh Venkatasubramanian <vigneshv@google.com> | 2014-02-20 10:50:35 -0800 |
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committer | Vignesh Venkatasubramanian <vigneshv@google.com> | 2014-02-20 22:40:47 -0800 |
commit | 2bd8b54017b5320bc0c1df9bf86f4cdc9f8db242 (patch) | |
tree | 46d79debe81d3b1db1f11b1c79b4edeb9318fedc /README | |
parent | 2010ddce09e55d41b92a36444a11cd747bfaf867 (diff) | |
download | libopus-2bd8b54017b5320bc0c1df9bf86f4cdc9f8db242.tar.gz |
Adding libopus source and Android.mk
Adding libopus source code and Android.mk. The source is based
on latest stable release libopus 1.1.
Change-Id: I0841894ee0766829e6d0e1b8379e6f6f87b0852f
Diffstat (limited to 'README')
-rw-r--r-- | README | 142 |
1 files changed, 142 insertions, 0 deletions
@@ -0,0 +1,142 @@ +== Opus audio codec == + +Opus is a codec for interactive speech and audio transmission over the Internet. + + Opus can handle a wide range of interactive audio applications, including +Voice over IP, videoconferencing, in-game chat, and even remote live music +performances. It can scale from low bit-rate narrowband speech to very high +quality stereo music. + + Opus, when coupled with an appropriate container format, is also suitable +for non-realtime stored-file applications such as music distribution, game +soundtracks, portable music players, jukeboxes, and other applications that +have historically used high latency formats such as MP3, AAC, or Vorbis. + + Opus is specified by IETF RFC 6716: + http://tools.ietf.org/html/rfc6716 + + The Opus format and this implementation of it are subject to the royalty- +free patent and copyright licenses specified in the file COPYING. + +This package implements a shared library for encoding and decoding raw Opus +bitstreams. Raw Opus bitstreams should be used over RTP according to + http://tools.ietf.org/html/draft-spittka-payload-rtp-opus + +The package also includes a number of test tools used for testing the +correct operation of the library. The bitstreams read/written by these +tools should not be used for Opus file distribution: They include +additional debugging data and cannot support seeking. + +Opus stored in files should use the Ogg encapsulation for Opus which is +described at: + http://wiki.xiph.org/OggOpus + +An opus-tools package is available which provides encoding and decoding of +Ogg encapsulated Opus files and includes a number of useful features. + +Opus-tools can be found at: + https://git.xiph.org/?p=opus-tools.git +or on the main Opus website: + http://opus-codec.org/ + +== Compiling libopus == + +To build from a distribution tarball, you only need to do the following: + +% ./configure +% make + +To build from the git repository, the following steps are necessary: + +1) Clone the repository: + +% git clone git://git.opus-codec.org/opus.git +% cd opus + +2) Compiling the source + +% ./autogen.sh +% ./configure +% make + +3) Install the codec libraries (optional) + +% sudo make install + +Once you have compiled the codec, there will be a opus_demo executable +in the top directory. + +Usage: opus_demo [-e] <application> <sampling rate (Hz)> <channels (1/2)> + <bits per second> [options] <input> <output> + opus_demo -d <sampling rate (Hz)> <channels (1/2)> [options] + <input> <output> + +mode: voip | audio | restricted-lowdelay +options: + -e : only runs the encoder (output the bit-stream) + -d : only runs the decoder (reads the bit-stream as input) + -cbr : enable constant bitrate; default: variable bitrate + -cvbr : enable constrained variable bitrate; default: + unconstrained + -bandwidth <NB|MB|WB|SWB|FB> + : audio bandwidth (from narrowband to fullband); + default: sampling rate + -framesize <2.5|5|10|20|40|60> + : frame size in ms; default: 20 + -max_payload <bytes> + : maximum payload size in bytes, default: 1024 + -complexity <comp> + : complexity, 0 (lowest) ... 10 (highest); default: 10 + -inbandfec : enable SILK inband FEC + -forcemono : force mono encoding, even for stereo input + -dtx : enable SILK DTX + -loss <perc> : simulate packet loss, in percent (0-100); default: 0 + +input and output are little-endian signed 16-bit PCM files or opus +bitstreams with simple opus_demo proprietary framing. + +== Testing == + +This package includes a collection of automated unit and system tests +which SHOULD be run after compiling the package especially the first +time it is run on a new platform. + +To run the integrated tests: +% make check + +There is also collection of standard test vectors which are not +included in this package for size reasons but can be obtained from: +http://opus-codec.org/testvectors/opus_testvectors.tar.gz + +To run compare the code to these test vectors: + +% curl -O http://opus-codec.org/testvectors/opus_testvectors.tar.gz +% tar -zxf opus_testvectors.tar.gz +% ./tests/run_vectors.sh ./ opus_testvectors 48000 + +== Portability notes == + +This implementation uses floating-point by default but can be compiled to +use only fixed-point arithmetic by setting --enable-fixed-point (if using +autoconf) or by defining the FIXED_POINT macro (if building manually). +The fixed point implementation has somewhat lower audio quality and is +slower on platforms with fast FPUs, it is normally only used in embedded +environments. + +The implementation can be compiled with either a C89 or a C99 compiler. +While it does not rely on any _undefined behavior_ as defined by C89 or +C99, it relies on common _implementation-defined behavior_ for two's +complement architectures: + +o Right shifts of negative values are consistent with two's + complement arithmetic, so that a>>b is equivalent to + floor(a/(2^b)), + +o For conversion to a signed integer of N bits, the value is reduced + modulo 2^N to be within range of the type, + +o The result of integer division of a negative value is truncated + towards zero, and + +o The compiler provides a 64-bit integer type (a C99 requirement + which is supported by most C89 compilers). |