Changelog

Entries are sorted chronologically from oldest to youngest within each release,
releases are sorted from youngest to oldest.


version <next>:

- WebM support in Matroska de/muxer
- low overhead Ogg muxing
- MMS-TCP support
- VP8 de/encoding via libvpx
- Demuxer for On2's IVF format
- Pictor/PC Paint decoder
- HE-AAC v2 decoder
- libfaad2 wrapper removed
- DTS-ES extension (XCh) decoding support
- native VP8 decoder
- RTSP tunneling over HTTP
- RTP depacketization of SVQ3
- -strict inofficial replaced by -strict unofficial
- ffplay -exitonkeydown and -exitonmousedown options added
- native GSM / GSM MS decoder
- RTP depacketization of QDM2
- ANSI/ASCII art playback system
- Lego Mindstorms RSO de/muxer
- libavcore added
- SubRip subtitle file muxer and demuxer
- Chinese AVS encoding via libxavs
- ffprobe -show_packets option added
- RTP packetization of Theora and Vorbis
- RTP depacketization of MP4A-LATM
- RTP packetization and depacketization of VP8
- hflip filter
- Apple HTTP Live Streaming demuxer
- a64 codec
- MMS-HTTP support
- G.722 ADPCM audio encoder/decoder
- R10k video decoder
- ocv_smooth filter
- frei0r wrapper filter
- change crop filter syntax to width:height:x:y
- make the crop filter accept parametric expressions
- make ffprobe accept AVFormatContext options
- yadif filter
- blackframe filter
- Demuxer for Leitch/Harris' VR native stream format (LXF)
- RTP depacketization of the X-QT QuickTime format
- SAP (Session Announcement Protocol, RFC 2974) muxer and demuxer
- cropdetect filter
- ffmpeg -crop* options removed
- transpose filter added
- ffmpeg -force_key_frames option added
- demuxer for receiving raw rtp:// URLs without an SDP description
- single stream LATM/LOAS decoder
- setpts filter added
- Win64 support for optimized asm functions
- MJPEG/AVI1 to JPEG/JFIF bitstream filter
- ASS subtitle encoder and decoder
- IEC 61937 encapsulation for E-AC3, TrueHD, DTS-HD (for HDMI passthrough)
- overlay filter added
- rename aspect filter to setdar, and pixelaspect to setsar
- IEC 61937 demuxer
- Mobotix .mxg demuxer
- frei0r source added
- hqdn3d filter added
- RTP depacketization of QCELP
- FLAC parser added
- gradfun filter added
- AMR-WB decoder
- replace the ocv_smooth filter with a more generic ocv filter
- Windows Televison (WTV) demuxer
- FFmpeg metadata format muxer and demuxer
- SubRip (srt) subtitle decoder
- floating-point AC-3 encoder added
- Lagarith decoder
- ffmpeg -copytb option added
- IVF muxer added
- Wing Commander IV movies decoder added
- movie source added
- Bink version 'b' audio and video decoder
- Bitmap Brothers JV playback system
- Apple HTTP Live Streaming protocol handler
- sndio support for playback and record
- Linux framebuffer input device added
- Chronomaster DFA decoder
- Mobotix MxPEG decoder


version 0.6:

- PB-frame decoding for H.263
- deprecated vhook subsystem removed
- deprecated old scaler removed
- VQF demuxer
- Alpha channel scaler
- PCX encoder
- RTP packetization of H.263
- RTP packetization of AMR
- RTP depacketization of Vorbis
- CorePNG decoding support
- Cook multichannel decoding support
- introduced avlanguage helpers in libavformat
- 8088flex TMV demuxer and decoder
- per-stream language-tags extraction in asfdec
- V210 decoder and encoder
- remaining GPL parts in AC-3 decoder converted to LGPL
- QCP demuxer
- SoX native format muxer and demuxer
- AMR-NB decoding/encoding, AMR-WB decoding via OpenCORE libraries
- DPX image decoder
- Electronic Arts Madcow decoder
- DivX (XSUB) subtitle encoder
- nonfree libamr support for AMR-NB/WB decoding/encoding removed
- experimental AAC encoder
- RTP depacketization of ASF and RTSP from WMS servers
- RTMP support in libavformat
- noX handling for OPT_BOOL X options
- Wave64 demuxer
- IEC-61937 compatible Muxer
- TwinVQ decoder
- Bluray (PGS) subtitle decoder
- LPCM support in MPEG-TS (HDMV RID as found on Blu-ray disks)
- WMA Pro decoder
- Core Audio Format demuxer
- Atrac1 decoder
- MD STUDIO audio demuxer
- RF64 support in WAV demuxer
- MPEG-4 Audio Lossless Coding (ALS) decoder
- -formats option split into -formats, -codecs, -bsfs, and -protocols
- IV8 demuxer
- CDG demuxer and decoder
- R210 decoder
- Auravision Aura 1 and 2 decoders
- Deluxe Paint Animation playback system
- SIPR decoder
- Adobe Filmstrip muxer and demuxer
- RTP depacketization of H.263
- Bink demuxer and audio/video decoders
- enable symbol versioning by default for linkers that support it
- IFF PBM/ILBM bitmap decoder
- concat protocol
- Indeo 5 decoder
- RTP depacketization of AMR
- WMA Voice decoder
- ffprobe tool
- AMR-NB decoder
- RTSP muxer
- HE-AAC v1 decoder
- Kega Game Video (KGV1) decoder
- VorbisComment writing for FLAC, Ogg FLAC and Ogg Speex files
- RTP depacketization of Theora
- HTTP Digest authentication
- RTMP/RTMPT/RTMPS/RTMPE/RTMPTE protocol support via librtmp
- Psygnosis YOP demuxer and video decoder
- spectral extension support in the E-AC-3 decoder
- unsharp video filter
- RTP hinting in the mov/3gp/mp4 muxer
- Dirac in Ogg demuxing
- seek to keyframes in Ogg
- 4:2:2 and 4:4:4 Theora decoding
- 35% faster VP3/Theora decoding
- faster AAC decoding
- faster H.264 decoding
- RealAudio 1.0 (14.4K) encoder


version 0.5:

- DV50 AKA DVCPRO50 encoder, decoder, muxer and demuxer
- TechSmith Camtasia (TSCC) video decoder
- IBM Ultimotion (ULTI) video decoder
- Sierra Online audio file demuxer and decoder
- Apple QuickDraw (qdrw) video decoder
- Creative ADPCM audio decoder (16 bits as well as 8 bits schemes)
- Electronic Arts Multimedia (WVE/UV2/etc.) file demuxer
- Miro VideoXL (VIXL) video decoder
- H.261 video encoder
- QPEG video decoder
- Nullsoft Video (NSV) file demuxer
- Shorten audio decoder
- LOCO video decoder
- Apple Lossless Audio Codec (ALAC) decoder
- Winnov WNV1 video decoder
- Autodesk Animator Studio Codec (AASC) decoder
- Indeo 2 video decoder
- Fraps FPS1 video decoder
- Snow video encoder/decoder
- Sonic audio encoder/decoder
- Vorbis audio decoder
- Macromedia ADPCM decoder
- Duck TrueMotion 2 video decoder
- support for decoding FLX and DTA extensions in FLIC files
- H.264 custom quantization matrices support
- ffserver fixed, it should now be usable again
- QDM2 audio decoder
- Real Cooker audio decoder
- TrueSpeech audio decoder
- WMA2 audio decoder fixed, now all files should play correctly
- RealAudio 14.4 and 28.8 decoders fixed
- JPEG-LS decoder
- build system improvements
- tabs and trailing whitespace removed from the codebase
- CamStudio video decoder
- AIFF/AIFF-C audio format, encoding and decoding
- ADTS AAC file reading and writing
- Creative VOC file reading and writing
- American Laser Games multimedia (*.mm) playback system
- Zip Motion Blocks Video decoder
- improved Theora/VP3 decoder
- True Audio (TTA) decoder
- AVS demuxer and video decoder
- JPEG-LS encoder
- Smacker demuxer and decoder
- NuppelVideo/MythTV demuxer and RTjpeg decoder
- KMVC decoder
- MPEG-2 intra VLC support
- MPEG-2 4:2:2 encoder
- Flash Screen Video decoder
- GXF demuxer
- Chinese AVS decoder
- GXF muxer
- MXF demuxer
- VC-1/WMV3/WMV9 video decoder
- MacIntel support
- AVISynth support
- VMware video decoder
- VP5 video decoder
- VP6 video decoder
- WavPack lossless audio decoder
- Targa (.TGA) picture decoder
- Vorbis audio encoder
- Delphine Software .cin demuxer/audio and video decoder
- Tiertex .seq demuxer/video decoder
- MTV demuxer
- TIFF picture encoder and decoder
- GIF picture decoder
- Intel Music Coder decoder
- Zip Motion Blocks Video encoder
- Musepack decoder
- Flash Screen Video encoder
- Theora encoding via libtheora
- BMP encoder
- WMA encoder
- GSM-MS encoder and decoder
- DCA decoder
- DXA demuxer and decoder
- DNxHD decoder
- Gamecube movie (.THP) playback system
- Blackfin optimizations
- Interplay C93 demuxer and video decoder
- Bethsoft VID demuxer and video decoder
- CRYO APC demuxer
- Atrac3 decoder
- V.Flash PTX decoder
- RoQ muxer, RoQ audio encoder
- Renderware TXD demuxer and decoder
- extern C declarations for C++ removed from headers
- sws_flags command line option
- codebook generator
- RoQ video encoder
- QTRLE encoder
- OS/2 support removed and restored again
- AC-3 decoder
- NUT muxer
- additional SPARC (VIS) optimizations
- Matroska muxer
- slice-based parallel H.264 decoding
- Monkey's Audio demuxer and decoder
- AMV audio and video decoder
- DNxHD encoder
- H.264 PAFF decoding
- Nellymoser ASAO decoder
- Beam Software SIFF demuxer and decoder
- libvorbis Vorbis decoding removed in favor of native decoder
- IntraX8 (J-Frame) subdecoder for WMV2 and VC-1
- Ogg (Theora, Vorbis and FLAC) muxer
- The "device" muxers and demuxers are now in a new libavdevice library
- PC Paintbrush PCX decoder
- Sun Rasterfile decoder
- TechnoTrend PVA demuxer
- Linux Media Labs MPEG-4 (LMLM4) demuxer
- AVM2 (Flash 9) SWF muxer
- QT variant of IMA ADPCM encoder
- VFW grabber
- iPod/iPhone compatible mp4 muxer
- Mimic decoder
- MSN TCP Webcam stream demuxer
- RL2 demuxer / decoder
- IFF demuxer
- 8SVX audio decoder
- non-recursive Makefiles
- BFI demuxer
- MAXIS EA XA (.xa) demuxer / decoder
- BFI video decoder
- OMA demuxer
- MLP/TrueHD decoder
- Electronic Arts CMV decoder
- Motion Pixels Video decoder
- Motion Pixels MVI demuxer
- removed animated GIF decoder/demuxer
- D-Cinema audio muxer
- Electronic Arts TGV decoder
- Apple Lossless Audio Codec (ALAC) encoder
- AAC decoder
- floating point PCM encoder/decoder
- MXF muxer
- DV100 AKA DVCPRO HD decoder and demuxer
- E-AC-3 support added to AC-3 decoder
- Nellymoser ASAO encoder
- ASS and SSA demuxer and muxer
- liba52 wrapper removed
- SVQ3 watermark decoding support
- Speex decoding via libspeex
- Electronic Arts TGQ decoder
- RV40 decoder
- QCELP / PureVoice decoder
- RV30 decoder
- hybrid WavPack support
- R3D REDCODE demuxer
- ALSA support for playback and record
- Electronic Arts TQI decoder
- OpenJPEG based JPEG 2000 decoder
- NC (NC4600) camera file demuxer
- Gopher client support
- MXF D-10 muxer
- generic metadata API


version 0.4.9-pre1:

- DV encoder, DV muxer
- Microsoft RLE video decoder
- Microsoft Video-1 decoder
- Apple Animation (RLE) decoder
- Apple Graphics (SMC) decoder
- Apple Video (RPZA) decoder
- Cinepak decoder
- Sega FILM (CPK) file demuxer
- Westwood multimedia support (VQA & AUD files)
- Id Quake II CIN playback support
- 8BPS video decoder
- FLIC playback support
- RealVideo 2.0 (RV20) decoder
- Duck TrueMotion v1 (DUCK) video decoder
- Sierra VMD demuxer and video decoder
- MSZH and ZLIB decoder support
- SVQ1 video encoder
- AMR-WB support
- PPC optimizations
- rate distortion optimal cbp support
- rate distorted optimal ac prediction for MPEG-4
- rate distorted optimal lambda->qp support
- AAC encoding with libfaac
- Sunplus JPEG codec (SP5X) support
- use Lagrange multipler instead of QP for ratecontrol
- Theora/VP3 decoding support
- XA and ADX ADPCM codecs
- export MPEG-2 active display area / pan scan
- Add support for configuring with IBM XLC
- floating point AAN DCT
- initial support for zygo video (not complete)
- RGB ffv1 support
- new audio/video parser API
- av_log() system
- av_read_frame() and av_seek_frame() support
- missing last frame fixes
- seek by mouse in ffplay
- noise reduction of DCT coefficients
- H.263 OBMC & 4MV support
- H.263 alternative inter vlc support
- H.263 loop filter
- H.263 slice structured mode
- interlaced DCT support for MPEG-2 encoding
- stuffing to stay above min_bitrate
- MB type & QP visualization
- frame stepping for ffplay
- interlaced motion estimation
- alternate scantable support
- SVCD scan offset support
- closed GOP support
- SSE2 FDCT
- quantizer noise shaping
- G.726 ADPCM audio codec
- MS ADPCM encoding
- multithreaded/SMP motion estimation
- multithreaded/SMP encoding for MPEG-1/MPEG-2/MPEG-4/H.263
- multithreaded/SMP decoding for MPEG-2
- FLAC decoder
- Metrowerks CodeWarrior suppport
- H.263+ custom pcf support
- nicer output for 'ffmpeg -formats'
- Matroska demuxer
- SGI image format, encoding and decoding
- H.264 loop filter support
- H.264 CABAC support
- nicer looking arrows for the motion vector visualization
- improved VCD support
- audio timestamp drift compensation
- MPEG-2 YUV 422/444 support
- polyphase kaiser windowed sinc and blackman nuttall windowed sinc audio resample
- better image scaling
- H.261 support
- correctly interleave packets during encoding
- VIS optimized motion compensation
- intra_dc_precision>0 encoding support
- support reuse of motion vectors/MB types/field select values of the source video
- more accurate deblock filter
- padding support
- many optimizations and bugfixes
- FunCom ISS audio file demuxer and according ADPCM decoding


version 0.4.8:

- MPEG-2 video encoding (Michael)
- Id RoQ playback subsystem (Mike Melanson and Tim Ferguson)
- Wing Commander III Movie (.mve) file playback subsystem (Mike Melanson
  and Mario Brito)
- Xan DPCM audio decoder (Mario Brito)
- Interplay MVE playback subsystem (Mike Melanson)
- Duck DK3 and DK4 ADPCM audio decoders (Mike Melanson)


version 0.4.7:

- RealAudio 1.0 (14_4) and 2.0 (28_8) native decoders. Author unknown, code from mplayerhq
  (originally from public domain player for Amiga at http://www.honeypot.net/audio)
- current version now also compiles with older GCC (Fabrice)
- 4X multimedia playback system including 4xm file demuxer (Mike
  Melanson), and 4X video and audio codecs (Michael)
- Creative YUV (CYUV) decoder (Mike Melanson)
- FFV1 codec (our very simple lossless intra only codec, compresses much better
  than HuffYUV) (Michael)
- ASV1 (Asus), H.264, Intel indeo3 codecs have been added (various)
- tiny PNG encoder and decoder, tiny GIF decoder, PAM decoder (PPM with
  alpha support), JPEG YUV colorspace support. (Fabrice Bellard)
- ffplay has been replaced with a newer version which uses SDL (optionally)
  for multiplatform support (Fabrice)
- Sorenson Version 3 codec (SVQ3) support has been added (decoding only) - donated
  by anonymous
- AMR format has been added (Johannes Carlsson)
- 3GP support has been added (Johannes Carlsson)
- VP3 codec has been added (Mike Melanson)
- more MPEG-1/2 fixes
- better multiplatform support, MS Visual Studio fixes (various)
- AltiVec optimizations (Magnus Damn and others)
- SH4 processor support has been added (BERO)
- new public interfaces (avcodec_get_pix_fmt) (Roman Shaposhnick)
- VOB streaming support (Brian Foley)
- better MP3 autodetection (Andriy Rysin)
- qpel encoding (Michael)
- 4mv+b frames encoding finally fixed (Michael)
- chroma ME (Michael)
- 5 comparison functions for ME (Michael)
- B-frame encoding speedup (Michael)
- WMV2 codec (unfinished - Michael)
- user specified diamond size for EPZS (Michael)
- Playstation STR playback subsystem, still experimental (Mike and Michael)
- ASV2 codec (Michael)
- CLJR decoder (Alex)

.. And lots more new enhancements and fixes.


version 0.4.6:

- completely new integer only MPEG audio layer 1/2/3 decoder rewritten
  from scratch
- Recoded DCT and motion vector search with gcc (no longer depends on nasm)
- fix quantization bug in AC3 encoder
- added PCM codecs and format. Corrected WAV/AVI/ASF PCM issues
- added prototype ffplay program
- added GOB header parsing on H.263/H.263+ decoder (Juanjo)
- bug fix on MCBPC tables of H.263 (Juanjo)
- bug fix on DC coefficients of H.263 (Juanjo)
- added Advanced Prediction Mode on H.263/H.263+ decoder (Juanjo)
- now we can decode H.263 streams found in QuickTime files (Juanjo)
- now we can decode H.263 streams found in VIVO v1 files(Juanjo)
- preliminary RTP "friendly" mode for H.263/H.263+ coding. (Juanjo)
- added GOB header for H.263/H.263+ coding on RTP mode (Juanjo)
- now H.263 picture size is returned on the first decoded frame (Juanjo)
- added first regression tests
- added MPEG-2 TS demuxer
- new demux API for libav
- more accurate and faster IDCT (Michael)
- faster and entropy-controlled motion search (Michael)
- two pass video encoding (Michael)
- new video rate control (Michael)
- added MSMPEG4V1, MSMPEGV2 and WMV1 support (Michael)
- great performance improvement of video encoders and decoders (Michael)
- new and faster bit readers and vlc parsers (Michael)
- high quality encoding mode: tries all macroblock/VLC types (Michael)
- added DV video decoder
- preliminary RTP/RTSP support in ffserver and libavformat
- H.263+ AIC decoding/encoding support (Juanjo)
- VCD MPEG-PS mode (Juanjo)
- PSNR stuff (Juanjo)
- simple stats output (Juanjo)
- 16-bit and 15-bit RGB/BGR/GBR support (Bisqwit)


version 0.4.5:

- some header fixes (Zdenek Kabelac <kabi at informatics.muni.cz>)
- many MMX optimizations (Nick Kurshev <nickols_k at mail.ru>)
- added configure system (actually a small shell script)
- added MPEG audio layer 1/2/3 decoding using LGPL'ed mpglib by
  Michael Hipp (temporary solution - waiting for integer only
  decoder)
- fixed VIDIOCSYNC interrupt
- added Intel H.263 decoding support ('I263' AVI fourCC)
- added Real Video 1.0 decoding (needs further testing)
- simplified image formats again. Added PGM format (=grey
  pgm). Renamed old PGM to PGMYUV.
- fixed msmpeg4 slice issues (tell me if you still find problems)
- fixed OpenDivX bugs with newer versions (added VOL header decoding)
- added support for MPlayer interface
- added macroblock skip optimization
- added MJPEG decoder
- added mmx/mmxext IDCT from libmpeg2
- added pgmyuvpipe, ppm, and ppm_pipe formats (original patch by Celer
  <celer at shell.scrypt.net>)
- added pixel format conversion layer (e.g. for MJPEG or PPM)
- added deinterlacing option
- MPEG-1/2 fixes
- MPEG-4 vol header fixes (Jonathan Marsden <snmjbm at pacbell.net>)
- ARM optimizations (Lionel Ulmer <lionel.ulmer at free.fr>).
- Windows porting of file converter
- added MJPEG raw format (input/ouput)
- added JPEG image format support (input/output)


version 0.4.4:

- fixed some std header definitions (Bjorn Lindgren
  <bjorn.e.lindgren at telia.com>).
- added MPEG demuxer (MPEG-1 and 2 compatible).
- added ASF demuxer
- added prototype RM demuxer
- added AC3 decoding (done with libac3 by Aaron Holtzman)
- added decoding codec parameter guessing (.e.g. for MPEG, because the
  header does not include them)
- fixed header generation in MPEG-1, AVI and ASF muxer: wmplayer can now
  play them (only tested video)
- fixed H.263 white bug
- fixed phase rounding in img resample filter
- add MMX code for polyphase img resample filter
- added CPU autodetection
- added generic title/author/copyright/comment string handling (ASF and RM
  use them)
- added SWF demux to extract MP3 track (not usable yet because no MP3
  decoder)
- added fractional frame rate support
- codecs are no longer searched by read_header() (should fix ffserver
  segfault)


version 0.4.3:

- BGR24 patch (initial patch by Jeroen Vreeken <pe1rxq at amsat.org>)
- fixed raw yuv output
- added motion rounding support in MPEG-4
- fixed motion bug rounding in MSMPEG4
- added B-frame handling in video core
- added full MPEG-1 decoding support
- added partial (frame only) MPEG-2 support
- changed the FOURCC code for H.263 to "U263" to be able to see the
  +AVI/H.263 file with the UB Video H.263+ decoder. MPlayer works with
  this +codec ;) (JuanJo).
- Halfpel motion estimation after MB type selection (JuanJo)
- added pgm and .Y.U.V output format
- suppressed 'img:' protocol. Simply use: /tmp/test%d.[pgm|Y] as input or
  output.
- added pgmpipe I/O format (original patch from Martin Aumueller
  <lists at reserv.at>, but changed completely since we use a format
  instead of a protocol)


version 0.4.2:

- added H.263/MPEG-4/MSMPEG4 decoding support. MPEG-4 decoding support
  (for OpenDivX) is almost complete: 8x8 MVs and rounding are
  missing. MSMPEG4 support is complete.
- added prototype MPEG-1 decoder. Only I- and P-frames handled yet (it
  can decode ffmpeg MPEGs :-)).
- added libavcodec API documentation (see apiexample.c).
- fixed image polyphase bug (the bottom of some images could be
  greenish)
- added support for non clipped motion vectors (decoding only)
  and image sizes non-multiple of 16
- added support for AC prediction (decoding only)
- added file overwrite confirmation (can be disabled with -y)
- added custom size picture to H.263 using H.263+ (Juanjo)


version 0.4.1:

- added MSMPEG4 (aka DivX) compatible encoder. Changed default codec
  of AVI and ASF to DIV3.
- added -me option to set motion estimation method
  (default=log). suppressed redundant -hq option.
- added options -acodec and -vcodec to force a given codec (useful for
  AVI for example)
- fixed -an option
- improved dct_quantize speed
- factorized some motion estimation code


version 0.4.0:

- removing grab code from ffserver and moved it to ffmpeg. Added
  multistream support to ffmpeg.
- added timeshifting support for live feeds (option ?date=xxx in the
  URL)
- added high quality image resize code with polyphase filter (need
  mmx/see optimization). Enable multiple image size support in ffserver.
- added multi live feed support in ffserver
- suppressed master feature from ffserver (it should be done with an
  external program which opens the .ffm url and writes it to another
  ffserver)
- added preliminary support for video stream parsing (WAV and AVI half
  done). Added proper support for audio/video file conversion in
  ffmpeg.
- added preliminary support for video file sending from ffserver
- redesigning I/O subsystem: now using URL based input and output
  (see avio.h)
- added WAV format support
- added "tty user interface" to ffmpeg to stop grabbing gracefully
- added MMX/SSE optimizations to SAD (Sums of Absolutes Differences)
  (Juan J. Sierralta P. a.k.a. "Juanjo" <juanjo at atmlab.utfsm.cl>)
- added MMX DCT from mpeg2_movie 1.5 (Juanjo)
- added new motion estimation algorithms, log and phods (Juanjo)
- changed directories: libav for format handling, libavcodec for
  codecs


version 0.3.4:

- added stereo in MPEG audio encoder


version 0.3.3:

- added 'high quality' mode which use motion vectors. It can be used in
  real time at low resolution.
- fixed rounding problems which caused quality problems at high
  bitrates and large GOP size


version 0.3.2: small fixes

- ASF fixes
- put_seek bug fix


version 0.3.1: added avi/divx support

- added AVI support
- added MPEG-4 codec compatible with OpenDivX. It is based on the H.263 codec
- added sound for flash format (not tested)


version 0.3: initial public release