exhale - ecodis extended high-efficiency and low-complexity encoder
^{Software Release Notes, Version History, Known Issues, Upcoming Feature Roadmap}

The version of this distribution of the «exhale» software release is 1.2.1 (official public minor release) from December 2023. Please check www.ecodis.de regularly for new versions of this software. A summary of each version up to this release, a list of known issues with this release, and a roadmap of additional functionality are provided below.

Chronological Version History

Version 1.2.1 Dec. 2023, this release

exhaleApp: always determine MPEG-4 instantaneous bit-rate across 2048 samples
exhaleLib: added code for MSE optimized encoding (for tests, disabled by default)
exhaleLib: code cleanup in quantization.*, increase max. IPF AU size to 10 kbit/ch
exhaleLib: fix two rare high-rate quality issues (only affects CVBR modes above 5)

Version 1.2.0 Dec. 2022

C API correction, some code sanitizing (issue 24, merge requests 8–11, J. Regan)
exhaleLib: code cleanup, very minor quality improvements in CVBR modes f and 5
exhaleLib: 5% speedup of all modes, better target rate matching in CVBR mode g
exhaleLib: work around MinGW compilation hickup (issue 26; thanks, C. Degawa!)

Version 1.1.9 Dec. 2021

exhaleApp: write encoder name and version as «udta» tool string into MP4 header
exhaleApp: optimize leading and trailing PCM read for gapless playback (issue 21)

Version 1.1.8 Oct. 2021

some final code cleanup, small code corrections and editorial changes for this year
exhaleLib: minor stereo quality tuning for low rates, optional CBR mode via macro

Version 1.1.7 Aug. 2021

minor tuning at low SBR rates, enabled SBR coding at 22050 Hz input sample rate
exhaleApp: added expert modes for loudness leveling, custom Intra frame interval

Version 1.1.6 May 2021

minor quality tuning and support for delayless operation (media time=0) with SBR
exhaleApp: fixed very rare output file corruption after finishing encoding with SBR
exhaleApp: fixed compilation error under Fedora (issue 20) and stdin hickup issue
exhaleLib: fixed some quality issues in SBR modes, no changes in non-SBR modes

Version 1.1.5 Apr. 2021

exhaleApp: correct print-out of Unicode file names and paths, minor code cleanup
exhaleLib: minor tuning of immediate playout frames, no changes to audio quality
makefile: support for compilation of Universal 2 binaries on MacOS™ (C. Snowhill)

Version 1.1.4 Mar. 2021

exhaleApp: removed LUFS/dBFS command arguments again, code now automatic
exhaleApp: consider the working instead of application path if no path is specified
exhaleLib: reduce enc. delay to closest integer multiple of frame length (issue 15)
exhaleLib: very minor tuning of transient coding especially on male speech signals

Version 1.1.3 Feb. 2021

exhaleApp: allow specifying loudness (LUFS) and peak sample (dBFS) after preset
exhaleLib: write UsacConfig in immediate playout frames (increases compatibility)

Version 1.1.2 Jan. 2021

further improved file interoperability and seekability with some playback software
exhaleLib: write all frames in «stss» data as immediate playout frames (issue 15)

Version 1.1.1 Dec. 2020

slightly improved audio quality with SBR, better compatibility with some decoders
exhaleLib: increased frequency resolution of coded SBR envelopes, minor cleanup
exhaleLib: workaround for time differential coding bug in some xHE-AAC decoders

Version 1.1.0 Nov. 2020

addition of basic SBR functionality for lower-rate coding down to 18 kbps/channel
exhaleApp: add support for CVBR modes a—g for encoding with SBR functionality
exhaleApp: show «ARM» in header and '-v' command on corresponding platforms
exhaleLib: basic 2:1 SBR encoding with ccfl = 2048, minor fixes and code cleanup

Version 1.0.8 Oct. 2020

minor quality improvements at low and high rates, some license text clarifications
exhaleApp: slightly improved loudness calculation for low and high sampling rates
exhaleLib: improved audio quality a bit for the lower and higher-rate CVBR modes
License: removed references to BSD text, clarified disclaimer and contributor text

Version 1.0.7 Aug. 2020

minor bugfixes in bit-rate control and higher-rate coding at 32 kHz sampling rate
exhaleApp: add support for CVBR mode 0 at codec sampling rates below 44.1 kHz
exhaleApp: write complete MP4 «stss» data for improved compatibility (issue 13)
exhaleApp: higher accuracy of loudness estimation, better BS.1770-4 compliance

Version 1.0.6 July 2020

bugfixes, improved quality on some transient signals, better decoder compatibility
exhaleApp: support for Extensible WAVE format, write MP4 «prol» data (issue 10)
exhaleApp: automatic downsampling of 48-kHz input to 32 kHz for CVBR mode 1
exhaleLib: fine-tuning of psychoacoustic model for difficult transient input signals

Version 1.0.5 June 2020

slightly reduced bit-rates with lower modes, better compatibility when using stdin
exhaleApp: support for Unicode text on Windows™, 44100 Hz with CVBR mode 1
exhaleApp: automatic upsampling of low-sample-rate input, fixed reader (issue 9)
exhaleLib: optimized noise filling tool for slightly lower bit-rates at CVBR mode <4
compilation: exhaleApp.exe -> exhale.exe (issue 8), support for Arm™, C header

Version 1.0.4 May 2020

finalized basic joint-stereo and TNS coding functionality, quality and stability fixes
exhaleApp: support for 32000 Hz with CVBR mode 1, added '-v' version command
exhaleLib: completed audio quality fine-tuning for very tonal and transient signals
compilation: support for MinGW (issue 5) and cmake (via CMakeList files, issue 6)

Version 1.0.3 Apr. 2020

extended basic joint-stereo coding functionality for mid/high rates, minor bugfixes
exhaleLib: band adaptive joint-stereo coding for all CVBR modes, fixed rare crash
exhaleLib: audio quality fine-tuning, especially for very tonal and transient signals
makefile: -std=c++11 to allow for compilation with older versions of gcc (issue 4)

Version 1.0.2 Mar. 2020

added basic low/mid-rate joint-stereo coding functionality, bugfixes, and speedups
exhaleApp: support for input sampling rates of up to 48000 Hz with CVBR mode 2
exhaleLib: frame adaptive joint-stereo preprocessing and coding (CVBR mode <5)
exhaleLib: accelerated R/D opt. coding, stability and quality fixes (issues 2 and 3)

Version 1.0.1 Feb. 2020

improved low-bitrate coding efficiency and support for MPEG-D loudness metadata
exhaleApp: increased MP4 file versatility (issue 1) and calculation of loudness info
exhaleLib: backward compatible API extension to support writing of loudness info
exhaleLib: extended R/D optimized coding, improved short-transform quantization

Version 1.0.0 Jan. 2020

compilation fixes and executable printout changes for Linux and MacOS™ platform
exhaleApp: fixed reading of WAVE files including metadata after the «data» chunk
exhaleLib: some tuning of transform and noise level detection for transient signals
exhaleLib: support for export as DLL on Microsoft Windows™ (not tested, though)

Version 1.0RC Dec. 2019

initial release for testing with only basic channel-independent coding functionality
only support for Microsoft Windows™ (32-bit and 64-bit) platform provided so far.

Known Issues with This Release

If you notice an issue with this release not mentioned below, please contact ecodis or a contributor with the details (configuration, input file) needed to reproduce the issue.

exhaleApp: At the end of each encoding run, the MPEG-4 file header with seeking information is written to the beginning of the output file to maximize compatibility in audio streaming applications. Since such a file operation is not supported with pipe based output, encoding to stdout instead of files is currently not supported.
exhaleApp: Only basic WAVE input file reading functionality has been implemented. Specifically, 8-bit WAVE input is assumed to contain an even number of audio samples, and ITU-R BS.2088 (RF64, Broadcast WAVE) files are not supported.

Roadmap of Upcoming Features

If you are in need of an additional library or application feature not mentioned below, please contact ecodis or a contributor with a request, and we will see what we can do.

exhaleLib: finalization of support for 5.1–7.1 multichannel coding, no version plan
exhaleLib: speed-ups and further quality tuning for difficult signals, as necessary.

exhale - ecodis extended high-efficiency and low-complexity encoderSoftware Release Notes, Version History, Known Issues, Upcoming Feature Roadmap

Chronological Version History

Version 1.2.1 Dec. 2023, this release

exhaleApp: always determine MPEG-4 instantaneous bit-rate across 2048 samples

exhaleLib: added code for MSE optimized encoding (for tests, disabled by default)

exhaleLib: code cleanup in quantization.*, increase max. IPF AU size to 10 kbit/ch

exhaleLib: fix two rare high-rate quality issues (only affects CVBR modes above 5)

Version 1.2.0 Dec. 2022

C API correction, some code sanitizing (issue 24, merge requests 8–11, J. Regan)

exhaleLib: code cleanup, very minor quality improvements in CVBR modes f and 5

exhaleLib: 5% speedup of all modes, better target rate matching in CVBR mode g

exhaleLib: work around MinGW compilation hickup (issue 26; thanks, C. Degawa!)

Version 1.1.9 Dec. 2021

exhaleApp: write encoder name and version as «udta» tool string into MP4 header

exhaleApp: optimize leading and trailing PCM read for gapless playback (issue 21)

Version 1.1.8 Oct. 2021

some final code cleanup, small code corrections and editorial changes for this year

exhaleLib: minor stereo quality tuning for low rates, optional CBR mode via macro

Version 1.1.7 Aug. 2021

minor tuning at low SBR rates, enabled SBR coding at 22050 Hz input sample rate

exhaleApp: added expert modes for loudness leveling, custom Intra frame interval

Version 1.1.6 May 2021

minor quality tuning and support for delayless operation (media time=0) with SBR

exhaleApp: fixed very rare output file corruption after finishing encoding with SBR

exhaleApp: fixed compilation error under Fedora (issue 20) and stdin hickup issue

exhaleLib: fixed some quality issues in SBR modes, no changes in non-SBR modes

Version 1.1.5 Apr. 2021

exhaleApp: correct print-out of Unicode file names and paths, minor code cleanup

exhaleLib: minor tuning of immediate playout frames, no changes to audio quality

makefile: support for compilation of Universal 2 binaries on MacOS™ (C. Snowhill)

Version 1.1.4 Mar. 2021

exhaleApp: removed LUFS/dBFS command arguments again, code now automatic

exhaleApp: consider the working instead of application path if no path is specified

exhaleLib: reduce enc. delay to closest integer multiple of frame length (issue 15)

exhaleLib: very minor tuning of transient coding especially on male speech signals

Version 1.1.3 Feb. 2021

exhaleApp: allow specifying loudness (LUFS) and peak sample (dBFS) after preset

exhaleLib: write UsacConfig in immediate playout frames (increases compatibility)

Version 1.1.2 Jan. 2021

further improved file interoperability and seekability with some playback software

exhaleLib: write all frames in «stss» data as immediate playout frames (issue 15)

Version 1.1.1 Dec. 2020

slightly improved audio quality with SBR, better compatibility with some decoders

exhaleLib: increased frequency resolution of coded SBR envelopes, minor cleanup

exhaleLib: workaround for time differential coding bug in some xHE-AAC decoders

Version 1.1.0 Nov. 2020

addition of basic SBR functionality for lower-rate coding down to 18 kbps/channel

exhaleApp: add support for CVBR modes a—g for encoding with SBR functionality

exhaleApp: show «ARM» in header and '-v' command on corresponding platforms

exhaleLib: basic 2:1 SBR encoding with ccfl = 2048, minor fixes and code cleanup

Version 1.0.8 Oct. 2020

minor quality improvements at low and high rates, some license text clarifications

exhaleApp: slightly improved loudness calculation for low and high sampling rates

exhaleLib: improved audio quality a bit for the lower and higher-rate CVBR modes

License: removed references to BSD text, clarified disclaimer and contributor text

Version 1.0.7 Aug. 2020

minor bugfixes in bit-rate control and higher-rate coding at 32 kHz sampling rate

exhaleApp: add support for CVBR mode 0 at codec sampling rates below 44.1 kHz

exhaleApp: write complete MP4 «stss» data for improved compatibility (issue 13)

exhaleApp: higher accuracy of loudness estimation, better BS.1770-4 compliance

Version 1.0.6 July 2020

bugfixes, improved quality on some transient signals, better decoder compatibility

exhaleApp: support for Extensible WAVE format, write MP4 «prol» data (issue 10)

exhaleApp: automatic downsampling of 48-kHz input to 32 kHz for CVBR mode 1

exhaleLib: fine-tuning of psychoacoustic model for difficult transient input signals

Version 1.0.5 June 2020

slightly reduced bit-rates with lower modes, better compatibility when using stdin

exhaleApp: support for Unicode text on Windows™, 44100 Hz with CVBR mode 1

exhaleApp: automatic upsampling of low-sample-rate input, fixed reader (issue 9)

exhaleLib: optimized noise filling tool for slightly lower bit-rates at CVBR mode <4

compilation: exhaleApp.exe -> exhale.exe (issue 8), support for Arm™, C header

Version 1.0.4 May 2020

finalized basic joint-stereo and TNS coding functionality, quality and stability fixes

exhaleApp: support for 32000 Hz with CVBR mode 1, added '-v' version command

exhaleLib: completed audio quality fine-tuning for very tonal and transient signals

compilation: support for MinGW (issue 5) and cmake (via CMakeList files, issue 6)

Version 1.0.3 Apr. 2020

extended basic joint-stereo coding functionality for mid/high rates, minor bugfixes

exhaleLib: band adaptive joint-stereo coding for all CVBR modes, fixed rare crash

exhaleLib: audio quality fine-tuning, especially for very tonal and transient signals

exhale - ecodis extended high-efficiency and low-complexity encoder
^{Software Release Notes, Version History, Known Issues, Upcoming Feature Roadmap}

exhaleApp: Only basic WAVE input file reading functionality has been implemented. Specifically, 8-bit WAVE input is assumed to contain an even number of audio samples, and ITU-R BS.2088 (RF64, Broadcast WAVE) files are not supported.