| George Zipperlen on 5 Oct 2017 17:08:46 -0700 |
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| Re: [PLUG] PLUG Central - Sound on Linux: JACK (Keith Perry) & Audacity (George Zipperlen) |
Thank you everyone for their patience, we managed to more-or-less cobble a presentation together in spite of my difficulties connecting audio and video... there's this: The third slide condenses to "Add a pinch of FFmpeg and LAME to your Audacity, simmer gently" # Audacity ## FOSS cross-platform audio software ## for multi-track recording and editing ### Available for * GNU/Linux (your favorite distro) * source tar balls (http://www.audacityteam.org/download/source/) * Mac OS X, MacOS, whatever they call it next * Windoze ### May also need FFmpeg library of codecs and/or LAME, more below * Audacity uses the wxWidgets toolkit to provide similar graphical user interface on several different operating systems * The interface shows your audio tracks with various controls with the appearance of an old analog recording system. * I have used Audacity to import vinyl records and tapes from an existing analog home audio system * It is easy to import one huge stereo blob and cut it into individual tracks. * Basic controls are available * volume, * equalizer (bass/treble++), * balance (for stereo tracks) * plus fancier multi-track mixing, * and advanced features like cross fading, effects, etc. * copy, cut, paste, combine tracks... * It is then possible to export to various formats. * E.G. AIFF files which can be combined with metadata * into an iso and burned to CD with dd I could do an entire presentation on DRM, Copy Protection, and audio CDs that install **malware** when opened on a computer (non Linux (;-)) Sony effectively killed the CD as an audio format... ## Audio File Formats There could be a whole presentation on audio formats, streams, containers, codecs (encoder/decoder)... ### TLDR: -- Get the FFmpeg library of audio (& video) codecs #### Two different issues - compressed versus uncompressed - losslesss versus lossy - proprietary versus open formats ### It is best to work with uncompressed audio #### - raw (l)pcm (linear) pulse code modulation : .raw, .WAV, .AIFF, .au, ... ### Lossless compression #### There are lossless (generic) data compression techniques #### - zip, gz, etc #### - FLAC lossless combination of linear predictive coding and run-length coding #### - (_Free Lossless Audio Compression_) gets you about 50% to 60% size compresion ### lossy compression #### - alaw/mulaw (_ancient low bitrate telephone audio_) #### - Vorbis / ogg (_FOSS_) #### - MPEG / MP3 (_Proprietary psychoacoustic based_) 75% to 95% #### - MP3 is still ubiquitous (WinAmp, Napster, Amazon, Walmart, Rhapsody...) #### - AAC / mp4 - comparable compression to mp3, supposedly better sound quality #### - AAC is used by iTunes / iThings, YouTube, Nokia, PlayStation... ### The FFmpeg Import/Export Library converts between formats **FFmpeg** makes codecs available as * library calls that can be called from C/C++, Python, Perl... * command line programs to run in a shell #### Because of issues with some audio formats... (patented compression algorithms) #### Although, as of April 23, 2017 these patents have expired You may still need the **LAME MP3** encoder * on the Mac I had to manually find where the LAME installer placed the codec; and put it where FFmpeg expected to find it (bash, ls, find, cp...) |
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