lossyWAV is a free, lossy pre-processor for PCM audio contained in the WAV file format. Proposed by David Robinson, it reduces bit depth of the input signal, which, when used in conjunction with certain lossless codecs, reduces the bitrate of the encoded file significantly compared to unpreprocessed compression. lossyWAV’s primary goal is to maintain transparency with a high degree of confidence when processing any audio data. ~ wiki.hydrogenaud.io/index.php?title=LossyWAV

lossyWAV is a near lossless audio processor which dynamically reduces the bit depth of the signal on a block-by-block basis. Bit Depth reduction adds noise to the processed output. The added noise is adaptively shaped by default and can alternatively be fixed noise shaped or white noise depending on command line parameters. When lossyWAV processed output is compressed with certain lossless codecs (FLAC, Wavpack, Tak, LPAC, MPEG-4 ALS and WMA-Lossless) the bitrate of the output file is significantly_[1] reduced compared to the lossless original.

[1]: on average, depending on content.

hydrogenaud.io/index.php/topic,112649
wiki.hydrogenaud.io/index.php?title=LossyWAV#lossyWAV_and_foobar2000
github.com/corrideat/lossywav
github.com/MoSal/lossywav-for-posix