Using WavPack Version 4.50
Home - Linux - WavPack options - WvUnpack options - WvGain options - Usage Guide - Non-CD - Plugins
WavPack consists of two complementary executable programs, WavPack and WvUnpack. These programs allow you to compress (and restore) audio files in the Microsoft .wav format. The audio files must be uncompressed PCM (not ADPCM, for example), but other than that there are few restrictions. The files may be any resolution from 8 to 32 bits; they may be mono, stereo, or multichannel; they may even be IEEE floating point data. The programs are full 32-bit executables and therefore must only be used under Windows (for real DOS applications it is possible to use the old WavPack 3.4 instead, but more recent versions of WavPack have been built for DOS by the author of Mpxplay and are available here). For version 4.31 an additional utility called WvGain was added to apply ReplayGain information to WavPack files. The programs are initiated from the MS-DOS command line prompt with the following syntax:

Usage:
`WAVPACK [-options] [@]infile[.wav]|- [[@]outfile[.wv]|outpath|-]`
`WVUNPACK [-options] [@]infile[.wv]|- [[@]outfile[.wav]|outpath|-]`
`WVGAIN [-options] [@]infile[.wv] [...]`

The filename extensions will be defaulted if not provided and the input filename may contain wildcards for doing batch operations. Specifying the output filename is optional, and if more than one input file is specified (with wildcards) then the only acceptable output specification is an output path. If the input filename begins with a '@' then the file is assumed to contain a list of newline separated filenames to be processed in batch mode (the output file may also be done this way although it may contain only a single line). The Windows frontend uses this mechanism for passing filenames, although it could be used for other purposes. Either filename can be replaced with "-" to allow use of stdin or stdout, although because the hybrid lossless mode uses two files it is not compatible with pipes.

Both programs will warn before overwriting any file (unless the -y switch is specified). The programs will also (unless the -q switch is specified) display progress in percentage complete and when finished with each file will give the compression ratio (or bitrate for lossy files), whether the compression was lossy or lossless, and the processing time. They will also display the progress percentage for the whole batch of files on the title bar which is useful when they are being run minimized. If a batch of files is run then both programs will indicate when complete whether any errors occurred and how many files were processed.

The compressed file format (.wv) contains all original header information and the compressed audio data for one .wav file. The file can be used by WvUnpack to restore the original file, or the .wv file can be played directly by a player that supports WavPack files natively like Foobar2000 or VUPlayer, or a player that can play WavPack files using a plugin like Winamp, dBpowerAMP, or Apollo. Also, there are plugins available to read and write WavPack files with Adobe Audition (and CoolEdit) and Nero Burning ROM.

A debugging mode is provided for the programs which is enabled by simply appending "_debug" to the the name of the executable (for example, wavpack.exe becomes wavpack_debug.exe). The debugging versions work exactly like the normal versions except that they report more detailed information about their operation. For instance, they will list their command-line arguments and wavpack.exe will display detailed information about the files it compresses (including how the audio data is interpreted). Also, all information displayed on the console (including any errors encountered) is dumped to a text file called "wavpack.log" (under Application Data). This is very handy for debugging in situations where the command-line window terminates before an error message can be read (or doesn't get displayed at all). It is not recommended that these debug version be used all the time because the log file will grow indefinitely.

Linux

This documentation was written specifically for the Windows command-line version of WavPack, however the version for Linux (and Unix) is essentially the same. There are some Windows-specific commands missing from the Linux version like the -e switch to create a Windows executable and the -l switch to run at low priority. The "debug" mode described above does not create a log file, but it does provide the extra information.

The most significant change is in the specification of the output filename or directory, which in the Linux case must be preceded with the -o switch. This was done to allow multiple input files to be specified, which is handy by itself but is especially useful in the default case where the shell is performing wildcard expansion.

WavPack Options

`-a = Adobe Audition (CoolEdit) mode for 32-bit floats`

The WAVEFORMATEXTENSIBLE structure is used (if present) to determine the format details. However, there are some programs that use their own non-standard format extensions. The most popular of these is Adobe's Audition (previously Syntrillium's CoolEdit) which created two new 32-bit floating point formats. An option has been added to WavPack (-a) to force the "adobe" interpretation of these floating point formats. If you are compressing integer files do NOT use this option.

`-bn = enable hybrid compression, n = 2.0 to 23.9 bits/sample, or`
`n = 24-9600 kbits/second (kbps)`

The default operation of WavPack is pure lossless, which means that the .wv file contains all the information that was in the original .wav file. The hybrid mode allows the user to specify a target bitrate for the output file, either in kilobits per second (kbps) or bits per sample. If the track can be losslessly compressed without exceeding the specified bitrate, then it will be and WavPack will report the compression as lossless. If lossless compression would exceed the specified bitrate, then WavPack will begin carefully discarding the least significant portion of the audio information to stay within the limit. Every effort is made to keep this inaudible, including the use of joint stereo, dynamic bit allocation and noise shaping. WavPack will report this as "lossy" compression. Although the option accepts bitrates as low as 24 kbps, the actual value that WavPack can achieve is usually much higher than that. For example, with CD-audio sampled at 44.1k the lower limit is about 196 kbps.

`--blocksize=n = specify block size in samples (n = 128 - 131072)`

WavPack normally determines the optimum number of samples to place into each WavPack block, however this option allows it to be directly specified. The most likely use for this option would be to improve the handling of audio files that have a variable number of redundant MSBs. For example, the output of the lossyWAV program or the output of a software HDCD decoder. This option is also often combined with the --merge-blocks option (which also reduces the minimum allowed block size to 16 samples).

`-c = create correction file (.wvc) for hybrid mode (=lossless)`

If the -c option is specified (in addition to the -b option), then WavPack will generate an additional file that will contain the information that was discarded to generate the lossy .wv file. This file will have the same name as the .wv file but will have the extension .wvc (the 'c' is for "correction"). When WvUnpack is used to restore the .wav file, it will attempt to find the .wvc file in the same directory as the .wv file. If it is found then the decompression will be lossless and will be reported as such, otherwise lossy decompression will be reported (assuming that any information was actually discarded during the original compression). If -c is specified but no actual information is discarded, the correction file will be deleted. The extra overhead involved with having these two files instead of a single pure lossless file is usually less than 1% of the original .WAV file and can be as low as 0.25% at high bitrates. Note that CRCs are stored for both the lossy and lossless versions, so error detection works correctly whether the .wvc file is used or not.

`-cc = maximum hybrid compression (hurts lossy quality & decode speed)`

Normally, when the -c option is used to create a correction file in the hybrid mode, WavPack attempts to optimize for the quality of the lossy file and lets the combined lossless compression of the two files fall where it may. This option tells WavPack to optimize for the overall compression ratio instead, even if this means some possible degradation of lossy quality (for example, dynamic noise shaping is not used in this mode). This can also have an effect on lossless decompression speed (however it does not affect lossy decoding). Keep in mind the effect of this option is not too significant either way.

`--channel-order=<list> = specify non-standard channel ordering)`

For multichannel audio WAV files, WavPack assumes that they are in the standard Microsoft order. However, some programs generate different channel orders (especially those that do not generate WAVEFORMATEXTENSIBLE headers). For those files, this command allows the user to override the Microsoft order and specify a list of channels from this list (which is in Microsoft order): FL,FR,FC,LFE,BL,BR,LC,FRC,BC,SL,SR,TC,TFL,TFC,TFR,TBL,TBC,TBR.

Note that this operation reorders the channels before encoding, so if the resulting WavPack file is subsequently unpacked it will not recreate the identical WAV file (because the channels will now be in the correct order). If you want the unpacked file to be identical to the original simply do not use this command (although this means that the resulting WavPack file will not have the correct channel information and so won't play correctly in multichannel software, and also means that the compression might not be as good because the "wrong" channels will be paired in stereo).

If this option is used then it might be a good idea to add the -r option also to generate a valid WAVEFORMATEXTENSIBLE header with the correct channel information. In fact, one could even pipe the output of WavPack directly to WvUnpack for the sole purpose of reordering WAV files and adding the correct WAV headers!

`-d = delete source file if successful (use with caution!)`

Self explanatory.

`-e = create self-extracting executable (needs wvselfx.exe)`

WavPack can be used to create self-extracting archives (Windows only) with a .exe extension. In this way it is possible to distribute compressed audio without having the recipient install any other programs (or have any dlls) to unpack the archives. When the .exe file is run (directly or by double-clicking) it extracts the original .wav file into the same directory. If it can't (because the file exists or it is run on a read-only device) then it displays a standard Windows "Extract to" dialog box and allows the user to specify the destination. The self-extracting feature can be used with WavPack's hybrid modes as well as pure lossless. If a .wvc file (with the correct name) is present in the same directory as the executable, then a lossless extraction is automatically performed. It is possible to turn the .exe file back into a valid WavPack by simply changing the extension back to .wv (although the extra 33k unpacking header will still be there).

As of version 4.40, the self-extraction module will also check for a CUESHEET field in the APEv2 tag and if it is present then the text in the CUESHEET field will be extracted into an appropriately named .cue file. Note that the cuesheet is not automatically modified to point to the correct .wav file; this must be handled either when the cuesheet is embedded or (if the .exe file is renamed) by the user after extraction.

To convert an existing WavPack 4.x file into a self-extracting executable use the DOS copy command to prepend the self-extracting stub (wvselfx.exe) to the .wv file:

> `C:\music_files>copy /b wvselfx.exe+music.wv music.exe`

`-f = fast mode (fast, but some compromise in compression ratio)`

The "fast" mode should be used when compression (or decompression) speed is more important than compression ratio (or, in lossy mode, audio quality).

`-h = high quality (better compression in all modes, but slower)`

The "high" mode should be used when compression ratio (or, in lossy mode, audio quality) is more important than compression (or decompression) speed. This option slows both by about a factor of about 1.5.

`-hh = very high quality (best compression in all modes, but slowest)`

The "very high" mode should be used when compression ratio (or, in lossy mode, audio quality) is much more important than compression (or decompression) speed. This option slows both by about a factor of about 2, and is not recommended for use on portable devices because of the high CPU load required for decoding.

`--help = extended help display`

Self explanatory.

`-i = ignore length in wav header (no pipe output allowed)`

Some programs that pipe data to encoders do not always give the correct length in the wav headers that they provide (foobar's clienc and CDex are examples). In these cases use this option to force WavPack to ignore the header and accept the actual length. Because WavPack must seek to the beginning of the file to write the correct length, this option cannot be used with piped output.

`-jn = joint-stereo override (0 = left/right, 1 = mid/side)`

WavPack normally defaults to joint stereo (sometimes called mid/side) in which the left and right channels are combined to form an alternate representation (essentially L+R and L-R) that compresses better in lossless mode and improves quality in lossy mode. This option allows this feature to be forced either on or off.

`-l = run at low priority (for smoother multitasking)`

This option can be used (in Windows only) to force WavPack to run at a low priority and is handy for doing large WavPack batch conversions in the background.

`-m = compute & store MD5 signature of raw audio data`

Calculate and display the MD5 checksum of the uncompressed audio data and store it in the compressed file. These sums are commonly used in file trading communities to compare versions of tracks, and as such the sums generated by WavPack match those of FLAC, OptimFROG, Shntool, and get_id3(). They can also be used by WvUnpack during decompression to verify the data integrity of lossless files.

`--merge-blocks = merge consecutive blocks of equal redundancy`

This option is only valid when generating lossless files and is only used with the --blocksize command. WavPack will always scan each block of audio data before compressing to determine the actual number of valid bits that need to be stored because, for various reasons, this is not always the same as the number of bits present. In some situations there can be many redundant bits, as for example in the output of the lossyWAV program or the output of software HDCD decoders. In these cases it may be advantagous to use a specific block size (or simply a small block size), but WavPack does not work very well with very small block sizes because of its relatively large block header.

The --merge-blocks option takes care of this situation by allowing WavPack to merge consecutive blocks with the same number of bits to remove. For example, if a blocksize of 512 is specified, and 10 512-sample blocks in a row all have exactly the same number of redundant bits, then these 10 blocks will be combined in to a single block of 5120 samples (which is much more efficient for WavPack). When the --merge-blocks option is specified the minimum block size that --blocksize will accept is reduced from 128 to 16 samples.

`-n = calculate average and peak quantization noise (hybrid only)`

This causes WavPack to calculate the average and peak quantization noise generated in the lossy version of the hybrid mode, both referenced in decibels below full scale. While it is impossible to use this as a guide to determine the audibility of the noise, it is useful for comparing the various compression options and for comparing WavPack's lossy performance to other programs. Note that this option does not currently produce meaningfull results for floating point or multichannel files.

`--optimize-mono = optimization for stereo files that are really mono`

Use this option on stereo files that may actually be mono (i.e. old recordings) to increase the compression ratio by up to 6%. Note that on stereo recordings that are almost mono (as many supposedly mono recordings are) this will not improve compression. This option does not significantly slow encoding, however the resulting files are not compatible with older WavPack decoders (before version 4.3).

`-p = practical float storage (also 32-bit ints, not lossless)`

This option reduces the storage of some floating-point data files by up to about 10% by eliminating some information that has virtually no effect on the audio data. While this does technically make the compression lossy, it retains all the advantages of floating point data (>600 dB of dynamic range, no clipping, and 25 bits of resolution). This also affects large integer compression by limiting the resolution to 24 bits.

`-q = quiet (keep console output to a minimum)`

Self explanatory.

`-r = generate new RIFF wav header (removing extra chunk info)`

WavPack normally saves all the RIFF header information contained in the wav file (including any chunks after the audio data). This is done so that WvUnpack.exe can restore the original wav files exactly. The -r option causes WavPack to discard the header contained in the source file (and any extra chunks) and generate a fresh wav header. Obviously the source wav header is still used to determine the format and size of the file (i.e. this is not a "raw" mode). Note that for multichannel files a WAVEFORMATEXTENSIBLE header is generated whether the source file had one or not. Also note that this option cannot be used with certain floating-point wav files generated by CoolEdit or Audition because they are not properly normalized.

`-sn = noise shaping override (hybrid only, n = -1.0 to 1.0, 0 = off)`

WavPack uses first-order noise shaping to improve the perceived quality of lossy files and to improve the hybrid lossless compression ratio. Normally WavPack will choose the noise shaping most appropriate for the application (based on the source sampling rate and whether the -cc option is specified), but this option allows the user to override the default with a fixed value. The parameter range is +/- 1.0, where positive values shift the noise higher in frequency and negative values shift the noise lower in frequency. Values very close to -1.0 are clipped to prevent problems associated with very high gain near DC and the value zero results in no noise shaping at all (i.e., white noise). This option should not be used with the --use-dns option which enables dynamic noise shaping.

`-t = copy input file's time stamp to output file(s)`

Self explanatory.

`--use-dns = force use of dynamic noise shaping (hybrid only)`

For version 4.50, dynamic noise shaping was added to the WavPack hybrid mode. This feature causes the noise shaping to continuously adjust to the spectral characteristics of the source signal and results in significantly improved subjective quality on samples that previously caused difficulty with WavPack's lossy mode (particularly material with loud high-frequency transients). This feature is used by default except for high sampling rates (>= 64 kHz) or when the -cc option is specified (because it can adversely effect compression ratio), however the --use-dns option allows the user to force the use of dynamic noise shaping even when it would not normally be used. This option should not be specified with the -s option which overrides the default with fixed noise shaping.

`-w "Field=Value" = write specified metadata to APEv2 tag`

Write specified information to APEv2 tag appended to WavPack file(s). May be used multiple times for multiple fields. APEv2 tags are the preferred tag format for WavPack files and are read by all the standard WavPack playback plugins. If the specified value begins with a '@', then the value is assumed to be a filename which is used to obtain the item's actual value. This is handy for including the CUESHEET field for use with images files + cuesheets and foobar2000. The filename may contain wildcards if it matches exactly one file. Also, if the file cannot be found in the current directory then the source and destination directories (if specifed) are also checked.

`-x[n] = extra encode processing (optional n = 1-6, 1 = default)`

Like pre-4.0 versions of WavPack (and many other compressors), WavPack 4.50 normally works "symmetrically" in that encoding and decoding operate at about the same rate (regardless of the mode used). However, WavPack has an option to work "asymmetrically", so that extra processing can be done during encoding to provide better compression, but with NO corresponding cost to decoding performance!

This is enabled with the -x option and provides an average improvement in CD music compression of about 1% in "fast" mode, about 0.5% in the normal mode, and still less in the higher modes. Because the standard compression parameters are optimized for "normal" CD music audio, this option works best with "non-standard" audio (synthesized sounds, non-standard sampling rates, etc.) where it can often achieve enormous gains. The default level (n=1) provides a decent improvement with little cost in encoding speed and is recommended for all but the most time critical encoding. Higher levels provide some marginal improvement with an increasing cost of encoding speed. The highest levels (n = 4-6) are extremely slow but can provide significant improvement in special situations (i.e. synthesized sounds).

`-y = yes to all warnings (use with caution!)`

Self explanatory.

WvUnpack Options

`-b = blindly decode all stream blocks & ignore length info`

This option uses the "streaming" mode of the WavPack decoder. Normally this doesn't make any difference except that the percentage complete display does not work. However, it causes the decoder to ignore all information contained in the WavPack blocks concerned with duration and location and blindly unpacks every valid WavPack block it encounters, and will do so indefinitely until it receives an EOF. This may be of some use to recover corrupted or partial WavPack files, or it could be used to decode a sequence of WavPack files that had been concatenated. If this is used to write a .wav file to stdout then note that the resulting .wav file will not indicate the correct length because it can't back up to fix it once it knows the actual length.

`-c = extract cuesheet only to stdout (no audio decode)`

If the specified WavPack contains an APEv2 tag, and that tag contains a CUESHEET field, then only dump that text to stdout without decoding any audio. If no cuesheet is found then an error is generated.

`-cc = extract cuesheet file (.cue) in addition to audio file`

If the specified WavPack contains an APEv2 tag, and that tag contains a CUESHEET field, then that text will be extracted into an appropriately named .cue file located in the same folder as the .wav file. Note that the cuesheet is not automatically modified to point to the correct .wav file; this must be handled either when the cuesheet is embedded or (if the .wv file is renamed) by the user after extraction. This option has no effect if there's no cuesheet.

`-d = delete source file if successful (use with caution!)`

Self explanatory.

`--help = this help display`

Self explanatory.

`-i = ignore .wvc file (forces hybrid lossy decompression)`

This option forces WvUnpack to not look for a corresponding correction file when unpacking hybrid mode files. This could be used to compare the effects of the hybrid lossy mode or in the case that the .wvc had become corrupt and was preventing decompression (although this is unlikely).

`-l = run at low priority (for smoother multitasking)`

This option can be used (in Windows only) to force WavPack to run at a low priority and is handy for doing large unpack or verification batch conversions in the background.

`-m = calculate and display MD5 signature; verify if lossless`

Enables the calculation and display of the MD5 checksum on the uncompressed audio data. If an MD5 sum for the original audio data is stored in the WavPack file then this will be displayed also. For lossless operation these numbers should match (and WvUnpack will verify that they match). For lossy operation these numbers should not match.

`-q = quiet (keep console output to a minimum)`

Self explanatory.

`-r = force raw audio decode (results in .raw extension)`

This option causes WvUnpack to strip off the standard wav file header (and any trailer) and only output the uncompressed audio data. If a file is created then it will be given the .raw extension instead of the standard .wav extension.

`-s = display summary information only to stdout (no decode)`

This option causes WvUnpack to simply display general information about the specified WavPack files including source information, encoder version and options and original MD5 checksum. This information can be directed into a file with the ">" operator. No file decoding or verification can occur with this option.

`-ss = display super summary (including tags) to stdout (no decode)`

This option is similar to -s except that information from any valid tag found (either APEv2 or ID3v1) is also listed.

`--skip=[sample|hh:mm:ss.ss] = start decoding at specified sample/time`

Specifies an alternate start position for decoding, as either an integer sample index or as a time in hours, minutes, and seconds (with fraction). The WavPack file must be seekable (i.e. not a pipe). This command can be used with the --until command to decode a specific region of a track.

`-t = copy input file's time stamp to output file(s)`

Self explanatory.

`--until=[+|-][sample|hh:mm:ss.ss] = stop decoding at specified sample/time`

Specifies an alternate stop position for decoding, as either an integer sample index or as a time in hours, minutes, and seconds (with fraction). If a plus ('+') or minus ('-') sign is inserted before the specified sample (or time) then it becomes a relative amount, either from the position specified by a --start command (if plus) or from the end of the file (if minus).

`-v = verify source data only (no output file created)`

This option allows the user to verify the integrity of WavPack files (including any correction file). Note that this option not only verfies that a WavPack file has not been corrupted since creation, but it also verfies that the audio data is being unpacked exactly as intended (even in the lossy mode). Therefore, it can also detect algorithm errors, incompatible implementations of the encoder or decoder, and even faulty processor hardware.

`-w = regenerate .wav header (ignore RIFF data in file)`

WavPack files normally have a copy of the RIFF headers (and trailers) that were contained in the original .wav file, and these are normally restored when the files are unpacked. Beginning with version 4.40, these headers are automatically regenerated at decode time if a WavPack file is missing them. This option allows the .wav header to be regenerated even if the WavPack file contains a valid header.

`-y = yes to overwrite warning (use with caution!)`

Self explanatory.

WvGain Options

`-a = album mode (all files scanned are considered an album)`

The default mode for WvGain is to operate in track mode where each WavPack file is independently analyzed for perceived volume (and peak level). This option causes WvGain to additionally operate in album mode where all the specified files are analyzed together as an "album" so that a set of composite values are also generated. Note that when this mode is specified, WvGain must wait until the end of scanning before making another pass through all the files to append the calculated values.

`-c = clean ReplayGain values from all files (no analysis)`

This option does not perform any analysis but simply removes all ReplayGain values from the specified files.

`-d = display calculated values only (no files are modified)`

This option causes WvGain to do the specified analysis (with or with the -a switch for album mode) and display the calculated values, but no values are actually written to the files.

`-i = ignore .wvc file (forces hybrid lossy decompression)`

This option forces WvGain to not look for a corresponding correction file when analyzing hybrid mode files.

`-l = run at low priority (for smoother multitasking)`

This option can be used (in Windows only) to force WvGain to run at a low priority and is handy for doing large batch operations in the background.

`-q = quiet (keep console output to a minimum)`

Self explanatory.

`-s = show stored values only (no analysis)`

This option does not perform any analysis but simply displays (to stdout) any ReplayGain values stored in the specified WavPack files.

Usage Guide

The options of WavPack can be a little confusing at first, so here's a little tutorial on what to try first if you're not sure. First of all, if you are only interested in lossless compression, try the default operation with no options. This will give a decent compression ratio at a very good speed for both packing and unpacking. Also, it is usually recommended to add the -x switch because it can provide a decent improvement in compression with only a minor cost in encoding time (about 2x) and no cost in decoding speed.

If speed is less of an issue try the "high" mode (-h), this will increase both the packing and unpacking time by about 50% (although still not nearly as slow as many other lossless compressors) while improving the compression ratio somewhat. If speed is paramount use the "fast" (-f) option. This gives the fastest packing and unpacking speed possible with WavPack, while still providing a very reasonable compression ratio. Again, the -x switch works well with these two modes.

If decoding speed is important, but the time to encode is not (because it happens only once), try using numeric parameters with the -x mode (valid values are 2-6). This will slow the encoding way down (depending on the level) but still have no effect on decoding speed. In some music files, this option can actually bump the compression ratio a whole mode (i.e. the "fast" mode can match the default mode, etc.). For the best lossless compression WavPack can offer, use -hhx6 (but be prepared to make yourself a sandwich!).

If you want to try the hybrid mode, all the above applies but you also have to choose a bitrate. The quality of WavPack's lossy mode cannot match the conventional lossy codecs like MP3 and WMA at similar bitrates, and in fact it won't even operate at the most common bitrate of 128 kbps (with CD audio, at least). The lowest bitrate that I recommend for WavPack lossy is 256 kbps which can provide transparent reproduction for most non-critical listening situations and is roughly equivalent to LAME MP3 encoding somewhere between 160 kbps and 192 kbps (CBR). Above 256 kbps the quality of WavPack's lossy mode increases rapidly, with added quantization noise (which is the only artifact) dropping by about 1 dB for every 15 kbps. At 320 kbps the quality is difficult for even critical listeners to distinguish from the original, and at 384 kbps WavPack becomes essentially transparent.

The various modes and options that apply to lossless mode also apply to hybrid mode. However the "extra" mode (-x) deserves a special mention. Most of the time, the "extra" mode makes only modest improvements because WavPack has already been finely tuned for ordinary music. However, sometimes there is an instrument or sound situation that does not compress well with the standard settings and the "extra" mode can make a significant improvement. In lossless mode this would slightly improve the overall compression ratio and would probably go unnoticed. However, in lossy mode that difficult section might trigger clearly audible noise to be added, and in this case the "extra" mode would save the day by greatly reducing the noise in the exact spot where it might have been audible.

Here is a chart of recommended settings for the various useful bitrates:

    	 Bitrate     High quality   Faster Encode   Faster Decode
     	 -------     ------------   -------------   -------------
     	 256 kbps    -hb256x3       -hb256x         -b256x3
     	 320 kbps    -hb320x3       -hb320x         -b320x3
     	 384 kbps    -b384x3        -hb384x         -fb384x3

Non-CD

In addition to regular CD audio data, WavPack hybrid mode is also well suited to other sampling rates, bitdepths, and channel configurations. For generating bitrates lower than the minimum of 196 kbps that applies to CD audio, it is necessary to resample the audio to lower sampling rates and/or convert to mono using an external program. Note that conventional lossy codecs accomplish the same thing by lowpass filtering the source when used for low bitrates.

For high-resolution audio (e.g., 24-bit/96-kHz) WavPack hybrid makes a particularly logical choice. The reasoning here is that standard lossless encoding achieves relatively poor compression on this type of material because the additional 8 bits are essentially noise and cannot be further compressed. In addition, conventional lossy codecs like MP3 or AAC are based on psychoacoustic models of hearing that presume CD audio quality (16-bit/44-kHz) to be "perfect", and therefore discard everything outside of that range.

When used at around 1024 kbps, WavPack hybrid preserves the full bandwidth and dynamic range of 24/96 sources. It accomplishes this by moving most of the quantization noise up above the audible audio band using first-order noise shaping in much the same way that DSD does. In fact, at normally loud listening levels, the added quantization noise remains completely inaudble, even without the masking effect of the material itself! While 1024 kbps may seem high at first, keep in mind that this is right in the range of some losslessly compressed CD-quality music, and is approximately 1/3 of the bitrate required to losslessly compress the same 24/96 material!

WavPack also handles multichannel audio like 5.1 and 7.1 channel configurations, and these can be stored in lossless and hybrid modes (including hybrid lossless). With all the combinations of sampling rates and numbers of channels it might become confusing to determine a desirable bitrate. This is an ideal application of the alternate form of the -b option which accepts a number of bits per sample rather than kilobits per second. When using this form a reasonable starting point of experimentation is 4 bits per sample (-b4). Except for extreme cases this will produce transparent results (it is equivalent to about 350 kbps for CD audio). Note that the compression algorithms are identical when using this form; it is simply an alternate way of specifying the bitrate.

Representative samples ranging from 24 kbps to 1024 kbps are found in the "hybrid_bitrates" directory of the WavPack Test Suite which is currently hosted here, but which can always be found on the WavPack website.

Plugins

The documentation for the various WavPack plugins is provided as readme.txt files included with those plugins.

WavPack and its associated utilities are free programs; feel free to give them to anyone who may find them useful. There is no warrantee provided and you agree to use them completely at your own risk. Be sure to visit www.wavpack.com for the latest version of WavPack.

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