The Traders' Den - FAQ: Audio Seeding and Trading

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File Types and descriptions.

Here are some of the file types you will find on this site and some information about each.

Free Lossless Audio Codec (.flac)
The Free Lossless Audio Codec (FLAC for short) is currently the preferred format for trading lossless audio shows amongst many members of the community. It has many superior features including good compression ratio, native support for Vorbis tagging, a fingerprinting feature which causes files to be unusable if they become corrupted, increasing support amongst standalone media players, and is supported by a dedicated group of open source developers.
A feature that sets FLAC apart from all other major lossless formats is it's ability to self-test itself. Basically, any FLAC file stores an md5 checksum of the audio content contained within the file (also called the FLAC Fingerprint) within the header of the file itself. By using FLAC's "test" function, you are able to run the check on the audio, compare it to the fingerprint stored when the file was encoded, and confirm that they are the same. This is extremely useful when trading files through BitTorrent as it will confirm that the files you were downloaded completely and without being corrupted. You should run a "test" on every batch of files after every time they are transferred, especially over BitTorrent.
Monkey's Audio Lossless (.ape)
Monkey's Audio (which uses the .ape extension) is a file format that has recently rivaled FLAC for the top seat in the lossless file format arena. It provides superior file compression (on the highest setting it can compres files 10% smaller even than FLAC), has support for a robust system of file tagging, and is distributed through a very straight-forward and simple software frontend. For straight file archiving, the ape is king, allowing the best bang for your media storage buck.
Ape's main disadvantage to FLAC is it's lack of an inherent fingerprinting check. Also, this format is much more processor intensive than it's main competitor, and playing back or decompressing the files may drag some middle-range computers to a halt. While it's the least used of the three lossless formats used at this site, it has a well-deserved following of devotees and is becoming more popular every month.
Shorten (.shn)
The older and most well established of the three formats used at this site is called Shorten (.shn). Originally named for it's revolutionary concept of "shortening" the length of PCM wav data, this format is very well supported and widely used. The praise of the Shorten codec, however, is no longer lavished by many of today's technically adept lossless traders. Newer and more robust formats such as FLAC and APE have surpassed SHN in every possible category.
This disadvantages to these newer formats that Shorten is faced with runs the gamut from larger filesize, to lack of native seekability in media players, to no file tagging support, to an overly restrictive licensing agreement. The SHN format has embedded itself well within the archives of many longtime traders, but is doomed to slowly but surely start fading out. Very few people remain who use this for new seeds, and an increasing number of older seeds are being converted over.

How do I extract audio data from an audio CD?

In order to make a seed, it is important to extract the audio data contained on an audio CD to a data format. This is not as simple as it sounds, and many programs may create errors which alter or ruin the audio quality (most noticable as clicks or skips in the resultant audio file). Programs like MusicMatch, older versions of iTunes, Microsoft Media Player and most other CD ripping software programs are unsuitable for creating perfect digital audio rips. If you are ripping to audio data file from audio CD, you MUST use one of the following programs and indicate which was used in the text file for your seed. This is NOT NEGOTIABLE!

EAC, using secure mode or dBpoweramp, using secure mode (Windows)

Exact Audio Copy (or EAC for short) is a powerful and freely available software package than can create verified bit-for-bit digital audio extraction (DAE, aka "Ripping") from audio CDs and CDRs. Most other packages do not check for jitter errors and will not report them when they occur. These errors will cause obnoxious clicks to become present when playing back the audio, and are thus not permitted to occur when doing audio trading. EAC is one of the few pieces of ripping software which has the feature of being able to spot, correct, and verify accuracy of the fix when extraction errors happen (when set to "secure mode"). It will output a log of the extraction to prove that the rip has completed 100% error-free.

Due to this unique feature, seeds to The Traders' Den MUST use this or a comparable "secure mode" ripping program. EAC can take some time to setup, but once you get the hang of it, it's rewarding to know that you're doing it right and sharing digitally clean audio files. For some excellent tutorials on setting up and using the ripping, encoding, audio editing, or CD burning features of this powerful software, please read the guide here: jiGGafellz' Step-by-Step Guide to Secure CD Ripping w/Exact Audio Copy. Most importantly of these for audio extraction is the EAC Drive Configuration guide (which explains secure mode and how to configure it) and the Extracting Tracks guide (for performing a verified rip).

A guide for setting up dBpoweramp may be found here.
XLD (Macintosh)

XLD is now the preferred method (as of December 2008). Please see this guide - X Lossless Decoder (XLD): How to create flawless CD rips on Mac OS X for setting up and using XLD.

Seeds to The Traders' Den MUST use this or a comparable "secure mode" ripping program.
cdparanoia (Linux)

cdparanoia is a software package than can create verified bit-for-bit digital audio extraction (DAE, aka "Ripping") from audio CDs and CDRs. Most other packages do not check for jitter errors and will not report them when they occur. These errors will cause obnoxious clicks to become present when playing back the audio, and are thus not permitted to occur when doing audio trading. Much like EAC, the most common "secure mode" DAE software package, cdparanoia can create perfect audio rips. It is the definitive software for this function on the Linux platform.

Seeds to The Traders' Den MUST use this or a comparable "secure mode" ripping program.

Free downloads, documentation, and tutorials can be found at the official CDDA Paranoia project page.

Why trade lossless media? Mp3 and Ogg sound good to me, what's the big deal?

Proponents of lossless and lossy audio formats seem immutably locked in a struggle for ideologic dominance. Each seems convinced of the superiority of each style and virtually unwilling to listen to the arguments presented by the opposing side. In this swarm of insults, baseless criticism, and pseudo-scientific testing methods, there is indeed an enormous difference, and understanding where each style of audio compression is appropriate is an extremely important facet of trading.

In simple terms, lossless compression schemes are capable of being decoded back to an identical .wav file as the one that created it. Lossy compression picks certain parts of the music and discards it in an attempt to shrink the filesize. The idea is to pick parts that the human ear is unable to discern and remove them, thus leaving no wasted space for storing files.

Quite simply, the latter is inappropriate for audio trading. The files which you trade will pass through hundreds, thousands, or even tens of thousands of hands. If each trader takes the liberty of compressing to their own lossy format of choice, the result will be catastrophic for the quality of the audio after several iterations. To ensure that everyone who desires a recording gets a chance to hear it in as good a quality as it was originally recorded, it is important to maintain a lossless lineage from user to user. Once a file has been compressed to a lossy format, that missing information can NEVER be replaced, and therefore files that have been compressed to lossy, even when converted back to lossless formats, are unsuitable for trading.

The truth about lossy file types is that, under proper scientific double blind studies, a very small percentage of humans are able to hear the difference between uncompressed .wav audio and high quality (192 KBps or higher) encoded lossy formats. These formats have their place. Many people compress their audio recordings to a lossy format for playing on portable players, their computers, or standalone home units. This is an effective method as the audio difference in one generation of lossless to lossy compression is likely to not cause an audible difference. Feel free to compress lossless recordings to whatever format you choose, but never, ever pass on files compressed to lossy formats or lossless files sourced from lossy formats to other traders.

For the good of the trading pool, please respect the difference between lossless (SHN, APE, FLAC, WAV, AIFF, etc) and lossy (MP3, OGG, AAC, etc) compression types. Only trade or pass on lossless files so that the overall quality of the trading pool remains high for everyone to enjoy.

Simply put, there are NO lossy file types (OGG-Vorbis, MP3, AAC, etc, etc) permitted for trade at this site. This is NOT a negotiable issue, there will be NO subforum for mp3 traders. If you ignore this rule and post lossy sourced material, there are ways to test for this and it will be discovered, resulting in your seed being deleted. Please respect the high quality standards we have put in place, and bring your mp3s elsewhere. If you are unsure of whether or not your seed is lossless, please post in the Technobabble forum and ask for assistance...we are glad to help.

Checksum Types - st5s, ffps, and md5s

Each of these three terms represent different employments of the md5 checksum algorithm. It has the ability to reduce any file to a single 128-bit number which is unique to that file. Most audio and video trading websites require the generation of checksums for any files as it has the ability to compare two files and determine if they are identical. If your file matches the checksum of the original file, you can confirm that it has not been altered in any way (intentionally or unintentionally) or corrupted during download. Verifying checksums every time a file is transferred is an essential step in the trading of lossless music.

For the more mathematically adept users, here's an actual description of RFC 1321 - The MD5 Message-Digest Algorithm.

If you were brave enough to muddle through the second link posted above, you will have discovered that the output from running an md5 check is a single 128-bit number. To make it easier to read, many programs that run the md5 algorithm will actually output an equivalent 32-digit hexadecimal number which has the same binary result as the original 128-bit would have. This makes reading it simpler using only 16 alpha-numeric characters (0-9, a-f). The result will look something like this (this is an shntool md5, .st5, which is what is desired at TTD):

cb8a42007fe797435826a76cb527be01 [shntool] sample2007-04-15t01.flac 25eb2520a33ed2b88edf41f5d6f09505 [shntool] sample2007-04-15t02.flac fbfced772c4d478f57072ffe9aeb2a69 [shntool] sample2007-04-15t03.flac

Each line contains the 32-digit hex-coded checksum, followed by the filename of the file it was run on. This 32-digit checksum is what most computer users are likely to see as the end result of a checksum calculation.

A great guide about the various types of checksums and how to use them and make them may be found here: Checksums Demystified.

Shntool md5 Checksums (.st5) - WE WANT THESE!

Shntool, a command line utility, is probably the most functional yet mysteriously underused lossless trading tool. Perhaps intimidated by the lack of frontend support, many people are reluctant to devote the time required to learn to use this fantastic tool. It has numerious features, including the ability to generate what's known as an shntool md5.
The shntool md5 performs the same function as the FLAC fingerprint discussed in the previous comment, but has the ability to perform it on any lossless file format. Since it only takes an md5 of the audio data contained within the file, shntool md5s are useful for validating recordings that may have been retagged, recompressed, or even converted between different lossless formats. As long as the audio data is identical, the shntool md5 will verify; this is truly the ideal method of audio file verification.
Inclusion of the shntool md5 into notes for original seeds is highly recommended, as it will help users confirm that they have clean filesets across many platforms and filetypes.

cb8a42007fe797435826a76cb527be01 [shntool] sample2007-04-15t01.flac 25eb2520a33ed2b88edf41f5d6f09505 [shntool] sample2007-04-15t02.flac fbfced772c4d478f57072ffe9aeb2a69 [shntool] sample2007-04-15t03.flac

Notice the 32-digit number is the same as the fingerprint 32-digit number in the flac fingerprints above.
FLAC Fingerprints (.ffp)

As an alternative to the wholefile md5 scheme required for .shn files, a newer format called the Free Lossless Audio Codec addressed this issue by making an md5 check of just the audio data contained within the file an inherent part of the file's structure. This elegant concept adds a short segment to the header of the FLAC file itself which contains an md5 of the original uncompressed PCM .wav data. This value is called the "fingerprint", a fitting title as it only validates the audio, not the extra data appended to the file. Using the FLAC fingerprint method, users could add or remove tags or change the compression setting and not change the actual audio contained within. Since the fingerprint only checks audio data, traders could change these values at will and they will still verify as identical to the original.
.flac gained rapid support of lossless traders over .shn for several other reasons. First, the filetype is both seekable and seamless, meaning no seek table data had to be appended to the file to use it in your favorite media player. It also contains a check during decoding that actually performs a check of the stored fingerprint value to what's actually inside the file, and if they don't match, the file will not decode. This double-checking ensures that files corrupted during transfer are unusable and therefore the error will not be passed on.
FLAC's use of the fingerprint allows users much more versatility while still maintaining the same core functionality : verifiying that the audio in your files has not altered since it was seeded. Of course, a user may still use wholefile md5 checks on .flac files if they see fit, but this is a practice performed out of ignorance rather than functionality. Using FLAC's fingerprinting is much more useful than wholefile md5 checking, and should be used 100% of the time.

sample2007-04-15t01.flac:cb8a42007fe797435826a76cb527be01 sample2007-04-15t02.flac:25eb2520a33ed2b88edf41f5d6f09505 sample2007-04-15t03.flac:fbfced772c4d478f57072ffe9aeb2a69

Notice the file name is at the front of each line.
Wholefile md5 Checksums (.md5) - not desired!

Note: Wholefile md5 checksums are the type generated by programs such as mdsum, mkwact, and others. Please read on to understand why these are forbidden as the primary form of file verificaton at The Traders' Den.
The most rudimentary form of md5 fingerprinting is to run the algorithm on an entire file. By comparing two md5 checksum values, one will be able to confirm that the files that generated the values are the same. In the early days of lossless file trading on the internet, this was used to track recordings encoded to the Shorten (.shn) file format. This very effective method of ensuring that all files remain identical from user to user is still popular today. However, there are some fundamental weaknesses to this method, many that have arisen with the advent of .flac and .ape lossless audio formats as the preferred trading format of many users. Both of these newer formats permit the use of file tags so that a user can add artist, date, venue, source, or any other information they want to the file's header for display in their preferred media player. While adding or removing these tags doesn't change the audio at all, it does alter the file to include the additional header data, and therefore changes the file's checksum. Two files would thus appear different in a checksum comparison while being acoustically identical.
Furthermore, there is certain additional data that can be stored in .wav files that .shn and .ape allow to remain during compression, but which .flac sees as unecessary and potentially harmful to your system and thus removes it. Again, it would be possible to convert from .shn to .flac and back and have two acoustically identical files result in different wholefile md5 checksum values.
Yet another weakness to relying on wholefile md5 checksums is the need to use seek tables in .shn files. The earliest version of Shorten's codec did not allow for the files to be seekable during playback. As a "band-aid" for this oversight, they allowed for the addition of a seek table that would be appended to the file to provide the necessary information to make the file seekable. The problem, again, is that by adding this information a user changed the file but not the audio. This problem has been further compounded by the recent addition of alternate versions of seek tables, so that even files with seek tables can contain one of a few versions and thus have differing md5 checksum results while being musically identical.
Wholefile md5 is an effective method of comparing files, but has been made somewhat obsolete by the more versatile methods of audio file verification listed below.

9c3bdb0b13e9822ff65599d6b331f775 *sample2007-04-15t01.flac 10fdca5fd9ddf55a1d21dc70d658d89c *sample2007-04-15t02.flac 544c32693e4766f08f82a3781b96da20 *sample2007-04-15t03.flac

Notice the asterisk, *, in each line and how the 32-digit number is not the same as the fingerprint or shntool md5 above.

Please see this guide on Checksums Demystified to find out how to use and make the various types of checksums.

So how do I store all this stuff?

If you're experiencing lossless trading for the first time, you're probably perplexed as to how to store your archives. Since converting to mp3 and lossy formats is against the rules and burning to audio CD devalues your recording with most traders, what's the best way to back everything up? There are many opinions on this, but the only rule is to make sure you keep original lossless files that are not compressed to lossy formats or burnt to audio CD for future trading. Many people use data CDRs and increasingly data DVDR discs for backing up shows. Others are using portable hard drives for this purpose, while still others employ combinations of these methods to ensure backups are always kept. Poke around on the boards and ask other how the categorize, backup, and organize their collections. Just remember that it is important to keep them in lossless audio formats only.

How can I listen to the lossless files that I downloaded?

The Trader's Den limits lossless file trading to file formats that are usable across the three major computer platforms, Linux, Windows, and Macintosh. If you've downloaded a lossless audio fileset from SR, it will be in either FLAC, SHN, or APE format as these are the only formats with broad cross-platform support.

Please note that if you choose to burn this music to an audio CD that you should always keep backups of the ORIGINAL lossless files, exactly as you recieved them. There are errors that can occur during CD burning and ripping which alter the audio. To keep the music as pure as possible always keep a data CD, data DVD, or backup hard drive with the original files and md5/ffp checksums for trading. Burn to audio CD, compress to lossy formats, etc only for personal use. Never trade or give to someone else CDs burned from lossless files or files compressed to lossy formats as it pollutes the trading pool.

Here's a lost of some of the more popular ways that traders play back their lossless audio files.

What does it mean to "test" a FLAC file?

A feature that sets FLAC apart from all other major lossless formats is it's ability to self-test itself. Basically, any FLAC file stores an md5 checksum of the audio content contained within the file (also called the FLAC Fingerprint) within the header of the file itself. By using FLAC's "test" function, you are able to run the check on the audio, compare it to the fingerprint stored when the file was encoded, and confirm that they are the same. This is extremely useful when trading files through BitTorrent as it will confirm that the files you were downloaded completely and without being corrupted. You should run a "test" on every batch of files after every time they are transferred, especially over BitTorrent.

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