Hydrogenaudio Knowledgebase - User contributions [en]

Comparison of CD rippers

2016-06-29T03:46:25Z

72.83.229.68: morituri uses cdparanoia for the actual rip handling, thus doesn't support c2 pointers.

On the Hydrogenaudio forums (e.g. [http://www.hydrogenaudio.org/forums/index.php?showtopic=37313&hl= here] and [http://www.hydrogenaudio.org/forums/index.php?showtopic=80863&hl= here]) there have been many discussions and questions about the differences between different Digital Audio Extraction (DAE) software packages (CD rippers). New rippers with secure ripping facilities have emerged in recent years, and it is now difficult to judge compared to some years ago when the only answer was [[Exact Audio Copy]] (EAC).

==Comparison chart==

{| cellspacing="2" style="text-align:center; border:1px solid blue;"
|width="200px"|'''Features'''
| width="95px" style="background: #00FFFF" | [[Exact Audio Copy|Exact Audio Copy (EAC)]]
| width="95px" style="background: #00FFFF" | [[dBpoweramp|dBpoweramp CD Ripper]]
| width="95px" style="background: #00FFFF" | [[Foobar2000:Foobar2000|foobar2000]]
| width="95px" style="background: #00FFFF" | [[iTunes]]
| width="95px" style="background: #00FFFF" | [[Windows Media Player]]
| width="95px" style="background: #00FFFF" | [http://www.cuetools.net/wiki/CUERipper CUERipper]
| width="95px" style="background: #00FFFF" | [[XLD]]
| width="95px" style="background: #00FFFF" | [http://sbooth.org/Rip/ Rip]
| width="95px" style="background: #00FFFF" | [[MusicBee]]
| width="95px" style="background: #00FFFF" | [http://perfectrip.cdfreaks.com/ PerfectRip]
| width="95px" style="background: #00FFFF" | [http://www.slysoft.com/en/clonecd.html CloneCD]
| width="95px" style="background: #00FFFF" | [[Cdparanoia]]{{ref|Cdparanoia_fronts|a}}
| width="95px" style="background: #00FFFF" | [http://www.easyaudiocopy.com/ Easy Audio Copy]
| width="95px" style="background: #00FFFF" | [https://www.poikosoft.com/ EZ CD Audio Converter]
| width="95px" style="background: #00FFFF" | [http://thomas.apestaart.org/morituri/trac/ morituri]
|-
!colspan="15" style="background: #ececec"| Data acquisition
|-
| align="left" style="background: #FFFF99" | One track per file
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
|-
| align="left" style="background: #FFFF99" | Image as single file
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes
| style="background: #00FF00" | binary
| style="background: #00FF00" | binary
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes{{ref|Easy-cue|j}}
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
|-
|align="left" style="background: #FFFF99" | [[Cue sheet|CUE sheet]] generation
| style="background: #00FF00" | yes{{ref|EAC-cue|b}}
| style="background: #CCFFCC" | [http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=82483&view=findpost&p=715699 limited], more [http://forum.dbpoweramp.com/showthread.php?t=20303 in beta]
| style="background: #CCFFCC" | limited
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes{{ref|EAC-noncompliant|c}}
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #CCFFCC" | limited
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes{{ref|Easy-cue|j}}
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
|-
| align="left" style="background: #FFFF99" | gap detection
| style="background: #00FF00" | yes
| style="background: #CCFFCC" | [http://forum.dbpoweramp.com/showthread.php?t=20303 in beta]
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes{{ref|ccd|h}}
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes{{ref|Easy-cue|j}}
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
|-
| align="left" style="background: #FFFF99" | [[pre-emphasis]] detection
| style="background: #00FF00" | yes (TOC only)
| style="background: #00FF00" | yes (which?)
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes (which?)
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes (TOC+subcode)
| style="background: #00FF00" | yes (TOC+subcode){{ref|XLDpe|p}}
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes (subcode)
| style="background: #CCFFCC" | limited (detects but does not add to cue sheet)
|-
|align="left" style="background: #FFFF99" | Offset correction
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #CCFFCC" | limited{{ref|prOC|f}}
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
|-
|align="left" style="background: #FFFF99" | [[HTOA]]
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
|-
|align="left" style="background: #FFFF99" | C2 pointers
| style="background: #CCFFCC" | initial pass{{ref|eacC2|m}}
| style="background: #00FF00" | initial pass, on re-reads
| style="background: #FFCC99" | no
| style="background: #FFCC99" | no
| style="background: #FFCC99" | no
| style="background: #00FF00" | initial pass, on re-reads
| style="background: #CCFFCC" | initial pass
| style="background: #00FF00" | initial pass, on re-reads
| style="background: #CCFFCC" | initial pass
| style="background: #CCFFCC" | limited{{ref|prC2|g}}
| style="background: #00FF00" | initial pass, on re-reads{{ref|ccdc2|i}}
| style="background: #FFCC99" | no
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | for error detection only{{ref|EZCDAC|n}}
| style="background: #FFCC99" | no
|-
|align="left" style="background: #FFFF99" | Defeat cache
| style="background: #00FF00" | over-reading, FUA
| style="background: #00FF00" | over-reading, FUA
| style="background: #00FF00" | over-reading
| style="background: #FFCC99" | no
| style="background: #FFCC99" | no
| style="background: #00FF00" | over-reading
| style="background: #00FF00" | over-reading
| style="background: #00FF00" | over-reading
| style="background: #00FF00" | yes
| style="background: #FFCC99" | no
| style="background: #FFCC99" | no
| style="background: #00FF00" | over-reading
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | FUA(?) in rare circumstances{{ref|EZCDAC|o}}
| style="background: #FFFFFF" | FUA(?)
|-
!colspan="15" style="background: #ececec"| Additional features
|-
|align="left" style="background: #FFFF99" | [[AccurateRip]]
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
|-
|align="left" style="background: #FFFF99" | [[AccurateRip]] checking across pressings/offsets
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | n/a
| style="background: #FFFFFF" | n/a
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | ?
| style="background: #FFFFFF" | n/a
| style="background: #FFFFFF" | n/a
| style="background: #FFFFFF" | n/a
| style="background: #FF9900" | no
| style="background: #FFFFFF" | n/a
| style="background: #FFFFFF" | ?
|-
| align="left" style="background: #FFFF99" | [http://db.cuetools.net/about.php CUEtools db]
| style="background: #00FF00" | [http://db.cuetools.net/plugin.php plugin]
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
|-
| align="left" style="background: #FFFF99" | log file
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
|-
| align="left" style="background: #FFFF99" | Metadata
| style="background: #00FF00" | [[freedb]],{{ref|EAC-ctdb-meta|e}} [[MusicBrainz]],{{ref|EAC-ctdb-meta|e}} [[Discogs]],{{ref|EAC-ctdb-meta|e}} [[CD-Text]]
| style="background: #00FF00" | freedb, MusicBrainz, AMG, GD3, SonataDB, CD-Text, [http://www.dbpoweramp.com/cd-ripper.htm PerfectMeta™]{{ref|compare_meta|d}}
| style="background: #00FF00" | freedb, MusicBrainz ([http://www.hydrogenaudio.org/forums/index.php?showtopic=70623 plugin]), Discogs ([http://www.hydrogenaudio.org/forums/index.php?showtopic=50523 plugin]), CD-Text
| style="background: #00FF00" | gracenote, MusicBrainz (Mac-only [http://musicbrainz.org/doc/FreeDB_Gateway hack]), CD-Text
| style="background: #00FF00" | AMG, CD-Text ([http://bmproductions.fixnum.org/index.htm?http://bmproductions.fixnum.org/moreprogs/wmpcdtext.htm plugin])
| style="background: #00FF00" | freedb, MusicBrainz, Discogs
| style="background: #00FF00" | freedb, MusicBrainz
| style="background: #00FF00" | freedb, MusicBrainz
| style="background: #00FF00" | freedb, MusicBrainz, CD-Text
| style="background: #00FF00" | freedb, CD-Text
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | GD3, others{{ref|Easy-meta|k}}
| style="background: #00FF00" | freedb, MusicBrainz, GD3
| style="background: #00FF00" | freedb, MusicBrainz
|-
|align="left" style="background: #FFFF99" | Download Album Art
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | [http://www.hydrogenaudio.org/forums/index.php?showtopic=50523 foo_discogs]
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #FF9900" | no
| style="background: #00FF00" | yes
| style="background: #00FF00" | yes
| style="background: #FF9900" | no
|-
| align="left" style="background: #FFFF99" | Cost
| style="background: #00FF00" | free
| style="background: #CCFFCC" | free (21 days), then $38
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #00FF00" | free
| style="background: #CCFFCC" | free (21 days), then €32.60–55.00
| style="background: #00FF00" | free
| style="background: #CCFFCC" | free (14 days), then $29.90
| style="background: #CCFFCC" | free (30 days), then $39.95 or €39.95
| style="background: #00FF00" | free
|-
| align="left" style="background: #FFFF99" | License
| style="background: #00FF00" | proprietary, freeware
| style="background: #CCFFCC" | proprietary, shareware
| style="background: #00FF00" | proprietary, freeware
| style="background: #00FF00" | proprietary, freeware
| style="background: #00FF00" | proprietary, freeware
| style="background: #00FF00" | GPL
| style="background: #00FF00" | GPL
| style="background: #FFFFFF" | ?
| style="background: #00FF00" | proprietary, freeware
| style="background: #00FF00" | freeware
| style="background: #CCFFCC" | proprietary, shareware
| style="background: #00FF00" | GPL
| style="background: #CCFFCC" | proprietary, shareware
| style="background: #CCFFCC" | proprietary
| style="background: #00FF00" | GPL
|-
|align="left" style="background: #FFFF99" | OS
| style="background: #CCFFCC" | Windows
| style="background: #00FF00" | Windows, Mac
| style="background: #CCFFCC" | Windows
| style="background: #00FF00" | Windows, Mac
| style="background: #CCFFCC" | Windows
| style="background: #CCFFCC" | Windows
| style="background: #CCFFCC" | Mac
| style="background: #CCFFCC" | Mac
| style="background: #CCFFCC" | Windows
| style="background: #CCFFCC" | Windows
| style="background: #CCFFCC" | Windows
| style="background: #00FF00" | Mac OS X, Linux/BSD, Windows via Cygwin{{ref|Cdparanoia_fronts|a}}
| style="background: #CCFFCC" | Windows
| style="background: #CCFFCC" | Windows
| style="background: #CCFFCC" | Linux (Unix-like)
|}
'''Notes:'''

*{{note|Cdparanoia_fronts|a}} Cdparanoia, a console application for Unix-like OSes, is one of many frontends to the Paranoia library, libparanoia. Additional OSes and features not directly related to the ripping process might be supported in other frontends. See [[Cdparanoia]] for details.
*{{note|EAC-cue|b}} A number of [[EAC and Cue Sheets|different types CUE sheet types]] are available. Flags are read from TOC only, not subcode.
*{{note|EAC-noncompliant|c}} The EAC-style [[EAC_and_Cue_Sheets#Multiple_WAV_Files_With_Gaps_.28Noncompliant.29_-_a.k.a._.22Append_Gaps_to_.28end_of.29_Previous_Track_.28default.29.22|"Multiple WAV Files With Gaps (Noncompliant)"]] type will be used in single track mode.
*{{note|compare_meta|d}} dBpoweramp is unique in being able to compare metadata from several sources automatically to eliminate erroneous data.
*{{note|EAC-ctdb-meta|e}} In EAC, freedb access can be direct (via the legacy built-in engine), via the bundled freedb plug-in, or via the bundled CTDB plug-in. MusicBrainz access can be via the bundled CTDB plug-in, or via the freedb options with the [http://musicbrainz.org/doc/FreeDB_Gateway MusicBrainz-to-freedb gateway]. Discogs access is via the bundled CTDB plug-in only.
*{{note|prOC|f}} In PerfectRip, offset correction only works if the drive supports overreading.
*{{note|prC2|g}} PerfectRip uses C2 pointers to know where possible errors are, but it does not re-read; it just flags the rip as "not perfect". However, it does write the C2 pointers to a file which can be used by a separate program to interpolate bad samples.
*{{note|ccdgap|h}} In CloneCD, gaps and indexes are detected only if "Read SubChannel Data from Audio Tracks" is enabled in the Audio CD profile.
*{{note|ccdc2|i}} CloneCD doesn't thoroughly explain its options or re-reading strategy. The disc type profiles allow setting Audio Extraction Quality(Bad/Medium/Good/Best), Fast Error Skip (Off/On/Automatic), Intelligent Bad Sector Scanner (enabled/disabled). The CD Reader (drive) configuration allows setting the number of Read Retries (0-15) and Error Correction (None/Software/Hardware). The effect of each of these options is undocumented, but seems to suggest C2 pointers are used.
*{{note|Easy-cue|j}} Easy Audio Copy offers image extraction and cue sheet generation, including gap detection, only when this functionality is enabled via an advanced settings app, downloadable separately (see [http://www.easyaudiocopy.com/faq.htm the FAQ]).
*{{note|Easy-meta|k}} Easy Audio Copy's website says CD information is obtained from "various internet sites (for example, from the GD³ database)."
*{{note|eacC2|m}} In EAC, C2 pointers are only considered if the Secure Mode option "Drive is capable of retrieving C2 error information" is checked. When checked, the lack of a pointer will prevent re-reads, thereby speeding up the rip, but possibly allowing errors to slip through, because at that point it is essentially the same as burst mode.
*{{note|EZCDAC|n}} In its two error-detection modes, EZ CD Audio Converter uses C2 pointers to know where possible errors are, but it does not re-read; it just logs the track as being ripped with errors. Likewise, despite being advertised as a "secure" ripper, it only uses CRC mismatch or sync errors to note the presence of possible errors; it does not try to get consistent results by re-reading.
*{{note|EZCDAC|o}} In EZ CD Audio Converter, the drive's caching is disabled only when error detection mode #2 is used on a drive which reports that it does not support Accurate Stream.
*{{note|XLDpe|p}} XLD detects pre-emphasis in the TOC since version 2009/11/8 and in subcode since version 2014/4/27.

==Explanation of features==
===One track per file===
A standard feature of rippers is the ability to rip each audio track to a separate file.

===Image as single file===
Some rippers can rip all the audio tracks to a single "image" file, either audio (WAV or AIFF) or raw binary (.bin file containing raw LPCM). The image file normally doesn't include data tracks from Enhanced CDs. This feature can be useful when combined with cue sheets.

===Cue sheet generation===
Cue sheet generation means the ripper can create a cue sheet to preserve, at a minimum, the relationship between extracted audio and the disc layout (e.g., a list of how an image file is to be split back up into tracks). It usually also indicates the ability to read at least some of the following info from the CD subcode for inclusion in the cue sheet: disc catalog number, track ISRC codes, track indexes (including gaps), disc & track CD-Text data, and track flags. Depending on the ripper, copyright & [[Pre-emphasis|pre-emphasis]] flags might only be taken from the TOC, and CD-Text data might only be filled in with metadata from external sources.

A "no" or "limited" in this row shouldn't be considered serious unless you're seeking to preserve as much info as possible, aside from the audio data.

===Gap detection===
Some rippers can read the disc's subcode to find each track's index 00 portion, i.e. the "gap" or "pre-gap", if one exists. Once detected, this info can be used to control whether & how these portions of the tracks are extracted, and the info can be written to a cue sheet so it can be written to a new CD later. Gap detection only refers to scanning for index 00, regardless of whether it contains silence or audible sound.

A "no" in this row is minor, unless, for example, you're 1. ripping a CD-R that was burned with pure-silence gaps that you want to remove, or 2. planning to burn a copy from the extracted audio (plus accompanying cue sheet) and you want the display on a regular CD player to count up from a negative number to 0:00 between certain tracks, just as it did on the original CD.

The ability to scan for other index points in the subcode is a related feature not yet covered by this table, and may be connected to other features like cue sheet generation. For example, EAC always scans the subcode for gaps and 02-and-higher index points when generating a cue sheet or when doing an index-based rip. Similarly, a ripper might have the option to scan for 01-index points (track boundaries) in the subcode rather than relying on the TOC, which is sometimes deliberately incorrect or unreadable on some drives, as a copy-protection measure.

===Pre-emphasis detection===
A small minority of audio CDs are authored with [[pre-emphasis]]. This means a high frequency boost was applied to the audio during the original digital recording. A corresponding high frequency cut must be applied for the audio to sound as originally intended. If a CD with pre-emphasis is played without this corresponding de-emphasis, the audio will have more high frequency content than intended, and will often sound like it is being replayed with the treble/tone control turned up.

Flags to tell a CD player to apply de-emphasis can be stored in a CD's subcode, the TOC, or ideally both. There are several CDs with pre-emphasis which only include the flag in the subcode, and not the TOC. A conventional hardware CD player will enable its de-emphasis circuit based on the subcode, not the TOC. Some CD rippers detect pre-emphasis based on the TOC, not the subcode. Where known, this is noted in the above table.

When detected by the ripper, the presence of pre-emphasis may be noted in the CUEsheet (if generated) or a tag. Alternatively the ripper may be configured to process the audio by applying a digital de-emphasis filter, thus generating audio without pre-emphasis that does not need to be tagged or flagged.

===Offset correction===
The ability of a ripper to compensate for a CD drive's inherent read offset, with sample-level precision, very slightly affects the accuracy of track boundaries, and plays a role in whether & how the fraction of a second of audio at the very beginning or very end of a disc is read. Properly configured rippers which correct for read offsets will produce consistent track boundaries, given the same discs to rip, thus allowing comparisons of ripped audio data made on different drives, e.g. via AccurateRip.

A "no" in this row should only be cause for concern if you need to be sure track boundaries aren't very slightly off from how they were encoded on the disc.

===HTOA===
This indicates the ability to read data in the portion of the disc where [[HTOA|Hidden Track One Audio (HTOA)]] may be located, if the drive also supports it. This is the index 00 portion of track 01, and if it exists at all, normally only contains a tiny amount of silence. If it does have non-silent audio, then to hear it, you would have to start playing track 1, then scan backward.

Very few CDs have HTOA, and not all drives support reading it, so a "no" in this row shouldn't be considered serious unless you're sure you need to read such CDs.

===C2 pointers===
This row indicates whether & how the ripper makes use of C2 pointers. A C2 pointer is a flag pointing to a particular byte in the audio data, indicating whether the drive suspects there was a read error which could not be corrected. This suspicion is based on the CD's built-in CIRC error detection and correction information.
* "None" means C2 pointers are ignored.
* "Initial pass" means that during the first read of a sector, an error-indicating C2 pointer results in the data being considered bad. This will prompt re-reads or flagging of the data as bad, depending on the ripper and its configuration. The lack of an error-indicating C2 pointer may be used by some rippers (such as EAC and XLD) as a reason to prevent re-reads.
* "On re-reads" means that the same check is done during re-reads, as well.

The CIRC system on audio CDs is not foolproof; a very tiny percentage of uncorrectable errors can fail to result in error-indicating C2 pointers, especially in error-heavy areas of a disc. Also, some drive firmware simply doesn't reliably report errors in the C2 pointers, for reasons unknown.

===Defeat cache===
This row indicates whether & how the ripper works around the automatic data caching that occurs in some drives. Overreading is a brute-force, slow method where extra data is read in order to flush the cache. Force Unit Access (FUA) is a more efficient method that is only supported in some drives. If you don't have a drive that caches during DAE, this row may not be of interest to you.

===AccurateRip===
This row indicates whether the ripper can check the AccurateRip database to see if other people got the same audio data when ripping tracks from the same CD. A "no" is nothing to worry about; any rip can be checked against AccurateRip later, using [[CUETools]].

===AccurateRip checking across pressings/offsets===
Rips of visually identical CDs can have identical audio data, but offset slightly (shifted by a fraction of a second in one direction or the other), for various reasons. For rippers that do check AccurateRip, a "yes" in this row indicates that AccurateRip will be checked for these slightly offset rips, thus increasing the chance of finding a match, if not also increasing the confidence of the rip's accuracy. A "no" indicates that only exact matches for the pressing are checked for.

===CUETools db===
The CUETools Database (CTDB) is similar to AccurateRip, but it's for whole-CD rips only (not separate tracks) and has cross-pressing support built-in. It also stores recovery data from believed-good rips, so that a bad rip can be corrected with CUETools. A "yes" in this row indicates the ripper can check for matching rips in CTDB and report whether a bad rip might be correctable. "Plugin" indicates support is provided through an optional component.

===log file===
This row indicates whether the ripper can generate a log file to document the ripping process, such as the ripper version and how it was configured, what data was checked for on the disc, any problems encountered, checksums, AccurateRip lookup results, etc.

===Metadata===
This row indicates whether and which metadata sources the ripper can use to get basic info about the CD (artist and title for the disc and each track, mainly). Most rippers use this info for naming and tagging files. Some include it in cue sheets, as if it were CD-TEXT.

===Download Album Art===
For rippers which tag files, this row indicates whether album art images are included in the metadata lookup capabilities. Some rippers only support album art via an optional component.

===Cost===
This row describes the pricing for a single-user license for the ripper.

===License===
This row describes the ripper's end-user licensing. "GPL" is a standard [http://www.gnu.org/licenses/gpl.html GNU Public License], which, among other things, implies the source code is open-source. "Proprietary" means a custom license and usually means the source code is private. "Freeware" means the license does not require that users pay for the software. "Shareware" means that payment is required, usually after a free trial period.

===OS===
This row indicates which operating systems the ripper natively works on.

[[Category:Comparison of CD ripping techniques]]

AccurateRip

2014-12-27T10:55:24Z

72.83.229.68: /* Offset accuracy */ link has gone away, switch to archive.org

'''AccurateRip''' is a online ripping accuracy database. Using submissions from people all around the world, a bit-perfect verification of an audio track rip can be assured with a positive match. AccurateRip also allows the offsets of drives to be determined.

The database is maintained by Illustrate Ltd., the company run by "Spoon", primary developer of [[dBpoweramp]]. All of the data is submitted by the Windows-based ripping programs dBpoweramp and [[Exact Audio Copy]] via a [[wikipedia:Dynamic-link library|DLL]] licensed from Illustrate.<ref>As per [http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77600&view=findpost&p=678407 a Jan. 2010 post by Spoon], "Only two programs submit to AR, EAC and dBpoweramp, these two submit through the standard AccurateRip access dll, which ensures that offsets are correct, we are not talking submissions to freedb where one record does not effect the submission of future records if keyed with a wrong offset. You might not like it, but it is the only way to ensure that the quality of the database is not impaired."</ref> Other rippers and tools, such as [[CUETools]] and Mac OS-based rippers, can receive info from the database in order to look up drive offsets or check rip quality, but they cannot submit their own rip results to it.

==Drive read offsets==
Very few CD drives actually start reading data from audio CDs exactly at the sector requested by DAE software. There are drives that are off by over 1 sector (1/75th of a second), but most are off by much less (1/250 to 1/350 second). Most modern CD drives have "Accurate Stream" technology, so there's rarely any "jitter", meaning in this case that the variance is usually consistent from read to read, and will tend to be the same for all drives of a certain make & model.

The AccurateRip database allows one to find out the read offset, which is normally constant for given make & model of CD drive. This number can then be used by DAE software to ensure that each track is ripped from its exact start to its exact finish.

The offset is given in samples. One "sample" on an audio CD is 4 bytes, consisting of a 2-byte left-channel value and a 2-byte right-channel value. There are 2352 bytes, or 588 samples, in each sector of an audio CD, corresponding to 1/75th of a second of sound. Therefore, an AccurateRip offset of +134 means the drive consistently delivers data from 536 bytes ''behind'' (earlier than) where it was asked to read from, so the DAE software needs to look that far ahead (hence the positive offset) in order to get the right data.

When offsets are taken into account, the DAE software might have to ask the drive to "overread" into the lead-in or lead-out portions of the disc, where there's no audio data. Some drives can't be asked to do it, some drives will try to do it and fail, and some will just return null samples (a stream of "0" bytes, a.k.a. digital silence). If the drive can't overread, then there will be samples missing from the extracted track. The DAE software can correct for this by padding the track with digital silence so it's the correct length.

===Offset accuracy===
Determining the actual read offset of a drive is difficult. The reference measurements Andre Wiethoff made and which were adopted by Spoon for the AccurateRip database were challenged in late 2006; [http://web.archive.org/web/20120903210117/http://www.digital-inn.de/exact-audio-copy-english/28787-andre-wiethoff-who-feels-have-say-offsets.html] to support a claim that the reference is actually off by 30 samples. The offsets are 30 samples too low, or the correction values are 30 samples too high, however you want to look at it. Wiethoff feels that it's too late to change to a different reference now that the database is populated. However, since all submissions are calibrated to the same reference, and the apparent error so small, the reliability of AccurateRip data is not compromised in any way whatsoever.

==Ripped track checksums==
Once all the samples for a track have been extracted and put into a file such as a WAV, a checksum can be generated to summarize the sample data. Identical data will produce identical checksums. If the data is the slightest bit different, the checksums will usually be very different. The checksums derived from the same tracks from the same pressings of the same CDs, so long as drive offsets have been accounted for, can be compared in order to determine whether the extraction was error-free. That is, if you rip a track and find that your checksum matches what everyone else got, then you can be confident there are no missing or incorrect samples (or that you've all got exactly the same damage, which is nearly impossible). See the [[secure ripping]] article for more on this subject.

The AccurateRip database contains over 2 million unique discs. DAE software can use this info to decide whether to try re-reading a track that produced a different checksum than was expected.

===Checksum calculation===
Technical details on checksum calculation can be found here: [http://forum.dbpoweramp.com/showthread.php?20641-AccurateRip-CRC-Calculation AccurateRip-CRC-Calculation]

A Linux command-line tool to compute AccurateRip checksums can be found here: https://github.com/leo-bogert/accuraterip-checksum

Each AccurateRip checksum is based on a complete track rip, from the beginning of the track to the end, as determined by the track's entry in the disc's table of contents. This means that any silence or "gap" at the beginning or end of the track, except before the first track, must be included in the rip. If your DAE software is configured to trim silence or to do anything with gaps other than put them at the end of the preceding track (as normally happens when gaps aren't taken into account), then it's unlikely the checksums of your rips will be submitted to or compared against those in the AccurateRip database.

The checksum algorithm ignores the first 2939 samples<ref name=Steffensen>Not 2940 samples; see http://jonls.dk/2009/10/calculating-accuraterip-checksums/</ref> (just under 5 frames, a little over 0.013s of audio) at the beginning of the first track, and ignores 2940 samples (exactly 5 frames) at the end of the last track. The largest drive offset in the database, as of late 2011, is only 1776 samples, so when an offset-corrected drive "overreads" beyond the boundaries of the audio data, it normally won't affect the checksum. If the overread were to exceed 2940 samples, though, the algorithm assumes the data is padded with digital silence (nothing but zeroes). If your drive isn't capable of overreading and your DAE software doesn't zero-pad the rip to simulate an overread, then it's unlikely the checksums of your rips will be submitted to or compared against those in the AccurateRip database.

An optimization oversight in the original AccurateRip checksum algorithm results in an unintended loss of accuracy: about 3% of the audio data is not counted in the checksum at all. The left channel's samples are fully included, but in a 65,536-sample cycle, half of the right-channel samples are treated as if they're missing anywhere from 1 bit to all 16 bits. [http://www.hydrogenaudio.org/forums/index.php?showtopic=61468 Proposals for improving the algorithm, the database, and the database's API were made] and an improved algorithm was implemented for AccurateRip v2 checksums, which are now the default calculated by the rippers which support AccurateRip. How much improvement the v2 checksum has over the original is suspect [http://www.hydrogenaudio.org/forums/index.php?showtopic=66233&st=1350&p=756260&#entry756260 link]. The v2 checksums are treated as separate pressings from the old ones, so there's no risk to the integrity of existing data.

==Pressings==
Pressings, for AccurateRip's purposes, are where a batch of identical audio CDs is created by the pressing plant, then another batch is created, usually at a later date, with the same data but a different offset. The offset is due to variations in the way the master discs are replicated for the pressing machinery. Apart from this offset, discs across pressings are identical; the audio data on them is exactly the same. AccurateRip, as it was originally written, could only verify results for a specific pressing (same data, same offset), though the program's calibration procedure still made checking against alternate pressings possible. A major update to the program CUETools offered a mathematical solution to quickly cross-check a rip against multiple pressings. AccurateRip v2 would later be released to incorporate cross-checking against alternate pressings as well.

==AccurateRip data analysis==
It is possible to run statistical analysis on the hundreds of millions of submissions to AccurateRip to determine how accurate a given drive is, with the idea that with enough spread of drive submissions, anomalous results from damaged CDs will be averaged out. The last such calculation can be found here: [http://forum.dbpoweramp.com/showthread.php?23074-CD-DVD-Drive-Accuracy-List-2011 CD-DVD-Drive-Accuracy-List-2011]

There is also a report of drive offsets here: [http://www.accuraterip.com/driveoffsets.htm CD Drive Offsets]

==Submitting offsets and checksums==
The database is designed to be anonymously accessed by DAE software, via HTTP. Submitting data should only be done through such software.

==Software that uses AccurateRip==
* [[Exact Audio Copy]]
* [[DBpowerAMP with AccurateRip]]
* [[Foobar2000]]
* [[MediaMonkey]]
* [[CueTools]]
* [[XLD]]
* [[Python Audio Tools]]
* [[Rip]]
* [[Songbook]]
* [https://github.com/thomasvs/morituri morituri]

==History==
AccurateRip was introduced as an add-on for dBpowerAMP Music Converter (dMC) in January 2003.


==Notes and references==
<references/>

==External links==
* [http://www.accuraterip.com/ AccurateRip web site]

[[Category:CD ripping]]