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Versión Completa: ¿CDs especiales?
emulEspaña > Musica > Música
alfema
Acabo de comprar el CD "Papito" de Miguel Bosé y compañía, lo estaba pasando a formato 'flac' para escucharlo en el ordenador, se me ocurrió ver su contenido y desde Linux me muestra:
  • /CDA, carpeta con todas las canciones en formato cda.
  • /CD Completo, las canciones juntas en formato CDA, OGG y WAV.
  • /Información, con el fichero CDDB Information.txt
  • /Off Vorbis, con las canciones en formato OGG
  • /, con todas las canciones en formato WAV

Si lo intento copiar a disco me dice que son 5.1 GiB, cosa que no entiendo mucho, ¿quizás alguna definición especial de CD?.

Sin embargo en XP sólo muestra el contenido de un CD normal.
samueru
Hombre, sin poder estudiar el CD, no puedo decir gran cosa pero también hay protecciones para CDDA. La mayoría difuntas para su uso comercial (una de ellas incluso se dice que rompía los altavoces donde se reproducía). Lo que tienen en común la mayoría de estas protecciones, es que fueron diseñadas para equipos con Windows. Lo que te puedo decir es que, si en el CD-ROM aparecen varias sesiones, la primera siempre tiene que ser de audio. Si la puedes extraer correctamente, pues bien. Si no se puede extraer, es que incluye algún tipo de protección estructural o un TOC falso para engañar a las unidades de ordenador.

En todo caso, sin poder ver el CD, sólo puedo especular.

Tengo por ahí un texto con una descripción breve de las protecciones utilizadas (y estrategias pensadas pero no utilizadas) para proteger CD-DA, a ver si lo encuentro.
alfema
El CD me lo ha dejado pasar sin problema a 'flac', incluso he probado a copia alguna de las partes del CD y reproducirlas sin mayor problema.

No es el primer CD de este tipo que me encuentro, tengo otro de Vangelis el himno de la FIFA 2002, por eso preguntaba si pudiera ser algún formato especial de CD.
samueru
Puede, pero por "especial" yo no me refiero a "estándar", que quede claro. Las modificaciones de este tipo producen cederrones que no son estándar y pueden dar problemas con según qué lector. Encontré el archivo donde tenía lo de las protecciones:
CITA
Audio CD Protections, in brief:

- Zeroth Generation (the Click Generation):

* Weak Sectors in ATIP: TTR Technologies MusicGuard (never deployed)

Flat out doesn't work at all, you probably wouldn't even notice they'd done anything. Any Lite-On, BenQ or Plextor wouldn't even skip a beat. Only CD-ROM tested which even gave a damn was a Sony (heh), the drive in the PlayStation 1 to be precise. Didn't get a contract, so TTR partnered with Macrovision, and tried harder. Much harder. Much too hard, in fact.

* Weak Sectors causing C2 Errors in Audio: TTR Technology/Macrovision SAFEAUDIO (limited deployment), Settec Alpha-Audio D-Type (data type, never deployed)

Extremely rare, no longer used; the market overwhelmingly rejected it, which is to say, it broke a music exec's speakers. High channel return rate because of obscenely low compatibility, duplicators returning whole batches as bad pressings because they couldn't perform any useful QA on discs deliberately damaged to this extent. Useless. (TTR apparently liquidated.)

Archiving: Alternate CDFS.VXD tools for Win9x may work, as they interpolate in exactly where SAFEAUDIO puts corruption. Other than that, deliberate damage = not perfectly playable, or rippable. Effectively an analogue medium with huge deliberate noise spikes. Use a mint disc, do the best you can, and high-order-interpolate over the scratches (Adobe Audition or something), just like archiving vinyl.

- First Generation (The Anti-CD Generation):

Archiving all first-generation formats merely needs a Good Drive and Good Software with Good Settings. Can be divided into roughly three groups:

* High Jitter Spike: Cactus Data Shield (classic): CDS-100/CDS-200, First4Internet XCP-Aurora XCP "Red"

(0'09", insert bad CIRC sector, 1200 weak sector/desync, 2 *blank* sectors with no sync, then start again with normal data.) Intent: Cause a "hiccup" during a burstmode rip which would be absorbed by a CD player's (tiny) buffer. Reality: Any quality drive firmware, buffer, or jitter correction, means you won't even skip a beat. Might slow down a little, but that's all. Now only marketed for internal releases/promos.

* Malformed TOC/Evil Session with no player: Early Sony key2audio (1.0), Settec Alpha-Audio S-Type (session type), First4Internet XCP-Aurora XCP1

Bread and butter, it's simple; include a normal or malformed TOC, and sprinkle liberally with a seriously malformed second session, relying on CD-ROMs being multisession and CD players being single session only.

* Malformed TOC/Evil Session with autorun player: Sony key2audio, SunnComm MediaClòQ

Differs from the above only in the second session being malformed, but having a valid data track containing a DRMv2 WMA player (or downloader). Players have evil EULAs, and may interfere with ripping while the player is running (although the first version of the key2audio player that appeared actually shifts the session enough to allow flawless ripping while the player is running...!) but as far as known, they don't leave behind malicious software.

- Second Generation (The Autorun Generation):

Rate of returns was still high, so Macrovision tried a weaker system with a much higher false negative, but a much lower false positive. Actually caught on; almost no returns. They could actually put the CD logo on these if they wanted.

* Valid CD-Extra with autorun player: Macrovision CDS-300, Macrovision TotalPlay CD, Alpha-Audio M-Type (main type)

Player (MS-DRMv2, as usual) interferes with ripping (while it's running) but doesn't seem to leave any malicious software behind. If the autorun isn't run (disable it, or hold SHIFT while inserting CD and be careful in Explorer) or supported, it's a normal CD-Extra. First session is valid Red Book.

- Third Generation (The Malicious Autorun Generation):

Apparently, the execs liked the low rate of returns of CDS-300, but wanted something with more meat to it. They got their meat, with only a little modification to the strategy CDS-300 used. Countermeasure: Disable autorun/use shift key.

* Valid CD-Extra with autorun trojan horse: SunnComm MediaMax (CD1, CD2, CD3)

Same kind of deal as CDS-300, but with one nasty catch; tries to install a Non-Plug-and-Play device driver called Sbcphid (CD1/2, CD3 has a customisable name), which lives as a LowerFilter for CD-ROM devices and scrambles all ripping (CD1), or ripping of CDs with a TOC it recognises (CD2/CD3). No uninstall, and it tries to keep quiet about it; indeed CD1 tries to install the driver before the EULA is displayed (and it is installed even if you do not agree), due to an unintentional bug in the installer that was fixed in CD2.

- Fourth Generation (The Very Malicious Autorun Generation):

Not evil enough for the execs? Apparently not, because someone one-upped it. Countermeasure: Disable autorun/use shift key.

* Valid CD-Extra with STEALTH autorun trojan horse: First4Internet XCP-Aurora XCP2 (aka the "Sony Rootkit")

Roughly the same deal as MediaMax, but worse programmed, by a programmer with no kernel-mode experience and a penchant for cut'n'paste plagiarism. Even nastier than MediaMax, XCP2 installs a whole suite of drivers (crater as a CD-ROM lowerfilter, corvus (cor) as an IDE channel upperfilter, and a service, DRMserver, which constantly monitors running applications and may corrupt their memory space), and as the infamous icing on the cake, a kernel-mode rootkit-style stealth driver, aries, which cloaks every file/registry entry/pipe with a $sys$ prefix; including, of course, the rest of the trojan horse.
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