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+This describes the program as shipped with cdrkit, a spinoff from the
+cdrtools project. However, the cdrtools developers are no longer 
+involved in the development of this spinoff and therefore shall not
+be made responsible for any problem caused by it. Do not try to get 
+support for this program by contacting the original authors.
+
+This is a small description for the Reed-Solomon library intended for
+CD sector formatting.
+
+Basics:
+It is assumed that you have a basic knowledge of cd sector formats.
+
+The library can handle three types of sector data:
+  data sectors,
+  audio sectors, and
+  sub channel r-w sectors
+
+Currently only encoding is implemented. Decoding and optionally
+error correction is planned for later.
+
+Stages:
+
+The process of sector formatting has several stages. Beginning with
+a data sector (2048, 2324, or 2336 bytes) a sector of 2352 bytes is
+built. This format can be read raw by SCSI MMC-2 and ATAPI drives and
+is accepted by cd burners. The additions are an optionally 32 bit CRC
+checksum and two layers of Reed-Solomon codes (called Reed-Solomon
+Product Code RSPC).
+This sector is then scrambled (exor'ed with a bitstream).
+The result is called F1 frames. Afterwards even and odd bytes are
+swapped, this is called F2 frames. The result is equivalent to an
+audio sector and is treated as such by the cd burner.
+So, if we wrote a series of sectors (F2 frames) into a CDR file and
+later burned them as 'audio', they would turn up as perfect data sectors.
+
+So, now we are at the level of audio sectors. Audio sectors get their
+own error correction data (called CIRC). Sector size goes up to 
+3136 bytes (that is 4/3 times 2352 bytes). Furthermore different
+words get delayed differently and swap positions. The result is ready
+to be fed into the so-called EightFourteenModulator (when subchannels
+have been added).
+
+Now, only sub channels are missing. While the p and q sub
+channels have to be generated elsewhere, any supplied r-w subchannel
+user data is protected by two levels of error correction
+codes. This format is read by cd burners when burning cd+graphics.
+The cdimage is a sequence of sectors, each containing audio data and
+after that subchannel data.
+Similar to audio sectors delaying and permutation of words
+takes place. After that the cd burner would mix sub channel data with
+the formatted audio sectors to feed the EFModulator.
+
+NOTE: Most of the described stages need not to be done in order to
+prepare sectors for burning, since all cd burners do at least CIRC,
+delaying and swaps. For data sectors they also do scrambling and f2
+frame generation.
+
+Encoding routines:
+
+For data sectors
+ int do_encode_L2(unsigned char *inout, int sectortype, unsigned address);
+
+ encodes data sectors. The returned data is __unscrambled__ and not in
+ F2-frame format.
+
+Parameters are:
+  inout        pointer to an array of at least 2352 bytes.
+  sectortype   One of the MODE_* constants from ecc.h. This defines
+               how to format the sector.
+  address      The logical address to be used in the header 
+               (150 = 0:2.0 MSF).
+
+NOTE: the data portion has be to aligned properly for performance
+reasons (see ecc.h for details). So, no moves are necessary here.
+
+Generating f2 frames to be used like audio sectors
+ int scramble_L2(unsigned char *inout)
+
+ generates f2 frames in place from sectors generated by do_encode_L2().
+
+Parameters are:
+  inout        pointer to an array of at least 2352 bytes.
+
+
+
+For sub channels
+ int do_encode_sub(unsigned char in[LSUB_RAW*PACKETS_PER_SUBCHANNELFRAME],
+		unsigned char out[(LSUB_RAW+LSUB_Q+LSUB_P)*
+					PACKETS_PER_SUBCHANNELFRAME],
+		int delay1, int permute);
+
+ repack user data and add error correction data. P and q subchannels
+should be added later, since all bytes are in place then.
+
+Parameters are:
+  in           pointer to an array of at least 72 bytes. It contains
+               the user data for one frame.
+  out          pointer to an array of at least 96 bytes. Here is
+               output frame is placed.
+  delay1       do low level delaying, when set to 1.
+  permute      do low level permutations, when set to 1.
+
+NOTE: Probably both options need either to be set on (1) or off (0) together.
+
+There is more, but that is seldomly used.
+
+Tests:
+The library is accompanied by small verify programs, that compare real
+raw sectors with the formatted results. They are also intended as demo
+applications (how to use the library). In order to be able to feed
+real raw sectors into them, the package read2448 is recommended/needed.
+You can only verify sector streams of one sector type, currently no mix.
+
+For more information have a look into ecc.h
+
+recommended Documents:
+Yellow Book or ISO 10149
+Appendix Red Book
+Red Book or IEC 908
+
+Source: libedc/README from cdrtools package
+Edited for cdrkit by Christian Fromme <kaner@strace.org>
+