Clarified CD and DVD peculiarities

cdrskin/cdrskin.1

@@ -125,10 +125,7 @@ Multiple cycles of blanking and overwriting with random numbers might be.
 ---------------
 .br
 Note: The support for sequentially recordable media is still emerging.
-.br
+DVD-R have not been tested yet.
-DVD-R have not been tested yet. If no Incremental Streaming feature (21h)
-is offered, then the media is regarded as unsuitable without further
-explanation. (One can torture DVD-RW to make them offer only DAO (2Fh)).
 .br
 ---------------
 .br
@@ -139,16 +136,28 @@ Used DVD-RW get into blank sequential state by option
 .B blank=deformat_sequential .
 .br
 Incremental Streaming is the default write mode if it is offered by the media.
-It may be selected explicitely by option -tao as it resembles much TAO writing
+It may be selected explicitely by option
-with CD by allowing track sources of unpredicted length and to keep media
+.B -tao
-appendable by option
+as it resembles much CD TAO by allowing track sources of
+unpredicted length and to keep media appendable by option
 .B -multi .
-Only restriction towards CD-RW is the lack of support for -audio tracks.
+The only restriction towards CD-R[W] is the lack of support for -audio tracks.
 Multiple tracks per session are permissible.
 .br
-(The other write mode, DAO, is not implemented yet. It will allow no -multi and
+The other write mode, DAO, has many restrictions. It does not work with
-only a single track. It will be selected explicitely by option -sao or by
+appendable media, allows no -multi and only a single track. The size of the
-default if no Incremental writing is available.)
+track needs to be known in advance. So either its source has to be a disk file
+of recognizable size or the size has to be announced explicitely by options
+.B tsize= 
+or
+.B tao_to_sao_tsize= .
+.br
+DAO is the default mode for media which do not offer feature 21h Incremental
+Streaming. It may also be selected explicitely by option
+.B -sao .
+.br
+Program growisofs uses DAO on sequential DVD-R[W] media for maximum
+DVD-ROM/-Video compatibility.
 .PP
 .B Overwriteable DVD Media:
 .br
@@ -233,7 +242,7 @@ audio track. Same is done for suffix .au and SUN Audio.
 Option -audio may be used only with CD media and not with DVD.
 .TP 
 .BI blank= type
-Blank a CD-RW or format a DVD+/-RW.
+Blank a CD-RW, a DVD-RW, or format a DVD+/-RW.
 This is combinable with burning in the same run of cdrskin.
 The type given with blank= selects the particular behavior:
 .RS
@@ -245,7 +254,7 @@ all
 Blank an entire CD-RW or an unformatted DVD-RW.
 .TP
 fast
-Minimally blank an entire CD-RW or an unformatted DVD-RW.
+Minimally blank an entire CD-RW or fully blank an unformatted DVD-RW.
 .TP
 format_overwrite
 Format a DVD-RW to "Restricted Overwrite". The user should bring some patience.
@@ -273,7 +282,12 @@ deformat_sequential
 Like blank=all but with the additional ability to blank overwriteable DVD-RW.
 This will destroy their formatting and make them sequentially recordable. 
 .br
-(Note: blank=deformat_sequential is not an original cdrecord option.)
+(Note: blank=deformat_sequential* are not original cdrecord options.)
+.TP
+deformat_sequential_quickest
+Like blank=deformat_sequential but blanking DVD-RW only minimally.
+This is faster than full blanking but may yield media incapable of
+Incremental Streaming (-tao).
 .RE
 .TP
 .BI \-checkdrive
@@ -281,7 +295,8 @@ Retrieve some info about the addressed drive.
 Exits with non-zero value if the drive cannot be found and opened.
 .TP
 .BI \-dao
-Alias for option -sao. Write disc in Session at Once mode.
+Alias for option -sao. Write CD in Session at Once mode
+or DVD-R[W] in Disc-at-once mode.
 .TP
 .BI \-data
 Subsequent tracks are data tracks. This option is default and only needed
@@ -311,8 +326,8 @@ even if attempted explicitely via "driveropts=burnfree".
 .TP
 .BI \-dummy
 Try to perform the drive operations without actually affecting the inserted
-media. There is no guarantee that this will work with a particular drive
+media. There is no guarantee that this will work with a particular combination
-in a particular write mode. Blanking is prevented reliably, though.
+of drive, media, and write mode. Blanking is prevented reliably, though.
 .TP
 .BI \-eject
 Eject the disc after work is done.
@@ -365,12 +380,13 @@ start address of the next session to be appended. The string is empty if
 the most recent session was not written with option -multi.
 .TP
 .BI \-multi
-This option keeps the CD or DVD-R[W] appendable after the current session has
+This option keeps the CD or unformatted DVD-R[W] appendable after the current
-been written.
+session has been written.
 Without it the disc gets closed and may not be written any more  - unless it
 is a -RW and gets blanked which causes loss of its content.
 .br
-The following sessions can only be written in -tao mode.
+The following sessions can only be written in -tao mode. -multi is prohibited
+with overwriteable DVD media and with DVD-R[W] DAO write mode.
 .br
 In order to have all filesystem content accessible, the eventual ISO-9660
 filesystem of a follow-up
@@ -403,11 +419,20 @@ then behave strange or even go bad for the next few attempts to burn a CD.
 One should use it only if inavoidable.
 .TP
 .BI \-sao
-Write disc in Session At Once mode. This mode is able to put several audio
+Write CD in Session At Once mode, resp. a sequential DVD-R[W] in Disc-at-once
-tracks on CD without producing audible gaps between them. It can only 
+(DAO) mode.
-be used for tracks of fixely predicted size. This implies that track arguments
+.br
-which depict stdin or named pipes need to be preceeded by option tsize= or
+With CD this mode is able to put several audio tracks on media without
-by option tao_to_sao_tsize=.
+producing audible gaps between them.
+.br
+With DVD-R[W] this mode can only write a single track.
+No -multi is allowed with DVD-R[W] -sao.
+.br
+-sao can only be used for tracks of fixely predicted size. This implies that
+track arguments which depict stdin or named pipes need to be preceeded by
+option tsize= or by option tao_to_sao_tsize=.
+.br
+-sao cannot be used on appendable media.
 .TP
 .BI \-scanbus
 Scan the system for drives. On Linux the drives at /dev/s* and at /dev/hd*
@@ -437,10 +462,13 @@ Less guesswork is needed if track sources are in format MS-WAVE in a file with
 suffix ".wav".
 .TP
 .BI \-tao
-Write disc in Track At Once (TAO) mode. This mode can be used with track
+Write CD in Track At Once (TAO) mode, resp. sequential DVD-R[W] in Incremental
-sources of unpredictable size, like standard input or named pipes. It is
+Streaming mode. This mode also applies pro-forma to overwriteable DVD media.
-also the only mode that can be used for writing to appendable CD or DVD-R[W]
+.br
-which already hold data.
+Mode -tao can be used with track sources of unpredictable size, like standard
+input or named pipes. It is also the only mode that can be used for writing
+to appendable media which already hold data. With unformatted DVD-R[W] it is
+the only mode which allows -multi.
 .TP
 .BI \-toc
 Print the table of content (TOC) which describes the tracks recorded on disc.
@@ -476,7 +504,7 @@ About size specifiers, see option fs=.
 If the track source does not deliver the predicted amount of bytes, the
 remainder of the track is padded with zeros. This is not considered an error.
 If on the other hand the track source delivers more than the announced bytes
-then the track on CD gets truncated to the predicted size and cdrskin exits
+then the track on media gets truncated to the predicted size and cdrskin exits
 with non-zero value.
 .TP
 .BI \-v
@@ -539,6 +567,19 @@ interpretation of eventual startup files. See section FILES below.
 .BI \--single_track
 Accept only the last argument of the command line as track source address.
 .TP
+.BI tao_to_sao_tsize= size
+Set an exact fixed size for the next track to be in effect only if the track
+source cannot deliver a size prediction and no tsize= was specified and an
+exact track size prediction is demanded by the write mode.
+.br
+This was the fallback from bad old times when cdrskin was unable to burn
+in mode -tao . It came back with minimally blanked DVD-RW which allow no
+Incremental Streaming (-tao) resp. with explicitly selected write mode -sao
+for best DVD-ROM compatibility.
+.br
+If the track source delivers less bytes than announced then the missing ones
+will be filled with zeros.
+.TP 
 .BI write_start_address= byte_offset
 Set the address on media where to start writing the track. With DVD+RW or
 DVD-RAM byte_offset must be aligned to 2 KB blocks, but better is 32 kB.
@@ -607,8 +648,8 @@ On signals exit even if the drive is in busy state. This is not a very good
 idea. You might end up with a stuck drive that refuses to hand out the media.
 .TP
 .BI \--no_blank_appendable
-Refuse to blank appendable CD-RW. This is a feature that was once builtin with
+Refuse to blank appendable CD-RW or DVD-RW. This is a feature that was once
-libburn. No information available for what use case it was needed.
+builtin with libburn. No information available for what use case it was needed.
 .TP
 .BI \--no_convert_fs_adr
 Do only literal translations of dev=. This prevents cdrskin from test-opening
@@ -625,12 +666,6 @@ Linux specific:
 Use and report literal Bus,Target,Lun addresses rather than real SCSI and
 pseudo ATA addresses. This method is outdated and was never compatible with
 original cdrecord.
-.TP
-.BI tao_to_sao_tsize= size
-Set an exact fixed size for the next track to be in effect only if the track
-source cannot deliver a size prediction and no tsize= was specified.
-This is the fallback from bad old times when cdrskin was unable to burn
-in mode -tao.
 .br
 .SH EXAMPLES
 .SS
@@ -664,7 +699,7 @@ cdrskin -v dev=/dev/sr0 blank=format_overwrite
 .br
 cdrskin -v dev=/dev/sr0 blank=deformat_sequential
 .SS
-.B Write ISO-9660 filesystem image:
+.B Write ISO-9660 filesystem image as only one to blank or formatted media:
 .br
 cdrskin -v dev=/dev/hdc speed=12 fs=8m \\
 .br
@@ -676,11 +711,11 @@ find . | afio -oZ - | \\
 .br
 cdrskin -v dev=0,1,0 fs=32m speed=8 \\
 .br
-padsize=300k -tao -
+-tao padsize=300k -
 .SS
 .B Write several sessions to the same CD or DVD-R[W]:
 .br
-cdrskin dev=/dev/hdc -v padsize=300k -multi 1.iso
+cdrskin dev=/dev/hdc -v padsize=300k -multi -tao 1.iso
 .br
 cdrskin dev=/dev/hdc -v padsize=300k -multi -tao 2.iso
 .br