The tape format may have a variable number of records before the image data, and a variable amount of non-image data at the beginning and end of the records. Image data can be packed with multiple lines per record, or with multiple records per line.
Progress of this program can be monitored. See MONITOR section.
Name Prompt Count Type MTIW Mag Tape Input Window 0-4 Int VDOW Video Output Window 0-4 Int MTIC Mag Tape Input Channel List 1-16 Int VDOC Video Output Channel List 1-16 Int STRUCTUR File Structure Information 2-4 Int PREFIX Record Prefix Bytes 0-16 Int SUFFIX Record Suffix Bytes 0-16 Int SKRC Records to Skip for Data 1 Int STARTFIL Start File on Tape 1 Int
EASI>MTIW=Xoffset,Yoffset,Xsize,Ysize EASI>MTIW= | defaults to entire image
EASI>VDOW=Xoffset,Yoffset,Xsize,Ysize EASI>VDOW= | defaults to entire display
EASI>MTIC=i,...,j,k
EASI>VDOC=i | integer
EASI> STRUCTUR = pixels,lines,bands,interleaving modeEach value has the following meaning:
Pixels - Number of pixels (width) per line.
Lines - Number of lines in the image.
Bands - Number of bands (channels) of imagery,
default is one.
Interleaving - Mode of interleaving:
0: band sequential (default)
data is band sequential, with no extra headers, or
file marks between bands.
1: line interleaved
2: pixel interleaved
3: band sequential by file
data is band sequential, with bands separated by
EOF marks. The SKRC record skip count is applied
for each file containing a band.
In combination with SUFFIX, the PREFIX value is used to compute how much of the record contains actual image data.
In combination with PREFIX, the SUFFIX value is used to compute how much of the record contains actual image data.
EASI>SKRC=n | integer
EASI>STARTFIL=1 | Rewind, read first image, and rewind. EASI>STARTFIL=n | Rewind, skip n-1 EOF's, read image, and rewind. EASI>STARTFIL=0 | Read image at current position; do NOT rewind. EASI>STARTFIL=-n | Skip n EOF's, and read image; do NOT rewind.
The parameters SUFFIX and PREFIX are used to compute the area of each record that is actually data, based on the size of the records read in.
Any file (image) on tape (STARTFIL) can be specified. MVB will advance or rewind to the selected file before transferring. As well SKRC can be specified to skip a selected number of header records before the image data. Note that for BSQ tapes no records can be skipped between bands. If a BSQ tape has a header before each band, it may be necessary to run MVB once for each band, setting MTIC=1, number of bands=1, and SKRC appropriately to beginning reading at the beginning of the band.
MVB is capable of reading tapes with multiple lines of data per record or multiple records per line. Which case (if either) applies is determined by MVB's knowledge about the tape organization (interleaving mode), the data area of the record (from PREFIX and SUFFIX) and size of the tape image (STRUCTUR(1) and STRUCTUR(2)).
If a line spans records, MVB assumes that the next line will always start on a new record, even if this means there is unused data area on the last record of the previous line of image data.
If one line of data does not tape up the entire data area on a record, MVB will only assume that additional lines of data exist on that record, if an entire additional line of data will fit in the data area of that record.
If the contents of the tape are not completely known the PCI tape program MAGSTRU is often helpful in determining the tape structure.
A TAPE MUST BE MOUNTED ON THE TAPE DRIVE BEFORE MVB CAN BE RUN. CLEANING THE TAPE HEADS IS RECOMMENDED TO MINIMIZE THE CHANCE OF TAPE READ ERRORS.
EASI>MONITOR="ON" | turn monitor ON (default)
EASI>MONITOR="OFF" | turn monitor OFF (recommended if
| running in batch/background mode)
Using a LAS LGSOWG tape from the EROS Data Center, which has two forms of data (AT and PT), as an example:
The value of SKRC is 1, to skip the header record.
The magtape data size for PT data is 7168 pixels by 5965 lines.
The magtape data size for AT data is 6656 pixels by 5984 lines.
The value of STARTFIL will depend on the tape that you have mounted. You must know what file on the tape the image data is on. Usually, this value for a seven tape volume set is 5 for the 1st tape, and 3 for the 2nd to 7th tape.
As only one band appears on each tape, we will represent each tape as an independent data set consisting of one band. Hence STURCTUR(3) is 1. As only image data appears on the actual data records, we do not need to set a PREFIX and SUFFIX value. As there is just one band of data, we do not need to specify an interleaving type.
LAS LGSOWG PT data comes packed four lines of data to a record. MVB will recognise that the 28672 bytes of data per record represent four lines of input data.
EASI>FILE="agrihot.pix" EASI>MTIW= EASI>VDOW= EASI>MTIC=1 EASI>VDOC=1 EASI>SKRC=1 EASI>STRUCTUR=7168,5965 EASI>STARTFIL=5 EASI>RUN MVBExample 2:
Read a sequence of files on tape without rewinding the tape in between runs of MIB, by specifying negative values for STARTFIL. Each 512 by 512 image is transferred to the first channel of different PCIDSK files. For the first file on tape, STARTFIL is set to 0, instead of 1, to prevent rewinding. Then, for subsequent files, STARTFIL is set to -1, to skip to the next file on tape.
EASI>MTIW= EASI>VBOW= EASI>MTIC=1 EASI>VBOC=1 EASI>STRUCTUR=512,512 EASI>STARTFIL=0 EASI>RUN MIB EASI>FILE="file2.pix" EASI>STARTFIL=-1 EASI>RUN MIB EASI>FILE="file3.pix" EASI>STARTFIL=-1 EASI>RUN MIBExample 3:
Running MAGSTRU on a tape produces the following report. It indicates seven bands of 6920 x 5728 data with each band separated by EOF marks.
EASI>RUN MAGSTRU
5728 records of 6920 bytes
*** EOF ***
5728 records of 6920 bytes
*** EOF ***
5728 records of 6920 bytes
*** EOF ***
5728 records of 6920 bytes
*** EOF ***
5728 records of 6920 bytes
*** EOF ***
5728 records of 6920 bytes
*** EOF ***
5728 records of 6920 bytes
*** EOF ***
Setting STRUCTUR(4) to 3 indicates band sequential with EOF marks
between bands, so we can read the entire tape in one pass.
EASI>MTIW= EASI>VBOW= EASI>MTID= EASI>MTIC=1,2,3,4,5,6,7 EASI>VBOC=1,2,3,4,5,6,7 EASI>STRUCTUR=6920,5728,7,3 EASI>RUN MIB