Ställa ner hastigheten på DVD:n

Annars borde du ju kunna öka cache mängden väl för din spelare, så den kan cache:a en större del utav skivan så slipper den gå stup i ett. Eller tänker jag helt fel?
Finns det någon fördel att istället dra ner på hastigheten på dvd-enheten?

Hittade denna kodsnutt i en newsgroup för nåt år sedan när jag hade samma problem. Har funkat kalasbra sedan dess.
hdparm -E verkar bara fungera för cdrom.

Kopiera koden och kompilera den med gcc.

Mvh/Nicklas

/*
* SpeedControl - use SET STREAMING command to set the speed of DVD-drives
*
*
* Copyright (c) 2004 Thomas Fritzsche <tf@noto.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/cdrom.h>

void dump_sense(unsigned char *cdb, struct request_sense *sense)
{
int i;

printf("Command failed: ");

for (i=0; i<12; i++)
printf("%02x ", cdb[i]);

if (sense) {
printf(" - sense: %02x.%02x.%02x\n", sense->sense_key, sense->asc,
sense->ascq);
} else {
printf(", no sense\n");
}
}

int main(int argc, char *argv[])
{
char *device = "/dev/cdrom";
int c,fd;
int speed = 0;
unsigned long rw_size;

unsigned char buffer[28];

struct cdrom_generic_command cgc;
struct request_sense sense;
extern char * optarg;

while((c=getopt(argc,argv,"x:"))!=EOF) {
switch(c) {
case 'x': speed = atoi(optarg); break;
default:
printf("Usage: speedcontrol [-x speed] [device]");
return -1;
}
}

if (argc > optind) device = argv[optind];

fd = open(device, O_RDONLY | O_NONBLOCK);
if (fd < 0) {
printf("Can't open device %s\n", device);
return -1;
}

memset(&cgc, 0, sizeof(cgc));
memset(&sense, 0, sizeof(sense));
memset(&buffer, 0, sizeof(buffer));

/* SET STREAMING command */
cgc.cmd[0] = 0xb6;
/* 28 byte parameter list length */
cgc.cmd[10] = 28;

cgc.sense = &sense;
cgc.buffer = buffer;
cgc.buflen = sizeof(buffer);
cgc.data_direction = CGC_DATA_WRITE;
cgc.quiet = 1;

if(speed == 0) {
/* set Restore Drive Defaults */
buffer[0] = 4;
}

buffer[8] = 0xff;
buffer[9] = 0xff;
buffer[10] = 0xff;
buffer[11] = 0xff;

rw_size = 177 * speed;

/* read size */
buffer[12] = (rw_size >> 24) & 0xff;
buffer[13] = (rw_size >> 16) & 0xff;
buffer[14] = (rw_size >> 8) & 0xff;
buffer[15] = rw_size & 0xff;

/* read time 1 sec. */
buffer[18] = 0x03;
buffer[19] = 0xE8;

/* write size */
buffer[20] = (rw_size >> 24) & 0xff;
buffer[21] = (rw_size >> 16) & 0xff;
buffer[22] = (rw_size >> 8) & 0xff;
buffer[23] = rw_size & 0xff;

/* write time 1 sec. */
buffer[26] = 0x03;
buffer[27] = 0xE8;

if (ioctl(fd, CDROM_SEND_PACKET, &cgc) != 0)
if (ioctl(fd, CDROM_SELECT_SPEED, speed) != 0) {
dump_sense(cgc.cmd, cgc.sense);
printf("ERROR.\n");
return -1;
}
printf("OK...\n");
return 0;
}