# Can't Read DVDs, But Can Read Audio And Data CDs [solved]

## Maat Ghandi

Hi all,

I'm not sure if this is a Gentoo issue or if this is an issue with the hardware itself. If my drive did not read CDs, I would think it was definitely a hardware issue, but CDs are mounted and played with no problem.

This is not an application problem, this is a mounting problem. It happened spontaneously last night when I tried watching a DVD. The previous day it was reading DVDs just fine. Nothing has changed with Gentoo as far as I know, and no one except me has access to this computer.

When putting in a DVD and closing the bay, it spins up and attempts to read the DVD, but it stays in a loop making clunking sounds as it tries to read the DVD. When reading CDs, it makes this sound once, then speeds up and mounts the CD. The first time I loaded a DVD Gentoo complained about /dev/sr0, but it only complained once, so I don't recall the error message. After that, no matter the DVD (burned or original), it just fails to mount the DVD after trying for about 20 seconds with no error message or anything.

There is nothing in dmesg

 *Quote:*   

> 
> 
> # dmesg | tail
> 
> kjournald starting.  Commit interval 5 seconds
> ...

 

The drive is clearly recognized by Gentoo

 *Quote:*   

> 
> 
> # cat /proc/scsi/scsi
> 
> Attached devices:
> ...

 

If I try to mount it manually with a DVD in the drive, it says there is no medium found. I have only tried movie DVDs as I don't have any data DVDs, so I'm not sure if this happens with all DVDs, or just with the movie format. I'm at a loss of what to do or what to try before I decide that this might be a hardware issue. Any suggestions would be much appreciated.

Jerome

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## rad7

Do you have word dvd in USE ?

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## Maat Ghandi

I do have dvd in USE

 *Quote:*   

> 
> 
> USE="a52 aac acpi alsa avahi bash-completion bcmath bzip cdr cern cgi clamav cry
> 
> pt cups dbus dvd dvdr dvdread emacs encode ffmpeg fftw firefox flac ftp gif glit
> ...

 

I'm pretty positive that I have not modified anything since yesterday. It could be a hardware issue, but it seems weird that it would still read CDs just fine. Thanks for your inquiry.

Jerome

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## Caprica

Im also having the same problem on my laptop, which also has the dvd (global) use flag

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## Maat Ghandi

I talked with the local computer repair shop and they said it is an issue with the drive itself. They said they use two different lasers to read Cds and DVDs (I have the combo drive) and that explains why I can read CDs but not DVDs. I must say I'm a bit confused by this since I can only see one optical head when I open up the drive. It seems like if there were two different lasers, they would have their own lens.

Anyways, it makes sense that it is an issue with the drive, so I went onto ebay and found another drive for $40 after tax and shipping. Not bad compared with the Lenovo site selling it for $120. Hopefully I didn't get screwed.  :Wink: 

Jerome

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## NeddySeagoon

Maat Ghandi,

Each laser is a diode. They are both in the same piece of silicon and can easily share the same optical components.

The working part of each laser is at most a few wavelengths of the emitted radiation (infra-red)

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## Caprica

I would suggest that you try a data dvd, first. Mainly suggesting that as mine is working for data but not video dvds.

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## NeddySeagoon

Caprica,

Video DVDs are Data DVDs.

You normally play a Video using raw device access, not the filesystem but you can access the data either way.

Raw device access requires that you be in the CDROM group.

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## Caprica

so if ive read that right, I should be able to read the dvd by vlc /dev/sr0 without mounting the disc? I currently get a error message saying Unable to open '/dev/sr0'. My user is in both cdrom and cdrw groups and there is no specific dvd group that i could see

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## NeddySeagoon

Caprica,

Video DVDs are played using files containing lists of data blocks on the DVD.

DVD copy protection schemes normally work by writing assorted illegal data blocks in unused (by the video) blocks on the DVD, so simply using /dev/sr0 to address the device normally fails fairly quickly. Also, DVDs may contain several titiles, so you need to specify which title you want to play and even the chapter range, if you only want to view a part of it. 

Look at mplayers syntax ... 

```
mplayer -dvd-device=/dev/sr0 dvd://<title_no>
```

The DVD is not mounted and you do not need UDF support in your kernel. The vlc man page suggests its similar 

```
dvd://[<device>][@<raw device>][@[<title>][,[<chapter>][,<angle>]]] DVD device (for instance dvd:///dev/dvd). The raw device is optional and must have been prepared beforehand.
```

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