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* Is controlling DVD speeds via SET_STREAMING supported?
@ 2004-11-20 16:17 David Härdeman
  2004-11-20 16:30 ` Jan Engelhardt
  2004-11-20 20:19 ` Jens Axboe
  0 siblings, 2 replies; 16+ messages in thread
From: David Härdeman @ 2004-11-20 16:17 UTC (permalink / raw)
  To: linux-kernel

Hi,

currently my DVD player sounds like a jet plane when playing ordinary 
audio CD's. I tried the different approaches to lowering playback speed 
that are commonly used (hdparm, setspeed, etc) but none of them worked.

Then I found this thread:
http://marc.theaimsgroup.com/?t=99366299900003&r=1&w=2

Which seems to indicate that DVD players need a different command 
(SET_STREAMING), the thread is from 2001, and I've not been able to find 
any more recent information.

So, my question is, is this implemented in the kernel and are there any 
userspace tools to set the playback speed?

Regards,
David

PS
Please CC replies to my email address...

^ permalink raw reply	[flat|nested] 16+ messages in thread
* Re: Re: Is controlling DVD speeds via SET_STREAMING supported?
@ 2004-11-26 19:59 Thomas Fritzsche
  2004-11-27  9:54 ` Thomas Fritzsche
  0 siblings, 1 reply; 16+ messages in thread
From: Thomas Fritzsche @ 2004-11-26 19:59 UTC (permalink / raw)
  To: linux-kernel

Hi Jens,

absolute correct! I just tested it with speed = 1 yesterday night
(quick&duty). This is just a code snap to show that it's possible to set
the speed of a DVD drive this way.

You also wrote about the "End LBA" field in your other mail.
I set this to 0xffffffff but you think that this could be a problem if the
device don't have this LBA. The spec only writes this:
"The End LBA field is the last logical block for which the performance
request is being made." So it should be standard conform if we set here a
higher block number. Do you have experience with other (than NEC ND-3500)
drive that don't support this?

Using this high last block number would make sence, because it looks like
this setting is still valid if the media is changed (other end block!?).

Spec:
"The performance setting is persistent and remains until a new descriptor
is sent. The setting only applies to the extent
identified by the Start and End LBA field. Only zero or one performance
extents shall be valid at any time."

What do you think?

I also found out, that the Realtime-Streaming Feature is mandatory for all
kinds of DVD-+R+-RW-RAM drives. So it might be sufficient to simply use
SET STREAMING for DVD drives and SET SPEED for CD-R's. Isn't it?

I will also enhance this tool by setting the RDD flag if the user selects
speed = 0.

Thanks and kind regards,
 Thomas Fritzsche

> I should have read this more closely... You need to fill the speed
fields correctly:
>
> 	unsigned long read_size = 177 * speed;
>
> 	buffer[12] = (read_size >> 24) & 0xff;
> 	buffer[13] = (read_size >> 16) & 0xff;
> 	buffer[14] = (read_size >>  8) & 0xff;
> 	buffer[15] = read_size & 0xff;
>
> Ditto for write size.
>
> --
> Jens Axboe
>
>





^ permalink raw reply	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2004-11-29  6:19 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-11-20 16:17 Is controlling DVD speeds via SET_STREAMING supported? David Härdeman
2004-11-20 16:30 ` Jan Engelhardt
2004-11-20 16:45   ` David Härdeman
2004-11-20 20:19 ` Jens Axboe
2004-11-20 23:50   ` David Härdeman
  -- strict thread matches above, loose matches on Subject: below --
2004-11-26 19:59 Thomas Fritzsche
2004-11-27  9:54 ` Thomas Fritzsche
2004-11-27 20:57   ` Pasi Savolainen
2004-11-27 21:02     ` Jan Engelhardt
2004-11-27 23:17     ` Thomas Fritzsche
2004-11-28 11:18       ` Pasi Savolainen
2004-11-28 14:25         ` Thomas Fritzsche
2004-11-28 16:52           ` Jens Axboe
2004-11-28 17:49             ` Pasi Savolainen
2004-11-28 16:53               ` Thomas Fritzsche
2004-11-28 18:53               ` Jens Axboe
2004-11-28 21:01                 ` Pasi Savolainen
2004-11-29  6:19                   ` Jens Axboe

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