[PlanetCCRMA] Re: DVD playback not fluent

Tue Apr 22 04:06:02 2003

hi,

just back from holidays, catching up with the emails.  :)
some reactions inline below:

 --- John Wheeler <jdw27_42@hotmail.com> wrote: > >Date: Fri, 11 Apr
2003 14:03:54 +0100 (BST)
> >From: =?iso-8859-1?q?Alex=20Timmer?= <mijn_troep@yahoo.com>
> >Subject: Re: DVD playback not fluent
> >To: planetccrma@ccrma.Stanford.EDU
> >
> >hi John,
> >
> >is your /dev/dvd a real device or just a symbolic link? if the
> latter
> >is the case, did you try hdparm as root on the 'real' dvdrom
> device?
> >in my case /dev/dvd is a symlink to /dev/hdc and i have to use
> hdparm
> >on /dev/hdc to get any effect.
> >
> >does your drive support dma? if you do 'hdparm /pathto/drivename'
> you
> >get a listing of capabilities of the drive.
> >
> >hope this helps, ALEX
> 
> Yes, /dev/dvd is a symbolic link:
> 
> # ls -l /dev/dvd
> lrwxrwxrwx    1 root     root           10 Nov 30 09:31 /dev/dvd ->
> 
> /dev/cdrom
> 
> AND /dev/cdrom is a symbolic link:
> 
> # ls -l /dev/cdrom
> lrwxrwxrwx    1 root     root            8 Nov 27 17:26 /dev/cdrom
> -> 
> /dev/hdd
> 
> but /dev/hdd is a real device:
> 
> # ls -l /dev/hdd
> brw-------    1 john     disk      22,  64 Aug 30  2002 /dev/hdd
> 
> but, I still get the same error:
> 
> # /sbin/hdparm -d 1 /dev/hdd
> 
> /dev/hdd:
> setting using_dma to 1 (on)
> HDIO_SET_DMA failed: Operation not permitted
> using_dma    =  0 (off)
> 
> and I get the following results:
> 
> # /sbin/hdparm -Tt /dev/hdd
> 
> /dev/hdd:
> Timing buffer-cache reads:   128 MB in  1.67 seconds = 76.65 MB/sec
> Timing buffered disk reads:  64 MB in  6.22 seconds = 10.29 MB/sec

interesting that you have a 10MB/sec read speed, as my drive will
only ever do as much as 1.40MB/sec (16*DVD, 48*CDROM, udma enabled).
when i can have fluent playback with that, and if hdparm isn't
fooling me, then i think that your drive must be more than fast
enough.

as for turning dma on. your information below seems to indicate that
the drive supports upto mode udma2 and with the * next to it, i think
this is already the current mode?
when i set the dma on a drive, i also specify which mode with the -X
parameter. for UltraDMA you have to supply a value of 64 + the
desired mode. (see the hdparm manpage)

so for your drive and udma2 this would be:
# /sbin/hdparm -d1 -X66 /dev/hdd

> # /sbin/hdparm /dev/hdd
> 
> /dev/hdd:
> HDIO_GET_MULTCOUNT failed: Invalid argument
> IO_support   =  3 (32-bit w/sync)
> unmaskirq    =  0 (off)
> using_dma    =  0 (off)
> keepsettings =  0 (off)
> readonly     =  1 (on)
> readahead    =  8 (on)
> HDIO_GETGEO failed: Invalid argument
> 
> # /sbin/hdparm -I /dev/hdd
> 
> /dev/hdd:
> 
> ATAPI CD-ROM, with removable media
>         Model Number:       DVD-ROM BDV212B
>         Serial Number:      MT1318  Firmware
>         Firmware Revision:  VER 0.37
> Standards:
>         Used: ATAPI for CD-ROMs, SFF-8020i, r2.5
>         Supported: CD-ROM ATAPI-2
> Configuration:
>         DRQ response: 50us.
>         Packet size: 12 bytes
> Capabilities:
>         LBA, IORDY(cannot be disabled)
>         DMA: mdma0 mdma1 mdma2 udma0 udma1 *udma2
>              Cycle time: min=120ns recommended=150ns
>         PIO: pio0 pio1 pio2 pio3 pio4
>              Cycle time: no flow control=227ns  IORDY flow
> control=120ns
> 
> So, it looks like the drive does have DMA capability.  Any idea
> what's going 
> on?  (Also, what is a good hdparm -Tt value for smooth DVD
> playback?)

as written above, i get a hdparm -Tt of 1.40MB/sec from my DVD drive.
with that i have fluent playback (NOTE... i did have to install the
nVidia drivers for my Geforce2 card to get smooth playback).

i don't have your original post anymore, what was the exact problem?

> Thanks for your help -- I'm hoping this is valuable for others, as
> well.
> John

__________________________________________________
Yahoo! Plus
For a better Internet experience
http://www.yahoo.co.uk/btoffer