Nekochan Net

Hi!

So I finally have an O2 video modul and started playing with dmrecord this evening.

I hooked up my Digital8 camera via Composite video. seemed to work beautifully until I tried to capture longer than around a minute or so.

Got this error:


There is a topic about a similar error in the forum but no solution yet...

Oh yeah...: R5k 180MHz, 128MB, 73GB Seagate Cheetah

jmc

hmm most likely a timebase error, search for TBC, there's a ton of threads about it (quickest shortcut is to get a decent tbc in order to capture properly)

making sure nothing heavy runs in the background will also help

edit: jimmer's quick explanation

In case it's of any help, my site has some example dmrecord commands for use with IMPACT
Compression:

http://www.sgidepot.co.uk/impcom.html

Just replace the definitions of 'device' and 'engine' with 'ice' instead of 'impact' and it should
work ok on O2.

It could be that without specifying the parameters fully, it's defaulting to something unwise,
like single-frame capture and fixed a percentage quality factor (MJPEG on O2 works better
with 2-field capture and fixed bitrate).

Thus, for example:



Hmm, my O2 is off atm. I'll check later, make sure the above is correct.

There are some other example commands on the page, and aliases to make things easier. See the
man page for dmrecord on your O2 for more info and other settings specific to O2. Note that the
comment on my IMPACT page about playing to the screen with audio is not relevant to O2.

Btw, I'd want more than 128MB RAM for doing video stuff on an O2. 256MB minimum is best IMO.

The one good thing though is that at least you are trying to use dmrecord. Very wise, as it's more
reliable than MediaRecorder; just a somewhat steeper learning curve. Worth the effort though. And
assuming you have a recent enough OS version, O2 can capture as AVI aswell, which makes it
easier to port files to a PC (convert to other formats for free with the MidVid JPEG codec, or
use the PIC codec which costs $99 but is 20% faster than MidVid; use VirtualDUB, AVIdemux or
other application to convert to DivX).

Cheers!

Ian.

_________________
SGI Systems/Parts/Spares/Upgrades For Sale: http://www.sgidepot.co.uk/sgidepot/
mapesdhs@yahoo.com, ian@sgidepot.co.uk, +44 (0)131 476 0796, check my auctions on eBid!

for O2's is corrcet this command:


only difference is that the device is not ice but mvp. Maybe for older Irixes is ice.

_________________
R7000/600 576MB Ram CDRW 18+9Gb HDD
http://www.tomosgi.co.cc

Ah yes, mvp. Sorry, I was trying to recall from memory. Been a while since I've done any
capture with O2.

Ian.

Thanks guys!

I tried it again with the command you posted but I can't get it to work.

It gives me: It works for around 8 seconds usually and then stops capturing. Without an audio track I was able to capture for minutes without a problem...

Is this related to the limited RAM (128MB) I have?

I also tried capturing using media tools -> movie recorder but after capturing it has to process the movie for ages... I mean, if the O2 does the jpeg compression in hardware it shouldn't have to do that right?!

And even using movie recorder it gave me buffer errors once or twice...

jmc

jmc wrotes:
> I tried it again with the command you posted but I can't get it to work.

What exactly did you enter?


> It gives me: It works for around 8 seconds usually
> and then stops capturing. Without an audio track I was able to capture for minutes without a problem...

Odd... perhaps the audio is not being dealt with properly.


> Is this related to the limited RAM (128MB) I have?

Hard to say, I've never done video stuff on an O2 with that little RAM.


> I also tried capturing using media tools -> movie recorder but after capturing it has to process the movie for ages...
> I mean, if the O2 does the jpeg compression in hardware it shouldn't have to do that right?!

That will happen if you select single-frame instead of 2-field for the compression format.

Ian.

Hi, I have this command(found similiar version on Ian's pages) modified in aliases:
dmrecord -a -v -p audio -p video,comp=jpeg,quality=98 output.mv

Only limitation on my system is disk speed so I cant write fast enough video with quality=100. My disks are old SGI/IBM 9gb 7200rpm and capabe of ~7-9mb/s writes in classic use (big files copying). But this is done with 100% system load (checked trough top, copying done with neko_mc). It is normal?

Also you must have on mind that as disk becomes more filled, it SLOWS down writes. Not even talking about this alert window:

1-2 seconds before this happends O2 becomes like kicked to the head. After displaying alert window everything becomes normal again.

My sugestion is start with low quality parameters eg. 75 and then go higher.
Also don't run anything system demanding on background. Check it trough top maybe you will be surprised how many cpu power is wasted on something that do nothing - like neko_xmms on my system it draws 3% of cpu - when idling (not playing anything and is displayed on other desktop) Seamonkey & etc are mutch worst on this.

If you don't solve this problem I can strip my sytem to minimal ram config (64) and try to record some video we will see...

_________________
R7000/600 576MB Ram CDRW 18+9Gb HDD
http://www.tomosgi.co.cc

tomo writes:
> dmrecord -a -v -p audio -p video,comp=jpeg,quality=98 output.mv

That command is specifying constant quality. O2's ICE system works better with a constant bitrate.

Constant quality means the size of each compressed frame can vary enormously, giving an uneven flow into
the compression engine. The microcode was optimised for constant bitrate, ie. a more even flow. Thus, instead
of quality=98, try brate=25000000. That should work better.


> Only limitation on my system is disk speed so I cant write fast enough video with quality=100. My disks are old SGI/IBM
> 9gb 7200rpm and capabe of ~7-9mb/s writes in classic use (big files copying). But this is done with 100% system load
> (checked trough top, copying done with neko_mc). It is normal?

For reference, if it's of any help, I have 73GB 1.6" SCA 10K disks normally for 35 UKP each, but make it 30 for any Neko
member (lots available, suitable as external drives, 60 day warranty). I also have R7K/600 CPU modules available, ready to use.


> My sugestion is start with low quality parameters eg. 75 and then go higher.

No, use lower bitrates, like 20M, and go higher. Assuming the disk can take it, 30Mbit gives good quality, no need to go
any higher than that.


> Also don't run anything system demanding on background. Check it trough top maybe you will be surprised how many
> cpu power is wasted on something that do nothing - like neko_xmms on my system it draws 3% of cpu - when idling
> (not playing anything and is displayed on other desktop) Seamonkey & etc are mutch worst on this.

My IMPCOM advice page has some suggestions on this. Turn off all unnecessary background daemons (except XLV
if you need it) and shut down mediad/httpd, and anything else not needed:



Naturally, make sure videod and verbose are on. Wise to see what's going on during bootup:



After the above is done, reboot, login as root, enter:



Use 'ps -ef' to see what's running. It should be pretty minimal. It goes without saying, don't have anything running
like Firefox or other apps.


I'll be writing a large article later this year on video capture with O2. Been meaning to for ages...

Ian.

So after leaving the O2 in the corner of the room for a few days I did another capturing session today.

I changed the mediarecord setting to 2-fields which reduced the processing time. Still slow on a R5000 ..ZZZZZzzzzzz

I then did another session with dmrecord with following command:



And: It worked I tried capturing sevaral movie files ranging from a few seconds to a few minutes and had no problem (yet)

I was wondering what the difference was to last time and the only thing I can think of is that I changed from NTSC to PAL in the mediarecord settings. Something I did not do when capturing with dmrecord the first time because the videoin signal was ok... at least on screen. Was this really it?! I will do another session and see if I get any errors... "touch wood"

jmc

Try using dminfo on the recorded movie, see what it says with respect to its stats.

Normally, if one records using 2-fields and constant bitrate, the post-processing time is barely a few seconds.

Oh yes, when I've been recording from VHS, the material is of course interlaced. The interlacing can be
removed later using a PC, etc.

Here's the dminfo for a typical 5 minute MJPEG I have stored away, file size 480MB:




Converted to DivX (720x544, 1500Kbits/sec bitrate), the movie is 57MB.

Ian.

Hi!

I haven't used my O2 to capture for a while now. Today I wanted to capture some new material from my Digital8... Yes, you're right it did not work the way I would like it to.

Here is some of the errors I am getting:

When trying to play one of the recorded movie files:


When using dmrecord (dmrecord -p audio test.mv)

This line keeps repeating with different buffer values and the recording is stopped.

When using mediarecorder sometimes it workes to capture as two-field full res Pal using JPEG compression... and the next time it won't work. Then the video input freezes every few seconds when capturing. When I stopped the recording I even got a completely frozen system and had to pull the plug...

Another mediaplayer error I got is this:


Why won't this damn thing work?! This O2 seems to be very moody...

I am starting to think that this is a hardware error in the video module or maybe faulty RAM? I still have to get a RAM upgrade so I can swap the DIMMs and see if this still happens...

Try running the IDE tests. The 1st error looks like the system disk is full. Anything in the SYSLOG?

More info please!

Ian.

Or maybe just df -k first ...

Or just do things from my sentence in a logical order.

-k is for wimps. I have it aliased...

Ian.