[libdv-dev] RE: Streaming DV

[Arne S. <ar...@sc...>]

Best of breed in the Windows world: The Microsoft DV codec does easily 30 fps 
fullscreen on my AMD 333 MHz with a Matrox Millenium card.

The trick with most Windows graphics software is that they use the hardware 
features of the graphics card, whereas on Linux it is all done in software. A 
very expensive operation is the YUV to RGB conversion and scaling. Many cards 
can do this in hardware -- write the YUV (or whatever other format) to the 
card's memory, setup source and destination rects in some registers and zap! 
RGB data is just there. I wrote a Quicktime codec for an obscure Macintosh PCI 
graphics card five years ago and using the hardware features I could do 25 fps 
fullscreen PAL videos on a PowerMac 100 MHz (compareable to a 100-150 MHz 
Pentium).

So to get decent codec performance somebody needs to look into how hardware 
acceleration is done under Linux / XFree86.


Another dvgrab user recommended this to improve harddisk performance:

>> Setting      hdparm -d1   on my drive helped a lot...  I assumed it was set
>> because I configured DMA as default when I built my kernel....
>>
>> Kirk

Arne

-----Original Message-----
From:	Mark W. Knecht [SMTP:mar...@ho...]
Sent:	Sunday, June 04, 2000 5:20 AM
To:	Linux1394-Developers List
Subject:	Streaming DV

I tried Daniel's live video program today and it seemed to work fine. I am
getting about 4.5 to 5 FPS on a 750 Athlon with a GeForce DDR card. I have
no idea how this compares to best of breed in the Windows world. Does anyone
else?

The program seemed quite friendly, which I also attribute to good underlying
driver code. I was able to leave the program running, but pull the camera
plug, or stop and restart the camera, and the video picked up again and
started playing just fine. No core dumps or other problems I could see.

I also recorded some longer clips using dvgrab-0.82 - like 5 minutes - just
to see what happens, and they basically worked fine. DV2 format plays back
at the right speed under NT using QuickTime and under Win98SE using WMP.
Audio was working under 98SE. I didn't have the speakers plugged in at the
time under NT. (Listening to Sting on my Linux box)

The one 'problem' I am dealing with on this system Athlon is that it seems
to drop a huge number of frames in dvgrab. I am quite surprised, as this
machine is far and away the fastest of the 5 machines I'm playing around
with, and it has the fastest hard disk, at least as far as specs go. It is
new though, so I need to figure out if it's really configured correctly.

My 433 Celeron has never dropped a frame, to the best of my knowledge. I
read Arne's README that talked about disk speed, which makes sense, but this
machine is supposed to be a great new chipset and certainly a fast
processor.

What benchmarks can I run to determine whether there is some problem with
the way I've built the kernel or the system itself? Any configuration files
to check?

Anyway, Daniel, cool job. I need to study the code a bit now.

Thanks!

Mark



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