160 lines
6.9 KiB
Plaintext
160 lines
6.9 KiB
Plaintext
Driver for Trust Computer Products Framegrabber, version 0.6.1
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------ --- ----- -------- -------- ------------ ------- - - -
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- ZORAN ------------------------------------------------------
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Author: Pauline Middelink <middelin@polyware.nl>
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Date: 18 September 1999
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Version: 0.6.1
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- Description ------------------------------------------------
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Video4Linux compatible driver for an unknown brand framegrabber
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(Sold in the Netherlands by TRUST Computer Products) and various
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other zoran zr36120 based framegrabbers.
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The card contains a ZR36120 Multimedia PCI Interface and a Philips
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SAA7110 Onechip Frontend videodecoder. There is also an DSP of
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which I have forgotten the number, since i will never get that thing
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to work without specs from the vendor itself.
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The SAA711x are capable of processing 6 different video inputs,
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CVBS1..6 and Y1+C1, Y2+C2, Y3+C3. All in 50/60Hz, NTSC, PAL or
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SECAM and delivering a YUV datastream. On my card the input
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'CVBS-0' corresponds to channel CVBS2 and 'S-Video' to Y2+C2.
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I have some reports of other cards working with the mentioned
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chip sets. For a list of other working cards please have a look
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at the cards named in the tvcards struct in the beginning of
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zr36120.c
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After some testing, I discovered that the carddesigner messed up
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on the I2C interface. The Zoran chip includes 2 lines SDA and SCL
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which (s)he connected reversely. So we have to clock on the SDA
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and r/w data on the SCL pin. Life is fun... Each cardtype now has
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a bit which signifies if you have a card with the same deficiency.
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Oh, for the completeness of this story I must mention that my
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card delivers the VSYNC pulse of the SAA chip to GIRQ1, not
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GIRQ0 as some other cards have. This is also incorporated in
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the driver be clearing/setting the 'useirq1' bit in the tvcard
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description.
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Another problems of continuous capturing data with a Zoran chip
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is something nasty inside the chip. It effectively halves the
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fps we ought to get... Here is the scenario: capturing frames
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to memory is done in the so-called snapshot mode. In this mode
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the Zoran stops after capturing a frame worth of data and wait
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till the application set GRAB bit to indicate readiness for the
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next frame. After detecting a set bit, the chip neatly waits
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till the start of a frame, captures it and it goes back to off.
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Smart ppl will notice the problem here. Its the waiting on the
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_next_ frame each time we set the GRAB bit... Oh well, 12,5 fps
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is still plenty fast for me.
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-- update 28/7/1999 --
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Don't believe a word I just said... Proof is the output
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of `streamer -t 300 -r 25 -f avi15 -o /dev/null`
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++--+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+- 25/25
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+-s+-+-+-+-+-+-+-+-+-+-+-+-+-s+-+-+-+-+-+-+-+-+-+-+-
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syncer: done
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writer: done
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(note the /dev/null is prudent here, my system is not able to
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grab /and/ write 25 fps to a file... gifts welcome :) )
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The technical reasoning follows: The zoran completed the last
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frame, the VSYNC goes low, and GRAB is cleared. The interrupt
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routine starts to work since its VSYNC driven, and again
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activates the GRAB bit. A few ms later the VSYNC (re-)rises and
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the zoran starts to work on a new and freshly broadcasted frame....
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For pointers I used the specs of both chips. Below are the URLs:
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http://www.zoran.com/ftp/download/devices/pci/ZR36120/36120data.pdf
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http://www-us.semiconductor.philips.com/acrobat/datasheets/SAA_7110_A_1.pdf
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The documentation has very little on absolute numbers or timings
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needed for the various modes/resolutions, but there are other
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programs you can borrow those from.
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------ Install --------------------------------------------
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Read the file called TODO. Note its long list of limitations.
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Build a kernel with VIDEO4LINUX enabled. Activate the
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BT848 driver; we need this because we have need for the
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other modules (i2c and videodev) it enables.
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To install this software, extract it into a suitable directory.
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Examine the makefile and change anything you don't like. Type "make".
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After making the modules check if you have the much needed
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/dev/video devices. If not, execute the following 4 lines:
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mknod /dev/video c 81 0
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mknod /dev/video1 c 81 1
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mknod /dev/video2 c 81 2
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mknod /dev/video3 c 81 3
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mknod /dev/video4 c 81 4
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After making/checking the devices do:
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modprobe i2c
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modprobe videodev
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modprobe saa7110 (optional)
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modprobe saa7111 (optional)
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modprobe tuner (optional)
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insmod zoran cardtype=<n>
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<n> is the cardtype of the card you have. The cardnumber can
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be found in the source of zr36120. Look for tvcards. If your
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card is not there, please try if any other card gives some
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response, and mail me if you got a working tvcard addition.
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PS. <TVCard editors behold!)
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Dont forget to set video_input to the number of inputs
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you defined in the video_mux part of the tvcard definition.
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Its a common error to add a channel but not incrementing
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video_input and getting angry with me/v4l/linux/linus :(
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You are now ready to test the framegrabber with your favorite
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video4linux compatible tool
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------ Application ----------------------------------------
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This device works with all Video4Linux compatible applications,
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given the limitations in the TODO file.
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------ API ------------------------------------------------
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This uses the V4L interface as of kernel release 2.1.116, and in
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fact has not been tested on any lower version. There are a couple
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of minor differences due to the fact that the amount of data returned
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with each frame varies, and no doubt there are discrepancies due to my
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misunderstanding of the API. I intend to convert this driver to the
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new V4L2 API when it has stabilized more.
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------ Current state --------------------------------------
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The driver is capable of overlaying a video image in screen, and
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even capable of grabbing frames. It uses the BIGPHYSAREA patch
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to allocate lots of large memory blocks when tis patch is
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found in the kernel, but it doesn't need it.
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The consequence is that, when loading the driver as a module,
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the module may tell you it's out of memory, but 'free' says
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otherwise. The reason is simple; the modules wants its memory
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contiguous, not fragmented, and after a long uptime there
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probably isn't a fragment of memory large enough...
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The driver uses a double buffering scheme, which should really
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be an n-way buffer, depending on the size of allocated framebuffer
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and the requested grab-size/format.
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This current version also fixes a dead-lock situation during irq
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time, which really, really froze my system... :)
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Good luck.
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Pauline
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