HDTV capture driver for cx2388x
jason.harmening at gmail.com
Sun Sep 30 13:17:06 PDT 2007
I've been working on a FreeBSD driver for cx2388x-based TV cards on and off
for several months since I came
into possession of an old pcHDTV HD-3000 in late 2006. I only recently
learned about jmg's work with cxd, but I'm making my driver available in case
anyone is interested. It works reliably with my HD-3000; I've managed to
capture several hours of live TV. I've only been able to test it on my own
machine, which is 6-STABLE/amd64/SMP. It'll need a little work (interrupt
filters, at least) to be usable with 7-CURRENT.
I've attached a tarball with full sources--I hope the mail server doesn't
remove the attachments, but if it does and you're interested, let me know and
I'll send you a copy.
The driver is called "cx88"--one of the few
things it has in common with the Linux driver. Here's a not-so-brief
overview of the contents in case you're interested:
Sources for cx88.ko, wich implements channel configuration, buffer
configuration, and RISC program routines common to all functions. Provides
a "board data" facility to allow drivers for different functions on the same
physical board to coordinate usage of shared resources (e.g. the SRAM).
Dynamically sizes the SRAM allocation for each DMA channel based on the total
number of DMA channels claimed by attached drivers (MPEG, analog video,
audio, etc.). Allows RISC programs to be placed in SRAM if there's enough
space. Allows for data buffers to either be allocated in the kernel and
mmap'ed or allocated in user mode and vslock'ed.
Sources for cx88i2c.ko, which controls the onboard i2c bus. Uses
interrupt-driven, hardware I2C. Directly implements the iicbus interface
instead of going through iicbb, so on 6.x it requires the attached patch to
get iicbus.ko to export its driver_t. I don't think this is necessary on
Driver for mpeg transport stream (cx88mpeg.ko). Depends on both
cx88.ko and cx88i2c.ko.
Skeleton analog video driver. Doesn't really do anything right now.
Sources for iicdev.ko--generic kernel mode driver for i2c device
control from user mode. Mostly I implemented this because I don't really
care for iic's use of Giant or its ioctl interface. iicdev isdevice-centric,
so an iicdev character device is created for each i2c device.
(libtuner.so) User-mode drivers for tuners, demodulators, and anything
that constitutes the "frontend". This idea, along with support for user-mode
buffers, I got from jmg's bktrau driver. Implemented in C++.
Currently only contains drivers for the Thomson DTT7612 tuner and Oren 51132
demod on the HD-3000. Configurable via text file. This is library is
designed to be easily extensible to support additional tuners/demods and to
possibly work with other drivers besides cx88.
Really lame capture apps I kludged up to test cx88mpeg.
cx88_client.cpp uses conventional (kernel-allocated) buffers, while
cx88_user_client.cpp uses user-allocated buffers. Mostly I included these
just to demonstrate how to use the cx88mpeg ioctl() interface.
Not-so-lame multi-threaded capture app. Allows simultaneous streaming over
UDP and capture to file. Also allows for channel to be changed and signal
status to be queried on-the-fly. Uses XML configuration file for channel
8VSB and QAM firmware files for the OR51132 demodulator.
Automatically loaded as necessary by the libtuner or51132 driver.
Whew! Anyway, here are my short-term goals for the driver:
0) Keep testing and fix any bugs I find.
1) Add decent comments and documentation--this is mostly done for the
kernel-mode pieces, but libtuner and the client application need
3) Get my hands on a pcHDTV HD-5500. If I've done things right, I'll only
need to add drivers for the LG tuner and demod to libtuner, and add a
pchdtv_hd5500 class to the capture application.
4) Work on analog video driver and maybe, once I get the 5500, audio as well.
5) When I'm ready to upgrade to FreeBSD 7.0 (probably during the beta phase),
add interrupt filters, ditch the iicbus patch, and do whatever else is
necessary to get this puppy working under 7.0.
Here are some quick instructions on how to use the driver:
1. Extract the source tarball.
2. To patch the iicbus driver:
patch < patch_iicbus
Reload iicbus.ko or recompile kernel
3. Install textproc/ezxml. The capture app uses this to parse its XML
channel map configuration file.
4. From cx88_20070930 directory extracted from source tarball, type 'make',
or, if you want your system log full of status messages from the driver,
type 'make -D DIAGNOSTIC'. This will compile all kernel-mode drivers,
libtuner.so, and the capture app (called 'cx88'--creative, I know).
5. From the same directory,
To use the client application:
The capture app (cx88) depends on libtuner, so make sure the libtuner/
directory (or wherever you're keeping libtuner.so) is in your library path.
Libtuner uses a simple text-based configuration file to allow for flexible
configuration of tuner drivers that may need it--an example can be found in
client/.tuner_config, which specifies the paths to the OR51132 firmware
files. The cx88 executable uses an XML configuration file to load its
channel maps--an example can be found in client/cx88.xml. At some point I'll
document the syntax for this file, but cx88.xml should be adequate for
receiving OTA HDTV broadcasts.
Here's a list of the command-line options for the cx88 executable:
-d <path>: [Required] Specify device from which to capture
-c <channel | profile:channel>: [Required] Specify initial channel, e.g. '7'
-u <host-ip | host-ip:port>: [Optional] Send capture over UDP to provided host
-f <filename>: [Optional] Send capture to specified file
-x <filename>: [Optional] Specify XML configuration file; default is
-t <filename>: [Optional] Specify libtuner configuration file; default is
-n <value>: [Optional] Specify non-interactive capture for provided number of
-? : Display this list of options.
If you omit the -n option, cx88 will run in interactive mode, in which case
you can enter the following commands to control the application on-the-fly:
Changes channel on-the-fly.
After entering the 'c' character, you'll be prompted to enter a channel
number, optionally prefixed with a channel profile name from the XML
configuration file. For example:
Display channel/signal stats:
Tuned to 725000000HZ
Signal strength: 80.8992%
Signal-to-noise ratio: 28.3147
Bit-error rate: 0
Uncorrected blocks: 0
'q': Quit the application.
To launch cx88 in interactive mode, using device /dev/cx88mpeg0 for capture,
initially tuned to channel 33 in the 'ATSC' profile, streaming data over UDP
to host 127.0.0.1, port 8802, and also storing the same data to a file
./cx88 -t ./.tuner_config -x ./cx88.xml -u 127.0.0.1:8802 -f abc.ts -c
ATSC:33 -d /dev/cx88mpeg0
To launch cx88 in non-interactive mode, capturing channel 33 in the 'ATSC'
profile to a file named abc.ts for 7.5 minutes:
./cx88 -t ./.tuner_config -x ./cx88.xml -f abc.ts -c
ATSC:33 -d /dev/cx88mpeg0 -n 7.5
For playing the transport stream, either from a file or live via UDP, the best
player I've found so far is multimedia/vlc. However, I haven't yet found a
player that allows you to select from multiple program streams broadcast on
the same channel.
Anyway, I hope there are people out there interested enough to wade through
this long e-mail and maybe give the driver a try and let me know how it
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