7.5. 設定電視卡(TV Cards)

7.5.1. 介紹

電視卡(TV card)可以讓您用電腦來看無線、有線電視節目。許多卡都是透過 RCA 或 S-video 輸入端子來接收視訊，而且有些卡還可接收 FM 廣播的功能。

FreeBSD 可透過 bktr(4) 驅動程式，來支援 PCI 介面的電視卡，只要這些卡使用的是 Brooktree Bt848/849/878/879 或 Conexant CN-878/Fusion 878a 視訊擷取晶片。此外，要再確認哪些卡上所附的選台功能是否有支援，可以參考 bktr(4) 說明，以查看所支援的硬體清單。

7.5.2. 設定相關驅動程式

要用電視卡的話，就要載入 bktr(4) 驅動程式，這個可以透過在 /boot/loader.conf 檔加上下面這一行就可以了：

bktr_load="YES"

此外，也可以把該 kernel module 直接與 kernel 編譯在一起，作法就是在你的 kernel 設定檔內，加上下面這幾行：

device	 bktr
device	iicbus
device	iicbb
device	smbus

之所以要加上這些額外的驅動程式，是因為卡的各組成部分都是透過 I2C 匯流排而相互連接的。接下來，請重新編譯、安裝新的 kernel 。

安裝好新的 kernel 之後，要重開機才會生效。開機時，應該會看到類似下面的正確偵測到 TV card 訊息：

bktr0: <BrookTree 848A> mem 0xd7000000-0xd7000fff irq 10 at device 10.0 on pci0
iicbb0: <I2C bit-banging driver> on bti2c0
iicbus0: <Philips I2C bus> on iicbb0 master-only
iicbus1: <Philips I2C bus> on iicbb0 master-only
smbus0: <System Management Bus> on bti2c0
bktr0: Pinnacle/Miro TV, Philips SECAM tuner.

當然，這些訊息可能因您的硬體不同而有所不同。However you should check if the tuner is correctly detected; it is still possible to override some of the detected parameters with sysctl(8) MIBs and kernel configuration file options. For example, if you want to force the tuner to a Philips SECAM tuner, you should add the following line to your kernel configuration file:

options OVERRIDE_TUNER=6

or you can directly use sysctl(8):

# sysctl hw.bt848.tuner=6

See the bktr(4) manual page and the /usr/src/sys/conf/NOTES file for more details on the available options. (If you are under FreeBSD 4.X, /usr/src/sys/conf/NOTES is replaced with /usr/src/sys/i386/conf/LINT.)

7.5.3. 好用的程式

要用電視卡，可以視需要安裝下列應用程式之一︰

• multimedia/fxtv provides TV-in-a-window and image/audio/video capture capabilities.

• multimedia/xawtv is also a TV application, with the same features as fxtv.

• misc/alevt decodes and displays Videotext/Teletext.

• audio/xmradio, an application to use the FM radio tuner coming with some TV cards.

• audio/wmtune, a handy desktop application for radio tuners.

More applications are available in the FreeBSD Ports Collection.

7.5.4. Troubleshooting

If you encounter any problem with your TV card, you should check at first if the video capture chip and the tuner are really supported by the bktr(4) driver and if you used the right configuration options. For more support and various questions about your TV card you may want to contact and use the archives of the freebsd-multimedia mailing list.