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Diffstat (limited to 'Documentation/video4linux/bttv/Sound-FAQ')
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diff --git a/Documentation/video4linux/bttv/Sound-FAQ b/Documentation/video4linux/bttv/Sound-FAQ deleted file mode 100644 index 646a47de0..000000000 --- a/Documentation/video4linux/bttv/Sound-FAQ +++ /dev/null @@ -1,148 +0,0 @@ - -bttv and sound mini howto -========================= - -There are a lot of different bt848/849/878/879 based boards available. -Making video work often is not a big deal, because this is handled -completely by the bt8xx chip, which is common on all boards. But -sound is handled in slightly different ways on each board. - -To handle the grabber boards correctly, there is a array tvcards[] in -bttv-cards.c, which holds the information required for each board. -Sound will work only, if the correct entry is used (for video it often -makes no difference). The bttv driver prints a line to the kernel -log, telling which card type is used. Like this one: - - bttv0: model: BT848(Hauppauge old) [autodetected] - -You should verify this is correct. If it isn't, you have to pass the -correct board type as insmod argument, "insmod bttv card=2" for -example. The file CARDLIST has a list of valid arguments for card. -If your card isn't listed there, you might check the source code for -new entries which are not listed yet. If there isn't one for your -card, you can check if one of the existing entries does work for you -(just trial and error...). - -Some boards have an extra processor for sound to do stereo decoding -and other nice features. The msp34xx chips are used by Hauppauge for -example. If your board has one, you might have to load a helper -module like msp3400.o to make sound work. If there isn't one for the -chip used on your board: Bad luck. Start writing a new one. Well, -you might want to check the video4linux mailing list archive first... - -Of course you need a correctly installed soundcard unless you have the -speakers connected directly to the grabber board. Hint: check the -mixer settings too. ALSA for example has everything muted by default. - - -How sound works in detail -========================= - -Still doesn't work? Looks like some driver hacking is required. -Below is a do-it-yourself description for you. - -The bt8xx chips have 32 general purpose pins, and registers to control -these pins. One register is the output enable register -(BT848_GPIO_OUT_EN), it says which pins are actively driven by the -bt848 chip. Another one is the data register (BT848_GPIO_DATA), where -you can get/set the status if these pins. They can be used for input -and output. - -Most grabber board vendors use these pins to control an external chip -which does the sound routing. But every board is a little different. -These pins are also used by some companies to drive remote control -receiver chips. Some boards use the i2c bus instead of the gpio pins -to connect the mux chip. - -As mentioned above, there is a array which holds the required -information for each known board. You basically have to create a new -line for your board. The important fields are these two: - -struct tvcard -{ - [ ... ] - u32 gpiomask; - u32 audiomux[6]; /* Tuner, Radio, external, internal, mute, stereo */ -}; - -gpiomask specifies which pins are used to control the audio mux chip. -The corresponding bits in the output enable register -(BT848_GPIO_OUT_EN) will be set as these pins must be driven by the -bt848 chip. - -The audiomux[] array holds the data values for the different inputs -(i.e. which pins must be high/low for tuner/mute/...). This will be -written to the data register (BT848_GPIO_DATA) to switch the audio -mux. - - -What you have to do is figure out the correct values for gpiomask and -the audiomux array. If you have Windows and the drivers four your -card installed, you might to check out if you can read these registers -values used by the windows driver. A tool to do this is available -from ftp://telepresence.dmem.strath.ac.uk/pub/bt848/winutil, but it -does'nt work with bt878 boards according to some reports I received. -Another one with bt878 support is available from -http://btwincap.sourceforge.net/Files/btspy2.00.zip - -You might also dig around in the *.ini files of the Windows applications. -You can have a look at the board to see which of the gpio pins are -connected at all and then start trial-and-error ... - - -Starting with release 0.7.41 bttv has a number of insmod options to -make the gpio debugging easier: - -bttv_gpio=0/1 enable/disable gpio debug messages -gpiomask=n set the gpiomask value -audiomux=i,j,... set the values of the audiomux array -audioall=a set the values of the audiomux array (one - value for all array elements, useful to check - out which effect the particular value has). - -The messages printed with bttv_gpio=1 look like this: - - bttv0: gpio: en=00000027, out=00000024 in=00ffffd8 [audio: off] - -en = output _en_able register (BT848_GPIO_OUT_EN) -out = _out_put bits of the data register (BT848_GPIO_DATA), - i.e. BT848_GPIO_DATA & BT848_GPIO_OUT_EN -in = _in_put bits of the data register, - i.e. BT848_GPIO_DATA & ~BT848_GPIO_OUT_EN - - - -Other elements of the tvcards array -=================================== - -If you are trying to make a new card work you might find it useful to -know what the other elements in the tvcards array are good for: - -video_inputs - # of video inputs the card has -audio_inputs - historical cruft, not used any more. -tuner - which input is the tuner -svhs - which input is svhs (all others are labeled composite) -muxsel - video mux, input->registervalue mapping -pll - same as pll= insmod option -tuner_type - same as tuner= insmod option -*_modulename - hint whenever some card needs this or that audio - module loaded to work properly. -has_radio - whenever this TV card has a radio tuner. -no_msp34xx - "1" disables loading of msp3400.o module -no_tda9875 - "1" disables loading of tda9875.o module -needs_tvaudio - set to "1" to load tvaudio.o module - -If some config item is specified both from the tvcards array and as -insmod option, the insmod option takes precedence. - - - -Good luck, - - Gerd - - -PS: If you have a new working entry, mail it to me. - --- -Gerd Knorr <kraxel@bytesex.org> |