[Home]Import Modules/Import Bktr

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The import_bktr module imports video frames into transcode from bktr(4) devices found on BSD systems. This module supports RGB, UYVY, and YV12 video formats.


   'format=<format>' Video norm, valid arguments:
       default: driver default

The video source format, or 'norm'. Shouldn't need much explanation.

   'vsource=<vsource>' Video source, valid arguments:
       default: driver default (usually 'composite')

The source of the video bktr(4) is to grab. 'composite' is the RCA jack, 'tuner' is for the internal tuner, 'svideo_comp' is for, according to the bktr sources, "S-VHS input, but with composite camera", 'svideo' is for S-Video, 'input3' is undocumented.

   'asource=<asource>' Audio source, valid arguments:
       default: driver default (usually 'tuner')

The card's audio source. 'tuner' is for the internal tuner, 'external' is for external audio jacks feeding the card, 'internal' is for FM radio (if it exists).

   'tunerdev=<tunerdev>' Tuner device, default: /dev/tuner0

Should be self explanatory.

   'mute' Mute the bktr device, off by default.

Use 'transcode -x bktr=mute,...' to get absolutely no audio from the bktr(4) card.

   'hwfps' Set frame rate in hardware, off by default.
      It's possible to get smoother captures by using
      -f to capture in the highest possible frame rate
      along with a frame rate filter to get a lower fps.

By default, import_bktr does not set the preferred frame rate in the bktr(4) device. What this means is that if the video source is NTSC and the particular invocation of transcode is able to run 'realtime', the the smoothest captures will be with 'transcode -f 29.97 -x bkrt,...'. For other frame rates, the hwfps option must be used, 'transcode -f 20 -x bktr=hwfps,...', or transcode will still grab frames as fast as they are available on the device. It's probably worth looking into the fps filters to get the smoothest possible reduced frame rate video.

   'help' show this help message

Use 'transcode -x bktr=help' to see get a help message.


Watch TV in USA ;)

  transcode -i /dev/bktr0 -x bktr=norm=ntsc:vsource=tuner:asource=tuner,null -g 640x480 -J pv

transcode can't probe bktr(4) devices, so it defaults to 720x576. The largest size NTSC frame bktr(4) can grab is 640x480, so the size must be given with -g. The bktr(4) driver defaults to using the composite video source, so the import_bktr option 'vsource' must be set to 'tuner'. Setting the import_bktr option 'norm' to 'ntsc' was not necessary, since that is what my version of bkrt(4) defaults to. Even though transcode defaults to 25 fps and USA TV is 29.97 fps, it is not necessary in this case to use the '-f' switch, because without using the import_bktr option 'hwfps', import_bktr still grabs frames as soon as bktr(4) has them ready. The '-J pv' option tells transcode to use filter_pv to display a 'preview' on the screen. filter_preview has a full screen option

Grab only video from camcorder through the composite video input for DVD

  transcode -i /dev/bktr0 -x bktr=mute,null -g 640x480 -y yuv4mpeg,null -k --export_prof dvd-ntsc -o movie.y4m

The '-f 29.97' option must be used

  mpeg2enc -f 8 -o movie.m2v < movie.y4m

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Last edited December 12, 2004 2:53 am by gateway (diff)