From 413a60419542895a13fa54640b44e074df8de162 Mon Sep 17 00:00:00 2001 From: nicolas Date: Sun, 23 Mar 2003 23:35:12 +0000 Subject: XML version of MPlayer's doc git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@9676 b3059339-0415-0410-9bf9-f77b7e298cf2 --- DOCS/xml/en/tvinput.xml | 203 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 203 insertions(+) create mode 100644 DOCS/xml/en/tvinput.xml (limited to 'DOCS/xml/en/tvinput.xml') diff --git a/DOCS/xml/en/tvinput.xml b/DOCS/xml/en/tvinput.xml new file mode 100644 index 0000000000..a0b7efd997 --- /dev/null +++ b/DOCS/xml/en/tvinput.xml @@ -0,0 +1,203 @@ + + +TV input + + +This section is about how to enable watching/grabbing +from V4L compatible TV tuner. + + + + +Compilation + + + + First, you have to recompile. ./configure will + autodetect kernel headers of v4l stuff and the existence of + /dev/video* entries. If they exist, TV support will + be built (see the output of ./configure). + + + Make sure your tuner works with another TV software in Linux, for + example xawtv. + + + + + +Usage tips + +The full listing of the options is available on the manual page. +Here are just a few tips: + + + + +Use the option. An example: +-tv on:channels=26-MTV1,23-TV2 +Explanation: using this option, only the 26 and 23 channels will be usable, +and there will be a nice OSD text upon channel switching, displaying the +channel's name. Spaces in the channel name must be replaced by the +"_" character. + + + + + +Choose some sane image dimensions. The dimensions of the resulting image should +be divisible by 16. + + + + + +If you capture the video with the vertical resolution higher than half of +the full resolution (i.e. 288 for PAL or 240 for NTSC), make sure you turned +deinterlacing on. Otherwise you'll get a movie which is distorted during +fast-motion scenes and the bitrate controller will be probably even unable +to retain the specified bitrate as the interlacing artifacts produce high +amount of detail and thus consume lot of bandwidth. You can enable +deinterlacing with . Usually + does a good job, but it can be matter of personal +preference. See other deinterlacing algorithms in the manual and give it a try. + + + + + +Crop out the dead space. When you capture the video, the areas at the edges +are usually black or contain some noise. These again consume lots of +unnecessary bandwidth. More precisely it's not the black areas themselves +but the sharp transitions between the black and the brighter video image +which do but that's not important for now. Before you start capturing, +adjust the arguments of the option so that all the +crap at the margins is cropped out. Again, don't forget to keep the resulting +dimensions sane. + + + + + +Watch out for CPU load. It shouldn't cross the 90% boundary for most of the +time. If you have a large capture buffer, MEncoder can survive an overload +for few seconds but nothing more. It's better to turn off the 3D OpenGL +screensavers and similar stuff. + + + + + +Don't mess with the system clock. MEncoder uses the +system clock for doing A/V sync. If you adjust the system clock (especially +backwards in time), MEncoder gets confused and you will lose frames. This is +an important issue if you are hooked to a network and run some time +synchronization software like NTP. You have to turn NTP off during the capture +process if you want to capture reliably. + + + + + +Don't change the unless you know what you are doing +or your card/driver really doesn't support the default (YV12 colorspace). +In the older versions of MPlayer/ +MEncoder it was necessary to specify the output +format. This issue should be fixed in the current releases and +isn't required anymore, and the default suits the most purposes. For example, +if you are capturing into DivX using libavcodec and specify + in order to increase the quality of the captured +images, the captured image will be actually later converted back into YV12 so +the only thing you achieve is a massive waste of CPU power. + + + + + +To specify the I420 colorspace (), you have to add an +option due to a fourcc conflict with an Intel Indeo +video codec. + + + + + +There are several ways of capturing audio. You can grab the sound either using +your soundcard via an external cable connection between video card and line-in, +or using the built-in ADC in the bt878 chip. In the latter case, you have to +load the btaudio driver. Read the +linux/Documentation/sound/btaudio file (in the kernel +tree, not MPlayer's) for some instructions on using this driver. + + + + + +If MEncoder cannot open the audio device, make +sure that it is really available. There can be some trouble with the sound +servers like arts (KDE) or esd (GNOME). If you have a full duplex soundcard +(almost any decent card supports it today), and you are using KDE, try to +check the "full duplex" option in the sound server preference menu. + + + + + + + +Examples + + + +Dummy output, to AAlib :) + +mplayer -tv on:driver=dummy:width=640:height=480 -vo aa + + + + + +Input from standard V4L: + +mplayer -tv on:driver=v4l:width=640:height=480:outfmt=i420 -vc rawi420 -vo xv + + + + + +A more sophisticated example. This makes MEncoder capture the full PAL +image, crop the margins, and deinterlace the picture using a linear blend +algorithm. Audio is compressed with a constant bitrate of 64kbps, using +LAME codec. This setup is suitable for capturing movies. + + mencoder -tv on:driver=v4l:width=768:height=576 \ + -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=900 \ + -oac mp3lame -lameopts cbr:br=64 \ + -vop pp=lb,crop=720:544:24:16 -o output.avi + + + + + + +This will additionally rescale the image to 384x288 and compresses the +video with the bitrate of 350kbps in high quality mode. The vqmax option +looses the quantizer and allows the video compressor to actualy reach so +low bitrate even at the expense of the quality. This can be used for +capturing long TV series, where the video quality isn't so important. + + mencoder -tv on:driver=v4l:width=768:height=576 \ + -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=350:vhq:vqmax=31:keyint=300 \ + -oac mp3lame -lameopts cbr:br=48 \ + -vop scale=384:288,pp=tn/lb,crop=720:540:24:18 -sws 1 -o output.avi + +It's also possible to specify smaller image dimensions in the +option and omit the software scaling but this approach uses the maximum available +information and is a little more resistant to noise. The bt8x8 chips can do the +pixel averaging only in the horizontal direction due to a hardware limitation. + + + + -- cgit v1.2.3