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<div><span class="gmail_quote">On 4/16/07, <b class="gmail_sendername">Bruce Markey</b> <<a href="mailto:bjm@lvcm.com">bjm@lvcm.com</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Yan Seiner wrote:<br>> I've yanked the PVR150 from my system and plugged in a BT878 card I've<br>
> had laying around. I have to loop the sound from the BT878 card to my<br>> sound card.<br><br>Good move. I've had a PVR-250 for years that I've yanked in<br>the past but currently is installed and configured as my
<br>last choice with lower input priority.<br><br>> The problem is that the sound comes in way, way too loud - about 4x<br>> louder than the digital feeds. I have not found any way to get myth to<br>> control the sound from /dev/dsp...
<br><br>$ alsamixer -V capture<br><br>Move the slider sub-captioned "Capture" (you must have been here<br>before if you got capture working in the first place). I've found<br>in the past that 100% can be raspy so I set mine at 90%. You can
<br>have this open in a shell window and adjust while you use "Y"<br>to switch between cards until you match your digital feeds.<br><br>> I would welcome any suggestions....<br><br>"Any"? I'm much happier with my software encoded MPEG-4 files
<br>than the MPEG-2 files from a hardware encoder. However, the<br>bttv defaults aren't good so most people assume that ivtv is<br>better when they compare the picture 'out-of-the-box'. Here are<br>some settings that I use:
<br><br>In my /etc/modprobe.d/misc (or wherever you set modprobe options)<br><br>options bttv chroma_agc=1 combfilter=2 full_luma_range=1 coring=1 video_nr=0 vbi_nr=0<br><br>AGC is automatic gain control which normalizes the chroma level
<br>so you get more consistent color saturation.<br><br>The combfilter fixes the multi-color flickering you may see on<br>small white lettering or striped shirts.<br><br>The full_luma_range expands the values to 0-255 rather than 16-253
<br>(no equivalent for ivtv). This can improve contrast and overall<br>detail.<br><br>The coring makes a hard cut off for the black level and can remove<br>low level noise and artifacts in dark areas.<br><br>"video_nr=0 vbi_nr=0" force the driver to take /dev/video0 and
<br>/dev/vbi0 to defeat the evil known as udev.<br><br><br>Xawtv (from the bttv dev) includes some other useful utilities.<br>I use "v4lctl list" to see driver attributes. This can also be<br>used to set attributes and I do so in a wrapper script to start
<br>mythbackend:<br><br>...<br>v4lctl -c /dev/video0 setattr 'mute' off > /dev/null 2>&1<br>v4lctl -c /dev/video0 setattr 'uv ratio' 52 > /dev/null 2>&1<br>v4lctl -c /dev/video0 setattr 'whitecrush upper' 253 > /dev/null 2>&1
<br>v4lctl -c /dev/video0 setattr 'luma decimation filter' on > /dev/null 2>&1<br>...<br><br>The "'mute' off" is because of an issue that came up it the<br>kernel a few revs back and I want to be sure that the driver
<br>is unmuted.<br><br>The "uv ratio" is like tint from purple to yellow rather than<br>red to green. I find that 52 makes yellow, gold and flesh tones<br>look more natural.<br><br>The color and hue are good at 50% (32768) but contrast and
<br>brightness are way off. I find that I need to set the contrast<br>to mid to low 20,000s (around 40%) and the brightness around<br>40,000 (like 60%). YMMV but for analog my cable today I am<br>using 26000, 40200 and for s-video from a digital cable box,
<br>26350, 43150 with the attributes listed above (coring and full<br>luma range will have a big impact on the best contrast and<br>brightness settings).<br><br>I also use the "quickdnr" filter for a handful of channels that
<br>have noticeable interference or noise. This cleans up the image<br>before ffmpeg MPEG-4 compression and not only makes the picture<br>cleaner but makes the compression more efficient.<br><br>-- bjm</blockquote>
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<div>I don't know about the original poster, but I just wanted to give you a quick thanks for the bttv tweaks. I'm currently using an old Athlon 1400 Backend system with a 80GB storage drive to simply record our favorite shows each week. When we miss an episode we just hookup the S-Video output of an old Windows laptop to the TV and use MythTV Player to watch it.
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<div>The image quality, skin tones and general color dullness, was the biggest hurdle for the WAF. Hopefully that will no longer be an issue!</div>
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<div>Thank you to the Mythtv developers and the wonderful community around them. You've given me a way to utilize old hardware destined for the scrap heap and a project/hobby to help me learn Linux.</div>
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<div>-Mark</div><br> </div>