// apply some filters to thumbnail extracted below (below) crop any black lines that we made and get the correct ar.
// This filter chain may have adverse effects on recorded tv thumbnails if ar changes during presentation ex. commercials @ diff ar
varvf=string.Empty;
if(threedFormat.HasValue)
varvf=threedFormatswitch
{
switch(threedFormat.Value)
{
caseVideo3DFormat.HalfSideBySide:
vf="-vf crop=iw/2:ih:0:0,scale=(iw*2):ih,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1";
// hsbs crop width in half,scale to correct size, set the display aspect,crop out any black bars we may have made. Work out the correct height based on the display aspect it will maintain the aspect where -1 in this case (3d) may not.
break;
caseVideo3DFormat.FullSideBySide:
vf="-vf crop=iw/2:ih:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1";
// fsbs crop width in half,set the display aspect,crop out any black bars we may have made
break;
caseVideo3DFormat.HalfTopAndBottom:
vf="-vf crop=iw:ih/2:0:0,scale=(iw*2):ih),setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1";
// htab crop heigh in half,scale to correct size, set the display aspect,crop out any black bars we may have made
break;
caseVideo3DFormat.FullTopAndBottom:
vf="-vf crop=iw:ih/2:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1";
// ftab crop heigt in half, set the display aspect,crop out any black bars we may have made
break;
default:
break;
}
}
// hsbs crop width in half,scale to correct size, set the display aspect,crop out any black bars we may have made. Work out the correct height based on the display aspect it will maintain the aspect where -1 in this case (3d) may not.
Video3DFormat.HalfSideBySide=>"-vf crop=iw/2:ih:0:0,scale=(iw*2):ih,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1",
// fsbs crop width in half,set the display aspect,crop out any black bars we may have made
Video3DFormat.FullSideBySide=>"-vf crop=iw/2:ih:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1",
// htab crop heigh in half,scale to correct size, set the display aspect,crop out any black bars we may have made
Video3DFormat.HalfTopAndBottom=>"-vf crop=iw:ih/2:0:0,scale=(iw*2):ih),setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1",
// ftab crop heigt in half, set the display aspect,crop out any black bars we may have made
Video3DFormat.FullTopAndBottom=>"-vf crop=iw:ih/2:0:0,setdar=dar=a,crop=min(iw\\,ih*dar):min(ih\\,iw/dar):(iw-min(iw\\,iw*sar))/2:(ih - min (ih\\,ih/sar))/2,setsar=sar=1",