mkanel
12th September 2002, 20:35
I've been experimenting with putting home video on SVCD. All my material is from a Sony Hi8 camcorder. The quality is good enough when playing from the original tape to TV but I would like to reduce the ever present video noise before putting it on SVCD or DVD. I assume the noise I see is present in some degree in most analog tape recorders (camcorders and VCR's). The noise I'm referring to is a constant shimmering, or sparkling, it's most visible in lower light scenes against a flat uniform background such as a wall. I like TemporalSoften, it does a good job on the noise but I do lose some fine detail and faces sometimes become waxy.
I noticed in the description of SpatialSoften that unlike TemporalSoften it only smoothes when BOTH the luma and chroma thresholds are met. So I did some experimenting with my video, it seems nearly all the noise is luma and that most of the noise is gone with a threshold of 5. Chroma doesn't seem to be too important. I tried these artificially high settings to test the chroma component: SpatialSoften(5,50,0), SpatialSoften(5,50,1), SpatialSoften(5,50,2), SpatialSoften(5,50,50). The first setting chroma=0 takes out most of the noise, chroma=1 seems to get almost all of the noise, chroma=2 appears to get it all, and I don't see any difference between chroma=2 and chroma=50. My conclusion is that the noise is almost all in the luma component and that a very low chroma threshold allows the luma smoothing to operate. If you want to try any of this for yourself I highly recommend The VirtualDub hack VirtualDubAVS by Belgabor, (Thanks Belgabor!:))it's really made this testing easy. See his September 1st, 2002 post for the download. http://forum.doom9.org/showthread.php?s=&threadid=32336&perpage=20&highlight=virtualdubavs&pagenumber=2
If there was an option to make TemporalSoften smooth only when both the luma and chroma thresholds were met I could set chroma very low, (for me chroma=1 or 2), I think this would allow the noise to be removed but might save a few detail pixels that had different chroma values from the target pixel, it might also greatly reduce ghosting for those using higher luma values.
If there's already a temporal filter that uses this I apologize, I missed it. Have any of you filter writers every experimented with this? If it's effective in preserving detail maybe it could be made an option in TemporalSoften, or maybe it would be easier just to have a nearly identical filter, the only change being that it would look for both values to be met. Is this worth trying and would it be hard to implement? Thanks.
I noticed in the description of SpatialSoften that unlike TemporalSoften it only smoothes when BOTH the luma and chroma thresholds are met. So I did some experimenting with my video, it seems nearly all the noise is luma and that most of the noise is gone with a threshold of 5. Chroma doesn't seem to be too important. I tried these artificially high settings to test the chroma component: SpatialSoften(5,50,0), SpatialSoften(5,50,1), SpatialSoften(5,50,2), SpatialSoften(5,50,50). The first setting chroma=0 takes out most of the noise, chroma=1 seems to get almost all of the noise, chroma=2 appears to get it all, and I don't see any difference between chroma=2 and chroma=50. My conclusion is that the noise is almost all in the luma component and that a very low chroma threshold allows the luma smoothing to operate. If you want to try any of this for yourself I highly recommend The VirtualDub hack VirtualDubAVS by Belgabor, (Thanks Belgabor!:))it's really made this testing easy. See his September 1st, 2002 post for the download. http://forum.doom9.org/showthread.php?s=&threadid=32336&perpage=20&highlight=virtualdubavs&pagenumber=2
If there was an option to make TemporalSoften smooth only when both the luma and chroma thresholds were met I could set chroma very low, (for me chroma=1 or 2), I think this would allow the noise to be removed but might save a few detail pixels that had different chroma values from the target pixel, it might also greatly reduce ghosting for those using higher luma values.
If there's already a temporal filter that uses this I apologize, I missed it. Have any of you filter writers every experimented with this? If it's effective in preserving detail maybe it could be made an option in TemporalSoften, or maybe it would be easier just to have a nearly identical filter, the only change being that it would look for both values to be met. Is this worth trying and would it be hard to implement? Thanks.