On Thu, Feb 17, 2005 at 01:58:23AM -0500, Chris Pinkham wrote: > Not sure if that's a limit of the Nuppel recorder or not, but unless you're > using current CVS, then you can't resize when you transcode. In 0.17 and > older, the height and width on transcoding profiles were ignored. I just > put a patch in CVS to allow resizing during transcoding for this very reason. > I just picked up an air2pc card yet don't have anything powerful enough to > play it yet so I am transcoding down to a more managable size. :)
Glad to hear. Because on my own todo list for some time has been looking into a smarter transcoder, which would have a set of profiles, and some simple rules for which one to pick. One simple idea is a set of rules of the form, "Program >= X lines -> Use transcoding profile Y" If the profiles handled the diff between interlaced and non on their own, you would probably just have one profile at 720 lines and above that xcoded to 1280x720 mp4 (deinterlace and scale down if 1080i) and another one for things from 480 to 719 lines which transcoded to 352x480. Though there is an argument about whether you want to deinterlace 480i if transocding to 480 lines or let the deinterlace take place on playback. With 1080i, deinterlace is a must if you are downsizing to 720 lines. This also answers why my own transcode experiments were going so poorly. I transcoded a 6gb 480i movie a couple of days and it only became 3.9gb which made little sense to me, and the quality also sucked (in spite of turning on most of the HQ options). My manual use of mencoder has been able to transcode to 40% of original mp2 size with almost equivalent quality, and that's my goal. Since my TV, like most these days, is 720 native resolution, xcode to 1280x720 makes the most sense for 1080i. These are just some ideas, but I don't know the transcoder logic at all yet, so it's been way down the list. Doing everything people want is hard, but a system that maps the number of lines seems like a good start, especially if the trancoder is smart enough not to try deinterlace on non-interlaced video. Turns out there is almost no 480p on TV right now, though that might change with time. > > My P3-1Ghz slave backend took about 3 hours to transcode/resize a 1-hour > recording down from 1920x1088 to 352x480 and that wasn't using the high > quality MPEG-4 modes. Yup, this is to be expected. Though most people with HD cards will have HD capable CPUs and it won't be so rough... Do you do 2 pass? I do that with mencoder, and it's not exactly fast. Because of that CPU load, my dream transcoder probably runs only at night or when the system is otherwise idle, and it has a threshold you can set in the profile that says "Don't transcode until recording is more than N days old." Such a setting means that you can arrange so recordings stay around a few days at full-res, but after a while they get smaller. This conserves lots of disk space but gives you a chance to watch at full res. Of course, if you are transoding to play at SDTV, you would set it to 0, as you want it right away. I would probably set it at 0 for 1080i recordings, but at a few days for 720p and even more for 480i. Not like you need more to do, of course, already plenty to do here.
_______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
