Hello,
I am running a FIC Condor using a Pentium 4 at 2.8 GHz, 1GB of Corsair DDR-400 CL2 memory, and a Maxtor 300 GB SATA drive. I am using the PVR-250 card for capture so nuvexport just uses transcode to convert from mpeg2.
In trying to use NUVExport for export to xvid I found that turning noise reduction, scaling, etc off made the export faster but I seem to hit a limit of about 20 Frames per Second (FPS). I decided to try and figure out any problems.
I am not recording anything today so I turned off Mythbackend and used a shell logon to get X out of the way. It still peaked at about 20 FPS. If I ran transcode using the same command line as NUVExport I peaked out at around 50 FPS! Something was wrong. When I used top to look at the processes it looked like transcode was breezing along at about 90% or so when run on it's own but would run at 90% for a few seconds then go down to 0% for a few seconds when run under nuvexport.
nuvexport gets the output of transcode, parses it, reformats, and prints it on the screen. It appears if the framerate gets over 20 FPS then nuvexport can not process every status line guickly. The stdout buffer fills thus stopping transcode until it empties. Reading the transcode man page I came across the --print_status option in transcode. I modified the transcode.pm file in nuvexport to add a --print_status 4 option in the transcode command line. This tells transcode to only print a status line for every 4 frames processed. This fixed the problem and increased the rate back to a peak of around 50 FPS when using nuvexport!
I also noticed nuvexport will still use the -Z option when the output resolution matches the input resolution. Transcode will still do zoom when the -Z option is specified with no change in resolution thus slowing down the frame rate for nothing.
Since my computer has a HT cpu I uncommented the option to specify the number of CPUs in the transcode.pm file and gained about 1 FPS. I noticed the first parameter for this option defaults to 10 but the code in transcode.pm set it to 100. I used 10 and even tried 20 with no change of framerate so I left it at 10. I assume 100 would be overkill and may even slow it down like the comment indicated.
Running nuvexport in X with mythbackend running only slowed things down a few frames per second. I am happier now with the results. A multiple pass conversion from MPEG2 to XviD now takes around an hour instead of around two hours.
73 Eric
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