I want to _generate_ HD output; ideally an ATSC-compliant TS but a
720p30 video ES would be a good start. I have my animation/rendering
program configured to produce 1280x720 PPM frames at 30 frames per
second.
Here's what I currently use, based on some wild guesses. Does anyone
see any glaring problems with these settings? I've kept all of the
source frames in case I need to re-encode them.
cat *.ppm \
| ppmtoy4m -n 150 -F 30:1 -A 1:1 -I p -S 420_mpeg2 \
| mpeg2enc \
--no-constraints \
--format 3 \
--b-per-refframe 0 \
--video-bitrate 19000 \
--video-buffer 500 \
--no-dummy-svcd-SOF \
--min-gop-size 15 \
--max-gop-size 15 \
--closed-gop \
--keep-hf \
--intra_dc_prec 11 \
--output outputfile.mpg
With the above settings I found that mjpegtools-1.6.2 initially
complained about the bitrate and/or dc precision being out of range.
Is there any way to select the high level and high profile settings on
the command line? I couldn't find any and ended up patching the
defaults in the code in order to fix it:
profile = 1;
level = 4;
I suspect the bitrate might be too high if I want to stay within the
bounds of broadcast ATSC, since packetization will add overhead. But
the data will probably be delivered over Ethernet from a file server
instead of actually sent over the air, so I'm not too concerned about
it. There's not intended to be any audio associated with the video,
so I don't think I need to leave any room for it.
FYI the intended application is a screensaver-like program for an HDTV
set-top box. The files as generated above do play with things like
mplayer, but I haven't had a chance to get them turned into transport
streams and try them with the intended hardware (the API there insists
on a TS). There seem to be several free programs to tear transport
streams apart but very few for constructing them.
-Dave Dodge
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