2. I don't like popping. I've noticed that depending on various parameters I've chosen for mpeg2enc I get intermittent popping.
"popping" is not a term usually associated with video. When I have
heard the word "popping" used it's been in the context of audio as
in "clicks and pops" or "chirps and popping". And sometimes the audible pops/clicks/chirps are due to the _de_coding software and/or
sound drivers (MPlayer comes to mind - depending on the version of
gcc used to compile MPlayer's MP2 audio decoder you'll hear artifacts).
What exactly do you mean by "popping"? Or are you in that case
thinking of 'mp2enc', the audio MPEG-1/Layer-II audio compression
program?
I couldn't think of another way to describe it. The image in the video erroneously glitches. An example can be found in some temporary web space at http://www.sci.utah.edu/~bigler/tmp/o1.m1v (~800KB). About halfway through and again towards the end of the video the video seems to pulse or "pop". I used this command line "mpeg2enc -f 0 -o o1.m1v".
-g 1 -G 1
This doesn't really seem to help. I've found that -g 1 -G 3 does much better, while -g 1 -G 2 causes severe popping.
That sounds like a bug in an earlier version - but I have no idea what is meant by 'popping' in "video".
An example of using -g 1 -G 2 can be found at http://www.sci.utah.edu/~bigler/tmp/o5.m1v (~800KB). I'm using a 1.6.1 version distributed for Mandrake 10 official.
My initial guess is that you're either using an older version of
the tools (or there's a bug in the cvs version that needs attending
to) _OR_ you're on a IA32 system and have specified "-q" of 3 or less.
My system is a dual 2GHz Xeon system running Mandrake 10. Should I not be specifying -q of 3 or less on this architecture?
I've read in the archive that -H can help with images that are pretty free of noise, but I don't notice much of a difference.
Differences might be more apparent when the viewing area is larger - full screen mode.
But the results should be better with the -H option instead of without correct?
I've also tried to crank up the bit rate, but that can result in poor quality images once the bit rate gets too high. Is there some intuition I'm missing?
That doesn't feel right at all. Past a certain point no more bits are needed to encode the data - i.e. you can specify 6 megabits/sec but if only 3 are needed then increasing the bitrate will not improve the image but it won't degrade the image either.
Possible I suppose that the playback software can't deal with high rate video.
I'm using xine to play back the video. I've discovered with further experimentation that in order take advantage of the increased bit rate I had to increase the video buffer size (I used -V 500). I guess the default video buffer size was limiting the effective bit rate of the video.
So if I don't care about file size, and I want the best quality movie what kind of parameters should I be using?
You are using the necessary options for VBR (Variable Bit Rate) I hope - by default I think the encoder uses CBR (Constant Bit Rate) for its MPEG-1 encoding. That might make a difference - more bits where they're needed type of thing.
I've been using -q 4. I've tried other values, but they don't seem to make a huge difference.
MPEG-2 is just as portable as MPEG-1 - I haven't seen a software
player yet that could only handle MPEG-1. Does 'popping' (whatever
that is;)) happen if you use MPEG-2? If not then that narrows somewhat
the areas to look for the problem(s).
The problem with MPEG-2 is the availability of decoders. Most Windows machines, for example, need a DVD player installed to get the proper codecs. I would like to be able to use MPEG-2, because it looks better. However, the powers that be want MPEG-1.
Thanks, James
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