On Sat, 22 Jun 2002, John Richard Smith wrote:
> Well I have your lame rpm and it installed itself flawlessly.
Great stuff ;-) At least I know it works on other systems.
> I'm currently repeating the process but with all 163 chapters of the
> film, this will take a while, no compression as yet, and it's
> hopefully all going on the correct partition now that I have CD to
> the subdirectory on that partition.
> However it occured to me to ask a few general questions before
> experimenting more.
> 1) Compression , does this come at a price. do you loose quality, is
> there a risk of picture and sound being out of synchronization or
> anything.
Yes, the more compression, the less quality, just like saving a jpeg
picture. As far as syncronisation goes, from what I have experienced there
is absolutely NO link between the two. Bad syncronisation comes from a bad
encoder / bad encoding.
> 2) parsing, I read from your website Ralph that at least 2 passes is
> adviseable so it is going to be one of the obvious options to include,
> I'm not sure of the option command and where to put it.
You talk about parsing and passes... 2 totally different things. I did a
comparrison with a 2-Pass rip. The example on the test do not work anymore
with libavcodec. Libavcodec has changed, and now uses it's own 2-pass
system, but mencoder has changed to support this. I cannot remember iof
this change was before or after the latest official release (I use the CVS
version, updated every couple of days). The examples on the mplayer site
(docs) should be pretty much accurate to the latest official release.
What I do generally is actually use a 3 pass rip. First pass rips the audio
only. The second rip rips the video only, writing a log file of the
movements, colors and so on... and at the end of that rip it adds the audio
to it. The last rip re-encodes the video only, but uses the logfile too,
producing a better quality (you saw the examples), and again, at the end
adds the first rip[ped audio. You see, the audio only needs to be done
once.
> 3) If compression does come at a price, could I specify breaking down
> the original decss list of chapters into reasonable amounts so that
> they would be small enough to write to disk. I might end up with 2 or
> more discs for a long film but , since they are not that expensive,
> and if it meant better quality screen pictures and more reliable
> sound then I might well go for that option.
Yes, this is the besat way. Mencoder / mplayer does not have a feature to
split files after a certain amount of MB's. The best way to do this is to
calculate the bitrate needed for let's say a 2 CD rip. Then you need to
know how long the film is and divide that by two. YOu can then use that
bitrate, and use the -ss and -endpos features to rip both halves.
> 4) The only compression command I have found in `man mencoder'
> is ratio=<value in 1-100%> I tried sticking it in a few slots in your
> sample command but it did not like anything I did. It's not simple I
> guess.
Ok, this is just a big guess, as I said before I can't remember when the
changes came to mencoder, but here is what I need to do to make my 3 pass
rip (actually a 2 pass video rip)
-----------------------
PASS 1 (Audio)
mencoder -dvd 1 \
-oac mp3lame -lameopts br=96:cbr \
-ovc frameno -o frameno.avi
Rips the DVD track 1, using lame with a constant bitrate at 96b/s, and
outputs the audio to the standard frameno.avi (yes, ti says avi, but it's
mp3). The video does not get outputted at all (frameno)
---------------------
PASS 2 (Video first pass)
mencoder -dvd 1 \
-ovc lavc \
-lavcopts vcodec=mpeg4:vhq:vbitrate=699:vpass=1 \
-oac copy -o Matrix.avi
Rips just the audio and copies the previously ripped audio (mp3). Rips
track 1, using DivX, Very High Quality (vhq), video bitrate of 699
(vbitrate) and makes a video pass 1 (vpass=1), and finally outputs the
output to Matrix.avi
---------------------
PASS 3 (Video second pass)
mencoder -dvd 1 \
-ovc lavc \
-lavcopts vcodec=mpeg4:vhq:vbitrate=699:vpass=2 \
-oac copy -o Matrix.avi
Exactly the same as the previos (must be), except that the vpass=2 states
the second pass.. You can add another output file here to compare the
difference.
----------------------
It's all written there on the mplayer pages though, really it is, and
please do read it. I don't know everything about it, really, just trying to
get you on your way and so on ;-)
Hope this explains some things
Greetings
Ralph
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