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Invisible <voi### [at] dev null> wrote:
> Weirdly, my PC will play DVDs, but if I tell Mencoder to produce an
> MPEG-2 file instead of MPEG-1, the result isn't playable.
Just because both use the same video standard doesn't mean that the same
codec can be used for both cases.
--
- Warp
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>> Weirdly, my PC will play DVDs, but if I tell Mencoder to produce an
>> MPEG-2 file instead of MPEG-1, the result isn't playable.
>
> Just because both use the same video standard doesn't mean that the same
> codec can be used for both cases.
It's just a little strange that if I have an MPEG-2 file on a DVD, it
plays, but if I have one on my harddrive, it doesn't. Oh well...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Invisible <voi### [at] devnull> wrote:
> Why can't I just say -ovc mpeg1? Why do I have to say -ovc lacv
> -lavcopts vcodec=mpeg1video? That seems unecessarily complex.
Because you might want to use some other library than lavc to create
your mpeg1 stream.
(Yes, creating an mpeg video is not an unambiguous process. Some encoders
do a better job than others.)
> Also, why is there *nowhere* in the manual that says "to produce a
> standard MPEG-1 file, type XYZ"?
Because mplayer is not an mpeg1 encoder?
> As far as I can tell, making Mencoder output any format is equally
> difficult and error-prone. [I still can't get it to produce an
> uncompressed AVI file that anything except MPlayer can comprehend.]
> Adding a rare codec like XviD would just make matters worse...
Why would it make matters worse? I would say all the contrary.
--
- Warp
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>> Why can't I just say -ovc mpeg1? Why do I have to say -ovc lacv
>> -lavcopts vcodec=mpeg1video? That seems unecessarily complex.
>
> Because you might want to use some other library than lavc to create
> your mpeg1 stream.
OK, so why does each library have its own completely unrelated interface
then? Why should I have to memorise which library does what just to
perform the very simple task of producing a plain ordinary MPEG file?
>> Also, why is there *nowhere* in the manual that says "to produce a
>> standard MPEG-1 file, type XYZ"?
>
> Because mplayer is not an mpeg1 encoder?
I... don't even know what to say to that.
>> As far as I can tell, making Mencoder output any format is equally
>> difficult and error-prone. [I still can't get it to produce an
>> uncompressed AVI file that anything except MPlayer can comprehend.]
>> Adding a rare codec like XviD would just make matters worse...
>
> Why would it make matters worse? I would say all the contrary.
My problem is with programs not being able to read the data. Surely the
correct course of action is to seek out more common file formats, not
more obscure ones?
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Invisible <voi### [at] devnull> wrote:
> OK, so why does each library have its own completely unrelated interface
> then? Why should I have to memorise which library does what just to
> perform the very simple task of producing a plain ordinary MPEG file?
Because it's not a GUI.
If you want a GUI, use VirtualDub.
> >> As far as I can tell, making Mencoder output any format is equally
> >> difficult and error-prone. [I still can't get it to produce an
> >> uncompressed AVI file that anything except MPlayer can comprehend.]
> >> Adding a rare codec like XviD would just make matters worse...
> >
> > Why would it make matters worse? I would say all the contrary.
> My problem is with programs not being able to read the data. Surely the
> correct course of action is to seek out more common file formats, not
> more obscure ones?
Which raw video format are you using? Those are obscure, if any.
--
- Warp
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Invisible wrote:
>> Just because both use the same video standard doesn't mean that the
>> same
>> codec can be used for both cases.
>
> It's just a little strange that if I have an MPEG-2 file on a DVD, it
> plays, but if I have one on my harddrive, it doesn't. Oh well...
That may say something about your media player on your computer.
--
Nostalgia just ain't what it used to be.
/\ /\ /\ /
/ \/ \ u e e n / \/ a w a z
>>>>>>mue### [at] nawazorg<<<<<<
anl
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Invisible wrote:
> Why can't I just say -ovc mpeg1? Why do I have to say -ovc lacv
> -lavcopts vcodec=mpeg1video? That seems unecessarily complex.
Warp answered that: Why should mencoder choose for you which library
you should use?
I think the problem you're dealing with is that mencoder is meant to be
somewhat general purpose. I can easily imagine another encoder out there
that's as easy to use as you want, but would simply be inflexible - lack
of choices. mencoder is designed for flexibility.
> Also, why is there *nowhere* in the manual that says "to produce a
> standard MPEG-1 file, type XYZ"? Do you have any idea how freakin long
> it took me to decode the manual to the point where I could construct
> this commandline?
They give various examples at the end of the man file. Yes, MPEG-1 is
not explicitly provided, but then why should they provide that over,
say, MPEG-4 or some other codec? I think you're mistaken in thinking
that most people do encoding into MPEG-1 - it's usually to encode to
xvid, divx or something similar.
In any case:
mencoder "mf://*.jpg" -mf fps=25 -o output.avi -ovc lavc -lavcopts
vcodec=mpeg4
It shouldn't be too hard to go from there to mpeg1.
> [E.g., nowhere is it actually documented that if you want to pass
> *multiple* options to lavc, you have to seperate them with colons.
Right in the beginning of the section for lavcopts, you see:
EXAMPLE:
vcodec=msmpeg4:vbitrate=1800:vhq:keyint=250
Should be enough of a hint.
> Eventually I noticed it in an example - an example demonstrating
> something completely unrelated to syntax - and copied it. In general,
> trying to figure out how the hell to make Mencoder do anything reduces
> to endless trail and cryptic error...]
Can't say I figured everything out by reading mencoder man file. I have
in the past done Google searches and looked at other people's scripts.
However, it's not obvious to me how it can be made better.
> As far as I can tell, making Mencoder output any format is equally
> difficult and error-prone. [I still can't get it to produce an
> uncompressed AVI file that anything except MPlayer can comprehend.]
> Adding a rare codec like XviD would just make matters worse...
xvid is not exactly rare.
I'd be curious to see if the same command you're giving will produce a
working avi file on my side...
--
Nostalgia just ain't what it used to be.
/\ /\ /\ /
/ \/ \ u e e n / \/ a w a z
>>>>>>mue### [at] nawazorg<<<<<<
anl
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Warp wrote:
> Fortunately mplayer isn't such a software.
I did not mean to imply it was, nor that all open source software is
that way.
> Can you give me an example of a library which is almost completely
> undocumented?
Many are, usually in the initial phases when they really need the most
help to get going. As I said, Freenet was essentially undocumented for
about 5 years when it started. Apache 2.0 was undocumented for over a
year, without even mentioning in the documentation distributed with the
package that the documentation was from a different and completely
incompatible version. CouchDB has no documentation on what the file
formats are, which makes it difficult to learn anything or understand
and of the code without learning all of it.
It's not so much that the project isn't documented. It's that the
project *is* documented, but the documentation isn't put anywhere that
people willing to help (or at least provide suggestions) can get to it.
I find it tremendously hard to believe that anyone would write a major
distributed database engine without ever once embodying the format of
the data stored in the files other than in the source code. It would be
like beliving Microsoft never documented the format of Word files, and
always told new programmers "just read the source to figure it out."
> In fact, many open source libraries have pretty decent documentations.
> One example: http://library.gnome.org/devel/gtk/stable/
Yes, many do. I have, sadly, run up against way too many that don't,
usually when my boss says something like "Hey, I just heard about X,
let's use that!"
--
Darren New / San Diego, CA, USA (PST)
Helpful housekeeping hints:
Check your feather pillows for holes
before putting them in the washing machine.
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Darren New wrote:
> Many are, usually in the initial phases when they really need the most
> help to get going.
Incidentally, I might see this more than you do, depending on how you do
your development stuff. The sorts of projects I work on usually involve
mash-ups of half a dozen different functionalities.
For example, the thing I did most recently (www.poundsky.com), we have
direct relationships with some 15 different suppliers, as well as
needing to meet the criteria of all our suppliers' suppliers. (I.e., we
not only have to work with the supplier, but what that supplier is
providing to us is access to *their* partners, who we also have to
satisfy. E.g., we not only have to fetch ads from the ad servers, we
have to only put the appropriate ads on the right pages.)
MG uses WebSphere, which is well-documented in an IBM Mainframe sort of
way - heaven help you if actually want to use it from a language other
than COBOL. (Heaven help you if you don't know COBOL, for that matter.)
STI uses SOAP libraries that are so poorly written they don't even talk
to other SOAP libraries, let alone export WSDL. And whatever XML parser
they mashed up for the other part doesn't quote strings right, so you
can't read it with a standard XML parser.
Every feed we get has a different format, none of which is documented.
So if I can drag out whether it's TCP or UDP they're sending, the next
step is to log all the bytes that come in and try to figure out what the
syntax of the messages is.
Another provider uses real SOAP, but their documentation doesn't match
their WSDL. They have "optional" fields that the WSDL requires you to
provide, and "required" fields that the WSDL lets you omit, just as one
example.
The ones giving us ads give you a blob of PHP that you're supposed to
run to fetch the ads. Often, it has a bunch of crap in there to make up
for deficiencies in their database. Often, it misformats the result
compared to how you want to format it (like, "no, thanks, we don't want
the ad centered" or even leaving mismatched tags in). It invariably just
dumps the ad to stdout, rather than giving it back to you so you can,
say, plug it into a template or log to the database what you got so you
can fix it when they break it. So every ad service I use, they drop me a
couple hundred lines of awful PHP and I have to figure out what it does
and rewrite it to actually work with our system.
(Yes, I'm being fairly vague about what I'm talking about specifically.
Welcome to commercial software. :-)
So, yeah, I probably wind up getting tasked more often with figuring out
WTF is going on with some new library thingie than most people.
Nowadays, of course, much of that sort of stuff is web services instead
of libraries, so it tends to be a bit better documented, because if
nothing else it's commercial and they know you won't use it if it isn't
documented.
--
Darren New / San Diego, CA, USA (PST)
Helpful housekeeping hints:
Check your feather pillows for holes
before putting them in the washing machine.
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>>> I think most people use ffmpeg for this kind of thing.
>>
>> I don't have that. [Note that we're talking about M$ Windoze here.]
>
> Did you install the binary mplayer codecs package? It may have it.
Turns out I do have it. I was mistaken - it seems I just used the wrong
codec name.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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