[FFmpeg-user] flame about confusing command line options.

[Roger Pack]

As a note, I just had to get this off my chest, and I'll only say this
once.  Some of FFmpeg's command line syntax is *confusing* and *super
confusing* for beginners.

For instance this:

ffmpeg -r 30 -i input_file

specifies a framerate *override* for the input, however if you specify
it for the output, its just the "normal" output frame rate...:

ffmpeg -i input -r 10 output

and this:
ffmpeg -i input -f rawvideo -f nut output.nut

Using (or being able to use)  "-f"
typically using two "-f" s would be an override.  But in this case it
isn't.  In fact, its using "-f" to specify two entirely different
aspects of the output file.  It's hard to see, but to beginners, this
is *super* confusing.

Being able to specify global settings "in the middle of an input file"
is also confusing..

Not that much can be done, but just so you're aware...the command line
syntax is  confusing to people just getting started with FFmpeg.
After using FFmpeg for like 5 years I'm only finally figuring it out
myself LOL.
Cheers, no offense intended of course, just a gripe.
-roger-
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Re: [FFmpeg-user] flame about confusing command line options.

[Carl Eugen Hoyos]

Roger Pack  gmail.com> writes:

> ffmpeg -i input -f rawvideo -f nut output.nut
> 
> Using (or being able to use)  "-f"
> typically using two "-f" s would be an override. 
> But in this case it isn't.  In fact, its using 
> "-f" to specify two entirely different aspects of 
> the output file.

I have no idea what this email is about (and it would 
be super-nice if you would not continue this thread) 
but please understand that in your command line the 
second -f is overriding the first -f option, so 
instead of being rawvideo, the output has format nut.
(Which it would also have if you had not specified 
any "-f" option as the extension "nut" defaults to 
the format "nut".)

Note that the input option "-r" is mostly a debug 
option with limited use and often does not work 
and that I consider it extremely useful that many 
input options (like -f) have the same name as the 
matching output options.

Finally, I don't think there is anything wrong with 
having codecs with the same name as formats, this 
includes "opus", "mp3" and "rawvideo" (and many 
others).

Carl Eugen

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Re: [FFmpeg-user] flame about confusing command line options.

[Reindl Harald]

Am 05.01.2016 um 16:32 schrieb Paul B Mahol:

On 1/5/16, Reindl Harald  wrote:



Am 05.01.2016 um 16:21 schrieb Michael Koch:

For example, Harald Reindl just wrote:
"and when you specify something twice the right one wins"

Is this already in the FFmpeg documentation?


that's common sense


for you, but not for a beginner


well, then i ask the question different

"--width=600 --width=300" - what would you expect?

900? why?



600 + 300 = 900, obviously


and you see a + sign somewhere?
well, then try to calc "-codec:a x -codec:a y" to a number
in the whole computerworld overrides are from left to right



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Re: [FFmpeg-user] flame about confusing command line options.

[Phil Rhodes]

> thinking one can develop a GUI which is usable and supports all of the > 
>features of ffmpeg or even a large part of them is naive
Well, possibly, but the problem is that the CLI doesn't do a very good job of 
it either. Inasmuch as CLI discoverability is effectively zero, it doesn't do 
any job of it.
Yes, there need to be possibly different GUIs, or a GUI with different pages, 
for various tasks. But it's madness to completely decry the idea on the basis 
that it can't include everything.
Phil
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Re: [FFmpeg-user] flame about confusing command line options.

[Reindl Harald]

Am 05.01.2016 um 17:00 schrieb Phil Rhodes:

  thinking one can develop a GUI which is usable and supports all of the > 
features of ffmpeg or even a large part of them is naive

Well, possibly, but the problem is that the CLI doesn't do a very good job of 
it either. Inasmuch as CLI discoverability is effectively zero, it doesn't do 
any job of it.
Yes, there need to be possibly different GUIs, or a GUI with different pages, 
for various tasks. But it's madness to completely decry the idea on the basis 
that it can't include everything.


no - the idea is to provide ffmpeg
that is what the developers are doing

when you want a GUI you can write one just sticking together the CLI 
params based on whatever forms and dialogs


or just use google and download one of the existing GUIs

http://avanti.arrozcru.org/#links
http://www.myffmpeg.com/



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Re: [FFmpeg-user] flame about confusing command line options.

[Phil Rhodes]

I think in general a lot of problems with commandline software in general exist 
when the software begins to exceed the ability of a commandline to act as a 
workable UI.
Naturally there are reasons to provide serialised instructions to a piece of 
software, but in many cases that isn't really intended as a user interface, 
it's intended as an API. The discoverability of a CLI is near zero, and the 
lack of examples in the documentation doesn't help.
For many tasks, software with as many complexities as ffmpeg desperately needs 
a GUI.
P
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Re: [FFmpeg-user] flame about confusing command line options.

[Reindl Harald]

Am 05.01.2016 um 16:03 schrieb Michael Koch:

What part of this mailing list thread is not
documented in your opinion?


For example, Harald Reindl just wrote:
"and when you specify something twice the right one wins"

Is this already in the FFmpeg documentation?


that's common sense



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Re: [FFmpeg-user] flame about confusing command line options.

[Paul B Mahol]

On 1/5/16, Reindl Harald  wrote:
>
>
> Am 05.01.2016 um 16:21 schrieb Michael Koch:
 For example, Harald Reindl just wrote:
 "and when you specify something twice the right one wins"

 Is this already in the FFmpeg documentation?
>>>
>>> that's common sense
>>
>> for you, but not for a beginner
>
> well, then i ask the question different
>
> "--width=600 --width=300" - what would you expect?
>
> 900? why?
>
>

600 + 300 = 900, obviously
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Re: [FFmpeg-user] flame about confusing command line options.

[Moritz Barsnick]

On Tue, Jan 05, 2016 at 07:04:11 -0700, Roger Pack wrote:
> As a note, I just had to get this off my chest, and I'll only say this
> once.  Some of FFmpeg's command line syntax is *confusing* and *super
> confusing* for beginners.

That may be the case. :-) Feel free to suggest improvements to
documentation and wiki.

> specifies a framerate *override* for the input, however if you specify
> it for the output, its just the "normal" output frame rate...:

No, in either case, it's an override. By default, ffmpeg processes the
timestamps on the input frames, and uses them (where possible) for the
output. For some cases, when there are no timestamps, it assumes a
default.

> Using (or being able to use)  "-f"
> typically using two "-f" s would be an override.  But in this case it
> isn't.  In fact, its using "-f" to specify two entirely different
> aspects of the output file.

That's not true. It specifies only one aspect, and your second use
overrides the first. (Yes, there could be a warning about that.) If I
use your nut example, "-f rawvideo" is ignored. (If you mean the
content, you need to use "-c:v rawvideo". Format and codec are very
well separated in ffmpeg. Some correlations apply.)

> Being able to specify global settings "in the middle of an input file"
> is also confusing..

What are you saying? That you can drop globally valid flags inbetween
input or output file flags? It would be confusing not to except them
*anywhere*, as they are *global*.

> Not that much can be done, but just so you're aware...the command line
> syntax is  confusing to people just getting started with FFmpeg.
> After using FFmpeg for like 5 years I'm only finally figuring it out
> myself LOL.

When going from mencoder to ffmpeg, it took me about five minutes to
grasp the syntax. Some of the details (more like: What is an input,
what an output, what a global option? Oh, I can specify multiple
outputs? Which flags are valid when?) came later.

I suggest you try to use cvlc for transcoding. For a simple case, I was
recently stuck for an hour! It may be *logical*, but nowhere as
intuitive as ffmpeg. :-)

> Cheers, no offense intended of course, just a gripe.

Of course.

As mentioned, documentation improvements are *always* welcome.

Cheers,
Moritz
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Re: [FFmpeg-user] flame about confusing command line options.

[Reindl Harald]

Am 05.01.2016 um 15:43 schrieb Phil Rhodes:

I think in general a lot of problems with commandline software in general exist 
when the software begins to exceed the ability of a commandline to act as a 
workable UI.
Naturally there are reasons to provide serialised instructions to a piece of 
software, but in many cases that isn't really intended as a user interface, 
it's intended as an API. The discoverability of a CLI is near zero, and the 
lack of examples in the documentation doesn't help.
For many tasks, software with as many complexities as ffmpeg desperately needs 
a GUI


thinking one can develop a GUI which is usable and supports all of the 
features of ffmpeg or even a large part of them is naive - it would be a 
completly weird application with a million dropdowns nobody understands 
how they work together depending of mediatypes or just support a small 
piece of ffmpeg


breaking news: you can write a GUI calling the ffmpeg-binary

we made a PHP wrapper as library-class years ago for ffmpeg which is 
then used by our cms-system as a GUI


but you can not to the other direction when you have a GUI software





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Re: [FFmpeg-user] flame about confusing command line options.

[Reindl Harald]

Am 05.01.2016 um 16:21 schrieb Michael Koch:

For example, Harald Reindl just wrote:
"and when you specify something twice the right one wins"

Is this already in the FFmpeg documentation?


that's common sense


for you, but not for a beginner


well, then i ask the question different

"--width=600 --width=300" - what would you expect?

900? why?



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Re: [FFmpeg-user] flame about confusing command line options.

[Carl Eugen Hoyos]

Michael Koch  t-online.de> writes:

> For many questions, it might be better not to answer 
> them here. Instead, please add the answers to the 
> documentation and then just post a link.

What part of this mailing list thread is not 
documented in your opinion?

Carl Eugen

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Re: [FFmpeg-user] flame about confusing command line options.

[Michael Koch]

As mentioned, documentation improvements are *always* welcome. 


I agree with Roger that for a beginner FFmpeg's documentation leaves 
many questions unanswered. It would be great to have more details and 
especially more examples in the documentation.
Many questions are answered in this user list, but later it's difficult 
to find these answers. So the same questions are asked again and again.
For many questions, it might be better not to answer them here. Instead, 
please add the answers to the documentation and then just post a link.


Michael
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Re: [FFmpeg-user] flame about confusing command line options.

[Michael Koch]

For example, Harald Reindl just wrote:
"and when you specify something twice the right one wins"

Is this already in the FFmpeg documentation?


that's common sense


for you, but not for a beginner.

Michael
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Re: [FFmpeg-user] flame about confusing command line options.

[Michael Koch]

What part of this mailing list thread is not
documented in your opinion?


For example, Harald Reindl just wrote:
"and when you specify something twice the right one wins"

Is this already in the FFmpeg documentation?

Michael
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Re: [FFmpeg-user] flame about confusing command line options.

[Michael Koch]

well, then i ask the question different

"--width=600 --width=300" - what would you expect?



before I saw your answer, it was unclear to me if it's 300 or 600.

Michael
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Re: [FFmpeg-user] flame about confusing command line options.

[Reindl Harald]

Am 05.01.2016 um 15:04 schrieb Roger Pack:

As a note, I just had to get this off my chest, and I'll only say this
once.  Some of FFmpeg's command line syntax is *confusing* and *super
confusing* for beginners.

For instance this:

ffmpeg -r 30 -i input_file

specifies a framerate *override* for the input, however if you specify
it for the output, its just the "normal" output frame rate...:


what else would you expect?


ffmpeg -i input -r 10 output

and this:
ffmpeg -i input -f rawvideo -f nut output.nut

Using (or being able to use)  "-f"
typically using two "-f" s would be an override.  But in this case it
isn't.  In fact, its using "-f" to specify two entirely different
aspects of the output file.  It's hard to see, but to beginners, this
is *super* confusing.


it *is* a override


Being able to specify global settings "in the middle of an input file"
is also confusing..


there is NOTHING "in the middle"

since it's *after* "-i" it's no longer for the input file and when you 
specify something twice the right one wins, the same for GCC because 
otherwise you would not be able to override at all





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Re: [FFmpeg-user] flame about confusing command line options.

[Carl Eugen Hoyos]

Reindl Harald  thelounge.net> writes:

> when you specify something twice the right one wins

I fear it's not that easy: It is actually undefined 
behaviour to specify an option twice (that is not 
supposed to be specified more than once), so for 
example ticket #4184.

Carl Eugen

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