Documentation for input -i options

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Documentation for input -i options

John Dexter
Bizarrely am struggling to find a thorough documentation of -i and relying
on examples online. Can anyone point me where in the online documentation
this is documented (not a man page) please? I know it supports
patterns e.g. for timelapse but I cannot find a reference.

Thanks.
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Re: Documentation for input -i options

Gyan Doshi-2


On 05-12-2019 08:44 pm, John Dexter wrote:
> Bizarrely am struggling to find a thorough documentation of -i and relying
> on examples online. Can anyone point me where in the online documentation
> this is documented (not a man page) please? I know it supports
> patterns e.g. for timelapse but I cannot find a reference.

All -i does is specify the input URL. Which options are applicable for
an input is determined by
the input format / codecs discovered by ffmpeg after probing the input.

What specifically are you trying to do?

Gyan
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Re: Documentation for input -i options

John Dexter
On Thu, 5 Dec 2019 at 15:23, Gyan <[hidden email]> wrote:

>
>
> On 05-12-2019 08:44 pm, John Dexter wrote:
> > Bizarrely am struggling to find a thorough documentation of -i and
> relying
> > on examples online. Can anyone point me where in the online documentation
> > this is documented (not a man page) please? I know it supports
> > patterns e.g. for timelapse but I cannot find a reference.
>
> All -i does is specify the input URL. Which options are applicable for
> an input is determined by
> the input format / codecs discovered by ffmpeg after probing the input.
>
> What specifically are you trying to do?
>

Time-lapse from a whole bunch of images. I've found examples online of
syntax I can use but no explanation exactly how this is working and how
flexible this is.
e.g. -i image%8d
I'd like to know how I can specify which files are used and in which order.
Maybe my question is where is the input URL functionality documented?

John

>
> Gyan
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> [hidden email] with subject "unsubscribe".
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Re: Documentation for input -i options

Gyan Doshi-2


On 05-12-2019 09:00 pm, John Dexter wrote:

> On Thu, 5 Dec 2019 at 15:23, Gyan <[hidden email]> wrote:
>
>>
>> On 05-12-2019 08:44 pm, John Dexter wrote:
>>> Bizarrely am struggling to find a thorough documentation of -i and
>> relying
>>> on examples online. Can anyone point me where in the online documentation
>>> this is documented (not a man page) please? I know it supports
>>> patterns e.g. for timelapse but I cannot find a reference.
>> All -i does is specify the input URL. Which options are applicable for
>> an input is determined by
>> the input format / codecs discovered by ffmpeg after probing the input.
>>
>> What specifically are you trying to do?
>>
> Time-lapse from a whole bunch of images. I've found examples online of
> syntax I can use but no explanation exactly how this is working and how
> flexible this is.
> e.g. -i image%8d
> I'd like to know how I can specify which files are used and in which order.
> Maybe my question is where is the input URL functionality documented?

For a sequence of images, the input URL serves as a pattern which is
interpreted by the image sequence demuxer (image2).
See ffmpeg -h demuxer=image2 to see its options, or on the web at
http://ffmpeg.org/ffmpeg-formats.html#image2-1
On linux, you should also have access to globbing support.

Gyan
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Re: Documentation for input -i options

Moritz Barsnick
In reply to this post by John Dexter
On Thu, Dec 05, 2019 at 15:30:16 +0000, John Dexter wrote:
> On Thu, 5 Dec 2019 at 15:23, Gyan <[hidden email]> wrote:
> > What specifically are you trying to do?
>
> Time-lapse from a whole bunch of images. I've found examples online of
> syntax I can use but no explanation exactly how this is working and how
> flexible this is.
> e.g. -i image%8d

This is basically the image2 demuxer.

> I'd like to know how I can specify which files are used and in which order.
> Maybe my question is where is the input URL functionality documented?

It's documented in the image2 demuxer's docs:
https://ffmpeg.org/ffmpeg-formats.html#image2-1

Look at the description of "pattern_type" and its restrictions.

If you want to specify an arbitrary list (random file names,
non-alphabetical order), it's probably easiest to rename the files - or
better, using a modern operating system, creating symbolic links - to
adhere to "somename%08d.suffix" in numerical order without gaps.

Cheers,
Moritz
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Re: Documentation for input -i options

Moritz Barsnick
In reply to this post by Gyan Doshi-2
On Thu, Dec 05, 2019 at 21:10:20 +0530, Gyan wrote:
> See ffmpeg -h demuxer=image2 to see its options, or on the web at

Funnily, of all self-documenting options, this one's default behavior
(and range) will look somewhat confusing to the user:

  -pattern_type      <int>        .D........ set pattern type (from 0 to INT_MAX) (default 4)
     glob_sequence   0            .D........ select glob/sequence pattern type
     glob            1            .D........ select glob pattern type
     sequence        2            .D........ select sequence pattern type
     none            3            .D........ disable pattern matching

Note "(from 0 to INT_MAX) (default 4)".

We may want to suggest a fix for that. :-)

Explanation: The default '4' is actually interpreted as "some default
behavior, either 'none' or 'glob_sequence', depending on some stuff".

Cheers,
Moritz
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