[libav-tools] How to use libav command to analyse an arbitrary video file?

JIA Pei jp4work at gmail.com
Sun Jul 29 22:04:26 CEST 2012


Hi, Luca Barbato:

The answer is fabulous!! Extremely detailed and everything has been clearly
explained by you !!!!!!!

By the way, have you been using gentoo all the way? I can't believe so for
gentoo is seriously complex to install ....
How do you think gentoo vs ubuntu?


Once again, thank you very much !!!!


Best Regards
Pei





On Sat, Jul 28, 2012 at 8:36 PM, Luca Barbato <lu_zero at gentoo.org> wrote:

> On 07/28/2012 02:32 PM, JIA Pei wrote:
> > Hi, all:
> >
> > Actually, I've got 2 naive questions:
> >
> > 1) Is libav able to replace ffmpeg (avcodec + avformat) ?
>
> If you mean avconv, yes, absolutely.
>
> Please refer to http://libav.org/about.html on why =)
>
> > 2) How to use libav command (avconv or some other commands?) to analyse
> an
> > arbitray video files?
>
> avprobe might be what you want.
>
> >
> > 3) It's convenient for me to encode a video file from multiple .jpg
> files,
> > for example:
> > [code]$ ffmpeg -i %3d.jpg video.mpg[/code]
>
> http://libav.org/avconv.html#image2-1
>
> > However, how can I use ffmpeg command (or other commands) to analyse how
> > many frames in such a .mpg file? It may have something to do with how I
> > encode (for example, the framerate, etc.), right? But, the default
> encoding
> > shouldn't change the number of frames in such a encoded .mpg file, right?
>
> Wrong. as many images you feed, so many frames you get, normally. If you
> ask avconv to filter the input frames to they get decimated that's
> another issue.
>
> > Anyway, can anybody please help how I can analyse a video file ---- how
> > many frames (better, both audio and video streams) in such a video file?
>
> http://libav.org/avprobe.html#Synopsis
>
> avprobe gathers information from multimedia streams and prints it in
> human- and machine-readable fashion.
>
> For example it can be used to check the format of the container used by
> a multimedia stream and the format and type of each media stream
> contained in it.
>
> If a filename is specified in input, avprobe will try to open and probe
> the file content. If the file cannot be opened or recognized as a
> multimedia file, a positive exit code is returned.
>
> avprobe may be employed both as a standalone application or in
> combination with a textual filter, which may perform more sophisticated
> processing, e.g. statistical processing or plotting.
>
> Options are used to list some of the formats supported by avprobe or for
> specifying which information to display, and for setting how avprobe
> will show it.
>
> avprobe output is designed to be easily parsable by any INI or JSON
> parsers.
>
> I hope it helps.
>
> --
>
> Luca Barbato
> Gentoo/linux
> http://dev.gentoo.org/~lu_zero
>
> _______________________________________________
> libav-tools mailing list
> libav-tools at libav.org
> https://lists.libav.org/mailman/listinfo/libav-tools
>



-- 

Pei JIA

Email: jp4work at gmail.com
cell:    +1 604-362-5816

Welcome to Vision Open
http://www.visionopen.com
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