[FFmpeg-devel] working with file descriptors on Android

[Olivier Ayache]

You're welcome.

Can I suggest you to try IContainer.open with InputStream/OutputStream. If
you use a FileInputStream created from the file descriptor retrieved with
https://developer.android.com/reference/android/content/Intent#ACTION_OPEN_DOCUMENT
Normally fd will be automatically closed by the stream.

If you're interested we could work together on this because I also need to
implement this type of feature for my projects.

Best

Olivier

Le lun. 27 juil. 2020 à 14:46, Alex Cohn <alexcohn at netvision.net.il> a
écrit :

> Thanks Olivier,
>
> Custom IO looks like a nice way to work around the protocol
> limitations. Unfortunately, it cannot work with avio_open(), so the
> API becomes trickier for end users.
>
> Also, just like with pipes, I cannot reliably close the file
> descriptor when ffmpeg execution is over, can I?
>
> BR,
> Alex Cohn
>
> On Mon, Jul 27, 2020 at 11:01 AM Olivier Ayache
> <olivier.ayache at gmail.com> wrote:
> >
> > A good alternative to work with FFmpeg on Android is Xuggler, it presents
> > FFmpeg's API directly to Java/Kotlin.
> >
> > To deal with fd you can declare and implement your own IO handler by
> > implementing
> >
> https://github.com/olivierayache/xuggle-xuggler/blob/ffmpeg-3.x-dev/src/com/xuggle/xuggler/io/IURLProtocolHandler.java
> >
> > I currently maintain a fork which is fully working on Android (work in
> > progress for iOS with Kotlin multiplatform).
> >
> > https://github.com/olivierayache/xuggle-xuggler
> >
> > Best
> >
> > Olivier Ayache
> >
> > Le dim. 26 juil. 2020 à 23:16, Alex Cohn <alexcohn at netvision.net.il> a
> > écrit :
> >
> > > On Sun, Jul 26, 2020 at 10:21 PM Martin Storsjö <martin at martin.st>
> wrote:
> > > >
> > > > Hi,
> > > >
> > > > Without having too much opinion on the JNI stuff (direct access to
> > > > content:// urls might be convenient, but on the other hand, it's not
> > > > really something you'd end up with if using the command line tool on
> its
> > > > own - if you have one of those you most probably have some java code
> for
> > > > getting it anyway - as far as I remember...)
> > >
> > >
> > > You are more than right, Martin.
> > >
> > > None of these approaches can work with a command line tool. Worse,
> > > running a command line tool in the context of an Android app is
> > > becoming trickier with every new release of the platform, and in this
> > > case I cannot blame it on poor engineering. This happens because
> > > Google tries to tighten the security on Android just as much as
> > > possible.
> > >
> > > There is a nice cross-platform alternative, though.
> > > https://github.com/tanersener/mobile-ffmpeg provides Java and
> > > Objective-C APIs to run ffmpeg shared library "as if it were an
> > > executable": it can receive the input as a string which mimics the
> > > ffmpeg (and ffprobe) command line, and the output to stdout and stderr
> > > is captured and passed back to the mobile app. In this scenario, it's
> > > easy to get a `content:` URI by conventional Android SAF (structured
> > > access framework) API in Java and pass it as string or as a derived
> > > file descriptor (converted to string) to the command line parser that
> > > will eventually call protocol->url_open().
> > >
> > > The latest release (Android Q a.k.a. Android 10, also API 29) made yet
> > > another small step in this direction and caused lots of problems for
> > > apps that rely upon file access by path. This was the incentive for me
> > > to work on the ways to teach avformat to work with the `content:` URIs
> > > correctly.
> > >
> > > BR,
> > > Alex Cohn
> > > _______________________________________________
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