[FFmpeg-devel] RFC: setting format parameters from the URL

Michael Niedermayer michaelni
Mon Apr 7 19:52:01 CEST 2008

On Mon, Apr 07, 2008 at 07:37:46PM +0200, Nicolas George wrote:
> Hi.
> Some format require that various parameters are already set before the call
> to av_open_input_file. This happen for raw format that lack sufficient
> headers, for capture formats, and sometimes when format detection fails.
> If an application wants to support these formats, it needs to implement some
> way for the user to specify these parameters. I find this is a case of
> reinventing the wheel, with all related problems: some application will
> implement some parameters and not others, new parameters will only be
> supported in new applications, etc.
> A convenient solution to this problem would be for av_open_input_file to be
> able to find these parameters in the user-given URL.
> There is a similar feature in ImageMagick: the user can specify PNG:- to
> write a PNG to a pipe, or X: to grab an image from the X11 server, and it
> works automatically with any application using the libMagick API. This is
> very convenient.
> Before I start to hack something, I would like some advice. Would it be
> considered an useful feature? And if so, the actual syntax needs to be
> devised carefully; I have a few ideas for that point, but nothing completely
> satisfactory. Any advice?

We have AVOption, an appliation should support that. If it does all parameters
are automatically supported.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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