[FFmpeg-devel] [RFC] Reading from a lavfi source

Stefano Sabatini stefano.sabatini-lala at poste.it
Sat Jun 11 19:51:27 CEST 2011

On date Saturday 2011-06-11 18:34:07 +0100, Mark Himsley encoded:
> On 10/06/2011 23:53, Stefano Sabatini wrote:
> For instance, I might have an HD source I want to scale to SD to output
> AND I want to scale to a proxy and output. Currently, if I inderstand
> the filter chain correctly, the two filter chains would have to scale
> from HD twice. But the proxy doesn't need to, it could scale from SD and
> be perfectly acceptable quality.
> Something like:
> ffmpeg -i file -vf "scale=720:576:1" -vcodec dvvideo primary.dv -vf
> "[out:0] scale=512:288" -vcodec libx264 proxy.m4v

Yes, right now we apply a separate filterchain to each input.

With the lavfi indev this should be possible, it generates a graph,
and each output of this graph is connected to a stream of the virtual
device, thus allowing to split a source, creating two separate
streams, and then you can use the usual -map mechanism to map each
input stream to the output.

This should also allow to test transmedia filtering since there is no
separate A/V path in the virtual device graph.
FFmpeg = Friendly and Fiendish Moronic Peaceful Empowered Gargoyle

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