[x264-devel] Encoding a single input files to multiple output files with different bitrates

[Kiran Kotla]

Jason,

Thanks for the response, the information is helpful.

Similarly, is it possible to generate multiple output files with different
video resolutions from a single input file? Does x.264 come with a scaler? I
looked up the source code, but have not been able to find such a function.

Appreciate any pointers.

Thanks in advance
Kiran

On Mon, Aug 22, 2011 at 8:09 PM, Jason Garrett-Glaser <jason at x264.com>wrote:

> On Mon, Aug 22, 2011 at 8:04 PM, Kiran Kotla <kotlakiran at gmail.com> wrote:
> > Hello,
> >
> > I am trying to use x.264 to generate multiple output files with different
> > bitrate from a single input file.
> >
> > I want to do this in the most efficient way possible. Does x.264 already
> > provide a way to do this?
> >
> > As in, after a common motion estimation step, is it possible to generate
> > multiple output files (with different bitrates), rather than having to go
> > through most estimation phase for each output bitrate?
> >
> > If, this functionality is not available, any pointers to where to make
> > changes, would be appreciated.
> >
> > I am looking at the function x264_macroblock_analyse and trying to use
> > multiple 'qp's each for one output bitrate, but the changes look quite
> > complex.
> >
> > Appreciate any suggestions.
>
> It's theoretically possible, but as the results of an optimal motion
> estimation and analysis pass are heavily dependent on the quantizer
> used, any algorithm which shares these between multiple
> vastly-different bitrates will have much worse compression.
>
> In short, you're probably better off doing 5 separate encodes at
> "superfast" than trying to share them all at "medium".
>
> Jason
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