[FFmpeg-devel] [PATCH] doc/ffmpeg: document more deeply -re option.

Lou Logan lou at lrcd.com
Wed Jul 11 22:44:44 CEST 2012

On Wed, 11 Jul 2012 21:23:53 +0200, Clément Bœsch wrote:

> From: burek <burek021 at gmail.com>
> Signed-off-by: Clément Bœsch <ubitux at gmail.com>
> ---
>  doc/ffmpeg.texi | 8 ++++++++
>  1 file changed, 8 insertions(+)
> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> index 3d3d78f..13b7512 100644
> --- a/doc/ffmpeg.texi
> +++ b/doc/ffmpeg.texi
> @@ -820,6 +820,14 @@ Dump each input packet to stderr.
>  When dumping packets, also dump the payload.
>  @item -re (@emph{input})
>  Read input at native frame rate. Mainly used to simulate a grab device.
> +Since @command{ffmpeg} always tries to read the input(s) as fast as possible to
> +finish the work as quickly as it can, when you want to have any sort of
> +real-time output (e.g. live streaming) you need "-re" option to tell
> + at command{ffmpeg} to slow down the reading of the input(s) for real-time. If
> +your input(s) is coming from some other live streaming source (through HTTP or
> +UDP for example) the server might already be in real-time, thus the option will
> +likely not be required. On the other hand, this is meaningful if your input(s)
> +comes from a file you are trying to push in real-time.	
>  @item -loop_input
>  Loop over the input stream. Currently it works only for image
>  streams. This option is used for automatic FFserver testing.

I think the first sentence is somewhat verbose can be improved for
readability. Maybe something like this?

By default @command{ffmpeg} attempts to read the input(s) as fast as
possible. This option will slow down the reading of the input(s) to the
native frame rate of the input(s) and is useful for real-time output
(e.g. live streaming). If your ...

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