[FFmpeg-devel] [PATCH] Command passing interface for libavfilter

[Stefano Sabatini]

On date Monday 2011-08-29 17:49:47 +0200, Michael Niedermayer encoded:
> On Mon, Aug 29, 2011 at 04:57:10PM +0200, Stefano Sabatini wrote:
> > On date Monday 2011-08-29 00:45:13 +0200, Michael Niedermayer encoded:
[...]
> Will apply attached patches soon if i hear no more comments
> 
> 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
> 
> Opposition brings concord. Out of discord comes the fairest harmony.
> -- Heraclitus

> From 074cda2ba4c10e39b7230a9030475c230a8336f8 Mon Sep 17 00:00:00 2001
> From: Michael Niedermayer <michaelni at gmx.at>
> Date: Sun, 28 Aug 2011 20:46:31 +0200
> Subject: [PATCH 1/5] avfilter: Add command passing support
> 
> Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> ---
>  libavfilter/avfilter.c      |   12 ++++++++++++
>  libavfilter/avfilter.h      |   22 +++++++++++++++++++++-
>  libavfilter/avfiltergraph.c |   30 ++++++++++++++++++++++++++++++
>  libavfilter/avfiltergraph.h |   20 ++++++++++++++++++++
>  4 files changed, 83 insertions(+), 1 deletions(-)
> 
> diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
> index 23bb26c..5c293dd 100644
> --- a/libavfilter/avfilter.c
> +++ b/libavfilter/avfilter.c
> @@ -26,6 +26,7 @@
>  #include "libavutil/audioconvert.h"
>  #include "libavutil/imgutils.h"
>  #include "libavutil/avassert.h"
> +#include "libavutil/avstring.h"
>  #include "avfilter.h"
>  #include "internal.h"
>  
> @@ -616,6 +617,17 @@ void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
>      draw_slice(link, y, h, slice_dir);
>  }
>  
> +int avfilter_process_command(AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags)
> +{
> +    if(!strcmp(cmd, "ping")){
> +        av_strlcatf(res, res_len, "pong from:%s %s\n", filter->filter->name, filter->name);
> +        return 0;
> +    }else if(filter->filter->process_command) {
> +        return filter->filter->process_command(filter, cmd, arg, res, res_len, flags);
> +    }
> +    return AVERROR(ENOSYS);
> +}
> +
>  void avfilter_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref)
>  {
>      void (*filter_samples)(AVFilterLink *, AVFilterBufferRef *);
> diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h
> index db6ff6d..4a8c436 100644
> --- a/libavfilter/avfilter.h
> +++ b/libavfilter/avfilter.h
> @@ -29,7 +29,7 @@
>  #include "libavutil/rational.h"
>  
>  #define LIBAVFILTER_VERSION_MAJOR  2
> -#define LIBAVFILTER_VERSION_MINOR 35
> +#define LIBAVFILTER_VERSION_MINOR 36
>  #define LIBAVFILTER_VERSION_MICRO  0
>  
>  #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
> @@ -552,6 +552,20 @@ typedef struct AVFilter {
>       * NULL_IF_CONFIG_SMALL() macro to define it.
>       */
>      const char *description;
> +
> +    /**
> +     * Make the filter instance process a command.
> +     *
> +     * @param cmd    the command to process, for handling simplicity all commands must be alphanumeric only
> +     * @param arg    the argument for the command
> +     * @param res    a buffer with size res_size where the filter(s) can write a response message / return a response. This must not change when the command is not supported.

> +     * @param flags  if AVFILTER_CMD_FLAG_FAST is set and the command would be
> +     *               timeconsuming then a filter should treat it like an unsupported command

maybe AVFILTER_CMD_FLAG_* should be defined in avfilter.h, so they can
be used without including avfiltergraph.h.

> +     *
> +     * @returns >=0 on success otherwise an error code.
> +     *          AVERROR(ENOSYS) on unsupported commands
> +     */
> +    int (*process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags);
>  } AVFilter;
>  
>  /** An instance of a filter */
> @@ -792,6 +806,12 @@ void avfilter_end_frame(AVFilterLink *link);
>  void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
>  
>  /**
> + * Make the filter instance process a command.
> + * It is recommanded to use avfilter_graph_send_command()

Nit++: missing ending point.

[...]
> diff --git a/libavfilter/avfiltergraph.h b/libavfilter/avfiltergraph.h
> index f4c88bc..e668104 100644
> --- a/libavfilter/avfiltergraph.h
> +++ b/libavfilter/avfiltergraph.h
> @@ -136,4 +136,24 @@ int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
>                           AVFilterInOut **inputs, AVFilterInOut **outputs,
>                           void *log_ctx);
>  

> +#define AVFILTER_CMD_FLAG_ONE   1 ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
> +#define AVFILTER_CMD_FLAG_FAST  2 ///< Only execute command when its fast (like a video out that supports contrast adjustment in hw)

as said, should be moved to avfilter.h

> +
> +/**
> + * Send a command to one or more filter instances.
> + *
> + * @param graph  the filter graph
> + * @param target the filter(s) to which the command should be sent
> + *               "all" sends to all filters
> + *               otherwise it can be a filter or filter instance name
> + *               which will send the command to all matching filters.
> + * @param cmd    the command to sent, for handling simplicity all commands must be alphanumeric only
> + * @param arg    the argument for the command

> + * @param res    a buffer with size res_size where the filter(s) can write a response message / return a response.

Nit+: please choose between "write a response message" or "return a
response", remove the other variant (the first one is more explicit ->
better IMO)

[...]

No more comments from me, thanks.
-- 
FFmpeg = Funny & Friendly Monstrous Picky Ecumenical Game