[FFmpeg-devel] [PATCH] lavu/opt: add av_opt_bprint()

[Nicolas George]

Le nonidi 19 nivôse, an CCXXI, Stefano Sabatini a écrit :
> >From 9b7de355afb61bab72bce682aacbd96eb4a9cb95 Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab at gmail.com>
> Date: Thu, 9 Aug 2012 19:59:48 +0200
> Subject: [PATCH] lavu/bprint: add av_bprint_options()
> 
> This function will be useful to serialize an object context.
> 
> TODO: add APIChanges entry, bump minor
> ---
>  libavutil/bprint.c |   23 +++++++++++++++++++++++
>  libavutil/bprint.h |   15 +++++++++++++++
>  libavutil/opt.c    |   10 +++++++++-
>  3 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/libavutil/bprint.c b/libavutil/bprint.c
> index 64cd8db..4565698 100644
> --- a/libavutil/bprint.c
> +++ b/libavutil/bprint.c
> @@ -28,6 +28,7 @@
>  #include "common.h"
>  #include "error.h"
>  #include "mem.h"
> +#include "opt.h"
>  
>  #define av_bprint_room(buf) ((buf)->size - FFMIN((buf)->len, (buf)->size))
>  #define av_bprint_is_allocated(buf) ((buf)->str != (buf)->reserved_internal_buffer)
> @@ -262,6 +263,28 @@ int av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_char
>      return dstbuf->len;
>  }
>  
> +void av_bprint_options(struct AVBPrint *bp, void *ctx,
> +                       const char *key_val_sep, const char *pairs_sep)
> +{
> +    const AVOption *opt = NULL, *prev_opt = NULL;
> +
> +    while (opt = av_opt_next(ctx, opt)) {
> +        uint8_t *val;
> +        char sep[2] = { pairs_sep[0], 0 };
> +
> +        /* skip duplicated option values */
> +        if (prev_opt && prev_opt->offset == opt->offset)
> +            continue;
> +        av_opt_get(ctx, opt->name, AV_OPT_SEARCH_CHILDREN, &val);
> +        if (opt->offset) {
> +            av_bprintf(bp, "%s%s%c", prev_opt ? sep : "", opt->name, key_val_sep[0]);
> +            av_bprint_escape(bp, val, pairs_sep, AV_ESCAPE_MODE_BACKSLASH, 0);
> +            av_freep(&val);
> +        }
> +        prev_opt = opt;
> +    }
> +}
> +
>  #ifdef TEST
>  
>  #undef printf
> diff --git a/libavutil/bprint.h b/libavutil/bprint.h
> index b9039bd..316f99c 100644
> --- a/libavutil/bprint.h
> +++ b/libavutil/bprint.h
> @@ -195,4 +195,19 @@ int av_bprint_finalize(AVBPrint *buf, char **ret_str);
>  int av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
>                       enum AVEscapeMode mode, int flags);
>  
> +/**
> + * Append a compact description of the context options to a bprint buffer.

> + * The obtained string is escape, and can be used to set options through the function

escaped

> + * av_opt_set_from_string() or equivalent.

"the foobar() function", I believe.

> + *
> + * @param bp           already inited destination bprint buffer
> + * @param ctx          pointer to a context whose first field is a pointer to an AVClass
> + * @param key_val_sep  a 0-terminated list of characters used to separate
> + *                     key from value, for example '='
> + * @param pairs_sep    a 0-terminated list of characters used to separate
> + *                     two pairs from each other, for example ':' or ','
> + */
> +void av_bprint_options(struct AVBPrint *bp, void *ctx,
> +                       const char *key_val_sep, const char *pairs_sep);
> +
>  #endif /* AVUTIL_BPRINT_H */
> diff --git a/libavutil/opt.c b/libavutil/opt.c
> index 61c76da..5a02113 100644
> --- a/libavutil/opt.c
> +++ b/libavutil/opt.c
> @@ -27,7 +27,7 @@
>  
>  #include "avutil.h"
>  #include "avstring.h"
> -#include "common.h"
> +#include "bprint.h"
>  #include "opt.h"
>  #include "eval.h"
>  #include "dict.h"
> @@ -1329,6 +1329,7 @@ static const AVOption test_options[]= {
>  {"lame",     "set lame flag ", 0,                AV_OPT_TYPE_CONST,    {.i64 = TEST_FLAG_LAME}, INT_MIN,  INT_MAX, 0, "flags" },
>  {"mu",       "set mu flag ",   0,                AV_OPT_TYPE_CONST,    {.i64 = TEST_FLAG_MU},   INT_MIN,  INT_MAX, 0, "flags" },
>  {"size",     "set size",       OFFSET(w),        AV_OPT_TYPE_IMAGE_SIZE,{0},             0,        0                   },

> +{"s",        "set size",       OFFSET(w),        AV_OPT_TYPE_IMAGE_SIZE,{0},             0,        0                   },

Not entirely related, but I see the point.

>  {"pix_fmt",  "set pixfmt",     OFFSET(pix_fmt),  AV_OPT_TYPE_PIXEL_FMT, {.i64 = AV_PIX_FMT_NONE}, -1, AV_PIX_FMT_NB-1},
>  {"sample_fmt", "set samplefmt", OFFSET(sample_fmt), AV_OPT_TYPE_SAMPLE_FMT, {.i64 = AV_SAMPLE_FMT_NONE}, -1, AV_SAMPLE_FMT_NB-1},
>  {NULL},
> @@ -1348,6 +1349,7 @@ static const AVClass test_class = {
>  int main(void)
>  {
>      int i;
> +    AVBPrint bp;
>  
>      printf("\nTesting av_set_options_string()\n");
>      {
> @@ -1395,6 +1397,12 @@ int main(void)
>                  av_log(&test_ctx, AV_LOG_ERROR, "Error setting options string: '%s'\n", options[i]);
>              printf("\n");
>          }
> +
> +        av_bprint_init(&bp, 1, AV_BPRINT_SIZE_UNLIMITED);
> +        av_bprint_options(&bp, &test_ctx, "=", ":");
> +        printf("test_ctx=%s\n", bp.str);
> +        av_bprint_clear(&bp);
> +
>          av_freep(&test_ctx.string);
>      }
>  

Looks good. Wild idea, not blocking: try to determine whether the options
are at their default or not.

Regards,

-- 
  Nicolas George
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