[FFmpeg-devel] [PATCH] avfilter/vf_delogo: support expr in delogo filter

[Liu Steven]

> 在 2019年8月27日，上午11:02，Steven Liu <lq at chinaffmpeg.org> 写道：
> 
> Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
> ---
> libavfilter/vf_delogo.c | 72 ++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 68 insertions(+), 4 deletions(-)
> 
> diff --git a/libavfilter/vf_delogo.c b/libavfilter/vf_delogo.c
> index 065d093641..b50699fb4d 100644
> --- a/libavfilter/vf_delogo.c
> +++ b/libavfilter/vf_delogo.c
> @@ -31,10 +31,52 @@
> #include "libavutil/imgutils.h"
> #include "libavutil/opt.h"
> #include "libavutil/pixdesc.h"
> +#include "libavutil/eval.h"
> #include "avfilter.h"
> #include "formats.h"
> #include "internal.h"
> #include "video.h"
> +static const char * const var_names[] = {
> +    "x",
> +    "y",
> +    "w",
> +    "h",
> +    "n",            ///< number of frame
> +    "t",            ///< timestamp expressed in seconds
> +    NULL
> +};
> +
> +enum var_name {
> +    VAR_X,
> +    VAR_Y,
> +    VAR_W,
> +    VAR_H,
> +    VAR_N,
> +    VAR_T,
> +    VAR_VARS_NB
> +};
> +#define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts) * av_q2d(tb))
> +
> +static int set_expr(AVExpr **pexpr, const char *expr, const char *option, void *log_ctx)
> +{
> +    int ret;
> +    AVExpr *old = NULL;
> +
> +    if (*pexpr)
> +        old = *pexpr;
> +    ret = av_expr_parse(pexpr, expr, var_names, NULL, NULL, NULL, NULL, 0, log_ctx);
> +    if (ret < 0) {
> +        av_log(log_ctx, AV_LOG_ERROR,
> +               "Error when parsing the expression '%s' for %s\n",
> +               expr, option);
> +        *pexpr = old;
> +        return ret;
> +    }
> +
> +    av_expr_free(old);
> +    return 0;
> +}
> +
> 
> /**
>  * Apply a simple delogo algorithm to the image in src and put the
> @@ -156,16 +198,19 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
> typedef struct DelogoContext {
>     const AVClass *class;
>     int x, y, w, h, band, show;
> +    char *x_expr, *y_expr, *w_expr, *h_expr;
> +    AVExpr *x_pexpr, *y_pexpr, *w_pexpr, *h_pexpr;
> +    double var_values[VAR_VARS_NB];
> }  DelogoContext;
> 
> #define OFFSET(x) offsetof(DelogoContext, x)
> #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
> 
> static const AVOption delogo_options[]= {
> -    { "x",    "set logo x position",       OFFSET(x),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> -    { "y",    "set logo y position",       OFFSET(y),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> -    { "w",    "set logo width",            OFFSET(w),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> -    { "h",    "set logo height",           OFFSET(h),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, FLAGS },
> +    { "x",    "set logo x position",       OFFSET(x_expr),    AV_OPT_TYPE_STRING, { .str = "-1" }, CHAR_MIN, CHAR_MAX, FLAGS },
> +    { "y",    "set logo y position",       OFFSET(y_expr),    AV_OPT_TYPE_STRING, { .str = "-1" }, CHAR_MIN, CHAR_MAX, FLAGS },
> +    { "w",    "set logo width",            OFFSET(w_expr),    AV_OPT_TYPE_STRING, { .i64 = "-1" }, CHAR_MIN, CHAR_MAX, FLAGS },
> +    { "h",    "set logo height",           OFFSET(h_expr),    AV_OPT_TYPE_STRING, { .i64 = "-1" }, CHAR_MIN, CHAR_MAX, FLAGS },
Ah, i64 should modify to str, i will resubmit new version patch.
> #if LIBAVFILTER_VERSION_MAJOR < 7
>     /* Actual default value for band/t is 1, set in init */
>     { "band", "set delogo area band size", OFFSET(band), AV_OPT_TYPE_INT, { .i64 =  0 },  0, INT_MAX, FLAGS },
> @@ -194,6 +239,18 @@ static int query_formats(AVFilterContext *ctx)
> static av_cold int init(AVFilterContext *ctx)
> {
>     DelogoContext *s = ctx->priv;
> +    int ret = 0;
> +
> +    if ((ret = set_expr(&s->x_pexpr, s->x_expr, "x", ctx)) < 0 ||
> +        (ret = set_expr(&s->y_pexpr, s->y_expr, "y", ctx)) < 0 ||
> +        (ret = set_expr(&s->w_pexpr, s->w_expr, "w", ctx)) < 0 ||
> +        (ret = set_expr(&s->h_pexpr, s->h_expr, "h", ctx)) < 0 )
> +        return ret;
> +
> +    s->x = av_expr_eval(s->x_pexpr, s->var_values, s);
> +    s->y = av_expr_eval(s->y_pexpr, s->var_values, s);
> +    s->w = av_expr_eval(s->w_pexpr, s->var_values, s);
> +    s->h = av_expr_eval(s->h_pexpr, s->var_values, s);
> 
> #define CHECK_UNSET_OPT(opt)                                            \
>     if (s->opt == -1) {                                            \
> @@ -252,6 +309,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
>     int plane;
>     AVRational sar;
> 
> +    s->var_values[VAR_N] = inlink->frame_count_out;
> +    s->var_values[VAR_T] = TS2T(in->pts, inlink->time_base);
> +    s->x = av_expr_eval(s->x_pexpr, s->var_values, s);
> +    s->y = av_expr_eval(s->y_pexpr, s->var_values, s);
> +    s->w = av_expr_eval(s->w_pexpr, s->var_values, s);
> +    s->h = av_expr_eval(s->h_pexpr, s->var_values, s);
> +
>     if (av_frame_is_writable(in)) {
>         direct = 1;
>         out = in;
> -- 
> 2.17.2 (Apple Git-113)
> 
> 
> 
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