[FFmpeg-devel] [PATCH] Port MPlayer blackframe filter.
Michael Niedermayer
michaelni
Sun Sep 26 01:25:49 CEST 2010
On Sun, Sep 26, 2010 at 01:15:29AM +0200, Stefano Sabatini wrote:
> On date Sunday 2010-09-26 01:10:40 +0200, Stefano Sabatini encoded:
> > ---
> > configure | 1 +
> > doc/filters.texi | 21 ++++++++
> > libavfilter/Makefile | 1 +
> > libavfilter/allfilters.c | 1 +
> > libavfilter/vf_blackframe.c | 120 +++++++++++++++++++++++++++++++++++++++++++
> > 5 files changed, 144 insertions(+), 0 deletions(-)
> > create mode 100644 libavfilter/vf_blackframe.c
>
> Fixed the wrong LGPL header.
>
> Regards.
> --
> FFmpeg = Faithful and Foolish Minimalistic Portable Exploitable Gadget
> configure | 1
> doc/filters.texi | 21 +++++++
> libavfilter/Makefile | 1
> libavfilter/allfilters.c | 1
> libavfilter/vf_blackframe.c | 120 ++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 144 insertions(+)
> 27f565415a3a00e2494659a5d2ade3dcc214b722 0001-Port-MPlayer-blackframe-filter.patch
> From 9cb3d9f571990c2af2dca33f52b07d83f5ee3f37 Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefano.sabatini-lala at poste.it>
> Date: Sun, 26 Sep 2010 00:17:09 +0200
> Subject: [PATCH] Port MPlayer blackframe filter.
>
> ---
> configure | 1 +
> doc/filters.texi | 21 ++++++++
> libavfilter/Makefile | 1 +
> libavfilter/allfilters.c | 1 +
> libavfilter/vf_blackframe.c | 120 +++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 144 insertions(+), 0 deletions(-)
> create mode 100644 libavfilter/vf_blackframe.c
>
> diff --git a/configure b/configure
> index 0538201..417145a 100755
> --- a/configure
> +++ b/configure
> @@ -1401,6 +1401,7 @@ tcp_protocol_deps="network"
> udp_protocol_deps="network"
>
> # filters
> +blackframe_filter_deps="gpl"
> ocv_smooth_filter_deps="libopencv"
> yadif_filter_deps="gpl"
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index d000276..5ebaf99 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -71,6 +71,27 @@ build.
>
> Below is a description of the currently available video filters.
>
> + at section blackframe
> +
> +Detect frames that are (almost) completely black. Can be useful to
> +detect chapter transitions or commercials. Output lines consist of
> +the frame number of the detected frame, the percentage of blackness,
> +the position in the file if known or -1 and the timestamp in seconds.
> +
> +In order to display the output lines, you need to set the loglevel at
> +least to the AV_LOG_INFO value.
> +
> +The filter accepts the syntax:
> + at example
> +blackframe[=@var{amount}:[@var{threshold}]]
> + at end example
> +
> + at var{amount} is the percentage of the pixels that have to be below the
> +threshold, and defaults to 98.
> +
> + at var{threshold} is the threshold below which a pixel value is
> +considered black, and defaults to 32.
> +
> @section crop
>
> Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 174b83e..51fe208 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -21,6 +21,7 @@ OBJS-$(CONFIG_ANULLSRC_FILTER) += asrc_anullsrc.o
> OBJS-$(CONFIG_ANULLSINK_FILTER) += asink_anullsink.o
>
> OBJS-$(CONFIG_ASPECT_FILTER) += vf_aspect.o
> +OBJS-$(CONFIG_BLACKFRAME_FILTER) += vf_blackframe.o
> OBJS-$(CONFIG_CROP_FILTER) += vf_crop.o
> OBJS-$(CONFIG_FIFO_FILTER) += vf_fifo.o
> OBJS-$(CONFIG_FORMAT_FILTER) += vf_format.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index ec7d933..d9681e6 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -41,6 +41,7 @@ void avfilter_register_all(void)
> REGISTER_FILTER (ANULLSINK, anullsink, asink);
>
> REGISTER_FILTER (ASPECT, aspect, vf);
> + REGISTER_FILTER (BLACKFRAME, blackframe, vf);
> REGISTER_FILTER (CROP, crop, vf);
> REGISTER_FILTER (FIFO, fifo, vf);
> REGISTER_FILTER (FORMAT, format, vf);
> diff --git a/libavfilter/vf_blackframe.c b/libavfilter/vf_blackframe.c
> new file mode 100644
> index 0000000..b896d5d
> --- /dev/null
> +++ b/libavfilter/vf_blackframe.c
> @@ -0,0 +1,120 @@
> +/*
> + * Copyright (C) 2010 Stefano Sabatini
> + * Copyright (C) 2006 Ivo van Poorten
> + * Copyright (C) 2006 Julian Hall
> + * Copyright (C) 2002-2003 Brian J. Murrell
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
> + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
> + */
> +
> +/**
> + * @file
> + * Search for black frames to detect scene transitions.
> + * Ported from MPlayer libmpcodecs/vf_blackframe.c.
> + */
> +
> +#include "avfilter.h"
> +
> +typedef struct {
> + unsigned int bamount; ///< black amount
> + unsigned int bthresh; ///< black threshold
> + unsigned int frame; ///< frame number
> +} BlackFrameContext;
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> + static const enum PixelFormat pix_fmts[] = {
> + PIX_FMT_YUV410P, PIX_FMT_YUV420P, PIX_FMT_GRAY8, PIX_FMT_NV12,
> + PIX_FMT_NV21, PIX_FMT_YUV444P, PIX_FMT_YUV422P, PIX_FMT_YUV411P,
> + PIX_FMT_NONE
> + };
> +
> + avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
> + return 0;
> +}
> +
> +static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
> +{
> + BlackFrameContext *blackframe = ctx->priv;
> +
> + blackframe->bamount = 98;
> + blackframe->bthresh = 32;
> + blackframe->frame = 0;
> +
> + if (args)
> + sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
> +
> + av_log(ctx, AV_LOG_INFO, "bamount:%u bthresh:%u\n",
> + blackframe->bamount, blackframe->bthresh);
> +
> + if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
> + av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
> + return AVERROR(EINVAL);
> + }
> +
> + return 0;
> +}
> +
> +static void null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir) { }
> +
> +static void end_frame(AVFilterLink *inlink)
> +{
> + AVFilterContext *ctx = inlink->dst;
> + BlackFrameContext *blackframe = ctx->priv;
> + AVFilterBufferRef *picref = inlink->cur_buf;
> + int x, y, nblack = 0, pblack = 0;
> + uint8_t *p = picref->data[0];
> +
> + for (y = 1; y <= inlink->h; y++) {
> + for (x = 0; x < inlink->w; x++)
> + nblack += p[x] < blackframe->bthresh;
> + pblack = nblack * 100 / (inlink->w * y);
> + if (pblack < blackframe->bamount)
> + break;
> + p += picref->linesize[0];
> + }
This code belongs in draw_slice()
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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