FFmpeg
vf_blackframe.c
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1 /*
2  * Copyright (c) 2010 Stefano Sabatini
3  * Copyright (c) 2006 Ivo van Poorten
4  * Copyright (c) 2006 Julian Hall
5  * Copyright (c) 2002-2003 Brian J. Murrell
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License along
20  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22  */
23 
24 /**
25  * @file
26  * Search for black frames to detect scene transitions.
27  * Ported from MPlayer libmpcodecs/vf_blackframe.c.
28  */
29 
30 #include <stdio.h>
31 #include <inttypes.h>
32 
33 #include "libavutil/internal.h"
34 #include "libavutil/opt.h"
35 #include "avfilter.h"
36 #include "formats.h"
37 #include "internal.h"
38 #include "video.h"
39 
40 typedef struct BlackFrameContext {
41  const AVClass *class;
42  int bamount; ///< black amount
43  int bthresh; ///< black threshold
44  unsigned int frame; ///< frame number
45  unsigned int nblack; ///< number of black pixels counted so far
46  unsigned int last_keyframe; ///< frame number of the last received key-frame
48 
50 {
51  static const enum AVPixelFormat pix_fmts[] = {
55  };
56 
58  if (!fmts_list)
59  return AVERROR(ENOMEM);
60  return ff_set_common_formats(ctx, fmts_list);
61 }
62 
63 #define SET_META(key, format, value) \
64  snprintf(buf, sizeof(buf), format, value); \
65  av_dict_set(metadata, key, buf, 0)
66 
68 {
69  AVFilterContext *ctx = inlink->dst;
70  BlackFrameContext *s = ctx->priv;
71  int x, i;
72  int pblack = 0;
73  uint8_t *p = frame->data[0];
74  AVDictionary **metadata;
75  char buf[32];
76 
77  for (i = 0; i < frame->height; i++) {
78  for (x = 0; x < inlink->w; x++)
79  s->nblack += p[x] < s->bthresh;
80  p += frame->linesize[0];
81  }
82 
83  if (frame->key_frame)
84  s->last_keyframe = s->frame;
85 
86  pblack = s->nblack * 100 / (inlink->w * inlink->h);
87  if (pblack >= s->bamount) {
88  metadata = &frame->metadata;
89 
90  av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
91  "type:%c last_keyframe:%d\n",
92  s->frame, pblack, frame->pts,
93  frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
94  av_get_picture_type_char(frame->pict_type), s->last_keyframe);
95 
96  SET_META("lavfi.blackframe.pblack", "%u", pblack);
97  }
98 
99  s->frame++;
100  s->nblack = 0;
101  return ff_filter_frame(inlink->dst->outputs[0], frame);
102 }
103 
104 #define OFFSET(x) offsetof(BlackFrameContext, x)
105 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
106 static const AVOption blackframe_options[] = {
107  { "amount", "percentage of the pixels that have to be below the threshold "
108  "for the frame to be considered black", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100, FLAGS },
109  { "threshold", "threshold below which a pixel value is considered black",
110  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
111  { "thresh", "threshold below which a pixel value is considered black",
112  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
113  { NULL }
114 };
115 
116 AVFILTER_DEFINE_CLASS(blackframe);
117 
119  {
120  .name = "default",
121  .type = AVMEDIA_TYPE_VIDEO,
122  .filter_frame = filter_frame,
123  },
124  { NULL }
125 };
126 
128  {
129  .name = "default",
130  .type = AVMEDIA_TYPE_VIDEO
131  },
132  { NULL }
133 };
134 
136  .name = "blackframe",
137  .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
138  .priv_size = sizeof(BlackFrameContext),
139  .priv_class = &blackframe_class,
143 };
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
opt.h
ff_make_format_list
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:286
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1094
inlink
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
Definition: filter_design.txt:212
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:324
AVOption
AVOption.
Definition: opt.h:248
AVDictionary
Definition: dict.c:30
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:149
avfilter_vf_blackframe_outputs
static const AVFilterPad avfilter_vf_blackframe_outputs[]
Definition: vf_blackframe.c:127
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
Definition: vf_blackframe.c:67
video.h
BlackFrameContext::nblack
unsigned int nblack
number of black pixels counted so far
Definition: vf_blackframe.c:45
AVFilterFormats
A list of supported formats for one end of a filter link.
Definition: formats.h:65
formats.h
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:54
inputs
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
Definition: filter_design.txt:243
ff_set_common_formats
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:587
s
#define s(width, name)
Definition: cbs_vp9.c:257
av_q2d
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
outputs
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
pix_fmts
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:303
ctx
AVFormatContext * ctx
Definition: movenc.c:48
AV_PIX_FMT_YUV420P
@ AV_PIX_FMT_YUV420P
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:67
SET_META
#define SET_META(key, format, value)
Definition: vf_blackframe.c:63
NULL
#define NULL
Definition: coverity.c:32
avfilter_vf_blackframe_inputs
static const AVFilterPad avfilter_vf_blackframe_inputs[]
Definition: vf_blackframe.c:118
AV_PIX_FMT_GRAY8
@ AV_PIX_FMT_GRAY8
Y , 8bpp.
Definition: pixfmt.h:74
BlackFrameContext::bthresh
int bthresh
black threshold
Definition: vf_blackframe.c:43
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
BlackFrameContext::bamount
int bamount
black amount
Definition: vf_blackframe.c:42
AV_LOG_INFO
#define AV_LOG_INFO
Standard information.
Definition: log.h:205
internal.h
FLAGS
#define FLAGS
Definition: vf_blackframe.c:105
av_get_picture_type_char
char av_get_picture_type_char(enum AVPictureType pict_type)
Return a single letter to describe the given picture type pict_type.
Definition: utils.c:88
i
int i
Definition: input.c:407
ff_vf_blackframe
AVFilter ff_vf_blackframe
Definition: vf_blackframe.c:135
internal.h
blackframe_options
static const AVOption blackframe_options[]
Definition: vf_blackframe.c:106
BlackFrameContext::frame
unsigned int frame
frame number
Definition: vf_blackframe.c:44
uint8_t
uint8_t
Definition: audio_convert.c:194
AV_PIX_FMT_NV21
@ AV_PIX_FMT_NV21
as above, but U and V bytes are swapped
Definition: pixfmt.h:90
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:60
OFFSET
#define OFFSET(x)
Definition: vf_blackframe.c:104
AVFilter
Filter definition.
Definition: avfilter.h:145
AV_PIX_FMT_NV12
@ AV_PIX_FMT_NV12
planar YUV 4:2:0, 12bpp, 1 plane for Y and 1 plane for the UV components, which are interleaved (firs...
Definition: pixfmt.h:89
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
query_formats
static int query_formats(AVFilterContext *ctx)
Definition: vf_blackframe.c:49
AV_PIX_FMT_NONE
@ AV_PIX_FMT_NONE
Definition: pixfmt.h:65
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:225
avfilter.h
AV_PIX_FMT_YUV444P
@ AV_PIX_FMT_YUV444P
planar YUV 4:4:4, 24bpp, (1 Cr & Cb sample per 1x1 Y samples)
Definition: pixfmt.h:71
AVFilterContext
An instance of a filter.
Definition: avfilter.h:341
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AV_PIX_FMT_YUV422P
@ AV_PIX_FMT_YUV422P
planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
Definition: pixfmt.h:70
AV_PIX_FMT_YUV411P
@ AV_PIX_FMT_YUV411P
planar YUV 4:1:1, 12bpp, (1 Cr & Cb sample per 4x1 Y samples)
Definition: pixfmt.h:73
AV_PIX_FMT_YUV410P
@ AV_PIX_FMT_YUV410P
planar YUV 4:1:0, 9bpp, (1 Cr & Cb sample per 4x4 Y samples)
Definition: pixfmt.h:72
BlackFrameContext::last_keyframe
unsigned int last_keyframe
frame number of the last received key-frame
Definition: vf_blackframe.c:46
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
BlackFrameContext
Definition: vf_blackframe.c:40
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(blackframe)