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lavfi: add select filter 

Address trac issue #92.
tags/n0.8
Stefano Sabatini 14 years ago
parent
3c2c52baec
commit
07586b68a8
6 changed files with 471 additions and 1 deletions
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  1. +1
    -0
      Changelog
  2. +116
    -0
      doc/filters.texi
  3. +1
    -0
      libavfilter/Makefile
  4. +1
    -0
      libavfilter/allfilters.c
  5. +1
    -1
      libavfilter/avfilter.h
  6. +351
    -0
      libavfilter/vf_select.c

+ 1
- 0
Changelog View File

@@ -18,6 +18,7 @@ version <next>:
- 9bit and 10bit H.264 decoding
- 9bit and 10bit FFV1 encoding / decoding
- split filter added
- select filter added


version 0.7_beta1:


+ 116
- 0
doc/filters.texi View File

@@ -1163,6 +1163,122 @@ scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
scale='min(500\, iw*3/2):-1'
@end example

@section select
Select frames to pass in output.

It accepts in input an expression, which is evaluated for each input
frame. If the expression is evaluated to a non-zero value, the frame
is selected and passed to the output, otherwise it is discarded.

The expression can contain the following constants:

@table @option
@item PI
Greek PI

@item PHI
golden ratio

@item E
Euler number

@item n
the sequential number of the filtered frame, starting from 0

@item selected_n
the sequential number of the selected frame, starting from 0

@item prev_selected_n
the sequential number of the last selected frame, NAN if undefined

@item TB
timebase of the input timestamps

@item pts
the PTS (Presentation TimeStamp) of the filtered video frame,
expressed in @var{TB} units, NAN if undefined

@item t
the PTS (Presentation TimeStamp) of the filtered video frame,
expressed in seconds, NAN if undefined

@item prev_pts
the PTS of the previously filtered video frame, NAN if undefined

@item prev_selected_pts
the PTS of the last previously filtered video frame, NAN if undefined

@item prev_selected_t
the PTS of the last previously selected video frame, NAN if undefined

@item start_pts
the PTS of the first video frame in the video, NAN if undefined

@item start_t
the time of the first video frame in the video, NAN if undefined

@item pict_type
the picture type of the filtered frame, can assume one of the following
values:
@table @option
@item PICT_TYPE_I
@item PICT_TYPE_P
@item PICT_TYPE_B
@item PICT_TYPE_S
@item PICT_TYPE_SI
@item PICT_TYPE_SP
@item PICT_TYPE_BI
@end table

@item interlace_type
the frame interlace type, can assume one of the following values:
@table @option
@item INTERLACE_TYPE_P
the frame is progressive (not interlaced)
@item INTERLACE_TYPE_T
the frame is top-field-first
@item INTERLACE_TYPE_B
the frame is bottom-field-first
@end table

@item key
1 if the filtered frame is a key-frame, 0 otherwise

@item pos
the position in the file of the filtered frame, -1 if the information
is not available (e.g. for synthetic video)
@end table

The default value of the select expression is "1".

Some examples follow:

@example
# select all frames in input
select

# the above is the same as:
select=1

# skip all frames:
select=0

# select only I-frames
select='eq(pict_type\,PICT_TYPE_I)'

# select one frame every 100
select='not(mod(n\,100))'

# select only frames contained in the 10-20 time interval
select='gte(t\,10)*lte(t\,20)'

# select only I frames contained in the 10-20 time interval
select='gte(t\,10)*lte(t\,20)*eq(pict_type\,PICT_TYPE_I)'

# select frames with a minimum distance of 10 seconds
select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
@end example

@anchor{setdar}
@section setdar



+ 1
- 0
libavfilter/Makefile View File

@@ -46,6 +46,7 @@ OBJS-$(CONFIG_OVERLAY_FILTER) += vf_overlay.o
OBJS-$(CONFIG_PAD_FILTER) += vf_pad.o
OBJS-$(CONFIG_PIXDESCTEST_FILTER) += vf_pixdesctest.o
OBJS-$(CONFIG_SCALE_FILTER) += vf_scale.o
OBJS-$(CONFIG_SELECT_FILTER) += vf_select.o
OBJS-$(CONFIG_SETDAR_FILTER) += vf_aspect.o
OBJS-$(CONFIG_SETPTS_FILTER) += vf_setpts.o
OBJS-$(CONFIG_SETSAR_FILTER) += vf_aspect.o


+ 1
- 0
libavfilter/allfilters.c View File

@@ -62,6 +62,7 @@ void avfilter_register_all(void)
REGISTER_FILTER (PAD, pad, vf);
REGISTER_FILTER (PIXDESCTEST, pixdesctest, vf);
REGISTER_FILTER (SCALE, scale, vf);
REGISTER_FILTER (SELECT, select, vf);
REGISTER_FILTER (SETDAR, setdar, vf);
REGISTER_FILTER (SETPTS, setpts, vf);
REGISTER_FILTER (SETSAR, setsar, vf);


+ 1
- 1
libavfilter/avfilter.h View File

@@ -26,7 +26,7 @@
#include "libavutil/samplefmt.h"

#define LIBAVFILTER_VERSION_MAJOR 2
#define LIBAVFILTER_VERSION_MINOR 10
#define LIBAVFILTER_VERSION_MINOR 11
#define LIBAVFILTER_VERSION_MICRO 0

#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \


+ 351
- 0
libavfilter/vf_select.c View File

@@ -0,0 +1,351 @@
/*
* Copyright (c) 2011 Stefano Sabatini
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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
* filter for selecting which frame passes in the filterchain
*/

#include "libavutil/eval.h"
#include "libavutil/fifo.h"
#include "avfilter.h"

static const char *var_names[] = {
"E", ///< Euler number
"PHI", ///< golden ratio
"PI", ///< greek pi

"TB", ///< timebase

"pts", ///< original pts in the file of the frame
"start_pts", ///< first PTS in the stream, expressed in TB units
"prev_pts", ///< previous frame PTS
"prev_selected_pts", ///< previous selected frame PTS

"t", ///< first PTS in seconds
"start_t", ///< first PTS in the stream, expressed in seconds
"prev_t", ///< previous frame time
"prev_selected_t", ///< previously selected time

"pict_type", ///< the type of picture in the movie
"PICT_TYPE_I",
"PICT_TYPE_P",
"PICT_TYPE_B",
"PICT_TYPE_S",
"PICT_TYPE_SI",
"PICT_TYPE_SP",
"PICT_TYPE_BI",

"interlace_type", ///< the frame interlace type
"INTERLACE_TYPE_P",
"INTERLACE_TYPE_T",
"INTERLACE_TYPE_B",

"n", ///< frame number (starting from zero)
"selected_n", ///< selected frame number (starting from zero)
"prev_selected_n", ///< number of the last selected frame

"key", ///< tell if the frame is a key frame
"pos", ///< original position in the file of the frame

NULL
};

enum var_name {
VAR_E,
VAR_PHI,
VAR_PI,

VAR_TB,

VAR_PTS,
VAR_START_PTS,
VAR_PREV_PTS,
VAR_PREV_SELECTED_PTS,

VAR_T,
VAR_START_T,
VAR_PREV_T,
VAR_PREV_SELECTED_T,

VAR_PICT_TYPE,
VAR_PICT_TYPE_I,
VAR_PICT_TYPE_P,
VAR_PICT_TYPE_B,
VAR_PICT_TYPE_S,
VAR_PICT_TYPE_SI,
VAR_PICT_TYPE_SP,
VAR_PICT_TYPE_BI,

VAR_INTERLACE_TYPE,
VAR_INTERLACE_TYPE_P,
VAR_INTERLACE_TYPE_T,
VAR_INTERLACE_TYPE_B,

VAR_N,
VAR_SELECTED_N,
VAR_PREV_SELECTED_N,

VAR_KEY,
VAR_POS,

VAR_VARS_NB
};

#define FIFO_SIZE 8

typedef struct {
AVExpr *expr;
double var_values[VAR_VARS_NB];
double select;
int cache_frames;
AVFifoBuffer *pending_frames; ///< FIFO buffer of video frames
} SelectContext;

static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
{
SelectContext *select = ctx->priv;
int ret;

if ((ret = av_expr_parse(&select->expr, args ? args : "1",
var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
return ret;
}

select->pending_frames = av_fifo_alloc(FIFO_SIZE*sizeof(AVFilterBufferRef*));
if (!select->pending_frames) {
av_log(ctx, AV_LOG_ERROR, "Failed to allocate pending frames buffer.\n");
return AVERROR(ENOMEM);
}
return 0;
}

#define INTERLACE_TYPE_P 0
#define INTERLACE_TYPE_T 1
#define INTERLACE_TYPE_B 2

static int config_input(AVFilterLink *inlink)
{
SelectContext *select = inlink->dst->priv;

select->var_values[VAR_E] = M_E;
select->var_values[VAR_PHI] = M_PHI;
select->var_values[VAR_PI] = M_PI;

select->var_values[VAR_N] = 0.0;
select->var_values[VAR_SELECTED_N] = 0.0;

select->var_values[VAR_TB] = av_q2d(inlink->time_base);

select->var_values[VAR_PREV_PTS] = NAN;
select->var_values[VAR_PREV_SELECTED_PTS] = NAN;
select->var_values[VAR_PREV_SELECTED_T] = NAN;
select->var_values[VAR_START_PTS] = NAN;
select->var_values[VAR_START_T] = NAN;

select->var_values[VAR_PICT_TYPE_I] = AV_PICTURE_TYPE_I;
select->var_values[VAR_PICT_TYPE_P] = AV_PICTURE_TYPE_P;
select->var_values[VAR_PICT_TYPE_B] = AV_PICTURE_TYPE_B;
select->var_values[VAR_PICT_TYPE_SI] = AV_PICTURE_TYPE_SI;
select->var_values[VAR_PICT_TYPE_SP] = AV_PICTURE_TYPE_SP;

select->var_values[VAR_INTERLACE_TYPE_P] = INTERLACE_TYPE_P;
select->var_values[VAR_INTERLACE_TYPE_T] = INTERLACE_TYPE_T;
select->var_values[VAR_INTERLACE_TYPE_B] = INTERLACE_TYPE_B;;

return 0;
}

#define D2TS(d) (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
#define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))

static int select_frame(AVFilterContext *ctx, AVFilterBufferRef *picref)
{
SelectContext *select = ctx->priv;
AVFilterLink *inlink = ctx->inputs[0];
double res;

if (isnan(select->var_values[VAR_START_PTS]))
select->var_values[VAR_START_PTS] = TS2D(picref->pts);

select->var_values[VAR_PTS] = TS2D(picref->pts);
select->var_values[VAR_T ] = picref->pts * av_q2d(inlink->time_base);
select->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;
select->var_values[VAR_PREV_PTS] = TS2D(picref ->pts);

select->var_values[VAR_INTERLACE_TYPE] =
!picref->video->interlaced ? INTERLACE_TYPE_P :
picref->video->top_field_first ? INTERLACE_TYPE_T : INTERLACE_TYPE_B;
select->var_values[VAR_PICT_TYPE] = picref->video->pict_type;

res = av_expr_eval(select->expr, select->var_values, NULL);
av_log(inlink->dst, AV_LOG_DEBUG,
"n:%d pts:%d t:%f pos:%d interlace_type:%c key:%d pict_type:%c "
"-> select:%f\n",
(int)select->var_values[VAR_N],
(int)select->var_values[VAR_PTS],
select->var_values[VAR_T],
(int)select->var_values[VAR_POS],
select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_P ? 'P' :
select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_T ? 'T' :
select->var_values[VAR_INTERLACE_TYPE] == INTERLACE_TYPE_B ? 'B' : '?',
(int)select->var_values[VAR_KEY],
av_get_picture_type_char(select->var_values[VAR_PICT_TYPE]),
res);

select->var_values[VAR_N] += 1.0;

if (res) {
select->var_values[VAR_PREV_SELECTED_N] = select->var_values[VAR_N];
select->var_values[VAR_PREV_SELECTED_PTS] = select->var_values[VAR_PTS];
select->var_values[VAR_PREV_SELECTED_T] = select->var_values[VAR_T];
select->var_values[VAR_SELECTED_N] += 1.0;
}
return res;
}

static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
{
SelectContext *select = inlink->dst->priv;

select->select = select_frame(inlink->dst, picref);
if (select->select) {
/* frame was requested through poll_frame */
if (select->cache_frames) {
if (!av_fifo_space(select->pending_frames))
av_log(inlink->dst, AV_LOG_ERROR,
"Buffering limit reached, cannot cache more frames\n");
else
av_fifo_generic_write(select->pending_frames, &picref,
sizeof(picref), NULL);
return;
}
avfilter_start_frame(inlink->dst->outputs[0], avfilter_ref_buffer(picref, ~0));
}
}

static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
{
SelectContext *select = inlink->dst->priv;

if (select->select && !select->cache_frames)
avfilter_draw_slice(inlink->dst->outputs[0], y, h, slice_dir);
}

static void end_frame(AVFilterLink *inlink)
{
SelectContext *select = inlink->dst->priv;
AVFilterBufferRef *picref = inlink->cur_buf;

if (select->select) {
if (select->cache_frames)
return;
avfilter_end_frame(inlink->dst->outputs[0]);
}
avfilter_unref_buffer(picref);
}

static int request_frame(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
SelectContext *select = ctx->priv;
AVFilterLink *inlink = outlink->src->inputs[0];
select->select = 0;

if (av_fifo_size(select->pending_frames)) {
AVFilterBufferRef *picref;
av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
avfilter_start_frame(outlink, avfilter_ref_buffer(picref, ~0));
avfilter_draw_slice(outlink, 0, outlink->h, 1);
avfilter_end_frame(outlink);
avfilter_unref_buffer(picref);
return 0;
}

while (!select->select) {
int ret = avfilter_request_frame(inlink);
if (ret < 0)
return ret;
}

return 0;
}

static int poll_frame(AVFilterLink *outlink)
{
SelectContext *select = outlink->src->priv;
AVFilterLink *inlink = outlink->src->inputs[0];
int count, ret;

if (!av_fifo_size(select->pending_frames)) {
if ((count = avfilter_poll_frame(inlink)) <= 0)
return count;
/* request frame from input, and apply select condition to it */
select->cache_frames = 1;
while (count-- && av_fifo_space(select->pending_frames)) {
ret = avfilter_request_frame(inlink);
if (ret < 0)
break;
}
select->cache_frames = 0;
}

return av_fifo_size(select->pending_frames)/sizeof(AVFilterBufferRef *);
}

static av_cold void uninit(AVFilterContext *ctx)
{
SelectContext *select = ctx->priv;
AVFilterBufferRef *picref;
int i;

av_expr_free(select->expr);
select->expr = NULL;

for (i = 0; i < av_fifo_size(select->pending_frames)/sizeof(picref); i++) {
av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL);
avfilter_unref_buffer(picref);
}
av_fifo_free(select->pending_frames);
}

AVFilter avfilter_vf_select = {
.name = "select",
.description = NULL_IF_CONFIG_SMALL("Select frames to pass in output."),
.init = init,
.uninit = uninit,

.priv_size = sizeof(SelectContext),

.inputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.get_video_buffer = avfilter_null_get_video_buffer,
.config_props = config_input,
.start_frame = start_frame,
.draw_slice = draw_slice,
.end_frame = end_frame },
{ .name = NULL }},
.outputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.poll_frame = poll_frame,
.request_frame = request_frame, },
{ .name = NULL}},
};

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