@@ -46,6 +46,7 @@ easier to use. The changes are:

 - showinfo filter

 - split filter

 - libcdio-paranoia input device for audio CD grabbing

+- select filter

 version 0.7:

@@ -1064,6 +1064,122 @@ 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 type of the filtered frame, can assume one of the following

+values:

+@table @option

+@item I

+@item P

+@item B

+@item S

+@item SI

+@item SP

+@item BI

+@end table

+

+@item interlace_type

+the frame interlace type, can assume one of the following values:

+@table @option

+@item PROGRESSIVE

+the frame is progressive (not interlaced)

+@item TOPFIRST

+the frame is top-field-first

+@item BOTTOMFIRST

+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\,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\,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

@@ -40,6 +40,7 @@ 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

@@ -61,6 +61,7 @@ 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);

@@ -29,7 +29,7 @@

 #include "libavutil/rational.h"

 #define LIBAVFILTER_VERSION_MAJOR  2

-#define LIBAVFILTER_VERSION_MINOR  6

+#define LIBAVFILTER_VERSION_MINOR  7

 #define LIBAVFILTER_VERSION_MICRO  0

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

new file mode 100644

@@ -0,0 +1,353 @@

+/*

+ * Copyright (c) 2011 Stefano Sabatini

+ *

+ * This file is part of Libav.

+ *

+ * Libav 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.

+ *

+ * Libav 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 Libav; 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 "libavutil/mathematics.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

+    "I",

+    "P",

+    "B",

+    "S",

+    "SI",

+    "SP",

+    "BI",

+

+    "interlace_type",    ///< the frame interlace type

+    "PROGRESSIVE",

+    "TOPFIRST",

+    "BOTTOMFIRST",

+

+    "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);

+    if (isnan(select->var_values[VAR_START_T]))

+        select->var_values[VAR_START_T] = TS2D(picref->pts) * av_q2d(inlink->time_base);

+

+    select->var_values[VAR_PTS] = TS2D(picref->pts);

+    select->var_values[VAR_T  ] = TS2D(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;

+

+    av_expr_free(select->expr);

+    select->expr = NULL;

+

+    while (select->pending_frames &&

+           av_fifo_generic_read(select->pending_frames, &picref, sizeof(picref), NULL) == sizeof(picref))

+        avfilter_unref_buffer(picref);

+    av_fifo_free(select->pending_frames);

+    select->pending_frames = NULL;

+}

+

+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}},

+};