PeerStreamer

/*

 * Copyright (c) 2010 Stefano Sabatini

 * Copyright (c) 2008 Victor Paesa

 *

 * 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

 * video presentation timestamp (PTS) modification filter

 */

/* #define DEBUG */

#include "libavutil/eval.h"

#include "avfilter.h"

static const char *var_names[] = {

    "E",           ///< Euler number

    "INTERLACED",  ///< tell if the current frame is interlaced

    "N",           ///< frame number (starting at zero)

    "PHI",         ///< golden ratio

    "PI",          ///< greek pi

    "POS",         ///< original position in the file of the frame

    "PREV_INPTS",  ///< previous  input PTS

    "PREV_OUTPTS", ///< previous output PTS

    "PTS",         ///< original pts in the file of the frame

    "STARTPTS",   ///< PTS at start of movie

    "TB",          ///< timebase

    NULL

};

enum var_name {

    VAR_E,

    VAR_INTERLACED,

    VAR_N,

    VAR_PHI,

    VAR_PI,

    VAR_POS,

    VAR_PREV_INPTS,

    VAR_PREV_OUTPTS,

    VAR_PTS,

    VAR_STARTPTS,

    VAR_TB,

    VAR_VARS_NB

};

typedef struct {

    AVExpr *expr;

    double var_values[VAR_VARS_NB];

} SetPTSContext;

static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)

{

    SetPTSContext *setpts = ctx->priv;

    int ret;

    if ((ret = av_expr_parse(&setpts->expr, args ? args : "PTS",

                             var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {

        av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);

        return ret;

    }

    setpts->var_values[VAR_E          ] = M_E;

    setpts->var_values[VAR_N          ] = 0.0;

    setpts->var_values[VAR_PHI        ] = M_PHI;

    setpts->var_values[VAR_PI         ] = M_PI;

    setpts->var_values[VAR_PREV_INPTS ] = NAN;

    setpts->var_values[VAR_PREV_OUTPTS] = NAN;

    setpts->var_values[VAR_STARTPTS   ] = NAN;

    return 0;

}

static int config_input(AVFilterLink *inlink)

{

    SetPTSContext *setpts = inlink->dst->priv;

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

    av_log(inlink->src, AV_LOG_INFO, "TB:%f\n", setpts->var_values[VAR_TB]);

    return 0;

}

#define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))

#define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))

static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)

{

    SetPTSContext *setpts = inlink->dst->priv;

    double d;

    AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);

    if (isnan(setpts->var_values[VAR_STARTPTS]))

        setpts->var_values[VAR_STARTPTS] = TS2D(inpicref->pts);

    setpts->var_values[VAR_INTERLACED] = inpicref->video->interlaced;

    setpts->var_values[VAR_PTS       ] = TS2D(inpicref->pts);

    setpts->var_values[VAR_POS       ] = inpicref->pos == -1 ? NAN : inpicref->pos;

    d = av_expr_eval(setpts->expr, setpts->var_values, NULL);

    outpicref->pts = D2TS(d);

#ifdef DEBUG

    av_log(inlink->dst, AV_LOG_DEBUG,

           "n:%"PRId64" interlaced:%d pos:%"PRId64" pts:%"PRId64" t:%f -> pts:%"PRId64" t:%f\n",

           (int64_t)setpts->var_values[VAR_N],

           (int)setpts->var_values[VAR_INTERLACED],

           inpicref ->pos,

           inpicref ->pts, inpicref ->pts * av_q2d(inlink->time_base),

           outpicref->pts, outpicref->pts * av_q2d(inlink->time_base));

#endif

    setpts->var_values[VAR_N] += 1.0;

    setpts->var_values[VAR_PREV_INPTS ] = TS2D(inpicref ->pts);

    setpts->var_values[VAR_PREV_OUTPTS] = TS2D(outpicref->pts);

    avfilter_start_frame(inlink->dst->outputs[0], outpicref);

}

static av_cold void uninit(AVFilterContext *ctx)

{

    SetPTSContext *setpts = ctx->priv;

    av_expr_free(setpts->expr);

    setpts->expr = NULL;

}

AVFilter avfilter_vf_setpts = {

    .name      = "setpts",

    .description = NULL_IF_CONFIG_SMALL("Set PTS for the output video frame."),

    .init      = init,

    .uninit    = uninit,

    .priv_size = sizeof(SetPTSContext),

    .inputs    = (AVFilterPad[]) {{ .name             = "default",

                                    .type             = AVMEDIA_TYPE_VIDEO,

                                    .get_video_buffer = avfilter_null_get_video_buffer,

                                    .config_props     = config_input,

                                    .start_frame      = start_frame, },

                                  { .name = NULL }},

    .outputs   = (AVFilterPad[]) {{ .name             = "default",

                                    .type             = AVMEDIA_TYPE_VIDEO, },

                                  { .name = NULL}},

};