@@ -148,7 +148,6 @@ typedef struct Stereo3DContext {

     int hsub, vsub;

     int pixstep[4];

     AVFrame *prev;

-    double ts_unit;

     int blanks;

     int in_off_left[4], in_off_right[4];

     Stereo3DDSPContext dsp;

@@ -544,7 +543,6 @@ static int config_output(AVFilterLink *outlink)

         return ret;

     s->nb_planes = av_pix_fmt_count_planes(outlink->format);

     av_image_fill_max_pixsteps(s->pixstep, NULL, desc);

-    s->ts_unit = av_q2d(av_inv_q(av_mul_q(outlink->frame_rate, outlink->time_base)));

     s->pheight[1] = s->pheight[2] = FF_CEIL_RSHIFT(s->height, desc->log2_chroma_h);

     s->pheight[0] = s->pheight[3] = s->height;

     s->hsub = desc->log2_chroma_w;

@@ -593,11 +591,21 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)

     AVFilterLink *outlink = ctx->outputs[0];

     AVFrame *out, *oleft, *oright, *ileft, *iright;

     int out_off_left[4], out_off_right[4];

-    int i;

+    int i, ret;

     if (s->in.format == s->out.format)

         return ff_filter_frame(outlink, inpicref);

+    switch (s->out.format) {

+    case ALTERNATING_LR:

+    case ALTERNATING_RL:

+        if (!s->prev) {

+            s->prev = inpicref;

+            return 0;

+        }

+        break;

+    };

+

     switch (s->in.format) {

     case ALTERNATING_LR:

     case ALTERNATING_RL:

@@ -624,8 +632,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)

          s->in.format == ABOVE_BELOW_RL ||

          s->in.format == ABOVE_BELOW_2_LR ||

          s->in.format == ABOVE_BELOW_2_RL)) {

-        oright = av_frame_clone(inpicref);

-        oleft  = av_frame_clone(inpicref);

+        oright = av_frame_clone(s->prev);

+        oleft  = av_frame_clone(s->prev);

         if (!oright || !oleft) {

             av_frame_free(&oright);

             av_frame_free(&oleft);

@@ -649,6 +657,25 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)

             av_frame_free(&inpicref);

             return AVERROR(ENOMEM);

         }

+    } else if ((s->out.format == MONO_L && s->in.format == ALTERNATING_LR) ||

+               (s->out.format == MONO_R && s->in.format == ALTERNATING_RL)) {

+        s->prev->pts /= 2;

+        ret = ff_filter_frame(outlink, s->prev);

+        av_frame_free(&inpicref);

+        s->prev = NULL;

+        return ret;

+    } else if ((s->out.format == MONO_L && s->in.format == ALTERNATING_RL) ||

+               (s->out.format == MONO_R && s->in.format == ALTERNATING_LR)) {

+        av_frame_free(&s->prev);

+        inpicref->pts /= 2;

+        return ff_filter_frame(outlink, inpicref);

+    } else if ((s->out.format == ALTERNATING_LR && s->in.format == ALTERNATING_RL) ||

+               (s->out.format == ALTERNATING_RL && s->in.format == ALTERNATING_LR)) {

+        FFSWAP(int64_t, s->prev->pts, inpicref->pts);

+        ff_filter_frame(outlink, inpicref);

+        ret = ff_filter_frame(outlink, s->prev);

+        s->prev = NULL;

+        return ret;

     } else {

         out = oleft = oright = ff_get_video_buffer(outlink, outlink->w, outlink->h);

         if (!out) {

@@ -667,7 +694,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)

                 av_frame_free(&inpicref);

                 return AVERROR(ENOMEM);

             }

-            av_frame_copy_props(oright, inpicref);

+            av_frame_copy_props(oright, s->prev);

         }

     }

@@ -902,18 +929,23 @@ copy:

         av_assert0(0);

     }

-    av_frame_free(&inpicref);

-    av_frame_free(&s->prev);

     if (oright != oleft) {

         if (s->out.format == ALTERNATING_LR)

             FFSWAP(AVFrame *, oleft, oright);

-        oright->pts = outlink->frame_count * s->ts_unit;

+        oright->pts = s->prev->pts * 2;

         ff_filter_frame(outlink, oright);

         out = oleft;

-        oleft->pts = outlink->frame_count * s->ts_unit;

+        oleft->pts = s->prev->pts + inpicref->pts;

+        av_frame_free(&s->prev);

+        s->prev = inpicref;

     } else if (s->in.format == ALTERNATING_LR ||

                s->in.format == ALTERNATING_RL) {

-        out->pts = outlink->frame_count * s->ts_unit;

+        out->pts = s->prev->pts / 2;

+        av_frame_free(&s->prev);

+        av_frame_free(&inpicref);

+    } else {

+        av_frame_free(&s->prev);

+        av_frame_free(&inpicref);

     }

     return ff_filter_frame(outlink, out);

 }