@@ -44,6 +44,7 @@ enum TInterlaceMode {

 typedef struct {

     const AVClass *class;

     enum TInterlaceMode mode;   ///< interlace mode selected

+    AVRational preout_time_base;

     int flags;                  ///< flags affecting interlacing algorithm

     int frame;                  ///< number of the output frame

     int vsub;                   ///< chroma vertical subsampling

@@ -35,6 +35,7 @@

 #define OFFSET(x) offsetof(TInterlaceContext, x)

 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

 #define TINTERLACE_FLAG_VLPF 01

+#define TINTERLACE_FLAG_EXACT_TB 2

 static const AVOption tinterlace_options[] = {

     {"mode",              "select interlace mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_MERGE}, 0, MODE_NB-1, FLAGS, "mode"},

@@ -49,6 +50,7 @@ static const AVOption tinterlace_options[] = {

     {"flags",             "set flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, 0, "flags" },

     {"low_pass_filter",   "enable vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },

     {"vlpf",              "enable vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },

+    {"exact_tb",          "force a timebase which can represent timestamps exactly", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_EXACT_TB}, INT_MIN, INT_MAX, FLAGS, "flags" },

     {NULL}

 };

@@ -62,6 +64,12 @@ static const enum AVPixelFormat full_scale_yuvj_pix_fmts[] = {

     FULL_SCALE_YUVJ_FORMATS, AV_PIX_FMT_NONE

 };

+static const AVRational standard_tbs[] = {

+    {1, 25},

+    {1, 30},

+    {1001, 30000},

+};

+

 static int query_formats(AVFilterContext *ctx)

 {

     static const enum AVPixelFormat pix_fmts[] = {

@@ -104,6 +112,7 @@ static int config_out_props(AVFilterLink *outlink)

     AVFilterLink *inlink = outlink->src->inputs[0];

     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);

     TInterlaceContext *tinterlace = ctx->priv;

+    int i;

     tinterlace->vsub = desc->log2_chroma_h;

     outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;

@@ -135,13 +144,23 @@ static int config_out_props(AVFilterLink *outlink)

                 tinterlace->mode);

         tinterlace->flags &= ~TINTERLACE_FLAG_VLPF;

     }

+    tinterlace->preout_time_base = inlink->time_base;

     if (tinterlace->mode == MODE_INTERLACEX2) {

-        outlink->time_base.num = inlink->time_base.num;

-        outlink->time_base.den = inlink->time_base.den * 2;

+        tinterlace->preout_time_base.den *= 2;

         outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){2,1});

+        outlink->time_base  = av_mul_q(inlink->time_base , (AVRational){1,2});

     } else if (tinterlace->mode != MODE_PAD) {

         outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){1,2});

+        outlink->time_base  = av_mul_q(inlink->time_base , (AVRational){2,1});

+    }

+

+    for (i = 0; i<FF_ARRAY_ELEMS(standard_tbs); i++){

+        if (!av_cmp_q(standard_tbs[i], outlink->time_base))

+            break;

     }

+    if (i == FF_ARRAY_ELEMS(standard_tbs) ||

+        (tinterlace->flags & TINTERLACE_FLAG_EXACT_TB))

+        outlink->time_base = tinterlace->preout_time_base;

     if (tinterlace->flags & TINTERLACE_FLAG_VLPF) {

         tinterlace->lowpass_line = lowpass_line_c;

@@ -326,6 +345,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *picref)

         if (cur->pts != AV_NOPTS_VALUE)

             out->pts = cur->pts*2;

+        out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);

         if ((ret = ff_filter_frame(outlink, out)) < 0)

             return ret;

@@ -359,6 +379,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *picref)

         av_assert0(0);

     }

+    out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);

     ret = ff_filter_frame(outlink, out);

     tinterlace->frame++;