@@ -1261,7 +1261,7 @@ static int output_packet(AVInputStream *ist, int ist_index,

                         goto discard_packet;

                     }

                     if (ist->st->codec->time_base.num != 0) {

-                        int ticks= ist->st->parser ? ist->st->parser->repeat_pict+1 : 1;

+                        int ticks= ist->st->parser ? ist->st->parser->repeat_pict+1 : ist->st->codec->ticks_per_frame;

                         ist->next_pts += ((int64_t)AV_TIME_BASE *

                                           ist->st->codec->time_base.num * ticks) /

                             ist->st->codec->time_base.den;

@@ -1290,7 +1290,7 @@ static int output_packet(AVInputStream *ist, int ist_index,

                 break;

             case CODEC_TYPE_VIDEO:

                 if (ist->st->codec->time_base.num != 0) {

-                    int ticks= ist->st->parser ? ist->st->parser->repeat_pict+1 : 1;

+                    int ticks= ist->st->parser ? ist->st->parser->repeat_pict+1 : ist->st->codec->ticks_per_frame;

                     ist->next_pts += ((int64_t)AV_TIME_BASE *

                                       ist->st->codec->time_base.num * ticks) /

                         ist->st->codec->time_base.den;

@@ -1750,9 +1750,10 @@ static int av_encode(AVFormatContext **output_files,

             codec->bit_rate = icodec->bit_rate;

             codec->extradata= icodec->extradata;

             codec->extradata_size= icodec->extradata_size;

-            if(av_q2d(icodec->time_base) > av_q2d(ist->st->time_base) && av_q2d(ist->st->time_base) < 1.0/1000)

+            if(av_q2d(icodec->time_base)*icodec->ticks_per_frame > av_q2d(ist->st->time_base) && av_q2d(ist->st->time_base) < 1.0/1000){

                 codec->time_base = icodec->time_base;

-            else

+                codec->time_base.num *= icodec->ticks_per_frame;

+            }else

                 codec->time_base = ist->st->time_base;

             switch(codec->codec_type) {

             case CODEC_TYPE_AUDIO:

@@ -30,7 +30,7 @@

 #include "libavutil/avutil.h"

 #define LIBAVCODEC_VERSION_MAJOR 52

-#define LIBAVCODEC_VERSION_MINOR 19

+#define LIBAVCODEC_VERSION_MINOR 20

 #define LIBAVCODEC_VERSION_MICRO  0

 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \

@@ -2323,6 +2323,15 @@ typedef struct AVCodecContext {

      * - decoding: Set by libavcodec

      */

     struct AVHWAccel *hwaccel;

+

+    /**

+     * For some codecs, the time base is closer to the field rate than the frame rate.

+     * Most notably, H.264 and MPEG-2 specify time_base as half of frame duration

+     * if no telecine is used ...

+     *

+     * Set to time_base ticks per frame. Default 1, e.g., H.264/MPEG-2 set it to 2.

+     */

+    int ticks_per_frame;

 } AVCodecContext;

 /**

@@ -2201,6 +2201,7 @@ static av_cold int decode_init(AVCodecContext *avctx){

     h->sei_dpb_output_delay = 0;

     h->sei_cpb_removal_delay = -1;

     h->sei_buffering_period_present = 0;

+    avctx->ticks_per_frame = 2;

     return 0;

 }

@@ -1269,7 +1269,7 @@ static int mpeg_decode_postinit(AVCodecContext *avctx){

             //MPEG-1 aspect

             avctx->sample_aspect_ratio= av_d2q(

                     1.0/ff_mpeg1_aspect[s->aspect_ratio_info], 255);

-

+            avctx->ticks_per_frame=1;

         }else{//MPEG-2

         //MPEG-2 fps

             av_reduce(

@@ -1278,6 +1278,7 @@ static int mpeg_decode_postinit(AVCodecContext *avctx){

                 ff_frame_rate_tab[s->frame_rate_index].num * s1->frame_rate_ext.num*2,

                 ff_frame_rate_tab[s->frame_rate_index].den * s1->frame_rate_ext.den,

                 1<<30);

+            avctx->ticks_per_frame=2;

         //MPEG-2 aspect

             if(s->aspect_ratio_info > 1){

                 //we ignore the spec here as reality does not match the spec, see for example

@@ -393,6 +393,7 @@ static const AVOption options[]={

 {"request_channel_layout", NULL, OFFSET(request_channel_layout), FF_OPT_TYPE_INT64, DEFAULT, 0, INT64_MAX, A|D, "request_channel_layout"},

 {"rc_max_vbv_use", NULL, OFFSET(rc_max_available_vbv_use), FF_OPT_TYPE_FLOAT, 1.0/3, 0.0, FLT_MAX, V|E},

 {"rc_min_vbv_use", NULL, OFFSET(rc_min_vbv_overflow_use),  FF_OPT_TYPE_FLOAT, 3,     0.0, FLT_MAX, V|E},

+{"ticks_per_frame", NULL, OFFSET(ticks_per_frame), FF_OPT_TYPE_INT, 1, 1, INT_MAX, A|V|E|D},

 {NULL},

 };

@@ -2201,9 +2201,9 @@ int av_find_stream_info(AVFormatContext *ic)

             if (!st->r_frame_rate.num){

                 if(    st->codec->time_base.den * (int64_t)st->time_base.num

-                    <= st->codec->time_base.num * (int64_t)st->time_base.den){

+                    <= st->codec->time_base.num * st->codec->ticks_per_frame * (int64_t)st->time_base.den){

                     st->r_frame_rate.num = st->codec->time_base.den;

-                    st->r_frame_rate.den = st->codec->time_base.num;

+                    st->r_frame_rate.den = st->codec->time_base.num * st->codec->ticks_per_frame;

                 }else{

                     st->r_frame_rate.num = st->time_base.den;

                     st->r_frame_rate.den = st->time_base.num;

@@ -2537,7 +2537,7 @@ static int compute_pkt_fields2(AVStream *st, AVPacket *pkt){

     if (pkt->duration == 0) {

         compute_frame_duration(&num, &den, st, NULL, pkt);

         if (den && num) {

-            pkt->duration = av_rescale(1, num * (int64_t)st->time_base.den, den * (int64_t)st->time_base.num);

+            pkt->duration = av_rescale(1, num * (int64_t)st->time_base.den * st->codec->ticks_per_frame, den * (int64_t)st->time_base.num);

         }

     }