Implement guessed_pts in avcodec_decode_video2

Signed-off-by: Nicolas George <nicolas.george@normalesup.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

2 files changed, 60 insertions, 1 deletions

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index dbfb77795d..f96ae84740 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1026,6 +1026,13 @@ typedef struct AVPanScan{
      * - decoding: Read by user.\
      */\
     int64_t pkt_dts;\
+\
+    /**\
+     * frame timestamp estimated using various heuristics, in stream time base\
+     * - encoding: unused\
+     * - decoding: set by libavcodec, read by user.\
+     */\
+    int64_t best_effort_timestamp;\
 
 
 #define FF_QSCALE_TYPE_MPEG1 0
@@ -2825,6 +2832,17 @@ typedef struct AVCodecContext {
      * - encoding: unused
      */
     AVPacket *pkt;
+
+    /**
+     * Current statistics for PTS correction.
+     * - decoding: maintained and used by libavcodec
+     * - encoding: unused
+     */
+    int64_t pts_correction_num_faulty_pts; /// Number of incorrect PTS values so far
+    int64_t pts_correction_num_faulty_dts; /// Number of incorrect DTS values so far
+    int64_t pts_correction_last_pts;       /// PTS of the last frame
+    int64_t pts_correction_last_dts;       /// DTS of the last frame
+
 } AVCodecContext;
 
 /**
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index e9db33e9d7..2a95975273 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -448,7 +448,7 @@ enum PixelFormat avcodec_default_get_format(struct AVCodecContext *s, const enum
 void avcodec_get_frame_defaults(AVFrame *pic){
     memset(pic, 0, sizeof(AVFrame));
 
-    pic->pts= AV_NOPTS_VALUE;
+    pic->pts = pic->best_effort_timestamp = AV_NOPTS_VALUE;
     pic->key_frame= 1;
 }
 
@@ -538,6 +538,11 @@ int attribute_align_arg avcodec_open(AVCodecContext *avctx, AVCodec *codec)
         goto free_and_end;
     }
 
+    avctx->pts_correction_num_faulty_pts =
+    avctx->pts_correction_num_faulty_dts = 0;
+    avctx->pts_correction_last_pts =
+    avctx->pts_correction_last_dts = INT64_MIN;
+
     if(avctx->codec->init){
         ret = avctx->codec->init(avctx);
         if (ret < 0) {
@@ -608,6 +613,39 @@ int avcodec_encode_subtitle(AVCodecContext *avctx, uint8_t *buf, int buf_size,
     return ret;
 }
 
+/**
+ * Attempt to guess proper monotonic timestamps for decoded video frames
+ * which might have incorrect times. Input timestamps may wrap around, in
+ * which case the output will as well.
+ *
+ * @param pts the pts field of the decoded AVPacket, as passed through
+ * AVFrame.pkt_pts
+ * @param dts the dts field of the decoded AVPacket
+ * @return one of the input values, may be AV_NOPTS_VALUE
+ */
+static int64_t guess_correct_pts(AVCodecContext *ctx,
+                                 int64_t reordered_pts, int64_t dts)
+{
+    int64_t pts = AV_NOPTS_VALUE;
+
+    if (dts != AV_NOPTS_VALUE) {
+        ctx->pts_correction_num_faulty_dts += dts <= ctx->pts_correction_last_dts;
+        ctx->pts_correction_last_dts = dts;
+    }
+    if (reordered_pts != AV_NOPTS_VALUE) {
+        ctx->pts_correction_num_faulty_pts += reordered_pts <= ctx->pts_correction_last_pts;
+        ctx->pts_correction_last_pts = reordered_pts;
+    }
+    if ((ctx->pts_correction_num_faulty_pts<=ctx->pts_correction_num_faulty_dts || dts == AV_NOPTS_VALUE)
+       && reordered_pts != AV_NOPTS_VALUE)
+        pts = reordered_pts;
+    else
+        pts = dts;
+
+    return pts;
+}
+
+
 #if FF_API_VIDEO_OLD
 int attribute_align_arg avcodec_decode_video(AVCodecContext *avctx, AVFrame *picture,
                          int *got_picture_ptr,
@@ -643,6 +681,9 @@ int attribute_align_arg avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi
         emms_c(); //needed to avoid an emms_c() call before every return;
 
         picture->pkt_dts= avpkt->dts;
+        picture->best_effort_timestamp = guess_correct_pts(avctx,
+                                                           picture->pkt_pts,
+                                                           picture->pkt_dts);
 
         if (*got_picture_ptr)
             avctx->frame_number++;