[FFmpeg-devel] [PATCH 2/2] avcodec/utils: calculate frame number of HEVC if the framerate > 30FPS

[lance.lmwang at gmail.com]

From: Limin Wang <lance.lmwang at gmail.com>

---
 libavcodec/internal.h |  3 ++-
 libavcodec/nvenc.c    |  2 +-
 libavcodec/utils.c    | 13 ++++++++++++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index 0a1c0a1..4c34d7d 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -382,6 +382,7 @@ int ff_alloc_a53_sei(const AVFrame *frame, size_t prefix_len,
  * Check AVFrame for S12M timecode side data and allocate and fill TC SEI message with timecode info
  *
  * @param frame      Raw frame to get S12M timecode side data from
+ * @param rate       The frame rate
  * @param prefix_len Number of bytes to allocate before SEI message
  * @param data       Pointer to a variable to store allocated memory
  *                   Upon return the variable will hold NULL on error or if frame has no S12M timecode info.
@@ -390,7 +391,7 @@ int ff_alloc_a53_sei(const AVFrame *frame, size_t prefix_len,
  * @param sei_size   Pointer to a variable to store generated SEI message length
  * @return           Zero on success, negative error code on failure
  */
-int ff_alloc_timecode_sei(const AVFrame *frame, size_t prefix_len,
+int ff_alloc_timecode_sei(const AVFrame *frame, AVRational rate, size_t prefix_len,
                      void **data, size_t *sei_size);
 
 /**
diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
index c6740c1..45a7b60 100644
--- a/libavcodec/nvenc.c
+++ b/libavcodec/nvenc.c
@@ -2218,7 +2218,7 @@ static int nvenc_send_frame(AVCodecContext *avctx, const AVFrame *frame)
             void *tc_data = NULL;
             size_t tc_size = 0;
 
-            if (ff_alloc_timecode_sei(frame, 0, (void**)&tc_data, &tc_size) < 0) {
+            if (ff_alloc_timecode_sei(frame, avctx->framerate, 0, (void**)&tc_data, &tc_size) < 0) {
                 av_log(ctx, AV_LOG_ERROR, "Not enough memory for timecode sei, skipping\n");
             }
 
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 2ece34f..51c4067 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -2254,7 +2254,7 @@ static unsigned bcd2uint(uint8_t bcd)
     return low + 10*high;
 }
 
-int ff_alloc_timecode_sei(const AVFrame *frame, size_t prefix_len,
+int ff_alloc_timecode_sei(const AVFrame *frame, AVRational rate, size_t prefix_len,
                      void **data, size_t *sei_size)
 {
     AVFrameSideData *sd = NULL;
@@ -2290,6 +2290,17 @@ int ff_alloc_timecode_sei(const AVFrame *frame, size_t prefix_len,
         unsigned ff   = bcd2uint(tcsmpte>>24 & 0x3f);    // 6-bit frames
         unsigned drop = tcsmpte & 1<<30 && !0;  // 1-bit drop if not arbitrary bit
 
+        /* Calculate frame number of HEVC by SMPTE ST 12-1:2014 Sec 12.2 if rate > 30FPS */
+        if (av_cmp_q(rate, (AVRational) {30, 1}) == 1) {
+            unsigned pc;
+            ff *= 2;
+            if (av_cmp_q(rate, (AVRational) {50, 1}) == 0)
+                pc = !!(tcsmpte & 1 << 7);
+            else
+                pc = !!(tcsmpte & 1 << 23);
+            ff = (ff + pc) & 0x7f;
+        }
+
         put_bits(&pb, 1, 1); // clock_timestamp_flag
         put_bits(&pb, 1, 1); // units_field_based_flag
         put_bits(&pb, 5, 0); // counting_type
-- 
2.9.4