[FFmpeg-devel] [PATCH] libavformat/matroskaenc.c: Add option to set timecodescale

[Thierry Foucu]

By default the time code scale in a MKV file in millisecond. With this
option we can set the time code scale to microsecond or nanoseconds for
very high frame rate.
---
 libavformat/matroskaenc.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 233c472b8f..cfad6a4693 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext {
     int                 default_mode;
 
     uint32_t            segment_uid[4];
+
+    int64_t             timecodescale;
 } MatroskaMuxContext;
 
 /** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint,
@@ -1827,7 +1829,7 @@ static int mkv_write_header(AVFormatContext *s)
         return ret;
     pb = mkv->info.bc;
 
-    put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000);
+    put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, mkv->timecodescale);
     if ((tag = av_dict_get(s->metadata, "title", NULL, 0)))
         put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value);
     if (!(s->flags & AVFMT_FLAG_BITEXACT)) {
@@ -1927,12 +1929,12 @@ static int mkv_write_header(AVFormatContext *s)
     // after 4k and on a keyframe
     if (IS_SEEKABLE(pb, mkv)) {
         if (mkv->cluster_time_limit < 0)
-            mkv->cluster_time_limit = 5000;
+            mkv->cluster_time_limit = 5*(1000000000/mkv->timecodescale);
         if (mkv->cluster_size_limit < 0)
             mkv->cluster_size_limit = 5 * 1024 * 1024;
     } else {
         if (mkv->cluster_time_limit < 0)
-            mkv->cluster_time_limit = 1000;
+            mkv->cluster_time_limit = 1*(1000000000/mkv->timecodescale);
         if (mkv->cluster_size_limit < 0)
             mkv->cluster_size_limit = 32 * 1024;
     }
@@ -2708,7 +2710,7 @@ static int mkv_init(struct AVFormatContext *s)
         }
 
         // ms precision is the de-facto standard timescale for mkv files
-        avpriv_set_pts_info(st, 64, 1, 1000);
+        avpriv_set_pts_info(st, 64, 1, 1000000000/mkv->timecodescale);
 
         if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) {
             if (mkv->mode == MODE_WEBM) {
@@ -2795,6 +2797,7 @@ static const AVOption options[] = {
     { "infer", "For each track type, mark the first track of disposition default as default; if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" },
     { "infer_no_subs", "For each track type, mark the first track of disposition default as default; for audio and video: if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" },
     { "passthrough", "Use the disposition flag as-is", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, "default_mode" },
+    { "timecodescale", "Time code scale for all tracks in nanoseconds", OFFSET(timecodescale), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 1, 1000000000, FLAGS },
     { NULL },
 };
 
-- 
2.29.2.684.gfbc64c5ab5-goog