[FFmpeg-devel] [PATCH 3/3] lavf/segment: add option to write empty filler segments as needed

[Rodger Combs]

---
 doc/muxers.texi       | 5 +++++
 libavformat/segment.c | 8 +++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/doc/muxers.texi b/doc/muxers.texi
index f2ad7fe..700ec88 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -1224,6 +1224,11 @@ muxers/codecs. It is set to @code{0} by default.
 @item initial_offset @var{offset}
 Specify timestamp offset to apply to the output packet timestamps. The
 argument must be a time duration specification, and defaults to 0.
+
+ at item write_empty_segments @var{1|0}
+If enabled, write an empty segment if there are no packets during the period a
+segment would usually span. Otherwise, the segment will be filled with the next
+packet written. Defaults to @code{0}.
 @end table
 
 @subsection Examples
diff --git a/libavformat/segment.c b/libavformat/segment.c
index 6ad991f..df1514f 100644
--- a/libavformat/segment.c
+++ b/libavformat/segment.c
@@ -116,6 +116,7 @@ typedef struct SegmentContext {
     char *reference_stream_specifier; ///< reference stream specifier
     int   reference_stream_index;
     int   break_non_keyframes;
+    int   write_empty;
 
     int use_rename;
     char temp_list_filename[1024];
@@ -774,6 +775,7 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
     if (!seg->avf)
         return AVERROR(EINVAL);
 
+calc_times:
     if (seg->times) {
         end_pts = seg->segment_count < seg->nb_times ?
             seg->times[seg->segment_count] : INT64_MAX;
@@ -805,7 +807,7 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
 
     if (pkt->stream_index == seg->reference_stream_index &&
         (pkt->flags & AV_PKT_FLAG_KEY || seg->break_non_keyframes) &&
-        seg->segment_frame_count > 0 &&
+        (seg->segment_frame_count > 0 || seg->write_empty) &&
         (seg->cut_pending || seg->frame_count >= start_frame ||
          (pkt->pts != AV_NOPTS_VALUE &&
           av_compare_ts(pkt->pts, st->time_base,
@@ -825,6 +827,9 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
         seg->cur_entry.start_time = (double)pkt->pts * av_q2d(st->time_base);
         seg->cur_entry.start_pts = av_rescale_q(pkt->pts, st->time_base, AV_TIME_BASE_Q);
         seg->cur_entry.end_time = seg->cur_entry.start_time;
+
+        if (seg->times || (!seg->frames && !seg->use_clocktime) && seg->write_empty)
+            goto calc_times;
     }
 
     if (pkt->stream_index == seg->reference_stream_index) {
@@ -956,6 +961,7 @@ static const AVOption options[] = {
     { "write_header_trailer", "write a header to the first segment and a trailer to the last one", OFFSET(write_header_trailer), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, E },
     { "reset_timestamps", "reset timestamps at the begin of each segment", OFFSET(reset_timestamps), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
     { "initial_offset", "set initial timestamp offset", OFFSET(initial_offset), AV_OPT_TYPE_DURATION, {.i64 = 0}, -INT64_MAX, INT64_MAX, E },
+    { "write_empty_segments", "allow writing empty 'filler' segments", OFFSET(write_empty), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
     { NULL },
 };
 
-- 
2.7.2