[FFmpeg-devel] [PATCH v2] avformat/hlsenc: fix hls_time not respected

[Ingo Oppermann]

This fixes the criterion when to split the segments based on the
elapsed time for the current segment instead of using the theoretical
elapsed time since start based on hls_time and the number of written
segments.

hls_time is used to define the minimum length of a segment, however
this is not respected in all cases when a stream has variable GOP
sizes.

Imagine a stream starts with a key frame every 10 seconds for
e.g. 30 seconds. After that, key frames will come every second. This
will result in segments that are first 10 seconds (as expected), then
1 second for some time (not as expected) and later 2 seconds (as
expected).

How to reproduce:
ffmpeg -t 30 -f lavfi -i testsrc2 -codec:v libx264 -g 250 part1.mp4
ffmpeg -t 30 -f lavfi -i testsrc2 -codec:v libx264 -g 25 part2.mp4
echo "file part1.mp4\nfile part2.mp4" > list.txt
ffmpeg -f concat -i list.txt -codec copy \
    -f hls -hls_time 2 -hls_list_size 0 parts.m3u8
cat parts.m3u8

Signed-off-by: Ingo Oppermann <ingo at datarhei.com>
---
 libavformat/hlsenc.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index 6148685f40..2c5d60500d 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -2474,7 +2474,6 @@ static int hls_write_packet(AVFormatContext *s, AVPacket *pkt)
     HLSContext *hls = s->priv_data;
     AVFormatContext *oc = NULL;
     AVStream *st = s->streams[pkt->stream_index];
-    int64_t end_pts = 0;
     int is_ref_pkt = 1;
     int ret = 0, can_split = 1, i, j;
     int stream_index = 0;
@@ -2512,14 +2511,9 @@ static int hls_write_packet(AVFormatContext *s, AVPacket *pkt)
         return AVERROR(ENOMEM);
     }
 
-    end_pts = hls->recording_time * vs->number;
-
     if (vs->sequence - vs->nb_entries > hls->start_sequence && hls->init_time > 0) {
-        /* reset end_pts, hls->recording_time at end of the init hls list */
-        int64_t init_list_dur = hls->init_time * vs->nb_entries;
-        int64_t after_init_list_dur = (vs->sequence - hls->start_sequence - vs->nb_entries) * hls->time;
+        /* reset hls->recording_time at end of the init hls list */
         hls->recording_time = hls->time;
-        end_pts = init_list_dur + after_init_list_dur ;
     }
 
     if (vs->start_pts == AV_NOPTS_VALUE) {
@@ -2560,8 +2554,8 @@ static int hls_write_packet(AVFormatContext *s, AVPacket *pkt)
     }
 
     can_split = can_split && (pkt->pts - vs->end_pts > 0);
-    if (vs->packets_written && can_split && av_compare_ts(pkt->pts - vs->start_pts, st->time_base,
-                                                          end_pts, AV_TIME_BASE_Q) >= 0) {
+    if (vs->packets_written && can_split && av_compare_ts(pkt->pts - vs->end_pts, st->time_base,
+                                                          hls->recording_time, AV_TIME_BASE_Q) >= 0) {
         int64_t new_start_pos;
         int byterange_mode = (hls->flags & HLS_SINGLE_FILE) || (hls->max_seg_size > 0);
         double cur_duration;

base-commit: f632ab53d98168b9b731cf5696547c26059c0822
-- 
2.39.5 (Apple Git-154)