> On Mar 18, 2022, at 8:20 PM, Steven Liu <l...@chinaffmpeg.org> wrote:
>
> From: Steven Liu <liuq...@kuaishou.com>
>
> There have some video stream usually cannot get precise duration,
> for example:
>
> command:
> ffmpeg -i input.mp4 -c copy -copyts -f hls -hls_time 5 -hls_list_size 0
> -hls_segment_type mpegts -t 20 a.m3u8
>
> the first segment should split at 5.133333,
> because 5.133333 - 0.133333 is 5.0000,
> pkt->pts = [5.133333] vs->end_pts = 0.133333, flags = [1]
> but the second segment will cannot split at 10.133322,
> because 10.133322 - 5.133333 is 4.999989, it small than hls_time,
It doesn’t looks like an issue.
Firstly, user can specify a smaller ‘hls_time'. '-hls_time 4.9'
is the same as '-hls_time 5 -hls_time_delta 0.1', right?
Secondly, if user want to have precise segment durations, they
need to control the timestamp of input packets, with fixed FPS.
> pkt->pts = [10.133322] vs->end_pts = 5.133333, flags = [1]
> so add hls_time_delta for approximation value to hls_time.
>
> Signed-off-by: Steven Liu <liuq...@kuaishou.com>
> ---
> doc/muxers.texi | 8 ++++++++
> libavformat/hlsenc.c | 4 +++-
> 2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 1af603b7f6..c91a7a9216 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -778,6 +778,14 @@ Segment will be cut on the next key frame after this
> time has passed on the firs
> After the initial playlist is filled @command{ffmpeg} will cut segments
> at duration equal to @code{hls_time}
>
> +@item hls_time_delta @var{duration}
> +Set approximation value used for the segment duration. Default value is
> @var{0}.
> +
> +@var{duration} must be a time duration specification,
> +see @ref{time duration syntax,,the Time duration section in the
> ffmpeg-utils(1) manual,ffmpeg-utils}.
> +
> +Segment will be cut on the key frame before @code{hls_time_delta} to
> @code{hls_time}.
> +
> @item hls_time @var{duration}
> Set the target segment length. Default value is 2.
>
> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> index 14eb7c4530..56cde7dd70 100644
> --- a/libavformat/hlsenc.c
> +++ b/libavformat/hlsenc.c
> @@ -200,6 +200,7 @@ typedef struct HLSContext {
>
> int64_t time; // Set by a private option.
> int64_t init_time; // Set by a private option.
> + int64_t time_delta;
> int max_nb_segments; // Set by a private option.
> int hls_delete_threshold; // Set by a private option.
> uint32_t flags; // enum HLSFlags
> @@ -2489,7 +2490,7 @@ 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) {
> + end_pts -
> hls->time_delta, AV_TIME_BASE_Q) >= 0) {
> int64_t new_start_pos;
> int byterange_mode = (hls->flags & HLS_SINGLE_FILE) ||
> (hls->max_seg_size > 0);
>
> @@ -3101,6 +3102,7 @@ static const AVOption options[] = {
> {"start_number", "set first number in the sequence",
> OFFSET(start_sequence),AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, E},
> {"hls_time", "set segment length",
> OFFSET(time), AV_OPT_TYPE_DURATION, {.i64 = 2000000}, 0, INT64_MAX,
> E},
> {"hls_init_time", "set segment length at init list",
> OFFSET(init_time), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, INT64_MAX,
> E},
> + {"hls_time_delta", "set approximation value used for the segment
> duration", OFFSET(time_delta), AV_OPT_TYPE_DURATION, {.i64 = 0},
> 0, INT64_MAX, E},
> {"hls_list_size", "set maximum number of playlist entries",
> OFFSET(max_nb_segments), AV_OPT_TYPE_INT, {.i64 = 5}, 0, INT_MAX,
> E},
> {"hls_delete_threshold", "set number of unreferenced segments to keep
> before deleting", OFFSET(hls_delete_threshold), AV_OPT_TYPE_INT, {.i64
> = 1}, 1, INT_MAX, E},
> #if FF_HLS_TS_OPTIONS
> --
> 2.25.0
>
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