[FFmpeg-devel] [PATCH] avformat/segment: add option min_seg_duration

[Gyan Doshi]

On 2022-12-21 09:08 pm, Gyan Doshi wrote:
> New option can be used to avoid creating very short segments with inputs
> whose GOP size is variable or unharmonic with segment_time.
>
> Only effective with segment_time.
Comments?

> ---
>   doc/muxers.texi       |  5 +++++
>   libavformat/segment.c | 12 +++++++++++-
>   2 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 4edbb22b00..ed5341be39 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -2369,6 +2369,11 @@ Note that splitting may not be accurate, unless you force the
>   reference stream key-frames at the given time. See the introductory
>   notice and the examples below.
>   
> + at item min_seg_duration @var{time}
> +Set minimum segment duration to @var{time}, the value must be a duration
> +specification. This prevents the muxer ending segments at a duration below
> +this value. Only effective with @code{segment_time}. Default value is "0".
> +
>   @item segment_atclocktime @var{1|0}
>   If set to "1" split at regular clock time intervals starting from 00:00
>   o'clock. The @var{time} value specified in @option{segment_time} is
> diff --git a/libavformat/segment.c b/libavformat/segment.c
> index c904e20708..c19c2a94ae 100644
> --- a/libavformat/segment.c
> +++ b/libavformat/segment.c
> @@ -93,6 +93,7 @@ typedef struct SegmentContext {
>       int list_type;         ///< set the list type
>       AVIOContext *list_pb;  ///< list file put-byte context
>       int64_t time;          ///< segment duration
> +    int64_t min_seg_duration;  ///< minimum segment duration
>       int use_strftime;      ///< flag to expand filename with strftime
>       int increment_tc;      ///< flag to increment timecode if found
>   
> @@ -710,6 +711,10 @@ static int seg_init(AVFormatContext *s)
>               }
>               seg->clocktime_offset = seg->time - (seg->clocktime_offset % seg->time);
>           }
> +        if (seg->min_seg_duration > seg->time) {
> +            av_log(s, AV_LOG_ERROR, "min_seg_duration cannot be greater than segment_time\n");
> +            return AVERROR(EINVAL);
> +        }
>       }
>   
>       if (seg->list) {
> @@ -839,7 +844,7 @@ static int seg_write_packet(AVFormatContext *s, AVPacket *pkt)
>   {
>       SegmentContext *seg = s->priv_data;
>       AVStream *st = s->streams[pkt->stream_index];
> -    int64_t end_pts = INT64_MAX, offset;
> +    int64_t end_pts = INT64_MAX, offset, pkt_pts_avtb;
>       int start_frame = INT_MAX;
>       int ret;
>       struct tm ti;
> @@ -890,11 +895,15 @@ calc_times:
>               pkt->flags & AV_PKT_FLAG_KEY,
>               pkt->stream_index == seg->reference_stream_index ? seg->frame_count : -1);
>   
> +    if (pkt->pts != AV_NOPTS_VALUE)
> +        pkt_pts_avtb = av_rescale_q(pkt->pts, st->time_base, AV_TIME_BASE_Q);
> +
>       if (pkt->stream_index == seg->reference_stream_index &&
>           (pkt->flags & AV_PKT_FLAG_KEY || seg->break_non_keyframes) &&
>           (seg->segment_frame_count > 0 || seg->write_empty) &&
>           (seg->cut_pending || seg->frame_count >= start_frame ||
>            (pkt->pts != AV_NOPTS_VALUE &&
> +          pkt_pts_avtb - seg->cur_entry.start_pts >= seg->min_seg_duration &&
>             av_compare_ts(pkt->pts, st->time_base,
>                           end_pts - seg->time_delta, AV_TIME_BASE_Q) >= 0))) {
>           /* sanitize end time in case last packet didn't have a defined duration */
> @@ -1031,6 +1040,7 @@ static const AVOption options[] = {
>       { "segment_clocktime_wrap_duration", "set segment clocktime wrapping duration", OFFSET(clocktime_wrap_duration), AV_OPT_TYPE_DURATION, {.i64 = INT64_MAX}, 0, INT64_MAX, E},
>       { "segment_time",      "set segment duration",                       OFFSET(time),AV_OPT_TYPE_DURATION, {.i64 = 2000000}, INT64_MIN, INT64_MAX,       E },
>       { "segment_time_delta","set approximation value used for the segment times", OFFSET(time_delta), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, INT64_MAX, E },
> +    { "min_seg_duration",  "set minimum segment duration",               OFFSET(min_seg_duration), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, INT64_MAX, E },
>       { "segment_times",     "set segment split time points",              OFFSET(times_str),AV_OPT_TYPE_STRING,{.str = NULL},  0, 0,       E },
>       { "segment_frames",    "set segment split frame numbers",            OFFSET(frames_str),AV_OPT_TYPE_STRING,{.str = NULL},  0, 0,       E },
>       { "segment_wrap",      "set number after which the index wraps",     OFFSET(segment_idx_wrap), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, E },