少宇李 <wolflee...@gmail.com> 于2022年6月24日周五 11:58写道：
>>
>>
>> Hi, Steven
>
>
> I got it.
>
> User could use "live_start_index" option even if #EXT-X-START in the playlist.
>
> I changed the priority about #EXT-X-START/live_start_index,
>
> this is new bellow:
>
> ---
> libavformat/hls.c | 69 +++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 64 insertions(+), 5 deletions(-)
>
> diff --git a/libavformat/hls.c b/libavformat/hls.c
> index b736f093a9..309471efce 100644
> --- a/libavformat/hls.c
> +++ b/libavformat/hls.c
> @@ -120,6 +120,8 @@ struct playlist {
> enum PlaylistType type;
> int64_t target_duration;
> int64_t start_seq_no;
> + int time_offset_flag;
> + int64_t start_time_offset;
> int n_segments;
> struct segment **segments;
> int needed;
> @@ -741,6 +743,7 @@ static int parse_playlist(HLSContext *c, const char *url,
> struct segment **prev_segments = NULL;
> int prev_n_segments = 0;
> int64_t prev_start_seq_no = -1;
> + const char *p;
>
> if (is_http && !in && c->http_persistent && c->playlist_pb) {
> in = c->playlist_pb;
> @@ -889,6 +892,18 @@ static int parse_playlist(HLSContext *c, const char *url,
> cur_init_section->key = NULL;
> }
>
> + } else if (av_strstart(line, "#EXT-X-START:", &ptr)) {
> + ret = ensure_playlist(c, &pls, url);
> + if (ret < 0) {
> + goto fail;
> + }
> + if (av_strstart(ptr, "TIME-OFFSET=", &p)) {
> + float offset = strtof(p, NULL);
> + pls->start_time_offset = offset * AV_TIME_BASE;
> + pls->time_offset_flag = 1;
> + } else {
> + goto fail;
> + }
> } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
> if (pls)
> pls->finished = 1;
> @@ -1721,10 +1736,54 @@ static int64_t select_cur_seq_no(HLSContext *c,
> struct playlist *pls)
>
> /* If this is a live stream, start live_start_index segments from the
> * start or end */
> - if (c->live_start_index < 0)
> - return pls->start_seq_no + FFMAX(pls->n_segments +
> c->live_start_index, 0);
> - else
> - return pls->start_seq_no + FFMIN(c->live_start_index,
> pls->n_segments - 1);
> + if (c->live_start_index != INT_MIN) {
Maybe you should not change current logic.
You can just add about process EXT-X-START sence,.
For example:
compute the start_seq_no and save the value to a temp varible and
don't return immediately, check the third scence which get EXT-X-START
tag from playlist.
process the temp varible after start_seq_no compute from
live_start_index or EXT-X-START.
> + if (c->live_start_index < 0)
> + return pls->start_seq_no + FFMAX(pls->n_segments +
> + c->live_start_index, 0);
> + else
> + return pls->start_seq_no + FFMIN(c->live_start_index,
> + pls->n_segments - 1);
> + } else if (c->live_start_index == INT_MIN && !pls->time_offset_flag)
> {
> + return pls->start_seq_no + FFMAX(pls->n_segments - 3, 0);
> + } else {
> + /* If playlist indicate a TIME-OFFSET and user not use
> live_start_index,
> + * need to recalculate seq_no */
> + int i;
> + int64_t start_timestamp;
> + int64_t playlist_duration = 0;
> + int64_t cur_timestamp = c->cur_timestamp == AV_NOPTS_VALUE ? 0 :
> + c->cur_timestamp;
> +
> + for (i = 0; i < pls->n_segments; i++) {
> + playlist_duration += pls->segments[i]->duration;
> + }
> + /* If the absolute value of TIME-OFFSET exceeds
> + * the duration of the playlist, it indicates either the end of
> the
> + * playlist (if positive) or the beginning of the playlist (if
> + * negative). */
> + if (pls->start_time_offset >=0 &&
> + pls->start_time_offset > playlist_duration)
> + start_timestamp = cur_timestamp + playlist_duration;
> + else if (pls->start_time_offset >= 0 &&
> + pls->start_time_offset <= playlist_duration)
> + start_timestamp = cur_timestamp + pls->start_time_offset;
> + else if (pls->start_time_offset < 0 &&
> + pls->start_time_offset < -playlist_duration)
> + start_timestamp = cur_timestamp;
> + else if (pls->start_time_offset < 0 &&
> + pls->start_time_offset > -playlist_duration)
> + start_timestamp = cur_timestamp + playlist_duration +
> + pls->start_time_offset;
> + else
> + start_timestamp = cur_timestamp;
> +
> + find_timestamp_in_playlist(c, pls, start_timestamp, &seq_no,
> NULL);
> + av_log(c, AV_LOG_DEBUG, "start_timestamp: %" PRId64
> + "cur_timestamp:%" PRId64
> + "cur_seq_no:%" PRId64 "\n",
> + start_timestamp, cur_timestamp, seq_no);
> + return seq_no;
> + }
> }
>
> /* Otherwise just start on the first segment. */
> @@ -2475,7 +2534,7 @@ static int hls_probe(const AVProbeData *p)
> #define FLAGS AV_OPT_FLAG_DECODING_PARAM
> static const AVOption hls_options[] = {
> {"live_start_index", "segment index to start live streams at (negative
> values are from the end)",
> - OFFSET(live_start_index), AV_OPT_TYPE_INT, {.i64 = -3}, INT_MIN,
> INT_MAX, FLAGS},
> + OFFSET(live_start_index), AV_OPT_TYPE_INT, {.i64 = INT_MIN},
> INT_MIN, INT_MAX, FLAGS},
This is unnecessary， because the default -3 is ok and be using by
users from many years ago.
> {"allowed_extensions", "List of file extensions that hls is allowed to
> access",
> OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
> {.str =
> "3gp,aac,avi,ac3,eac3,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
> --
> 2.24.1 (Apple Git-126)
>
>
> Thanks Steven
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