segment.c

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/*
 * Copyright (c) 2011, Luca Barbato
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
 
/**
 * @file generic segmenter
 * M3U8 specification can be find here:
 * @url{http://tools.ietf.org/id/draft-pantos-http-live-streaming}
 */
 
#include "config_components.h"
 
#include <time.h>
 
#include "avformat.h"
#include "internal.h"
#include "mux.h"
 
#include "libavutil/avassert.h"
#include "libavutil/internal.h"
#include "libavutil/log.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "libavutil/avstring.h"
#include "libavutil/bprint.h"
#include "libavutil/parseutils.h"
#include "libavutil/mathematics.h"
#include "libavutil/time.h"
#include "libavutil/timecode.h"
#include "libavutil/time_internal.h"
#include "libavutil/timestamp.h"
 
typedef struct SegmentListEntry {
    int index;
    double start_time, end_time;
    int64_t start_pts;
    int64_t offset_pts;
    char *filename;
    struct SegmentListEntry *next;
    int64_t last_duration;
} SegmentListEntry;
 
typedef enum {
    LIST_TYPE_UNDEFINED = -1,
    LIST_TYPE_FLAT = 0,
    LIST_TYPE_CSV,
    LIST_TYPE_M3U8,
    LIST_TYPE_EXT, ///< deprecated
    LIST_TYPE_FFCONCAT,
    LIST_TYPE_NB,
} ListType;
 
#define SEGMENT_LIST_FLAG_CACHE 1
#define SEGMENT_LIST_FLAG_LIVE  2
 
typedef struct SegmentContext {
    const AVClass *class;  /**< Class for private options. */
    int segment_idx;       ///< index of the segment file to write, starting from 0
    int segment_idx_wrap;  ///< number after which the index wraps
    int segment_idx_wrap_nb;  ///< number of time the index has wrapped
    int segment_count;     ///< number of segment files already written
    const AVOutputFormat *oformat;
    AVFormatContext *avf;
    char *format;              ///< format to use for output segment files
    AVDictionary *format_options;
    char *list;            ///< filename for the segment list file
    int   list_flags;      ///< flags affecting list generation
    int   list_size;       ///< number of entries for the segment list file
 
    int is_nullctx;       ///< whether avf->pb is a nullctx
    int use_clocktime;    ///< flag to cut segments at regular clock time
    int64_t clocktime_offset; //< clock offset for cutting the segments at regular clock time
    int64_t clocktime_wrap_duration; //< wrapping duration considered for starting a new segment
    int64_t last_val;      ///< remember last time for wrap around detection
    int cut_pending;
    int header_written;    ///< whether we've already called avformat_write_header
 
    char *entry_prefix;    ///< prefix to add to list entry filenames
    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
 
    char *times_str;       ///< segment times specification string
    int64_t *times;        ///< list of segment interval specification
    int nb_times;          ///< number of elements in the times array
 
    char *frames_str;      ///< segment frame numbers specification string
    int *frames;           ///< list of frame number specification
    int nb_frames;         ///< number of elements in the frames array
    int frame_count;       ///< total number of reference frames
    int segment_frame_count; ///< number of reference frames in the segment
 
    int64_t time_delta;
    int  individual_header_trailer; /**< Set by a private option. */
    int  write_header_trailer; /**< Set by a private option. */
    char *header_filename;  ///< filename to write the output header to
 
    int reset_timestamps;  ///< reset timestamps at the beginning of each segment
    int64_t initial_offset;    ///< initial timestamps offset, expressed in microseconds
    char *reference_stream_specifier; ///< reference stream specifier
    int   reference_stream_index;
    int64_t reference_stream_first_pts;    ///< initial timestamp, expressed in microseconds
    int   break_non_keyframes;
    int   write_empty;
 
    int use_rename;
    char *temp_list_filename;
 
    SegmentListEntry cur_entry;
    SegmentListEntry *segment_list_entries;
    SegmentListEntry *segment_list_entries_end;
} SegmentContext;
 
static void print_csv_escaped_str(AVIOContext *ctx, const char *str)
{
    int needs_quoting = !!str[strcspn(str, "\",\n\r")];
 
    if (needs_quoting)
        avio_w8(ctx, '"');
 
    for (; *str; str++) {
        if (*str == '"')
            avio_w8(ctx, '"');
        avio_w8(ctx, *str);
    }
    if (needs_quoting)
        avio_w8(ctx, '"');
}
 
static int segment_mux_init(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc;
    int i;
    int ret;
 
    ret = avformat_alloc_output_context2(&seg->avf, seg->oformat, NULL, NULL);
    if (ret < 0)
        return ret;
    oc = seg->avf;
 
    oc->interrupt_callback = s->interrupt_callback;
    oc->max_delay          = s->max_delay;
    av_dict_copy(&oc->metadata, s->metadata, 0);
    oc->opaque             = s->opaque;
    oc->io_close2          = s->io_close2;
    oc->io_open            = s->io_open;
    oc->flags              = s->flags;
 
    for (i = 0; i < s->nb_streams; i++) {
        AVStream *st, *ist = s->streams[i];
        AVCodecParameters *ipar = ist->codecpar, *opar;
 
        st = ff_stream_clone(oc, ist);
        if (!st)
            return AVERROR(ENOMEM);
        opar = st->codecpar;
        if (!oc->oformat->codec_tag ||
            av_codec_get_id (oc->oformat->codec_tag, ipar->codec_tag) == opar->codec_id ||
            av_codec_get_tag(oc->oformat->codec_tag, ipar->codec_id) <= 0) {
            opar->codec_tag = ipar->codec_tag;
        } else {
            opar->codec_tag = 0;
        }
    }
 
    return 0;
}
 
static int set_segment_filename(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    size_t size;
    int ret;
    AVBPrint filename;
    char *new_name;
 
    av_bprint_init(&filename, 0, AV_BPRINT_SIZE_UNLIMITED);
    if (seg->segment_idx_wrap)
        seg->segment_idx %= seg->segment_idx_wrap;
    if (seg->use_strftime) {
        time_t now0;
        struct tm *tm, tmpbuf;
        time(&now0);
        tm = localtime_r(&now0, &tmpbuf);
        av_bprint_strftime(&filename, s->url, tm);
        if (!av_bprint_is_complete(&filename)) {
            av_bprint_finalize(&filename, NULL);
            return AVERROR(ENOMEM);
        }
    } else {
        ret = ff_bprint_get_frame_filename(&filename, s->url, seg->segment_idx, 0);
        if (ret < 0) {
            av_bprint_finalize(&filename, NULL);
            av_log(oc, AV_LOG_ERROR, "Invalid segment filename template '%s'\n", s->url);
            return ret;
        }
    }
    ret = av_bprint_finalize(&filename, &new_name);
    if (ret < 0)
        return ret;
    ff_format_set_url(oc, new_name);
 
    /* copy modified name in list entry */
    size = strlen(av_basename(oc->url)) + 1;
    if (seg->entry_prefix)
        size += strlen(seg->entry_prefix);
 
    if ((ret = av_reallocp(&seg->cur_entry.filename, size)) < 0)
        return ret;
    snprintf(seg->cur_entry.filename, size, "%s%s",
             seg->entry_prefix ? seg->entry_prefix : "",
             av_basename(oc->url));
 
    return 0;
}
 
static int segment_start(AVFormatContext *s, int write_header)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    int err = 0;
 
    if (write_header) {
        avformat_free_context(oc);
        seg->avf = NULL;
        if ((err = segment_mux_init(s)) < 0)
            return err;
        oc = seg->avf;
    }
 
    seg->segment_idx++;
    if ((seg->segment_idx_wrap) && (seg->segment_idx % seg->segment_idx_wrap == 0))
        seg->segment_idx_wrap_nb++;
 
    if ((err = set_segment_filename(s)) < 0)
        return err;
 
    if ((err = s->io_open(s, &oc->pb, oc->url, AVIO_FLAG_WRITE, NULL)) < 0) {
        av_log(s, AV_LOG_ERROR, "Failed to open segment '%s'\n", oc->url);
        return err;
    }
    if (!seg->individual_header_trailer)
        oc->pb->seekable = 0;
 
    if (oc->oformat->priv_class && oc->priv_data)
        av_opt_set(oc->priv_data, "mpegts_flags", "+resend_headers", 0);
 
    if (write_header) {
        AVDictionary *options = NULL;
        av_dict_copy(&options, seg->format_options, 0);
        av_dict_set(&options, "fflags", "-autobsf", 0);
        err = avformat_write_header(oc, &options);
        av_dict_free(&options);
        if (err < 0)
            return err;
    }
 
    seg->segment_frame_count = 0;
    return 0;
}
 
static int segment_list_open(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    int ret;
 
    av_freep(&seg->temp_list_filename);
    seg->temp_list_filename = av_asprintf(seg->use_rename ? "%s.tmp" : "%s", seg->list);
    if (!seg->temp_list_filename)
        return AVERROR(ENOMEM);
    ret = s->io_open(s, &seg->list_pb, seg->temp_list_filename, AVIO_FLAG_WRITE, NULL);
    if (ret < 0) {
        av_log(s, AV_LOG_ERROR, "Failed to open segment list '%s'\n", seg->list);
        return ret;
    }
 
    if (seg->list_type == LIST_TYPE_M3U8 && seg->segment_list_entries) {
        SegmentListEntry *entry;
        double max_duration = 0;
 
        avio_printf(seg->list_pb, "#EXTM3U\n");
        avio_printf(seg->list_pb, "#EXT-X-VERSION:3\n");
        avio_printf(seg->list_pb, "#EXT-X-MEDIA-SEQUENCE:%d\n", seg->segment_list_entries->index);
        avio_printf(seg->list_pb, "#EXT-X-ALLOW-CACHE:%s\n",
                    seg->list_flags & SEGMENT_LIST_FLAG_CACHE ? "YES" : "NO");
 
        av_log(s, AV_LOG_VERBOSE, "EXT-X-MEDIA-SEQUENCE:%d\n",
               seg->segment_list_entries->index);
 
        for (entry = seg->segment_list_entries; entry; entry = entry->next)
            max_duration = FFMAX(max_duration, entry->end_time - entry->start_time);
        avio_printf(seg->list_pb, "#EXT-X-TARGETDURATION:%"PRId64"\n", (int64_t)ceil(max_duration));
    } else if (seg->list_type == LIST_TYPE_FFCONCAT) {
        avio_printf(seg->list_pb, "ffconcat version 1.0\n");
    }
 
    return ret;
}
 
static void segment_list_print_entry(AVIOContext      *list_ioctx,
                                     ListType          list_type,
                                     const SegmentListEntry *list_entry,
                                     void *log_ctx)
{
    switch (list_type) {
    case LIST_TYPE_FLAT:
        avio_printf(list_ioctx, "%s\n", list_entry->filename);
        break;
    case LIST_TYPE_CSV:
    case LIST_TYPE_EXT:
        print_csv_escaped_str(list_ioctx, list_entry->filename);
        avio_printf(list_ioctx, ",%f,%f\n", list_entry->start_time, list_entry->end_time);
        break;
    case LIST_TYPE_M3U8:
        avio_printf(list_ioctx, "#EXTINF:%f,\n%s\n",
                    list_entry->end_time - list_entry->start_time, list_entry->filename);
        break;
    case LIST_TYPE_FFCONCAT:
    {
        char *buf;
        if (av_escape(&buf, list_entry->filename, NULL, AV_ESCAPE_MODE_AUTO, AV_ESCAPE_FLAG_WHITESPACE) < 0) {
            av_log(log_ctx, AV_LOG_WARNING,
                   "Error writing list entry '%s' in list file\n", list_entry->filename);
            return;
        }
        avio_printf(list_ioctx, "file %s\n", buf);
        av_free(buf);
        break;
    }
    default:
        av_assert0(!"Invalid list type");
    }
}
 
static int segment_end(AVFormatContext *s, int write_trailer, int is_last)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    int ret = 0;
    AVTimecode tc;
    AVRational rate;
    AVDictionaryEntry *tcr;
    char buf[AV_TIMECODE_STR_SIZE];
    int i;
    int err;
 
    if (!oc || !oc->pb)
        return AVERROR(EINVAL);
 
    av_write_frame(oc, NULL); /* Flush any buffered data (fragmented mp4) */
    if (write_trailer)
        ret = av_write_trailer(oc);
 
    if (ret < 0)
        av_log(s, AV_LOG_ERROR, "Failure occurred when ending segment '%s'\n",
               oc->url);
 
    if (seg->list) {
        if (seg->list_size || seg->list_type == LIST_TYPE_M3U8) {
            SegmentListEntry *entry = av_mallocz(sizeof(*entry));
            if (!entry) {
                ret = AVERROR(ENOMEM);
                goto end;
            }
 
            /* append new element */
            memcpy(entry, &seg->cur_entry, sizeof(*entry));
            entry->filename = av_strdup(entry->filename);
            if (!seg->segment_list_entries)
                seg->segment_list_entries = seg->segment_list_entries_end = entry;
            else
                seg->segment_list_entries_end->next = entry;
            seg->segment_list_entries_end = entry;
 
            /* drop first item */
            if (seg->list_size && seg->segment_count >= seg->list_size) {
                entry = seg->segment_list_entries;
                seg->segment_list_entries = seg->segment_list_entries->next;
                av_freep(&entry->filename);
                av_freep(&entry);
            }
 
            if ((ret = segment_list_open(s)) < 0)
                goto end;
            for (entry = seg->segment_list_entries; entry; entry = entry->next)
                segment_list_print_entry(seg->list_pb, seg->list_type, entry, s);
            if (seg->list_type == LIST_TYPE_M3U8 && is_last)
                avio_printf(seg->list_pb, "#EXT-X-ENDLIST\n");
            ff_format_io_close(s, &seg->list_pb);
            if (seg->use_rename)
                ff_rename(seg->temp_list_filename, seg->list, s);
        } else {
            segment_list_print_entry(seg->list_pb, seg->list_type, &seg->cur_entry, s);
            avio_flush(seg->list_pb);
        }
    }
 
    av_log(s, AV_LOG_VERBOSE, "segment:'%s' count:%d ended\n",
           seg->avf->url, seg->segment_count);
    seg->segment_count++;
 
    if (seg->increment_tc) {
        tcr = av_dict_get(s->metadata, "timecode", NULL, 0);
        if (tcr) {
            /* search the first video stream */
            for (i = 0; i < s->nb_streams; i++) {
                if (s->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
                    rate = s->streams[i]->avg_frame_rate;/* Get fps from the video stream */
                    err = av_timecode_init_from_string(&tc, rate, tcr->value, s);
                    if (err < 0) {
                        av_log(s, AV_LOG_WARNING, "Could not increment global timecode, error occurred during timecode creation.\n");
                        break;
                    }
                    tc.start += (int)((seg->cur_entry.end_time - seg->cur_entry.start_time) * av_q2d(rate));/* increment timecode */
                    av_dict_set(&s->metadata, "timecode",
                                av_timecode_make_string(&tc, buf, 0), 0);
                    break;
                }
            }
        } else {
            av_log(s, AV_LOG_WARNING, "Could not increment global timecode, no global timecode metadata found.\n");
        }
        for (i = 0; i < s->nb_streams; i++) {
            if (s->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
                char st_buf[AV_TIMECODE_STR_SIZE];
                AVTimecode st_tc;
                AVRational st_rate = s->streams[i]->avg_frame_rate;
                AVDictionaryEntry *st_tcr = av_dict_get(s->streams[i]->metadata, "timecode", NULL, 0);
                if (st_tcr) {
                    if ((av_timecode_init_from_string(&st_tc, st_rate, st_tcr->value, s) < 0)) {
                        av_log(s, AV_LOG_WARNING, "Could not increment stream %d timecode, error occurred during timecode creation.\n", i);
                        continue;
                    }
                st_tc.start += (int)((seg->cur_entry.end_time - seg->cur_entry.start_time) * av_q2d(st_rate));    // increment timecode
                av_dict_set(&s->streams[i]->metadata, "timecode", av_timecode_make_string(&st_tc, st_buf, 0), 0);
                }
            }
        }
    }
 
end:
    ff_format_io_close(oc, &oc->pb);
 
    return ret;
}
 
static int parse_times(void *log_ctx, int64_t **times, int *nb_times,
                       const char *times_str)
{
    char *p;
    int i, ret = 0;
    char *times_str1 = av_strdup(times_str);
    char *saveptr = NULL;
 
    if (!times_str1)
        return AVERROR(ENOMEM);
 
#define FAIL(err) ret = err; goto end
 
    *nb_times = 1;
    for (p = times_str1; *p; p++)
        if (*p == ',')
            (*nb_times)++;
 
    *times = av_malloc_array(*nb_times, sizeof(**times));
    if (!*times) {
        av_log(log_ctx, AV_LOG_ERROR, "Could not allocate forced times array\n");
        FAIL(AVERROR(ENOMEM));
    }
 
    p = times_str1;
    for (i = 0; i < *nb_times; i++) {
        int64_t t;
        char *tstr = av_strtok(p, ",", &saveptr);
        p = NULL;
 
        if (!tstr || !tstr[0]) {
            av_log(log_ctx, AV_LOG_ERROR, "Empty time specification in times list %s\n",
                   times_str);
            FAIL(AVERROR(EINVAL));
        }
 
        ret = av_parse_time(&t, tstr, 1);
        if (ret < 0) {
            av_log(log_ctx, AV_LOG_ERROR,
                   "Invalid time duration specification '%s' in times list %s\n", tstr, times_str);
            FAIL(AVERROR(EINVAL));
        }
        (*times)[i] = t;
 
        /* check on monotonicity */
        if (i && (*times)[i-1] > (*times)[i]) {
            av_log(log_ctx, AV_LOG_ERROR,
                   "Specified time %f is smaller than the last time %f\n",
                   (float)((*times)[i])/1000000, (float)((*times)[i-1])/1000000);
            FAIL(AVERROR(EINVAL));
        }
    }
 
end:
    av_free(times_str1);
    return ret;
}
 
static int parse_frames(void *log_ctx, int **frames, int *nb_frames,
                        const char *frames_str)
{
    const char *p;
    int i;
 
    *nb_frames = 1;
    for (p = frames_str; *p; p++)
        if (*p == ',')
            (*nb_frames)++;
 
    *frames = av_malloc_array(*nb_frames, sizeof(**frames));
    if (!*frames) {
        av_log(log_ctx, AV_LOG_ERROR, "Could not allocate forced frames array\n");
        return AVERROR(ENOMEM);
    }
 
    p = frames_str;
    for (i = 0; i < *nb_frames; i++) {
        long int f;
        char *tailptr;
 
        if (*p == '\0' || *p == ',') {
            av_log(log_ctx, AV_LOG_ERROR, "Empty frame specification in frame list %s\n",
                   frames_str);
            return AVERROR(EINVAL);
        }
        f = strtol(p, &tailptr, 10);
        if (*tailptr != '\0' && *tailptr != ',' || f <= 0 || f >= INT_MAX) {
            av_log(log_ctx, AV_LOG_ERROR,
                   "Invalid argument '%s', must be a positive integer < INT_MAX\n",
                   p);
            return AVERROR(EINVAL);
        }
        if (*tailptr == ',')
            tailptr++;
        p = tailptr;
        (*frames)[i] = f;
 
        /* check on monotonicity */
        if (i && (*frames)[i-1] > (*frames)[i]) {
            av_log(log_ctx, AV_LOG_ERROR,
                   "Specified frame %d is smaller than the last frame %d\n",
                   (*frames)[i], (*frames)[i-1]);
            return AVERROR(EINVAL);
        }
    }
 
    return 0;
}
 
static int open_null_ctx(AVIOContext **ctx)
{
    int buf_size = 32768;
    uint8_t *buf = av_malloc(buf_size);
    if (!buf)
        return AVERROR(ENOMEM);
    *ctx = avio_alloc_context(buf, buf_size, 1, NULL, NULL, NULL, NULL);
    if (!*ctx) {
        av_free(buf);
        return AVERROR(ENOMEM);
    }
    return 0;
}
 
static void close_null_ctxp(AVIOContext **pb)
{
    av_freep(&(*pb)->buffer);
    avio_context_free(pb);
}
 
static int select_reference_stream(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    int ret, i;
 
    seg->reference_stream_index = -1;
    if (!strcmp(seg->reference_stream_specifier, "auto")) {
        /* select first index of type with highest priority */
        int type_index_map[AVMEDIA_TYPE_NB];
        static const enum AVMediaType type_priority_list[] = {
            AVMEDIA_TYPE_VIDEO,
            AVMEDIA_TYPE_AUDIO,
            AVMEDIA_TYPE_SUBTITLE,
            AVMEDIA_TYPE_DATA,
            AVMEDIA_TYPE_ATTACHMENT
        };
        enum AVMediaType type;
 
        for (i = 0; i < AVMEDIA_TYPE_NB; i++)
            type_index_map[i] = -1;
 
        /* select first index for each type */
        for (i = 0; i < s->nb_streams; i++) {
            type = s->streams[i]->codecpar->codec_type;
            if ((unsigned)type < AVMEDIA_TYPE_NB && type_index_map[type] == -1
                /* ignore attached pictures/cover art streams */
                && !(s->streams[i]->disposition & AV_DISPOSITION_ATTACHED_PIC))
                type_index_map[type] = i;
        }
 
        for (i = 0; i < FF_ARRAY_ELEMS(type_priority_list); i++) {
            type = type_priority_list[i];
            if ((seg->reference_stream_index = type_index_map[type]) >= 0)
                break;
        }
    } else {
        for (i = 0; i < s->nb_streams; i++) {
            ret = avformat_match_stream_specifier(s, s->streams[i],
                                                  seg->reference_stream_specifier);
            if (ret < 0)
                return ret;
            if (ret > 0) {
                seg->reference_stream_index = i;
                break;
            }
        }
    }
 
    if (seg->reference_stream_index < 0) {
        av_log(s, AV_LOG_ERROR, "Could not select stream matching identifier '%s'\n",
               seg->reference_stream_specifier);
        return AVERROR(EINVAL);
    }
 
    return 0;
}
 
static void seg_free(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    SegmentListEntry *cur;
 
    ff_format_io_close(s, &seg->list_pb);
    if (seg->avf) {
        if (seg->is_nullctx)
            close_null_ctxp(&seg->avf->pb);
        else
            ff_format_io_close(s, &seg->avf->pb);
        avformat_free_context(seg->avf);
        seg->avf = NULL;
    }
    av_freep(&seg->times);
    av_freep(&seg->frames);
    av_freep(&seg->cur_entry.filename);
    av_freep(&seg->temp_list_filename);
 
    cur = seg->segment_list_entries;
    while (cur) {
        SegmentListEntry *next = cur->next;
        av_freep(&cur->filename);
        av_free(cur);
        cur = next;
    }
}
 
static int seg_init(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    AVDictionary *options = NULL;
    int ret;
    int i;
 
    seg->segment_count = 0;
    if (!seg->write_header_trailer)
        seg->individual_header_trailer = 0;
 
    if (seg->header_filename) {
        seg->write_header_trailer = 1;
        seg->individual_header_trailer = 0;
    }
 
    if (seg->initial_offset > 0) {
        av_log(s, AV_LOG_WARNING, "NOTE: the option initial_offset is deprecated,"
               "you can use output_ts_offset instead of it\n");
    }
 
    if ((seg->time != 2000000) + !!seg->times_str + !!seg->frames_str > 1) {
        av_log(s, AV_LOG_ERROR,
               "segment_time, segment_times, and segment_frames options "
               "are mutually exclusive, select just one of them\n");
        return AVERROR(EINVAL);
    }
 
    if (seg->times_str || seg->frames_str)
        seg->min_seg_duration = 0;
 
    if (seg->times_str) {
        if ((ret = parse_times(s, &seg->times, &seg->nb_times, seg->times_str)) < 0)
            return ret;
    } else if (seg->frames_str) {
        if ((ret = parse_frames(s, &seg->frames, &seg->nb_frames, seg->frames_str)) < 0)
            return ret;
    } else {
        if (seg->use_clocktime) {
            if (seg->time <= 0) {
                av_log(s, AV_LOG_ERROR, "Invalid negative segment_time with segment_atclocktime option set\n");
                return AVERROR(EINVAL);
            }
            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) {
        if (seg->list_type == LIST_TYPE_UNDEFINED) {
            if      (av_match_ext(seg->list, "csv" )) seg->list_type = LIST_TYPE_CSV;
            else if (av_match_ext(seg->list, "ext" )) seg->list_type = LIST_TYPE_EXT;
            else if (av_match_ext(seg->list, "m3u8")) seg->list_type = LIST_TYPE_M3U8;
            else if (av_match_ext(seg->list, "ffcat,ffconcat")) seg->list_type = LIST_TYPE_FFCONCAT;
            else                                      seg->list_type = LIST_TYPE_FLAT;
        }
        if (!seg->list_size && seg->list_type != LIST_TYPE_M3U8) {
            if ((ret = segment_list_open(s)) < 0)
                return ret;
        } else {
            const char *proto = avio_find_protocol_name(seg->list);
            seg->use_rename = proto && !strcmp(proto, "file");
        }
    }
 
    if (seg->list_type == LIST_TYPE_EXT)
        av_log(s, AV_LOG_WARNING, "'ext' list type option is deprecated in favor of 'csv'\n");
 
    if ((ret = select_reference_stream(s)) < 0)
        return ret;
    av_log(s, AV_LOG_VERBOSE, "Selected stream id:%d type:%s\n",
           seg->reference_stream_index,
           av_get_media_type_string(s->streams[seg->reference_stream_index]->codecpar->codec_type));
 
    seg->reference_stream_first_pts = AV_NOPTS_VALUE;
 
    seg->oformat = av_guess_format(seg->format, s->url, NULL);
 
    if (!seg->oformat)
        return AVERROR_MUXER_NOT_FOUND;
    if (seg->oformat->flags & AVFMT_NOFILE) {
        av_log(s, AV_LOG_ERROR, "format %s not supported.\n",
               seg->oformat->name);
        return AVERROR(EINVAL);
    }
 
    if ((ret = segment_mux_init(s)) < 0)
        return ret;
 
    if ((ret = set_segment_filename(s)) < 0)
        return ret;
    oc = seg->avf;
 
    if (seg->write_header_trailer) {
        if ((ret = s->io_open(s, &oc->pb,
                              seg->header_filename ? seg->header_filename : oc->url,
                              AVIO_FLAG_WRITE, NULL)) < 0) {
            av_log(s, AV_LOG_ERROR, "Failed to open segment '%s'\n", oc->url);
            return ret;
        }
        if (!seg->individual_header_trailer)
            oc->pb->seekable = 0;
    } else {
        if ((ret = open_null_ctx(&oc->pb)) < 0)
            return ret;
        seg->is_nullctx = 1;
    }
 
    av_dict_copy(&options, seg->format_options, 0);
    av_dict_set(&options, "fflags", "-autobsf", 0);
    ret = avformat_init_output(oc, &options);
    if (av_dict_count(options)) {
        av_log(s, AV_LOG_ERROR,
               "Some of the provided format options are not recognized\n");
        av_dict_free(&options);
        return AVERROR(EINVAL);
    }
    av_dict_free(&options);
 
    if (ret < 0) {
        return ret;
    }
    seg->segment_frame_count = 0;
 
    av_assert0(s->nb_streams == oc->nb_streams);
    if (ret == AVSTREAM_INIT_IN_WRITE_HEADER) {
        ret = avformat_write_header(oc, NULL);
        if (ret < 0)
            return ret;
        seg->header_written = 1;
    }
 
    for (i = 0; i < s->nb_streams; i++) {
        AVStream *inner_st  = oc->streams[i];
        AVStream *outer_st = s->streams[i];
        avpriv_set_pts_info(outer_st, inner_st->pts_wrap_bits, inner_st->time_base.num, inner_st->time_base.den);
    }
 
    if (oc->avoid_negative_ts > 0 && s->avoid_negative_ts < 0)
        s->avoid_negative_ts = 1;
 
    return ret;
}
 
static int seg_write_header(AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    int ret;
 
    if (!seg->header_written) {
        ret = avformat_write_header(oc, NULL);
        if (ret < 0)
            return ret;
    }
 
    if (!seg->write_header_trailer || seg->header_filename) {
        if (seg->header_filename) {
            av_write_frame(oc, NULL);
            ff_format_io_close(oc, &oc->pb);
        } else {
            close_null_ctxp(&oc->pb);
            seg->is_nullctx = 0;
        }
        if ((ret = oc->io_open(oc, &oc->pb, oc->url, AVIO_FLAG_WRITE, NULL)) < 0)
            return ret;
        if (!seg->individual_header_trailer)
            oc->pb->seekable = 0;
    }
 
    return 0;
}
 
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, pkt_pts_avtb;
    int start_frame = INT_MAX;
    int ret;
    struct tm ti;
    int64_t usecs;
    int64_t wrapped_val;
 
    if (!seg->avf || !seg->avf->pb)
        return AVERROR(EINVAL);
 
    if (!st->codecpar->extradata_size) {
        size_t pkt_extradata_size;
        uint8_t *pkt_extradata = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, &pkt_extradata_size);
        if (pkt_extradata && pkt_extradata_size > 0) {
            ret = ff_alloc_extradata(st->codecpar, pkt_extradata_size);
            if (ret < 0) {
                av_log(s, AV_LOG_WARNING, "Unable to add extradata to stream. Output segments may be invalid.\n");
                goto calc_times;
            }
            memcpy(st->codecpar->extradata, pkt_extradata, pkt_extradata_size);
        }
    }
 
calc_times:
    if (seg->times) {
        end_pts = seg->segment_count < seg->nb_times ?
            seg->times[seg->segment_count] : INT64_MAX;
    } else if (seg->frames) {
        start_frame = seg->segment_count < seg->nb_frames ?
            seg->frames[seg->segment_count] : INT_MAX;
    } else {
        if (seg->use_clocktime) {
            int64_t avgt = av_gettime();
            time_t sec = avgt / 1000000;
            localtime_r(&sec, &ti);
            usecs = (int64_t)(ti.tm_hour * 3600 + ti.tm_min * 60 + ti.tm_sec) * 1000000 + (avgt % 1000000);
            wrapped_val = (usecs + seg->clocktime_offset) % seg->time;
            if (wrapped_val < seg->last_val && wrapped_val < seg->clocktime_wrap_duration)
                seg->cut_pending = 1;
            seg->last_val = wrapped_val;
        } else {
            end_pts = seg->time * (seg->segment_count + 1);
        }
    }
 
    ff_dlog(s, "packet stream:%d pts:%s pts_time:%s duration_time:%s is_key:%d frame:%d\n",
            pkt->stream_index, av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
            av_ts2timestr(pkt->duration, &st->time_base),
            pkt->flags & AV_PKT_FLAG_KEY,
            pkt->stream_index == seg->reference_stream_index ? seg->frame_count : -1);
 
    if (seg->reference_stream_first_pts == AV_NOPTS_VALUE &&
        pkt->stream_index == seg->reference_stream_index &&
        pkt->pts != AV_NOPTS_VALUE) {
        seg->reference_stream_first_pts = av_rescale_q(pkt->pts, st->time_base, AV_TIME_BASE_Q);
    }
 
    if (seg->reference_stream_first_pts != AV_NOPTS_VALUE) {
        end_pts += (INT64_MAX - end_pts >= seg->reference_stream_first_pts) ?
                    seg->reference_stream_first_pts :
                    INT64_MAX - end_pts;
    }
 
    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 */
        if (seg->cur_entry.last_duration == 0)
            seg->cur_entry.end_time = (double)pkt->pts * av_q2d(st->time_base);
 
        if ((ret = segment_end(s, seg->individual_header_trailer, 0)) < 0)
            goto fail;
 
        if ((ret = segment_start(s, seg->individual_header_trailer)) < 0)
            goto fail;
 
        seg->cut_pending = 0;
        seg->cur_entry.index = seg->segment_idx + seg->segment_idx_wrap * seg->segment_idx_wrap_nb;
        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) {
        if (pkt->pts != AV_NOPTS_VALUE)
            seg->cur_entry.end_time =
                FFMAX(seg->cur_entry.end_time, (double)(pkt->pts + pkt->duration) * av_q2d(st->time_base));
        seg->cur_entry.last_duration = pkt->duration;
    }
 
    if (seg->segment_frame_count == 0) {
        av_log(s, AV_LOG_VERBOSE, "segment:'%s' starts with packet stream:%d pts:%s pts_time:%s frame:%d\n",
               seg->avf->url, pkt->stream_index,
               av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base), seg->frame_count);
    }
 
    av_log(s, AV_LOG_DEBUG, "stream:%d start_pts_time:%s pts:%s pts_time:%s dts:%s dts_time:%s",
           pkt->stream_index,
           av_ts2timestr(seg->cur_entry.start_pts, &AV_TIME_BASE_Q),
           av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
           av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
 
    /* compute new timestamps */
    offset = av_rescale_q(seg->initial_offset - (seg->reset_timestamps ? seg->cur_entry.start_pts : 0),
                          AV_TIME_BASE_Q, st->time_base);
    if (pkt->pts != AV_NOPTS_VALUE)
        pkt->pts += offset;
    if (pkt->dts != AV_NOPTS_VALUE)
        pkt->dts += offset;
 
    av_log(s, AV_LOG_DEBUG, " -> pts:%s pts_time:%s dts:%s dts_time:%s\n",
           av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &st->time_base),
           av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &st->time_base));
 
    ret = ff_write_chained(seg->avf, pkt->stream_index, pkt, s,
                           seg->initial_offset || seg->reset_timestamps ||
                           ffofmt(seg->avf->oformat)->interleave_packet);
 
fail:
    /* Use st->index here as the packet returned from ff_write_chained()
     * is blank if interleaving has been used. */
    if (st->index == seg->reference_stream_index) {
        seg->frame_count++;
        seg->segment_frame_count++;
    }
 
    return ret;
}
 
static int seg_write_trailer(struct AVFormatContext *s)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    int ret;
 
    if (!oc)
        return 0;
 
    if (!seg->write_header_trailer) {
        if ((ret = segment_end(s, 0, 1)) < 0)
            return ret;
        if ((ret = open_null_ctx(&oc->pb)) < 0)
            return ret;
        seg->is_nullctx = 1;
        ret = av_write_trailer(oc);
    } else {
        ret = segment_end(s, 1, 1);
    }
    return ret;
}
 
static int seg_check_bitstream(AVFormatContext *s, AVStream *st,
                               const AVPacket *pkt)
{
    SegmentContext *seg = s->priv_data;
    AVFormatContext *oc = seg->avf;
    if (ffofmt(oc->oformat)->check_bitstream) {
        AVStream *const ost = oc->streams[st->index];
        int ret = ffofmt(oc->oformat)->check_bitstream(oc, ost, pkt);
        if (ret == 1) {
            FFStream *const  sti = ffstream(st);
            FFStream *const osti = ffstream(ost);
             sti->bsfc = osti->bsfc;
            osti->bsfc = NULL;
        }
        return ret;
    }
    return 1;
}
 
#define OFFSET(x) offsetof(SegmentContext, x)
#define E AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
    { "reference_stream",  "set reference stream", OFFSET(reference_stream_specifier), AV_OPT_TYPE_STRING, {.str = "auto"}, 0, 0, E },
    { "segment_format",    "set container format used for the segments", OFFSET(format),  AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       E },
    { "segment_format_options", "set list of options for the container format used for the segments", OFFSET(format_options), AV_OPT_TYPE_DICT, {.str = NULL}, 0, 0, E },
    { "segment_list",      "set the segment list filename",              OFFSET(list),    AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       E },
    { "segment_header_filename", "write a single file containing the header", OFFSET(header_filename), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E },
 
    { "segment_list_flags","set flags affecting segment list generation", OFFSET(list_flags), AV_OPT_TYPE_FLAGS, {.i64 = SEGMENT_LIST_FLAG_CACHE }, 0, UINT_MAX, E, .unit = "list_flags"},
    { "cache",             "allow list caching",                                    0, AV_OPT_TYPE_CONST, {.i64 = SEGMENT_LIST_FLAG_CACHE }, INT_MIN, INT_MAX,   E, .unit = "list_flags"},
    { "live",              "enable live-friendly list generation (useful for HLS)", 0, AV_OPT_TYPE_CONST, {.i64 = SEGMENT_LIST_FLAG_LIVE }, INT_MIN, INT_MAX,    E, .unit = "list_flags"},
 
    { "segment_list_size", "set the maximum number of playlist entries", OFFSET(list_size), AV_OPT_TYPE_INT,  {.i64 = 0},     0, INT_MAX, E },
 
    { "segment_list_type", "set the segment list type",                  OFFSET(list_type), AV_OPT_TYPE_INT,  {.i64 = LIST_TYPE_UNDEFINED}, -1, LIST_TYPE_NB-1, E, .unit = "list_type" },
    { "flat", "flat format",     0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_FLAT }, INT_MIN, INT_MAX, E, .unit = "list_type" },
    { "csv",  "csv format",      0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_CSV  }, INT_MIN, INT_MAX, E, .unit = "list_type" },
    { "ext",  "extended format", 0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_EXT  }, INT_MIN, INT_MAX, E, .unit = "list_type" },
    { "ffconcat", "ffconcat format", 0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_FFCONCAT }, INT_MIN, INT_MAX, E, .unit = "list_type" },
    { "m3u8", "M3U8 format",     0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_M3U8 }, INT_MIN, INT_MAX, E, .unit = "list_type" },
    { "hls", "Apple HTTP Live Streaming compatible", 0, AV_OPT_TYPE_CONST, {.i64=LIST_TYPE_M3U8 }, INT_MIN, INT_MAX, E, .unit = "list_type" },
 
    { "segment_atclocktime",      "set segment to be cut at clocktime",  OFFSET(use_clocktime), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E},
    { "segment_clocktime_offset", "set segment clocktime offset",        OFFSET(clocktime_offset), AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, 86400000000LL, E},
    { "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 },
    { "segment_list_entry_prefix", "set base url prefix for segments", OFFSET(entry_prefix), AV_OPT_TYPE_STRING,  {.str = NULL}, 0, 0, E },
    { "segment_start_number", "set the sequence number of the first segment", OFFSET(segment_idx), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, E },
    { "segment_wrap_number", "set the number of wrap before the first segment", OFFSET(segment_idx_wrap_nb), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, E },
    { "strftime",          "set filename expansion with strftime at segment creation", OFFSET(use_strftime), AV_OPT_TYPE_BOOL, {.i64 = 0 }, 0, 1, E },
    { "increment_tc", "increment timecode between each segment", OFFSET(increment_tc), AV_OPT_TYPE_BOOL, {.i64 = 0 }, 0, 1, E },
    { "break_non_keyframes", "allow breaking segments on non-keyframes", OFFSET(break_non_keyframes), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
 
    { "individual_header_trailer", "write header/trailer to each segment", OFFSET(individual_header_trailer), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, E },
    { "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 beginning 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 },
};
 
static const AVClass seg_class = {
    .class_name = "(stream) segment muxer",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};
 
#if CONFIG_SEGMENT_MUXER
const FFOutputFormat ff_segment_muxer = {
    .p.name          = "segment",
    .p.long_name     = NULL_IF_CONFIG_SMALL("segment"),
    .p.flags         = AVFMT_NOFILE|AVFMT_GLOBALHEADER,
    .p.priv_class    = &seg_class,
    .priv_data_size = sizeof(SegmentContext),
    .init           = seg_init,
    .write_header   = seg_write_header,
    .write_packet   = seg_write_packet,
    .write_trailer  = seg_write_trailer,
    .deinit         = seg_free,
    .check_bitstream = seg_check_bitstream,
};
#endif
 
#if CONFIG_STREAM_SEGMENT_MUXER
const FFOutputFormat ff_stream_segment_muxer = {
    .p.name          = "stream_segment,ssegment",
    .p.long_name     = NULL_IF_CONFIG_SMALL("streaming segment muxer"),
    .p.flags         = AVFMT_NOFILE,
    .p.priv_class    = &seg_class,
    .priv_data_size  = sizeof(SegmentContext),
    .init           = seg_init,
    .write_header   = seg_write_header,
    .write_packet   = seg_write_packet,
    .write_trailer  = seg_write_trailer,
    .deinit         = seg_free,
    .check_bitstream = seg_check_bitstream,
};
#endif