static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    HLSContext *c = s->priv_data;
    int ret, i, minvariant = -1;

    if (c->first_packet) {
        recheck_discard_flags(s, 1);
        c->first_packet = 0;
    }

start:
    c->end_of_segment = 0;
    for (i = 0; i < c->n_variants; i++) {
        struct variant *var = c->variants[i];
        /* Make sure we've got one buffered packet from each open variant
         * stream */
        if (var->needed && !var->pkt.data) {
            while (1) {
                int64_t ts_diff;
                AVStream *st;
                ret = av_read_frame(var->ctx, &var->pkt);
                if (ret < 0) {
                    if (!var->pb.eof_reached)
                        return ret;
                    reset_packet(&var->pkt);
                    break;
                } else {
                    if (c->first_timestamp == AV_NOPTS_VALUE)
                        c->first_timestamp = var->pkt.dts;
                }

                if (c->seek_timestamp == AV_NOPTS_VALUE)
                    break;

                if (var->pkt.dts == AV_NOPTS_VALUE) {
                    c->seek_timestamp = AV_NOPTS_VALUE;
                    break;
                }

                st = var->ctx->streams[var->pkt.stream_index];
                ts_diff = av_rescale_rnd(var->pkt.dts, AV_TIME_BASE,
                                         st->time_base.den, AV_ROUND_DOWN) -
                          c->seek_timestamp;
                if (ts_diff >= 0 && (c->seek_flags  & AVSEEK_FLAG_ANY ||
                                     var->pkt.flags & AV_PKT_FLAG_KEY)) {
                    c->seek_timestamp = AV_NOPTS_VALUE;
                    break;
                }
            }
        }
        /* Check if this stream has the packet with the lowest dts */
        if (var->pkt.data) {
            if (minvariant < 0 ||
                var->pkt.dts < c->variants[minvariant]->pkt.dts)
                minvariant = i;
        }
    }
    if (c->end_of_segment) {
        if (recheck_discard_flags(s, 0))
            goto start;
    }
    /* If we got a packet, return it */
    if (minvariant >= 0) {
        *pkt = c->variants[minvariant]->pkt;
        pkt->stream_index += c->variants[minvariant]->stream_offset;
        reset_packet(&c->variants[minvariant]->pkt);
        return 0;
    }
    return AVERROR_EOF;
}