diff --git a/doc/demuxers.texi b/doc/demuxers.texi
index 3c15ab9eee..4cdbd95962 100644
--- a/doc/demuxers.texi
+++ b/doc/demuxers.texi
@@ -321,6 +321,9 @@ available in a metadata key named "variant_bitrate".
 It accepts the following options:
 
 @table @option
+@item abr
+enable abr to switch streams.
+
 @item live_start_index
 segment index to start live streams at (negative values are from the end).
 
diff --git a/libavformat/hls.c b/libavformat/hls.c
index 3798bdd5d1..b8f202e6a8 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -189,6 +189,15 @@ struct variant {
     char subtitles_group[MAX_FIELD_LEN];
 };
 
+struct throughput {
+    int n_throughputs;
+
+    /* throughputs are in kbps, always record the last 20 times */
+    float throughput_fifo[20];
+    int head;
+    int tail;
+};
+
 typedef struct HLSContext {
     AVClass *class;
     AVFormatContext *ctx;
@@ -213,8 +222,36 @@ typedef struct HLSContext {
     int http_multiple;
     int http_seekable;
     AVIOContext *playlist_pb;
+
+    int abr;
+    struct throughput *throughputs;
+    int can_switch;
+    int switch_request2;
+    int switch_delay;
+    int64_t switch_timestamp;
+    int64_t delta_timestamp;
+    int cur_pls;
 } HLSContext;
 
+static struct segment *next_segment(struct playlist *pls);
+static int open_input(HLSContext *c, struct playlist *pls, struct segment *seg, AVIOContext **in);
+
+static void sync_cur_seq(HLSContext *c) {
+    int i;
+    for (i = 0; i < c->n_playlists; i++) {
+        struct playlist *pls = c->playlists[i];
+        pls->cur_seq_no = c->cur_seq_no;
+    }
+}
+
+static struct segment *next2_segment(struct playlist *pls)
+{
+    int n = pls->cur_seq_no - pls->start_seq_no + 2;
+    if (n >= pls->n_segments)
+        return NULL;
+    return pls->segments[n];
+}
+
 static void free_segment_dynarray(struct segment **segments, int n_segments)
 {
     int i;
@@ -624,6 +661,33 @@ static int open_url_keepalive(AVFormatContext *s, AVIOContext **pb,
 #endif
 }
 
+static int update_throughputs(struct throughput *thr, float time, int pb_size)
+{
+    if (pb_size <= 0 || time <= 0)
+        return -1;
+    if (thr->n_throughputs < 20) {
+        ++thr->n_throughputs;
+        thr->throughput_fifo[thr->tail] = (float)(pb_size) / time;
+    } else {
+        thr->throughput_fifo[thr->tail] = (float)(pb_size) / time;
+        ++thr->head;
+    }
+
+    thr->tail = (thr->tail + 1) % 20;
+    return 0;
+}
+
+static int64_t get_switch_timestamp(HLSContext *c, struct playlist *pls)
+{
+    int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ?
+                  0 : c->first_timestamp;
+
+    for (int i = 0; i < pls->cur_seq_no + 2; i++) {
+        pos += pls->segments[i]->duration;
+    }
+    return pos;
+}
+
 static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
                     AVDictionary *opts, AVDictionary *opts2, int *is_http_out)
 {
@@ -633,7 +697,10 @@ static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
     int ret;
     int is_http = 0;
 
-    if (av_strstart(url, "crypto", NULL)) {
+    if (av_strstart(url, "abr", NULL)) {
+        if (url[3] == '+' || url[3] == ':')
+            proto_name = avio_find_protocol_name(url + 4);
+    } else if (av_strstart(url, "crypto", NULL)) {
         if (url[6] == '+' || url[6] == ':')
             proto_name = avio_find_protocol_name(url + 7);
     } else if (av_strstart(url, "data", NULL)) {
@@ -665,6 +732,8 @@ static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
 
     if (!strncmp(proto_name, url, strlen(proto_name)) && url[strlen(proto_name)] == ':')
         ;
+    else if (av_strstart(url, "abr", NULL) && !strncmp(proto_name, url + 4, strlen(proto_name)) && url[4 + strlen(proto_name)] == ':')
+        ;
     else if (av_strstart(url, "crypto", NULL) && !strncmp(proto_name, url + 7, strlen(proto_name)) && url[7 + strlen(proto_name)] == ':')
         ;
     else if (av_strstart(url, "data", NULL) && !strncmp(proto_name, url + 5, strlen(proto_name)) && url[5 + strlen(proto_name)] == ':')
@@ -690,6 +759,31 @@ static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
     } else {
         ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
     }
+    if (c->abr) {
+        AVDictionary *abr_ret = NULL;
+        AVDictionaryEntry *en = NULL;
+        struct segment *seg;
+        int pb_size, switch_request;
+        av_opt_get_dict_val(*pb, "abr-metadata", AV_OPT_SEARCH_CHILDREN, &abr_ret);
+        en = av_dict_get(abr_ret, "download_time", NULL, 0);
+        pb_size = avio_size(*pb);
+        update_throughputs(c->throughputs, atoi(en->value) / 1000.0, pb_size);
+        av_log(s, AV_LOG_VERBOSE, "[abr] time=%.2fms, size=%.2fkb\n", atoi(en->value) / 1000.0, pb_size / 1000.0);
+        en = av_dict_get(abr_ret, "switch_request", NULL, 0);
+        switch_request = atoi(en->value);
+        av_log(s, AV_LOG_VERBOSE, "[abr] switch request: %s\n", en->value);
+        if (switch_request != -1) {
+            c->switch_request2 = switch_request;
+            c->switch_delay = 2;
+            c->can_switch = 0;
+            sync_cur_seq(c);
+            seg = next2_segment(c->playlists[c->switch_request2]);
+            c->switch_timestamp = get_switch_timestamp(c,  c->playlists[c->switch_request2]);
+            av_log(s, AV_LOG_VERBOSE, "[abr] switch timestamp: %ld\n", c->switch_timestamp);
+            c->playlists[c->switch_request2]->input_next_requested = 1;
+            ret = open_input(c, c->playlists[c->switch_request2], seg, &c->playlists[c->switch_request2]->input_next);
+        }
+    }
     if (ret >= 0) {
         // update cookies on http response with setcookies.
         char *new_cookies = NULL;
@@ -1219,6 +1313,33 @@ static void intercept_id3(struct playlist *pls, uint8_t *buf,
         pls->is_id3_timestamped = (pls->id3_mpegts_timestamp != AV_NOPTS_VALUE);
 }
 
+static int abrinfo_to_dict(HLSContext *c, char **abr_info)
+{
+    struct throughput *thr = c->throughputs;
+    char buffer[MAX_URL_SIZE];
+    int size, i;
+    size = snprintf(buffer, sizeof(buffer), "format=hls:");
+    size += snprintf(buffer + size, sizeof(buffer) - size, "cur_pls=%d:", c->cur_pls);
+    size += snprintf(buffer + size, sizeof(buffer) - size, "can_switch=%d:", c->can_switch);
+    size += snprintf(buffer + size, sizeof(buffer) - size, "n_variants=%d:", c->n_variants);
+    for (i = 0; i < c->n_variants; i++) {
+        struct variant *v = c->variants[i];
+        size += snprintf(buffer + size, sizeof(buffer) - size, "variant_bitrate%d=%d:", i, v->bandwidth);
+    }
+    size += snprintf(buffer + size, sizeof(buffer) - size, "n_throughputs=%d:", thr->n_throughputs);
+    if (thr->n_throughputs > 0) {
+        i = thr->head;
+        do {
+            size += snprintf(buffer + size, sizeof(buffer) - size, "throughputs%d=%.2f:", i, thr->throughput_fifo[i]);
+            i = (i + 1) % 20;
+        } while (i != thr->tail);
+    }
+    *abr_info = av_malloc(size);
+    snprintf(*abr_info, size, "%s", buffer);
+    av_log(c, AV_LOG_DEBUG, "[abr] abr_info: %s\n", *abr_info);
+    return 0;
+}
+
 static int open_input(HLSContext *c, struct playlist *pls, struct segment *seg, AVIOContext **in)
 {
     AVDictionary *opts = NULL;
@@ -1238,8 +1359,20 @@ static int open_input(HLSContext *c, struct playlist *pls, struct segment *seg,
     av_log(pls->parent, AV_LOG_VERBOSE, "HLS request for url '%s', offset %"PRId64", playlist %d\n",
            seg->url, seg->url_offset, pls->index);
 
+    if (c->abr) {
+        char *abr_opts;
+        abrinfo_to_dict(c, &abr_opts);
+        av_dict_set(&opts, "abr-params", abr_opts, 0); // how to setup flag?
+        av_free(abr_opts);
+    }
     if (seg->key_type == KEY_NONE) {
-        ret = open_url(pls->parent, in, seg->url, c->avio_opts, opts, &is_http);
+        char url_abr[MAX_URL_SIZE];
+        if (c->abr) {
+            snprintf(url_abr, sizeof(url_abr), "abr:%s", seg->url); // + or : tbd
+            ret = open_url(pls->parent, in, url_abr, c->avio_opts, opts, &is_http);
+        } else {
+            ret = open_url(pls->parent, in, seg->url, c->avio_opts, opts, &is_http);
+        }
     } else if (seg->key_type == KEY_AES_128) {
         char iv[33], key[33], url[MAX_URL_SIZE];
         if (strcmp(seg->key, pls->key_url)) {
@@ -1273,6 +1406,7 @@ static int open_input(HLSContext *c, struct playlist *pls, struct segment *seg,
             goto cleanup;
         }
         ret = 0;
+        // TODO: Add abr prefix for crypto
     } else if (seg->key_type == KEY_SAMPLE_AES) {
         av_log(pls->parent, AV_LOG_ERROR,
                "SAMPLE-AES encryption is not supported yet\n");
@@ -1435,7 +1569,17 @@ restart:
         /* Check that the playlist is still needed before opening a new
          * segment. */
         v->needed = playlist_needed(v);
-
+        if (c->abr) {
+            if (c->switch_request2 == -1)
+                ;
+            else if (v->needed && c->switch_request2 != v->index && c->switch_delay <= 0) {
+                av_log(v->parent, AV_LOG_VERBOSE, "read_data: needed but not download playlist %d ('%s')\n",
+                       v->index, v->url);
+                return AVERROR_EOF;
+            }
+            if (!c->can_switch)
+                c->can_switch = 1;
+        }
         if (!v->needed) {
             av_log(v->parent, AV_LOG_INFO, "No longer receiving playlist %d ('%s')\n",
                    v->index, v->url);
@@ -1530,7 +1674,12 @@ reload:
     }
 
     seg = next_segment(v);
-    if (c->http_multiple == 1 && !v->input_next_requested &&
+
+    // when get switch_request, old stream should stop downloading next seg
+    if (c->abr && c->switch_request2 != v->index && c->switch_timestamp != AV_NOPTS_VALUE
+         && ((c->cur_timestamp + seg->duration * 2) >= c->switch_timestamp) )
+        ;
+    else if (c->http_multiple == 1 && !v->input_next_requested &&
         seg && seg->key_type == KEY_NONE && av_strstart(seg->url, "http", NULL)) {
         ret = open_input(c, v, seg, &v->input_next);
         if (ret < 0) {
@@ -1563,11 +1712,17 @@ reload:
 
         return ret;
     }
-    if (c->http_persistent &&
+    if (c->http_persistent && !c->abr &&
         seg->key_type == KEY_NONE && av_strstart(seg->url, "http", NULL)) {
         v->input_read_done = 1;
     } else {
         ff_format_io_close(v->parent, &v->input);
+        if (c->abr) {
+            if (c->switch_delay > 0)
+                c->switch_delay--;
+            av_log(v->parent, AV_LOG_VERBOSE, "read_data: close pls[%d]->input, v->cur_seq_no=%d, c->switch_delay= %d\n",
+                    v->index, v->cur_seq_no, c->switch_delay);
+        }
     }
     v->cur_seq_no++;
 
@@ -1860,6 +2015,17 @@ static int hls_read_header(AVFormatContext *s)
     c->first_packet = 1;
     c->first_timestamp = AV_NOPTS_VALUE;
     c->cur_timestamp = AV_NOPTS_VALUE;
+    c->switch_request2 = -1;
+    c->switch_delay = 0;
+    c->switch_timestamp = AV_NOPTS_VALUE;
+    c->delta_timestamp = AV_NOPTS_VALUE;
+    c->can_switch = -1;
+
+    if (c->abr) {
+        c->http_persistent = 0;
+        c->http_multiple = 1;
+        c->throughputs = av_mallocz(sizeof(struct throughput));
+    }
 
     if ((ret = save_avio_options(s)) < 0)
         goto fail;
@@ -2047,6 +2213,9 @@ static int hls_read_header(AVFormatContext *s)
         add_metadata_from_renditions(s, pls, AVMEDIA_TYPE_SUBTITLE);
     }
 
+    if (c->abr && c->can_switch == -1)
+        c->can_switch = 1;
+
     update_noheader_flag(s);
 
     return 0;
@@ -2055,6 +2224,13 @@ fail:
     return ret;
 }
 
+static void change_discard_flags(struct playlist *pls, int flag)
+{
+    for (int i = 0; i < pls->n_main_streams; i++) {
+        pls->main_streams[i]->discard = flag;
+    }
+}
+
 static int recheck_discard_flags(AVFormatContext *s, int first)
 {
     HLSContext *c = s->priv_data;
@@ -2065,6 +2241,22 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
     for (i = 0; i < c->n_playlists; i++) {
         struct playlist *pls = c->playlists[i];
 
+        if (c->abr) {
+            if (c->switch_request2 == -1)
+                ;
+            else if (c->switch_request2 == i && c->switch_delay <= 0
+                    && c->cur_timestamp + c->delta_timestamp >= c->switch_timestamp
+                    && c->switch_timestamp != AV_NOPTS_VALUE) {
+                av_log(s, AV_LOG_VERBOSE, "[switch point] cur_timestamp:%ld\n", c->cur_timestamp);
+                change_discard_flags(pls, AVDISCARD_DEFAULT);
+                c->switch_timestamp = AV_NOPTS_VALUE;
+            } else if (c->switch_request2 != -1 && c->switch_request2 != i && c->switch_delay <= 0
+                    && c->cur_timestamp + c->delta_timestamp >= c->switch_timestamp
+                    && c->switch_timestamp != AV_NOPTS_VALUE) {
+                change_discard_flags(pls, AVDISCARD_ALL);
+            }
+        }
+
         cur_needed = playlist_needed(c->playlists[i]);
 
         if (pls->broken) {
@@ -2075,6 +2267,11 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
             changed = 1;
             pls->cur_seq_no = select_cur_seq_no(c, pls);
             pls->pb.eof_reached = 0;
+            if (c->abr) {
+                pls->cur_seq_no = select_cur_seq_no(c, pls) + 1;
+                avio_flush(&pls->pb);
+                avformat_flush(pls->ctx);
+            }
             if (c->cur_timestamp != AV_NOPTS_VALUE) {
                 /* catch up */
                 pls->seek_timestamp = c->cur_timestamp;
@@ -2082,7 +2279,7 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
                 pls->seek_stream_index = -1;
             }
             av_log(s, AV_LOG_INFO, "Now receiving playlist %d, segment %d\n", i, pls->cur_seq_no);
-        } else if (first && !cur_needed && pls->needed) {
+        } else if ((first || c->abr) && !cur_needed && pls->needed) {
             ff_format_io_close(pls->parent, &pls->input);
             pls->input_read_done = 0;
             ff_format_io_close(pls->parent, &pls->input_next);
@@ -2091,6 +2288,9 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
             changed = 1;
             av_log(s, AV_LOG_INFO, "No longer receiving playlist %d\n", i);
         }
+
+        if (c->abr && changed && cur_needed)
+            c->cur_pls = i;
     }
     return changed;
 }
@@ -2165,7 +2365,13 @@ static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
                         /* audio elementary streams are id3 timestamped */
                         fill_timing_for_id3_timestamped_stream(pls);
                     }
-
+                    if (c->abr && c->first_timestamp != AV_NOPTS_VALUE && c->delta_timestamp == AV_NOPTS_VALUE && !i) {
+                        c->delta_timestamp = av_rescale_q(pls->pkt.dts,
+                            get_timebase(pls), AV_TIME_BASE_Q) - c->first_timestamp + 1;
+                        av_log(s, AV_LOG_VERBOSE, "[abr] delta_timestamp=%ld, %ld, %ld\n",
+                             c->delta_timestamp, c->first_timestamp,av_rescale_q(pls->pkt.dts,
+                            get_timebase(pls), AV_TIME_BASE_Q));
+                    }
                     if (c->first_timestamp == AV_NOPTS_VALUE &&
                         pls->pkt.dts       != AV_NOPTS_VALUE)
                         c->first_timestamp = av_rescale_q(pls->pkt.dts,
@@ -2373,6 +2579,8 @@ static int hls_probe(const AVProbeData *p)
 #define OFFSET(x) offsetof(HLSContext, x)
 #define FLAGS AV_OPT_FLAG_DECODING_PARAM
 static const AVOption hls_options[] = {
+    {"abr", "enable abr to switch streams",
+        OFFSET(abr), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, FLAGS },
     {"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},
     {"allowed_extensions", "List of file extensions that hls is allowed to access",
