diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index 2fb0bc8ffa..e3ace8ee65 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -1313,6 +1313,17 @@ List all hardware acceleration components enabled in this build of ffmpeg.
 Actual runtime availability depends on the hardware and its suitable driver
 being installed.
 
+@item -fix_sub_duration_heartbeat[:@var{stream_specifier}]
+Set a specific output video stream as the heartbeat stream according to which
+to split and push through currently in-progress subtitle upon receipt of a
+random access packet.
+
+This lowers the latency of subtitles for which the end packet or the following
+subtitle has not yet been received.
+
+Requires @option{-fix_sub_duration} to be set for the relevant input subtitle
+stream for this to have any effect.
+
 @end table
 
 @section Audio Options
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 019d6b821b..aae650c45c 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -128,6 +128,7 @@ typedef struct BenchmarkTimeStamps {
     int64_t sys_usec;
 } BenchmarkTimeStamps;
 
+static int trigger_fix_sub_duration_heartbeat(OutputStream *ost, const AVPacket *pkt);
 static BenchmarkTimeStamps get_benchmark_time_stamps(void);
 static int64_t getmaxrss(void);
 static int ifilter_has_all_input_formats(FilterGraph *fg);
@@ -981,6 +982,13 @@ static int encode_frame(OutputFile *of, OutputStream *ost, AVFrame *frame)
                    av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, &enc->time_base));
         }
 
+        if ((ret = trigger_fix_sub_duration_heartbeat(ost, pkt)) < 0) {
+            av_log(NULL, AV_LOG_ERROR,
+                   "Subtitle heartbeat logic failed in %s! (%s)\n",
+                   __func__, av_err2str(ret));
+            exit_program(1);
+        }
+
         if (enc->codec_type == AVMEDIA_TYPE_VIDEO)
             update_video_stats(ost, pkt, !!vstats_filename);
 
@@ -1931,6 +1939,16 @@ static void do_streamcopy(InputStream *ist, OutputStream *ost, const AVPacket *p
 
     ost->sync_opts += opkt->duration;
 
+    {
+        int ret = trigger_fix_sub_duration_heartbeat(ost, pkt);
+        if (ret < 0) {
+            av_log(NULL, AV_LOG_ERROR,
+                   "Subtitle heartbeat logic failed in %s! (%s)\n",
+                   __func__, av_err2str(ret));
+            exit_program(1);
+        }
+    }
+
     output_packet(of, opkt, ost, 0);
 
     ost->streamcopy_started = 1;
@@ -2363,6 +2381,130 @@ out:
     return ret;
 }
 
+static int copy_av_subtitle(AVSubtitle *dst, AVSubtitle *src)
+{
+    int ret = AVERROR_BUG;
+    AVSubtitle tmp = {
+        .format = src->format,
+        .start_display_time = src->start_display_time,
+        .end_display_time = src->end_display_time,
+        .num_rects = 0,
+        .rects = NULL,
+        .pts = src->pts
+    };
+
+    if (!src->num_rects)
+        goto success;
+
+    if (!(tmp.rects = av_calloc(src->num_rects, sizeof(*tmp.rects))))
+        return AVERROR(ENOMEM);
+
+    for (int i = 0; i < src->num_rects; i++) {
+        AVSubtitleRect *src_rect = src->rects[i];
+        AVSubtitleRect *dst_rect;
+
+        if (!(dst_rect = tmp.rects[i] = av_mallocz(sizeof(*tmp.rects[0])))) {
+            ret = AVERROR(ENOMEM);
+            goto cleanup;
+        }
+
+        tmp.num_rects++;
+
+        dst_rect->type      = src_rect->type;
+        dst_rect->flags     = src_rect->flags;
+
+        dst_rect->x         = src_rect->x;
+        dst_rect->y         = src_rect->y;
+        dst_rect->w         = src_rect->w;
+        dst_rect->h         = src_rect->h;
+        dst_rect->nb_colors = src_rect->nb_colors;
+
+        if (src_rect->text)
+            if (!(dst_rect->text = av_strdup(src_rect->text))) {
+                ret = AVERROR(ENOMEM);
+                goto cleanup;
+            }
+
+        if (src_rect->ass)
+            if (!(dst_rect->ass = av_strdup(src_rect->ass))) {
+                ret = AVERROR(ENOMEM);
+                goto cleanup;
+            }
+
+        for (int j = 0; j < 4; j++) {
+            // SUBTITLE_BITMAP images are special in the sense that they
+            // are like PAL8 images. first pointer to data, second to
+            // palette. This makes the size calculation match this.
+            size_t buf_size = src_rect->type == SUBTITLE_BITMAP && j == 1 ?
+                              AVPALETTE_SIZE :
+                              src_rect->h * src_rect->linesize[j];
+
+            if (!src_rect->data[j])
+                continue;
+
+            if (!(dst_rect->data[j] = av_memdup(src_rect->data[j], buf_size))) {
+                ret = AVERROR(ENOMEM);
+                goto cleanup;
+            }
+            dst_rect->linesize[j] = src_rect->linesize[j];
+        }
+    }
+
+success:
+    *dst = tmp;
+
+    return 0;
+
+cleanup:
+    avsubtitle_free(&tmp);
+
+    return ret;
+}
+
+static int fix_sub_duration_heartbeat(InputStream *ist, int64_t signal_pts)
+{
+    int ret = AVERROR_BUG;
+    int got_output = 1;
+    AVSubtitle *prev_subtitle = &ist->prev_sub.subtitle;
+    AVSubtitle subtitle;
+
+    if (!ist->fix_sub_duration || !prev_subtitle->num_rects ||
+        signal_pts <= prev_subtitle->pts)
+        return 0;
+
+    if ((ret = copy_av_subtitle(&subtitle, prev_subtitle)) < 0)
+        return ret;
+
+    subtitle.pts = signal_pts;
+
+    return process_subtitle(ist, &subtitle, &got_output);
+}
+
+static int trigger_fix_sub_duration_heartbeat(OutputStream *ost, const AVPacket *pkt)
+{
+    int64_t signal_pts = av_rescale_q(pkt->pts, ost->mux_timebase,
+                                      AV_TIME_BASE_Q);
+
+    if (!ost->fix_sub_duration_heartbeat || !(pkt->flags & AV_PKT_FLAG_KEY))
+        // we are only interested in heartbeats on streams configured, and
+        // only on random access points.
+        return 0;
+
+    for (int index = 0; index < nb_input_streams; index++) {
+        InputStream *subtitle_ist = input_streams[index];
+        int ret = AVERROR_BUG;
+
+        if (!subtitle_ist->decoding_needed ||
+            subtitle_ist->dec_ctx->codec_type != AVMEDIA_TYPE_SUBTITLE)
+            continue;
+
+        if ((ret = fix_sub_duration_heartbeat(subtitle_ist, signal_pts)) < 0)
+            return ret;
+    }
+
+    return 0;
+}
+
 static int transcode_subtitles(InputStream *ist, AVPacket *pkt, int *got_output,
                                int *decode_failed)
 {
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 6417db03bd..89c97f102f 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -220,6 +220,8 @@ typedef struct OptionsContext {
     int        nb_reinit_filters;
     SpecifierOpt *fix_sub_duration;
     int        nb_fix_sub_duration;
+    SpecifierOpt *fix_sub_duration_heartbeat;
+    int        nb_fix_sub_duration_heartbeat;
     SpecifierOpt *canvas_sizes;
     int        nb_canvas_sizes;
     SpecifierOpt *pass;
@@ -584,6 +586,12 @@ typedef struct OutputStream {
 
     int sq_idx_encode;
     int sq_idx_mux;
+
+    /*
+     * bool on whether this stream should be utilized for splitting
+     * subtitles utilizing fix_sub_duration at random access points.
+     */
+    unsigned int fix_sub_duration_heartbeat;
 } OutputStream;
 
 typedef struct Muxer Muxer;
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index a8b064e070..62c55b16ab 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -98,6 +98,7 @@ static const char *const opt_name_filters[]                   = {"filter", "af",
 static const char *const opt_name_filter_scripts[]            = {"filter_script", NULL};
 static const char *const opt_name_reinit_filters[]            = {"reinit_filter", NULL};
 static const char *const opt_name_fix_sub_duration[]          = {"fix_sub_duration", NULL};
+static const char *const opt_name_fix_sub_duration_heartbeat[] = {"fix_sub_duration_heartbeat", NULL};
 static const char *const opt_name_canvas_sizes[]              = {"canvas_size", NULL};
 static const char *const opt_name_pass[]                      = {"pass", NULL};
 static const char *const opt_name_passlogfiles[]              = {"passlogfile", NULL};
@@ -1758,6 +1759,9 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
     MATCH_PER_STREAM_OPT(bits_per_raw_sample, i, ost->bits_per_raw_sample,
                          oc, st);
 
+    MATCH_PER_STREAM_OPT(fix_sub_duration_heartbeat, i, ost->fix_sub_duration_heartbeat,
+                         oc, st);
+
     if (oc->oformat->flags & AVFMT_GLOBALHEADER && ost->enc_ctx)
         ost->enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
 
@@ -4105,6 +4109,11 @@ const OptionDef options[] = {
     { "autoscale",        HAS_ARG | OPT_BOOL | OPT_SPEC |
                           OPT_EXPERT | OPT_OUTPUT,                               { .off = OFFSET(autoscale) },
         "automatically insert a scale filter at the end of the filter graph" },
+    { "fix_sub_duration_heartbeat", OPT_VIDEO | OPT_BOOL | OPT_EXPERT |
+                                    OPT_SPEC | OPT_OUTPUT,                       { .off = OFFSET(fix_sub_duration_heartbeat) },
+        "set this video output stream to be a heartbeat stream for "
+        "fix_sub_duration, according to which subtitles should be split at "
+        "random access points" },
 
     /* audio options */
     { "aframes",        OPT_AUDIO | HAS_ARG  | OPT_PERFILE | OPT_OUTPUT,           { .func_arg = opt_audio_frames },
diff --git a/tests/fate/ffmpeg.mak b/tests/fate/ffmpeg.mak
index 38a1ae7ed5..39eb26f295 100644
--- a/tests/fate/ffmpeg.mak
+++ b/tests/fate/ffmpeg.mak
@@ -117,6 +117,20 @@ fate-ffmpeg-fix_sub_duration: CMD = fmtstdout srt -fix_sub_duration \
   -real_time 1 -f lavfi \
   -i "movie=$(TARGET_SAMPLES)/sub/Closedcaption_rollup.m2v[out0+subcc]"
 
+# Basic test for fix_sub_duration_heartbeat, which causes a buffered subtitle
+# to be pushed out when a video keyframe is received from an encoder.
+FATE_SAMPLES_FFMPEG-$(call FILTERDEMDECENCMUX, MOVIE, MPEGVIDEO, \
+                           MPEG2VIDEO, SUBRIP, SRT, LAVFI_INDEV  \
+                           MPEGVIDEO_PARSER CCAPTION_DECODER \
+                           MPEG2VIDEO_ENCODER NULL_MUXER PIPE_PROTOCOL) \
+                           += fate-ffmpeg-fix_sub_duration_heartbeat
+fate-ffmpeg-fix_sub_duration_heartbeat: CMD = fmtstdout srt -fix_sub_duration \
+  -real_time 1 -f lavfi \
+  -i "movie=$(TARGET_SAMPLES)/sub/Closedcaption_rollup.m2v[out0+subcc]" \
+  -map 0:v -fix_sub_duration_heartbeat:v:0 \
+  -c mpeg2video -b:v 2M -g 30 -sc_threshold 1000000000 \
+  -f null -
+
 FATE_STREAMCOPY-$(call REMUX, MP4 MOV, EAC3_DEMUXER) += fate-copy-trac3074
 fate-copy-trac3074: CMD = transcode eac3 $(TARGET_SAMPLES)/eac3/csi_miami_stereo_128_spx.eac3\
                      mp4 "-codec copy -map 0" "-codec copy"
diff --git a/tests/ref/fate/ffmpeg-fix_sub_duration_heartbeat b/tests/ref/fate/ffmpeg-fix_sub_duration_heartbeat
new file mode 100644
index 0000000000..957a410921
--- /dev/null
+++ b/tests/ref/fate/ffmpeg-fix_sub_duration_heartbeat
@@ -0,0 +1,48 @@
+1
+00:00:00,968 --> 00:00:01,001
+<font face="Monospace">{\an7}(</font>
+
+2
+00:00:01,001 --> 00:00:01,168
+<font face="Monospace">{\an7}(</font>
+
+3
+00:00:01,168 --> 00:00:01,368
+<font face="Monospace">{\an7}(<i> inaudibl</i></font>
+
+4
+00:00:01,368 --> 00:00:01,568
+<font face="Monospace">{\an7}(<i> inaudible radio chat</i></font>
+
+5
+00:00:01,568 --> 00:00:02,002
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )</font>
+
+6
+00:00:02,002 --> 00:00:03,003
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )</font>
+
+7
+00:00:03,003 --> 00:00:03,103
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )</font>
+
+8
+00:00:03,103 --> 00:00:03,303
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )
+>></font>
+
+9
+00:00:03,303 --> 00:00:03,503
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )
+>> Safety rema</font>
+
+10
+00:00:03,504 --> 00:00:03,704
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )
+>> Safety remains our numb</font>
+
+11
+00:00:03,704 --> 00:00:04,004
+<font face="Monospace">{\an7}(<i> inaudible radio chatter</i> )
+>> Safety remains our number one</font>
+
