core: automatically pause on low cache

When the cache fill status goes below a certain threshold, automatically
pause the player. When the cache is filled again, unpause again.

This is intended to help with streaming from http. It's better to pause
a while, rather than exposing extremely crappy behavior when packet
reads during decoding block the entire player.

In theory, we should try to increase the cache if underruns happen too
often. Unfortunately, changing the cache implementation would be very
hard, because it's insane code (forks, uses shared memory and "volatile"
etc.). So for now, this just reduces the frequency of the stuttering if
the network is absolutely too slow to play the stream in realtime.

1 files changed, 41 insertions, 3 deletions

diff --git a/core/mplayer.c b/core/mplayer.c
index e60c7e173c..04ea0e2597 100644
--- a/core/mplayer.c
+++ b/core/mplayer.c
@@ -1051,6 +1051,14 @@ static int get_cache_percent(struct MPContext *mpctx)
     return -1;
 }
 
+static bool get_cache_idle(struct MPContext *mpctx)
+{
+    int idle = 0;
+    if (mpctx->stream)
+        stream_control(mpctx->stream, STREAM_CTRL_GET_CACHE_IDLE, &idle);
+    return idle;
+}
+
 /**
  * \brief append a formatted string
  * \param buf buffer to print into
@@ -1131,8 +1139,12 @@ static void print_status(struct MPContext *mpctx)
     line[0] = '\0';
 
     // Playback status
-    if (mpctx->paused)
+    if (mpctx->paused_for_cache) {
+        saddf(line, width, "(Buffering) ");
+    } else if (mpctx->paused) {
         saddf(line, width, "(Paused) ");
+    }
+
     if (mpctx->sh_audio)
         saddf(line, width, "A");
     if (mpctx->sh_video)
@@ -1458,8 +1470,15 @@ static void sadd_osd_status(char *buffer, int len, struct MPContext *mpctx,
 {
     bool fractions = mpctx->opts.osd_fractions;
     int sym = mpctx->osd_function;
-    if (!sym)
-        sym = mpctx->paused || mpctx->step_frames ? OSD_PAUSE : OSD_PLAY;
+    if (!sym) {
+        if (mpctx->paused_for_cache) {
+            sym = OSD_CLOCK;
+        } else if (mpctx->paused || mpctx->step_frames) {
+            sym = OSD_PAUSE;
+        } else {
+            sym = OSD_PLAY;
+        }
+    }
     saddf_osd_function_sym(buffer, len, sym);
     sadd_hhmmssff(buffer, len, get_current_time(mpctx), fractions);
     if (full) {
@@ -2579,6 +2598,7 @@ void unpause_player(struct MPContext *mpctx)
         return;
     mpctx->paused = 0;
     mpctx->osd_function = 0;
+    mpctx->paused_for_cache = false;
 
     if (mpctx->ao && mpctx->sh_audio)
         ao_resume(mpctx->ao);
@@ -3070,6 +3090,22 @@ static void update_avsync(struct MPContext *mpctx)
     }
 }
 
+static void handle_pause_on_low_cache(struct MPContext *mpctx)
+{
+    struct MPOpts *opts = &mpctx->opts;
+    int cache = get_cache_percent(mpctx);
+    bool idle = get_cache_idle(mpctx);
+    if (mpctx->paused && mpctx->paused_for_cache) {
+        if (cache < 0 || cache >= opts->stream_cache_min_percent || idle)
+            unpause_player(mpctx);
+    } else if (!mpctx->paused) {
+        if (cache >= 0 && cache <= opts->stream_cache_pause && !idle) {
+            pause_player(mpctx);
+            mpctx->paused_for_cache = true;
+        }
+    }
+}
+
 static void run_playloop(struct MPContext *mpctx)
 {
     struct MPOpts *opts = &mpctx->opts;
@@ -3390,6 +3426,8 @@ static void run_playloop(struct MPContext *mpctx)
 
     //================= Keyboard events, SEEKing ====================
 
+    handle_pause_on_low_cache(mpctx);
+
     mp_cmd_t *cmd;
     while ((cmd = mp_input_get_cmd(mpctx->input, 0, 1)) != NULL) {
         /* Allow running consecutive seek commands to combine them,