From aaec2aba3890e1b2ea8f4dc158d884bc85a59517 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Tue, 27 Oct 2015 20:56:46 +0100
Subject: player: add audio drop/duplicate mode

Not very robust in the moment.
---
 player/audio.c | 36 ++++++++++++++++++++++++++++++++++++
 player/core.h  |  2 ++
 player/video.c |  2 +-
 3 files changed, 39 insertions(+), 1 deletion(-)

(limited to 'player')

diff --git a/player/audio.c b/player/audio.c
index ce72e3d0f1..9207986892 100644
--- a/player/audio.c
+++ b/player/audio.c
@@ -551,6 +551,27 @@ void fill_audio_out_buffers(struct MPContext *mpctx, double endpts)
         playsize = MPMAX(1, playsize + skip); // silence will be prepended
     }
 
+    int skip_duplicate = 0; // >0: skip, <0: duplicate
+    if (mpctx->display_sync_active && opts->video_sync == VS_DISP_ADROP &&
+        fabs(mpctx->last_av_difference) >= opts->sync_audio_drop_size &&
+        mpctx->audio_status == STATUS_PLAYING)
+    {
+        int samples = ceil(opts->sync_audio_drop_size * play_samplerate);
+        int align = af_format_sample_alignment(out_format.format);
+        samples = (samples + align / 2) / align * align;
+
+        skip_duplicate = mpctx->last_av_difference >= 0 ? -samples : samples;
+
+        // safeguard against excessively growing audio buffer sizes
+        if (skip_duplicate < 0 && mp_audio_buffer_seconds(mpctx->ao_buffer) > 5) {
+            skip_duplicate = 0;
+            samples = 0;
+        }
+
+        if (playsize < samples)
+            playsize = samples;
+    }
+
     int status = AD_OK;
     bool working = false;
     if (playsize > mp_audio_buffer_samples(mpctx->ao_buffer)) {
@@ -598,6 +619,21 @@ void fill_audio_out_buffers(struct MPContext *mpctx, double endpts)
         end_sync = true;
     }
 
+    if (skip_duplicate) {
+        int max = mp_audio_buffer_samples(mpctx->ao_buffer);
+        if (abs(skip_duplicate) > max)
+            skip_duplicate = skip_duplicate >= 0 ? max : -max;
+        mpctx->last_av_difference += skip_duplicate / play_samplerate;
+        if (skip_duplicate >= 0) {
+            mp_audio_buffer_skip(mpctx->ao_buffer, skip_duplicate);
+            MP_STATS(mpctx, "drop-audio");
+        } else {
+            mp_audio_buffer_duplicate(mpctx->ao_buffer, -skip_duplicate);
+            MP_STATS(mpctx, "duplicate-audio");
+        }
+        MP_VERBOSE(mpctx, "audio skip_duplicate=%d\n", skip_duplicate);
+    }
+
     if (mpctx->audio_status == STATUS_SYNCING) {
         if (end_sync)
             mpctx->audio_status = STATUS_FILLING;
diff --git a/player/core.h b/player/core.h
index b775e52535..b5c2077e5a 100644
--- a/player/core.h
+++ b/player/core.h
@@ -84,6 +84,7 @@ enum video_sync {
     VS_DISP_RESAMPLE,
     VS_DISP_RESAMPLE_VDROP,
     VS_DISP_RESAMPLE_NONE,
+    VS_DISP_ADROP,
     VS_DISP_VDROP,
     VS_DISP_NONE,
     VS_NONE,
@@ -92,6 +93,7 @@ enum video_sync {
 #define VS_IS_DISP(x) ((x) == VS_DISP_RESAMPLE ||       \
                        (x) == VS_DISP_RESAMPLE_VDROP || \
                        (x) == VS_DISP_RESAMPLE_NONE ||  \
+                       (x) == VS_DISP_ADROP ||          \
                        (x) == VS_DISP_VDROP ||          \
                        (x) == VS_DISP_NONE)
 
diff --git a/player/video.c b/player/video.c
index 7d423cb50c..3ea5607b35 100644
--- a/player/video.c
+++ b/player/video.c
@@ -912,7 +912,7 @@ static void handle_display_sync_frame(struct MPContext *mpctx,
     bool resample = mode == VS_DISP_RESAMPLE || mode == VS_DISP_RESAMPLE_VDROP ||
                     mode == VS_DISP_RESAMPLE_NONE;
     bool drop = mode == VS_DISP_VDROP || mode == VS_DISP_RESAMPLE ||
-                mode == VS_DISP_RESAMPLE_VDROP;
+                mode == VS_DISP_ADROP || mode == VS_DISP_RESAMPLE_VDROP;
     drop &= (opts->frame_dropping & 1);
 
     if (resample && using_spdif_passthrough(mpctx))
-- 
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