[FFmpeg-devel] [PATCH] avfilter/acrossfade: allow skipping fade on inputs

Gyan ffmpeg at gyani.pro
Wed Jan 23 10:11:15 EET 2019


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From 1aa1db056e1e9887e6467a0c9e10276be78ff623 Mon Sep 17 00:00:00 2001
From: Gyan Doshi <ffmpeg at gyani.pro>
Date: Wed, 23 Jan 2019 13:35:23 +0530
Subject: [PATCH] avfilter/acrossfade: allow skipping fade on inputs

---
 doc/filters.texi       |  2 ++
 libavfilter/af_afade.c | 10 +++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index d06dfe089f..9e805bc1cd 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -475,6 +475,8 @@ Set curve for cross fade transition for first stream.
 Set curve for cross fade transition for second stream.
 
 For description of available curve types see @ref{afade} filter description.
+In addition, acrossfade supports skipping application of fade to an input,
+if curve value is set to @code{nofade}.
 @end table
 
 @subsection Examples
diff --git a/libavfilter/af_afade.c b/libavfilter/af_afade.c
index 751db7da4d..f1e80013d9 100644
--- a/libavfilter/af_afade.c
+++ b/libavfilter/af_afade.c
@@ -51,7 +51,7 @@ typedef struct AudioFadeContext {
                               int curve0, int curve1);
 } AudioFadeContext;
 
-enum CurveType { TRI, QSIN, ESIN, HSIN, LOG, IPAR, QUA, CUB, SQU, CBR, PAR, EXP, IQSIN, IHSIN, DESE, DESI, LOSI, NB_CURVES };
+enum CurveType { TRI, QSIN, ESIN, HSIN, LOG, IPAR, QUA, CUB, SQU, CBR, PAR, EXP, IQSIN, IHSIN, DESE, DESI, LOSI, NONE, NB_CURVES };
 
 #define OFFSET(x) offsetof(AudioFadeContext, x)
 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
@@ -153,6 +153,9 @@ static double fade_gain(int curve, int64_t index, int64_t range)
                    gain = (A - B) / (C - B);
                }
         break;
+    case NONE:
+        gain = 1.0;
+        break;
     }
 
     return gain;
@@ -241,8 +244,8 @@ static const AVOption afade_options[] = {
     { "st",           "set time to start fading",                    OFFSET(start_time),   AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
     { "duration",     "set fade duration",                           OFFSET(duration),     AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
     { "d",            "set fade duration",                           OFFSET(duration),     AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
-    { "curve",        "set fade curve type",                         OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
-    { "c",            "set fade curve type",                         OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
+    { "curve",        "set fade curve type",                         OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 2, FLAGS, "curve" },
+    { "c",            "set fade curve type",                         OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 2, FLAGS, "curve" },
     { "tri",          "linear slope",                                0,                    AV_OPT_TYPE_CONST,  {.i64 = TRI  }, 0, 0, FLAGS, "curve" },
     { "qsin",         "quarter of sine wave",                        0,                    AV_OPT_TYPE_CONST,  {.i64 = QSIN }, 0, 0, FLAGS, "curve" },
     { "esin",         "exponential sine wave",                       0,                    AV_OPT_TYPE_CONST,  {.i64 = ESIN }, 0, 0, FLAGS, "curve" },
@@ -380,6 +383,7 @@ static const AVOption acrossfade_options[] = {
     {     "dese",     "double-exponential seat",                       0,                    AV_OPT_TYPE_CONST,  {.i64 = DESE }, 0, 0, FLAGS, "curve" },
     {     "desi",     "double-exponential sigmoid",                    0,                    AV_OPT_TYPE_CONST,  {.i64 = DESI }, 0, 0, FLAGS, "curve" },
     {     "losi",     "logistic sigmoid",                              0,                    AV_OPT_TYPE_CONST,  {.i64 = LOSI }, 0, 0, FLAGS, "curve" },
+    {     "nofade",   "no fade; keep audio as-is",                     0,                    AV_OPT_TYPE_CONST,  {.i64 = NONE }, 0, 0, FLAGS, "curve" },
     { "curve2",       "set fade curve type for 2nd stream",            OFFSET(curve2),       AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
     { "c2",           "set fade curve type for 2nd stream",            OFFSET(curve2),       AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
     { NULL }
-- 
2.19.2


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