[FFmpeg-cvslog] ffplay: change keyboard volume control to logarithmic

Marton Balint git at videolan.org
Wed Feb 8 23:52:01 EET 2017


ffmpeg | branch: master | Marton Balint <cus at passwd.hu> | Sun Feb  5 01:16:29 2017 +0100| [3aae1eff1263a91086f48ae5162aa28f8f9dc072] | committer: Marton Balint

ffplay: change keyboard volume control to logarithmic

The command line parameter remains linear.

Signed-off-by: Marton Balint <cus at passwd.hu>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3aae1eff1263a91086f48ae5162aa28f8f9dc072
---

 ffplay.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/ffplay.c b/ffplay.c
index 1c9db73..cf138dc 100644
--- a/ffplay.c
+++ b/ffplay.c
@@ -73,8 +73,8 @@ const int program_birth_year = 2003;
 /* Calculate actual buffer size keeping in mind not cause too frequent audio callbacks */
 #define SDL_AUDIO_MAX_CALLBACKS_PER_SEC 30
 
-/* Step size for volume control */
-#define SDL_VOLUME_STEP (SDL_MIX_MAXVOLUME / 50)
+/* Step size for volume control in dB */
+#define SDL_VOLUME_STEP (0.75)
 
 /* no AV sync correction is done if below the minimum AV sync threshold */
 #define AV_SYNC_THRESHOLD_MIN 0.04
@@ -1450,9 +1450,11 @@ static void toggle_mute(VideoState *is)
     is->muted = !is->muted;
 }
 
-static void update_volume(VideoState *is, int sign, int step)
+static void update_volume(VideoState *is, int sign, double step)
 {
-    is->audio_volume = av_clip(is->audio_volume + sign * step, 0, SDL_MIX_MAXVOLUME);
+    double volume_level = is->audio_volume ? (20 * log(is->audio_volume / (double)SDL_MIX_MAXVOLUME) / log(10)) : -1000.0;
+    int new_volume = lrint(SDL_MIX_MAXVOLUME * pow(10.0, (volume_level + sign * step) / 20.0));
+    is->audio_volume = av_clip(is->audio_volume == new_volume ? (is->audio_volume + sign) : new_volume, 0, SDL_MIX_MAXVOLUME);
 }
 
 static void step_to_next_frame(VideoState *is)



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