dec_sub: introduce sub_control(), use it for sub_step

This means the direct libass usage can be removed from command.c, and no
weird hacks for retrieving the ASS_Track are needed.

Also fix a bug when using this feature with ordered chapters.

1 files changed, 13 insertions, 1 deletions

diff --git a/sub/dec_sub.c b/sub/dec_sub.c
index 1a7180b260..5fb8722296 100644
--- a/sub/dec_sub.c
+++ b/sub/dec_sub.c
@@ -102,7 +102,7 @@ bool sub_is_initialized(struct dec_sub *sub)
     return !!sub->num_sd;
 }
 
-struct sd *sub_get_last_sd(struct dec_sub *sub)
+static struct sd *sub_get_last_sd(struct dec_sub *sub)
 {
     return sub->num_sd ? sub->sd[sub->num_sd - 1] : NULL;
 }
@@ -482,6 +482,18 @@ void sub_reset(struct dec_sub *sub)
     }
 }
 
+int sub_control(struct dec_sub *sub, enum sd_ctrl cmd, void *arg)
+{
+    for (int n = 0; n < sub->num_sd; n++) {
+        if (sub->sd[n]->driver->control) {
+            int r = sub->sd[n]->driver->control(sub->sd[n], cmd, arg);
+            if (r != CONTROL_UNKNOWN)
+                return r;
+        }
+    }
+    return CONTROL_UNKNOWN;
+}
+
 #define MAX_PACKETS 10
 #define MAX_BYTES 10000