fix multiple plugin runs over same file

- add deinit() functions to help

examples/middle_amp.scri

@@ -0,0 +1,8 @@
+load :0;
+amp 5 1 8;
+amp 7 4 2;
+amp 80 70 10;
+amp 80 73 20;
+amp 80 75 20;
+amp 80 76 20;
+quicksave;

examples/middle_echo.scri

@@ -1,4 +0,0 @@
-load :0;
-amp 3 1 20;
-# echo 3 0 1 0.2;
-quicksave;

src/image.zig

@@ -13,6 +13,7 @@ pub const ImageError = error{
     UnknownPlugin,
     InvalidSymbol,
     InstantiateFail,
+    WriteFail,
 };
 
 /// Low level integration function with libsndfile.
@@ -41,22 +42,13 @@ fn sopen(
     return file.?;
 }
 
-///Read a single frame from a file into an interleaved buffer.
-///If more channels are required than are available in the file, the remaining
-///channels are distributed in a round-robin fashion (LRLRL).
-fn sread(file_opt: ?*c.SNDFILE, file_chans: c_int, buf: []f32) bool {
-    var file = file_opt.?;
+fn swrite(file: *c.SNDFILE, buf: [*]f32, frames: i64) !void {
+    const count = c.sf_writef_float(file, buf, frames);
 
-    const n_read: c.sf_count_t = c.sf_readf_float(file, buf.ptr, 1);
-    const buf_chans = @intCast(c_int, buf.len);
-
-    var i = file_chans - 1;
-    while (i < buf_chans) : (i += 1) {
-        //buf[@intCast(usize, i)] = buf[i % file_chans];
-        buf[@intCast(usize, i)] = buf[@intCast(usize, @mod(i, file_chans))];
+    if (count != frames) {
+        std.debug.warn("Wanted to read {}, got {}\n", frames, count);
+        return ImageError.WriteFail;
     }
-
-    return n_read == 1;
 }
 
 fn getEndPos(path: []const u8) !usize {
@@ -174,8 +166,7 @@ pub const Image = struct {
         params: plugins.ParamList,
     ) !void {
         var ctx = try plugins.makeContext(self.allocator, plugin_uri);
-        std.debug.warn("\tworld: {}\n", ctx.world);
-        std.debug.warn("\tplugin: {}\n", ctx.plugin);
+        defer ctx.deinit();
 
         var ports = try lv2.setupPorts(&ctx);
 
@@ -184,6 +175,8 @@ pub const Image = struct {
             return ImageError.InvalidPlugin;
         }
 
+        // TODO check n_audio_out
+
         // now, for each param for the plugin, we find its port, and set
         // the value for the port there.
         var it = params.iterator();
@@ -213,12 +206,14 @@ pub const Image = struct {
         // now we need to generate a temporary file and put the output of
         // running the plugin on that file
         var tmpnam = try temporaryName(self.allocator);
-        std.debug.warn("temporary name: {}\n", tmpnam);
+        std.debug.warn("\trunning plugin from '{}' to '{}'\n", self.curpath, tmpnam);
 
         var out_fmt = mkSfInfo();
         var out_file = try sopen(self.allocator, tmpnam, c.SFM_WRITE, &out_fmt);
 
         var rctx = try plugins.RunContext.init(self.allocator, ctx.plugin);
+        defer rctx.deinit();
+
         rctx.connectPorts(ports);
         lv2.lilv_instance_activate(rctx.instance);
 
@@ -226,41 +221,41 @@ pub const Image = struct {
         // just copy the original image and the part where we run the plugin
         // over the image.
 
-        const end_pos = (try getEndPos(self.path)) - BMPHeaderSize;
-        std.debug.warn("file end: {}\n", end_pos);
-        const seek_pos = position.seekPos(end_pos);
+        const file_end = try getEndPos(self.curpath);
+        const seek_pos = position.seekPos(file_end);
         std.debug.warn("start {} end {}\n", seek_pos.start, seek_pos.end);
 
+        var seeked = c.sf_seek(self.sndfile, 0, c.SEEK_SET);
+        std.debug.warn("in: seek {}\n", seeked);
+
         var i: usize = 0;
 
-        while (i < end_pos) : (i += 1) {
+        while (i < file_end) : (i += 1) {
             // if we're still on the bmp header phase, copy bytes
             // if we aren't in the range from seek_pos, copy bytes
             // if we are in the range, run lilv plugin
 
             // TODO speed this up by not reading byte-by-byte.
-            // TODO check value of this
-            _ = c.sf_readf_float(self.sndfile, rctx.in_buf.ptr, 1);
+            const read_bytes = c.sf_readf_float(self.sndfile, rctx.in_buf.ptr, 1);
+            if (read_bytes == 0) {
+                std.debug.warn("WARN! reached EOF at idx={}\n", i);
+                break;
+            }
 
             if (i < BMPHeaderSize or !seek_pos.contains(i)) {
-                _ = c.sf_writef_float(out_file, rctx.in_buf.ptr, 1);
+                try swrite(out_file, rctx.in_buf.ptr, 1);
             } else {
                 lv2.lilv_instance_run(rctx.instance, 1);
-
-                var count = c.sf_writef_float(out_file, rctx.out_buf.ptr, 1);
-                if (count != 1) {
-                    std.debug.warn(
-                        "Failed to write to output file at idx {}.\n",
-                        i,
-                    );
-
-                    // maybe we return an error?
-                }
+                try swrite(out_file, rctx.out_buf.ptr, 1);
             }
         }
 
+        c.sf_write_sync(out_file);
+        _ = c.sf_close(out_file);
         _ = c.sf_close(self.sndfile);
-        self.sndfile = out_file;
+
+        // reopen the file as SFM_READ so we can run plugin chains etc
+        self.sndfile = try sopen(self.allocator, tmpnam, c.SFM_READ, &out_fmt);
         self.curpath = tmpnam;
     }
 

src/plugin.zig

@@ -51,6 +51,10 @@ pub const Context = struct {
     // they should both be 1.
     n_audio_in: usize = 0,
     n_audio_out: usize = 0,
+
+    pub fn deinit(self: *Context) void {
+        c.lilv_world_free(self.world);
+    }
 };
 
 /// Represents the specific run context of plugin instantation.
@@ -75,6 +79,10 @@ pub const RunContext = struct {
         };
     }
 
+    pub fn deinit(self: *RunContext) void {
+        c.lilv_instance_free(self.instance);
+    }
+
     pub fn connectPorts(self: *RunContext, ports: []*lv2.Port) void {
         var i: usize = 0;
         var o: usize = 0;