Fix FlacDecoder::total_duration().

It was ignoring the channels count.

Author: IohannRabeson

src/decoder/flac.rs

@@ -41,13 +41,14 @@ where
 
         let spec = reader.streaminfo();
         let sample_rate = spec.sample_rate;
+        let channels = spec.channels;
 
         // `samples` in FLAC means "inter-channel samples" aka frames
         // so we do not divide by `self.channels` here.
         let total_duration = spec.samples.map(|s| {
             // Calculate duration as (samples * 1_000_000) / sample_rate
             // but do the division first to avoid overflow
-            let sample_rate = sample_rate as u64;
+            let sample_rate = sample_rate as u64 * channels as u64;
             let secs = s / sample_rate;
             let nanos = ((s % sample_rate) * 1_000_000_000) / sample_rate;
             Duration::new(secs, nanos as u32)