EXTINF tags need to be in floating-point format to work with AWS Elemental MediaConvert

AWS Elemental MediaConvert rejects playlists with EXTINF tags that are not in floating point format. When m3u8 MediaSegment self.duration is an exact number without trailing decimals, writeln cuts off the decimal places and prints it like an integer.

This change adds support for fixed length floating point numbers.

tests/lib.rs

@@ -8,6 +8,7 @@ use std::collections::HashMap;
 use std::fs::File;
 use std::io::Read;
 use std::path;
+use std::sync::atomic::Ordering;
 use std::{fs, io};
 
 fn all_sample_m3u_playlists() -> Vec<path::PathBuf> {
@@ -198,6 +199,36 @@ fn create_and_parse_master_playlist_empty() {
     assert_eq!(playlist_original, playlist_parsed);
 }
 
+#[test]
+fn create_segment_float_inf() {
+    let playlist = Playlist::MediaPlaylist(MediaPlaylist {
+        version: Some(6),
+        target_duration: 3,
+        media_sequence: 338559,
+        discontinuity_sequence: 1234,
+        end_list: true,
+        playlist_type: Some(MediaPlaylistType::Vod),
+        segments: vec![MediaSegment {
+            uri: "20140311T113819-01-338559live.ts".into(),
+            duration: 2.000f32,
+            title: Some("title".into()),
+            ..Default::default()
+        }],
+        ..Default::default()
+    });
+
+    let mut v: Vec<u8> = Vec::new();
+    playlist.write_to(&mut v).unwrap();
+    let m3u8_str: &str = std::str::from_utf8(&v).unwrap();
+    assert!(m3u8_str.contains("#EXTINF:2,title"));
+
+    WRITE_OPT_FLOAT_PRECISION.store(5, Ordering::Relaxed);
+
+    playlist.write_to(&mut v).unwrap();
+    let m3u8_str: &str = std::str::from_utf8(&v).unwrap();
+    assert!(m3u8_str.contains("#EXTINF:2.00000,title"));
+}
+
 #[test]
 fn create_and_parse_master_playlist_full() {
     let mut playlist_original = Playlist::MasterPlaylist(MasterPlaylist {
@@ -382,6 +413,7 @@ fn create_and_parse_media_playlist_full() {
                 tag: "X-CUE-OUT".into(),
                 rest: Some("DURATION=2.002".into()),
             }],
+            ..Default::default()
         }],
         unknown_tags: vec![],
     });