From 9eccea8a7fa16f8a2115aa889db67edeab3ad4ed Mon Sep 17 00:00:00 2001
From: Luro02 <24826124+Luro02@users.noreply.github.com>
Date: Sun, 29 Mar 2020 12:58:32 +0200
Subject: [PATCH] automatically infer start of ByteRange

---
 src/media_playlist.rs   | 23 +++++++++++++++++++++--
 tests/media_playlist.rs |  3 ++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/media_playlist.rs b/src/media_playlist.rs
index 9fb4aad..892e398 100644
--- a/src/media_playlist.rs
+++ b/src/media_playlist.rs
@@ -8,8 +8,9 @@ use derive_builder::Builder;
 use crate::line::{Line, Lines, Tag};
 use crate::media_segment::MediaSegment;
 use crate::tags::{
-    ExtM3u, ExtXDiscontinuitySequence, ExtXEndList, ExtXIFramesOnly, ExtXIndependentSegments,
-    ExtXKey, ExtXMediaSequence, ExtXStart, ExtXTargetDuration, ExtXVersion,
+    ExtM3u, ExtXByteRange, ExtXDiscontinuitySequence, ExtXEndList, ExtXIFramesOnly,
+    ExtXIndependentSegments, ExtXKey, ExtXMediaSequence, ExtXStart, ExtXTargetDuration,
+    ExtXVersion,
 };
 use crate::types::{
     DecryptionKey, EncryptionMethod, InitializationVector, KeyFormat, PlaylistType, ProtocolVersion,
@@ -295,6 +296,8 @@ impl MediaPlaylistBuilder {
         }
 
         let mut position = sequence_number;
+        let mut previous_range: Option<ExtXByteRange> = None;
+
         for segment in segments
             .iter()
             .filter_map(|(_, s)| if s.explicit_number { None } else { Some(s) })
@@ -322,6 +325,22 @@ impl MediaPlaylistBuilder {
                 }
             }
 
+            // add the lower bound to the byterange automatically
+            if let Some(range) = &mut segment.byte_range {
+                if range.start().is_none() {
+                    if let Some(previous_range) = previous_range {
+                        // the end of the previous_range is the start of the next range
+                        *range = range.saturating_add(previous_range.end());
+                        range.set_start(Some(previous_range.end()));
+                    } else {
+                        // assume that the byte range starts at zero
+                        range.set_start(Some(0));
+                    }
+                }
+
+                previous_range = segment.byte_range;
+            }
+
             result_segments.insert(segment.number, segment);
             position += 1;
         }
diff --git a/tests/media_playlist.rs b/tests/media_playlist.rs
index 7477910..b1fb799 100644
--- a/tests/media_playlist.rs
+++ b/tests/media_playlist.rs
@@ -43,6 +43,7 @@ generate_tests! {
                     .unwrap(),
                 MediaSegment::builder()
                     .duration(ExtInf::new(Duration::from_secs_f64(10.0)))
+                    // 834433..904297
                     .byte_range(ExtXByteRange::from(..69864))
                     .uri("video.ts")
                     .build()
@@ -64,7 +65,7 @@ generate_tests! {
             "#EXTINF:10,\n",
             "video.ts\n",
 
-            "#EXT-X-BYTERANGE:69864\n",
+            "#EXT-X-BYTERANGE:69864@834433\n",
             "#EXTINF:10,\n",
             "video.ts\n"
         )