Remove error for when an AVIF has no iloc box.

Item locations can be omitted for AVIS-major files which don't contain `pitm` boxes. When no `iloc` is present, the locations map is default-initialized, and if the `pitm` references a nonexistent item, an error is thrown in strict mode.

Author: Zaggy1024

mp4parse/src/lib.rs

@@ -222,7 +222,6 @@ pub enum Status {
     IlocBadQuantity,
     IlocBadSize,
     IlocDuplicateItemId,
-    IlocMissing,
     IlocNotFound,
     IlocOffsetOverflow,
     ImageItemType,
@@ -260,6 +259,7 @@ pub enum Status {
     NoImage,
     PitmBadQuantity,
     PitmMissing,
+    PitmNotFound,
     PixiBadChannelCount,
     PixiMissing,
     PsshSizeOverflow,
@@ -597,9 +597,6 @@ impl From<Status> for &str {
             Status::IlocDuplicateItemId => {
                 "duplicate item_ID in iloc"
             }
-            Status::IlocMissing => {
-                "iloc missing"
-            }
             Status::IlocNotFound => {
                 "ItemLocationBox (iloc) contains an extent not present in any mdat or idat box"
             }
@@ -732,6 +729,9 @@ impl From<Status> for &str {
                 "Missing required PrimaryItemBox (pitm), required \
                  per HEIF (ISO/IEC 23008-12:2017) § 10.2.1"
             }
+            Status::PitmNotFound => {
+                "PrimaryItemBox (pitm) referenced an item ID that was not present"
+            }
             Status::PixiBadChannelCount => {
                 "invalid num_channels"
             }
@@ -2708,6 +2708,12 @@ pub fn read_avif<T: Read>(f: &mut T, strictness: ParseStrictness) -> Result<Avif
         assert!(item.is_some());
     }
 
+    if (primary_item_id.is_some() && primary_item.is_none())
+        || (alpha_item_id.is_some() && alpha_item.is_none())
+    {
+        fail_with_status_if(strictness == ParseStrictness::Strict, Status::PitmNotFound)?;
+    }
+
     assert!(primary_item.is_none() || primary_item_id.is_some());
     assert!(alpha_item.is_none() || alpha_item_id.is_some());
 
@@ -2918,7 +2924,7 @@ fn read_avif_meta<T: Read + Offset>(
         item_references: item_references.unwrap_or_default(),
         primary_item_id,
         item_infos: item_infos.unwrap_or_default(),
-        iloc_items: iloc_items.ok_or_else(|| Error::from(Status::IlocMissing))?,
+        iloc_items: iloc_items.unwrap_or_default(),
         item_data_box,
     })
 }

mp4parse/tests/avis_with_no_ptim_no_iloc.avif

@@ -86,6 +86,8 @@ static AVIF_AVIS_MAJOR_NO_PITM: &str =
 /// This is av1-avif/testFiles/Netflix/avis/alpha_video.avif
 /// but with https://github.com/AOMediaCodec/av1-avif/issues/177 fixed
 static AVIF_AVIS_MAJOR_WITH_PITM_AND_ALPHA: &str = "tests/alpha_video_fixed.avif";
+static AVIF_AVIS_WITH_NO_PITM_NO_ILOC: &str = "tests/avis_with_no_ptim_no_iloc.avif";
+static AVIF_AVIS_WITH_PITM_NO_ILOC: &str = "tests/avis_with_pitm_no_iloc.avif";
 static AVIF_AVIS_MAJOR_NO_MOOV: &str = "tests/corrupt/alpha_video_moov_is_moop.avif";
 static AVIF_AVIS_NO_LOOP: &str = "tests/loop_none.avif";
 static AVIF_AVIS_LOOP_FOREVER: &str = "tests/loop_forever.avif";
@@ -1240,6 +1242,17 @@ fn public_avif_avis_major_no_moov() {
     assert_avif_shall(AVIF_AVIS_MAJOR_NO_MOOV, Status::MoovMissing);
 }
 
+#[test]
+fn public_avif_avis_with_no_pitm_no_iloc() {
+    let input = &mut File::open(AVIF_AVIS_WITH_NO_PITM_NO_ILOC).expect("Unknown file");
+    assert!(mp4::read_avif(input, ParseStrictness::Normal).is_ok());
+}
+
+#[test]
+fn public_avif_avis_with_pitm_no_iloc() {
+    assert_avif_should(AVIF_AVIS_WITH_PITM_NO_ILOC, Status::PitmNotFound);
+}
+
 fn public_avis_loop_impl(path: &str, looped: bool) {
     let input = &mut File::open(path).expect("Unknown file");
     match mp4::read_avif(input, ParseStrictness::Normal) {