link-u/avif-sample-images

AVIF example images, licensed under CC-BY-SA.

avif-sample-images's Issues

Alpha test images have multiple ipma boxes with same values of version and flags

Per ISO 23008-12:2017 § 9.3.1 (emphasis added):

Each ItemPropertyAssociation box shall be ordered by increasing item_ID, and there shall be at most one association box for each item_ID, in any ItemPropertyAssociation box. The version 0 should be used unless 32-bit item_ID values are needed; similarly, flags should be equal to 0 unless there are more than 127 properties in the ItemPropertyContainerBox. There shall be at most one ItemPropertyAssociationbox with a given pair of values of version and flags.

Looking at plum-blossom-large.profile0.10bpc.yuv420.alpha-full.avif, we can see the entirety of the the iprp box starting at byte offset 272 (0x110):

00000110: 0000 010d 6970 7270 0000 00d6 6970 636f  ....iprp....ipco
00000120: 0000 0010 7061 7370 0000 0001 0000 0001  ....pasp........
00000130: 0000 0014 6973 7065 0000 0000 0000 0800  ....ispe........
00000140: 0000 0800 0000 0010 7069 7869 0000 0000  ........pixi....
00000150: 030a 0a0a 0000 0018 6176 3143 810c 4c00  ........av1C..L.
00000160: 0a0a 1b2a bfff ffe2 8086 8482 0000 0010  ...*............
00000170: 7061 7370 0000 0001 0000 0001 0000 0014  pasp............
00000180: 6973 7065 0000 0000 0000 0800 0000 0800  ispe............
00000190: 0000 000e 7069 7869 0000 0000 010a 0000  ....pixi........
000001a0: 0018 6176 3143 810c 5c00 0a0a 1b2a bfff  ..av1C..\....*..
000001b0: ffe3 8086 84d0 0000 0038 6175 7843 0000  .........8auxC..
000001c0: 0000 7572 6e3a 6d70 6567 3a6d 7065 6742  ..urn:mpeg:mpegB
000001d0: 3a63 6963 703a 7379 7374 656d 733a 6175  :cicp:systems:au
000001e0: 7869 6c69 6172 793a 616c 7068 6100 0000  xiliary:alpha...
000001f0: 0017 6970 6d61 0000 0000 0000 0001 0001  ..ipma..........
00000200: 0401 0283 8400 0000 1869 706d 6100 0000  .........ipma...
00000210: 0000 0000 0100 0205 0506 8788 89         .............

The 4 bytes prior to iprp (0000 010d = 269) represent the length of the box, so we dump through offset 0000 021d.

Looking more closely at the 2 ipma boxes:

000001ee: 0000 0017  .... ; size: 23 bytes
000001f2: 6970 6d61  ipma
000001f6: 0000 0000  .... ; version: 0x00, flags: 0x000000
000001fa: 0000 0001  .... ; entry_count: 1
000001fe: 0001 0401  .... ; (2 bytes) item_ID: 1, (1 byte) association_count: 4, (1 bit) essential: 0, (7 bits) property_index: 1
00000202: 0283 84    ...  ; (1 bit) essential: false, (7 bits) property_index: 2, (1 bit) essential: true, (7 bits) property_index: 3, (1 bit) essential: true, (7 bits) property_index: 4

00000205: 0000 0018  .... ; size = 24 bytes
00000209: 6970 6d61  ipma
0000020d: 0000 0000  .... ; version = 0x00, flags = 0x000000
00000211: 0000 0001  .... ; entry_count = 1
00000215: 0002 0505  .... ; (2 bytes) item_ID: 2, (1 byte) association_count: 5, (1 bit) essential: 0, (7 bits) property_index: 5
00000219: 0687 8889  .... ; (1 bit) essential: 0, (7 bits) property_index: 6, (1 bit) essential: true, (7 bits) property_index: 7, (1 bit) essential: true, (7 bits) property_index: 8, (1 bit) essential: true, (7 bits) property_index: 9

They're adjacent to one another as expected since an ItemPropertiesBox (iprp) box contains an array of ItemPropertyAssociation (ipma) boxes:

aligned(8) class ItemPropertiesBox extends Box('iprp') {
ItemPropertyContainerBox property_container;
       ItemPropertyAssociation association[];
}

However, multiple ipma boxes should only be used when they require different versions or flag values. Given that both of these ipma boxes have version 0x00 and flags 0x000000, they should be combined into a single iprp box with 2 entries like so:

6970 6d61  ipma
0000 0000  .... ; version = 0x00, flags = 0x000000
0000 0002  .... ; entry_count = 2
0001 0401  .... ; (2 bytes) item_ID: 1, (1 byte) association_count: 4, (1 bit) essential: 0, (7 bits) property_index: 1
0283 8400  .... ; (1 bit) essential: false, (7 bits) property_index: 2, (1 bit) essential: true, (7 bits) property_index: 3, (1 bit) essential: true, (7 bits) property_index: 4, first byte of 2-byte item_ID…
0205 0506  .... ; (2 bytes) item_ID: 2, (1 byte) association_count: 5, (1 bit) essential: 0, (7 bits) property_index: 5, (1 bit) essential: 0, (7 bits) property_index: 6
8788 89    ...  ; (7 bits) property_index: 7, (1 bit) essential: true, (7 bits) property_index: 8, (1 bit) essential: true, (7 bits) property_index: 9

Chrome 85 downloads avif files

I'm on Chrome 85 - why doesn't any of the avif images render in the browser ? All are getting downloaded to my downloads folder.

`plum-blossom-large.profile0.8bpc.yuv420.alpha-limited.monochrome.avif` failed strict checks in libavif

>avifdec --no-strict --info D:\images\avif\plum-blossom-large.profile0.8bpc.yuv420.alpha-limited.monochrome.avif
ERROR: Failed to decode image: BMFF parsing failed
Diagnostics:
 * Multiple Box[ipma] with a given pair of values of version and flags. See HEIF (ISO 23008-12:2017) 9.3.1

libavif: https://github.com/AOMediaCodec/libavif