- From: Chris Lilley <chris@w3.org>
- Date: Mon, 3 Feb 2025 14:01:02 -0500
- To: public-png@w3.org
- Message-ID: <a37faddc-3932-4015-b7bb-6c7157328537@w3.org>
I have extended my pngcheck fork[0] to add APNG support. It now reports
whether a PNG is static or animated. In non-verbose mode, if there are
no errors, it also reports the number of frames.
Sample non-verbose output (on the Philip Taylor test suite)[1] - files
040 to 058 are known to be invalid.
I notice it fails to detect errors in 044 (missing fdAT), will look into
that.
chris@SuperNomad:/mnt/c/Users/chris/Documents/PNG/philip_APNG_tests_files$ pngcheck -c *.png
OK: 000.png (128x64, 32-bit RGB+alpha, non-interlaced, static, 99.2%).
OK: 001.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (1 frame), 99.1%).
OK: 002.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (1 frame), 98.6%).
OK: 003.png (128x64, 32-bit RGB+alpha, non-interlaced, static, 99.2%).
OK: 004.png (128x64, 32-bit RGB+alpha, non-interlaced, static, 99.2%).
OK: 005.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (1 frame), 98.5%).
OK: 006.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (1 frame), 98.5%).
OK: 007.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (3 frames), 98.1%).
OK: 008.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (3 frames), 98.3%).
OK: 009.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.4%).
OK: 010.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (3 frames), 97.6%).
OK: 011.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.4%).
OK: 012.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.9%).
OK: 013.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (3 frames), 98.1%).
OK: 014.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 99.0%).
OK: 015.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (3 frames), 98.5%).
OK: 016.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (3 frames), 97.9%).
OK: 017.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 018.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.4%).
OK: 019.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.1%).
OK: 020.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.2%).
OK: 021.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (128 frames), 12.1%).
OK: 022.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (16 frames), 89.8%).
OK: 023.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (16 frames), 89.4%).
OK: 024.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.4%).
OK: 025.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (4 frames), 96.7%).
OK: 026.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 027.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 028.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 029.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (4 frames), 96.7%).
OK: 030.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 031.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 032.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.0%).
OK: 033.png (128x64, 64-bit RGB+alpha, non-interlaced, animated (2 frames), 98.6%).
OK: 034.png (128x64, 8-bit grayscale, non-interlaced, animated (2 frames), 96.0%).
OK: 035.png (128x64, 16-bit grayscale+alpha, non-interlaced, animated (2 frames), 95.9%).
OK: 036.png (128x64, 1-bit palette, non-interlaced, animated (2 frames), 74.4%).
OK: 037.png (128x64, 2-bit palette+trns, non-interlaced, animated (2 frames), 85.0%).
OK: 038.png (128x64, 1-bit palette+trns, non-interlaced, animated (2 frames), 73.0%).
OK: 039.png (128x64, 32-bit RGB+alpha, non-interlaced, static, 98.6%).
040.png multiple acTL not allowed
ERROR: 040.png
041.png acTL must be before first IDAT
ERROR: 041.png
043.png sequence numbers must be sequential
ERROR: 043.png
OK: 044.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 98.4%).
045.png acTL number of frames cannot be zero
ERROR: 045.png
046.png acTL number of frames cannot be zero
ERROR: 046.png
047.png Expected 1 frames, but found 2
ERROR: 047.png
048.png Expected 3 frames, but found 2
ERROR: 048.png
049.png Expected 4 frames, but found 2
ERROR: 049.png
050.png Expected 2147483649 frames, but found 1
ERROR: 050.png
051.png sequence numbers must start at zero
ERROR: 051.png
052.png sequence numbers must be sequential
ERROR: 052.png
053.png sequence numbers must be sequential
ERROR: 053.png
054.png sequence numbers must be sequential
ERROR: 054.png
055.png sequence numbers must be sequential
ERROR: 055.png
056.png sequence numbers must be sequential
ERROR: 056.png
057.png sequence numbers must be sequential
ERROR: 057.png
058.png First frame is IDAT, so first frame must be same size as static image
ERROR: 058.png
OK: 059.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (1 frame), 98.8%).
OK: 060.png (128x64, 32-bit RGB+alpha, non-interlaced, animated (1 frame), 98.1%).
OK: lime.png (128x64, 24-bit RGB, non-interlaced, static, 99.3%).
OK: underconstruction.png (51x50, 32-bit RGB+alpha, non-interlaced, animated (2 frames), 86.0%).
Errors were detected in 17 of the 62 files tested.
No errors were detected in 45 of the 62 files tested.
Sample verbose output on a single file:
chris@SuperNomad:/mnt/c/Users/chris/Documents/PNG/APNG samples$ pngcheck -c -v 012-dispose-previous.png
File: 012-dispose-previous.png (2669 bytes)
chunk IHDR at offset 0x0000c, length 13
200 x 200 image, 32-bit RGB+alpha, non-interlaced
chunk bKGD at offset 0x00025, length 6
red = 0x00ff, green = 0x00ff, blue = 0x00ff
chunk acTL at offset 0x00037, length 8
Animated PNG, 3 frames, plays continuously
chunk fcTL at offset 0x0004b, length 26
Frame, sequence number 0
Width 200, height 200 starting at (0, 0)
Frame delay 65537 (65537 / 1) sec
No disposal before next frame
Frame composites (source over) with buffer
chunk IDAT at offset 0x00071, length 1132
zlib: deflated, 32K window, default compression
chunk fcTL at offset 0x004e9, length 26
Frame, sequence number 1
Width 200, height 200 starting at (0, 0)
Frame delay 65537 (65537 / 1) sec
Reverts to previous contents before next frame
Frame composites (source over) with buffer
chunk fdAT at offset 0x0050f, length 443
Frame data, sequence number 2
chunk fcTL at offset 0x006d6, length 26
Frame, sequence number 3
Width 200, height 200 starting at (0, 0)
Frame delay 65537 (65537 / 1) sec
No disposal before next frame
Frame composites (source over) with buffer
chunk fdAT at offset 0x006fc, length 861
Frame data, sequence number 4
chunk IEND at offset 0x00a65, length 0
No errors detected in 012-dispose-previous.png (10 chunks, 98.3% compression).
[0] https://github.com/svgeesus/pngcheck
[1] https://philip.html5.org/tests/apng/tests.html
--
Chris Lilley
@svgeesus
Technical Director @ W3C
W3C Strategy Team, Core Web Design
W3C Architecture & Technology Team, Core Web & Media
Received on Monday, 3 February 2025 19:01:02 UTC