These original files provide known pixel and audio data for checking an import, export or playback workflow. Keep the source file and record any transformation separately. The accompanying verification concerns file contents, rather than the performance of a particular device.
PNG alpha reference
A 640 × 360 RGBA image. RGB stays at 24, 96, 168; the alpha channel provides the transition. The preview scales to fit this page; open the original PNG for a full-size view.
Use the PNG comparison checklist to record the same light and dark background checks for a saved export.
The centre is at pixel coordinates (319.5, 179.5), using zero-based coordinates. It is fully opaque inside radius 108 pixels. Alpha falls linearly to zero at radius 132 pixels and is rounded to the nearest integer, giving a 24-pixel radial transition. Outside that radius the image is transparent.
Place the image over both light and dark backgrounds at its native dimensions. Then repeat with a separately saved export. If you resize or rotate it, record that operation and retain the untransformed copy for comparison.
The PNG specification defines its alpha representation: in eight-bit alpha, 0 is transparent and 255 is opaque, with colour samples stored without premultiplying by alpha. The reference has no embedded ICC profile, so keep the chosen colour interpretation consistent when comparing copies. It is not a calibrated display target.
Continuous audio and two matching tracks
The files contain an original 997 Hz tone at 48,000 samples per second, mono, 16-bit PCM. The tone amplitude is 3,000 out of a possible positive 32,767. Start playback at a low volume.
The continuous file contains 192,000 sample frames and each half contains 96,000. Joining the two decoded PCM payloads reproduces the continuous payload exactly. That equality was checked locally; concatenating the complete WAV files, including their headers, is not the same operation.
Listen to the source files
Start at a low volume. These individual previews let you hear each source file; they do not run a two-track gapless playback check in this browser.
Use the audio files carefully
- Keep the supplied WAV files unchanged and choose a player that can import your local files.
- Place tracks 1 and 2 in order. Record any crossfade, shuffle or transition settings.
- Compare the two-track route with the continuous file through the same output connection.
- If investigating AAC, create separate encoded copies and record the encoder version, container and settings.
- Record what you actually observe: pause, click, overlap or uninterrupted transition. Keep the playback route and software versions with the result.
A matching source join does not establish how a player or encoder will handle it. Apple’s Audio Queue guidance explains priming and remainder frames in compressed audio. Its numerical examples belong to those examples; they are not universal iPad delays.
Open the audio transition checklist to keep the player, output route, settings and join observations in one downloadable record.
Colour calculations need their own references
For colour-profile work, the International Color Consortium provides background. Sharma, Wu and Dalal’s CIEDE2000 implementation paper and supporting reference data can help verify a colour-difference calculation. The PNG here is intended for transparency checks and should not be substituted for those colour references.
See the file verification record (JSON), SHA-256 list and readme. Download all files through the resource library. Corrections: contact@csec3888.com.