Tomo-e Gozen

A preliminary support for Tomo-e Gozen optical FITS files:

• upon detecting the Kiso Observatory via the "TELESCOP" keyword in the FITS header, switch to the optical mode using the "ratio" image tone mapping function & automatic brightness adjustment

• the "ratio" tone-mapping is most suitable for viewing both faint and bright objects present in the same image

maintenance

• fixes the "panicked at 'attempted to zero-initialize type vpx_codec_enc_cfg." errors

• improves handling of FITS files opened via an external URL

• enhances compatibility with the latest Rust 1.52 (fixes compilation warnings)

maintenance

• updated various Rust crates dependencies
• tweaked the spectrum colours in both dark and bright UI modes
• fixed the tileTimeout() JavaScript function (only relevant when viewing multiple datasets at the same time in a non-composite mode)

initial JavaScript loading time speed-ups

• switched to using automatically minified JavaScript files via the worldwide jsDelivr Content Delivery Network (CDN)

ffmpeg WebAssembly refresh

• ffmpeg-4.1.5 HEVC decoder has been recompiled with the latest Emscripten

spectrum compression

• back-ported from v5 real-time spectrum compression using FPZIP (https://github.com/LLNL/fpzip)
• the server-side compression takes place after the spectrum downsampling, prior to sending the compressed spectra over WebSockets to the client web browser
• client-side decompression in JavaScript has been accelerated with WebAssembly
• a typical size of binary WebSocket messages containing compressed spectra is between 500 and 1000 bytes, which ensures most messages will fit within one Raw Ethernet frame

speed improvements

• Back-ported from the new C/C++ v5 to Rust down-sampling of the spectrum when the number of cube channels exceeds the width of the browser window. Previously this downsizing step had been handled client-side in a web browser. The new version moves down-sampling server-side prior to sending the down-sampled spectrum over the network to the end users, which in many cases will result in a reduction in the bandwidth usage (smoother real-time spectrum updates over slow/unreliable network connections), plus a lesser CPU demand due to omitting the downsizing step client-side in JavaScript.
• Fixes a compilation warning when using Rust ≥ 1.44 (unused braces).

maintenance

• update dependencies
• works with the latest Intel ispc v1.13

actix-web upgrade

A general upgrade of all dependencies. In particular

• [server] upgraded the networking library to the current stable actix-web 2.0 from the previous v1.0
• [server] updated the asynchronous code to tokio-0.2 and futures-0.3.4
• [client] revised the calculation of the default font size to better suit widescreen monitors

a bug fix

Works around a bug in either Rust or Rust bzip2 bindings whereby an unused but initialised bzip2 streaming decompressor could not be dropped in a clean manner. As a result a return from a Rust function would hang indefinitely. A workaround uses Option<Rc<RefCell<bzip2::write::BzDecoder<Vec<u8>>>>> etc.

The problem affected the JVO server version of FITSWebQL.