global-catch-up/README.md

Global Catch Up

Downloader for Global Radio show catch ups. Made during and for their Stranger Things broadcast between 24 Nov and 31 Dec 2025.

Useful Tools

Compare two files ignoring tags (Global embeds different timestamps depending on when a file was (re-)generated. So, the same catch up file can have different timestamps if downloaded at different times.):

ffmpeg -i input.m4a -map_metadata -1 -c copy -f adts pipe:1 | sha256sum -b

Can be strung into a find call to calculate checksums of multiple files at once:

find myfolder -type f -iname "*.m4a" -exec sh -c "ffmpeg -i '{}' -map_metadata -1 -c copy -f adts pipe:1 | sha256sum -b" \; 2>/dev/null

Strip metadata:

1. Get creation_time:

   ffprobe -i input.m4a

2. Remove unwanted metadata and streams (copy the creation_time value from above's output):

   ffmpeg -i input.m4a -metadata track= -metadata album= -metadata artist= -metadata title= -metadata comment= -metadata creation_time=2025-12-03T11:55:04.000000Z -map 0:0 -c copy -fflags +bitexact -movflags +faststart output.m4a