The ffmpeg -headers option was receiving the User-Agent value split across
multiple arguments due to spaces not being properly quoted. This caused ffmpeg
to interpret "Mozilla/5.0" as an output format, resulting in:
[NULL @ ...] Unable to find a suitable output format for 'Mozilla/5.0'
Fixed by wrapping the entire headers string in quotes so parseArgsStringToArgv
treats it as a single argument. The headers string is now properly passed to
ffmpeg as: -headers "User-Agent: ... \r\nConnection: ..."
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
