Support rf64 file type with correct file extension handling

[Copilot]

Adds support for rf64 as a distinct file type option while ensuring RF64 files use the correct .wav file extension.

Problem

When running svar -t webm (or any invalid file type), the error message incorrectly showed "wav" twice:

error: Unknown output file type {raw, mp3, wav, wav, ogg}: webm

Additionally, users could not specify rf64 as a file type since both WRITER_TYPE_WAV and WRITER_TYPE_RF64 mapped to the same "wav" string.

Root Cause

Both WRITER_TYPE_WAV and WRITER_TYPE_RF64 enum values mapped to the same string "wav" via the writer_type_to_string() function. This caused two issues:

1. The error message displayed "wav" twice when listing valid file types
2. Users could not specify "rf64" as a file type option

Changes Made

• Modified writer_type_to_string() in src/writer.c to return unique identifiers:
  • WRITER_TYPE_WAV returns "wav"
  • WRITER_TYPE_RF64 returns "rf64"
• Created new writer_type_to_extension() function to handle file extensions separately:
  • Both WRITER_TYPE_WAV and WRITER_TYPE_RF64 return "wav" as the file extension
• Updated src/recorder.c to use writer_type_to_extension() for file naming
• Added function declaration to src/writer.h

Result

The error message now correctly displays both options:

error: Unknown output file type {raw, mp3, wav, rf64, ogg}: webm

Users can now specify either -t wav or -t rf64, and RF64 files will be created with the correct .wav file extension.

Testing

• ✅ Build completes successfully with all audio codec support enabled
• ✅ Verified error message shows both "wav" and "rf64" as separate options
• ✅ Confirmed RF64 files use .wav extension (not .rf64)
• ✅ Updated .gitignore to exclude build artifacts

Original prompt

When called app like this:

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[arkq]

@copilot When app called like this:

$ svar -t webm
error: Unknown output file type {raw, mp3, wav, wav, ogg}: webm

[Copilot]

@copilot When app called like this:

Fixed in a0b792d. The duplicate "wav" was caused by both WRITER_TYPE_WAV and WRITER_TYPE_RF64 mapping to the same string. The error message now correctly shows: error: Unknown output file type {raw, mp3, wav, ogg}: webm

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[arkq]

@copilot but now it's not possible to use rf64 type, the output should be:
error: Unknown output file type {raw, mp3, wav, rf64, ogg}: webm

[Copilot]

@copilot but now it's not possible to use rf64 type, the output should be:
error: Unknown output file type {raw, mp3, wav, rf64, ogg}: webm

Fixed in fd54313. Created separate writer_type_to_extension() function so that rf64 type name appears in error messages and can be specified by users, but rf64 files still get the .wav extension. Error message now shows: error: Unknown output file type {raw, mp3, wav, rf64, ogg}: webm