Add Opus encoding support

[Copilot]

Adds Opus audio encoding as a new output format option alongside existing RAW, WAV, MP3, and OGG formats.

Implementation

• New writer: writer-opus.{c,h} implements Opus encoding via libopus

  • Manually handles OGG muxing using libogg (similar to Vorbis writer)
  • Creates RFC 7845 compliant OpusHead and OpusTags headers
  • Supports 16-bit PCM input, configurable bitrate
  • Buffers PCM data to match 20ms Opus frame size requirements

• Build system: Added ENABLE_OPUS CMake option requiring opus and ogg packages

• Integration: Updated writer.{c,h} and main.c to register WRITER_TYPE_OPUS and handle -t opus flag

• Tests: Added unit tests in tc-writer.c covering writer creation and encoding

Usage

# Build with Opus support
cmake .. -DENABLE_OPUS=ON

# Record with Opus encoding
svar -t opus output-template

Error messages now correctly list available formats:

error: Unknown output file type {raw, wav, rf64, ogg, opus}: unknown

[!WARNING]

Original prompt

---

This section details on the original issue you should resolve

<filter_complete></filter_complete>

<issue_title>support opus</issue_title>
<issue_description>I noticed encoding in VORBIS is possible, but the newer and better algorithm OPUS would be also nice to have.

BTW the output filetype says wav twice in its help message:

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

Thanks for the SW.
Cheers!</issue_description>

Comments on the Issue (you are @copilot in this section)

@arkq > BTW the output filetype says wav twice in its help message

Thanks for reporting that, I've pushed the fix into the master.</comment_new>

• Fixes support opus #22

Original prompt

---

This section details on the original issue you should resolve

<issue_title>support opus</issue_title>
<issue_description>I noticed encoding in VORBIS is possible, but the newer and better algorithm OPUS would be also nice to have.

BTW the output filetype says wav twice in its help message:

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

Thanks for the SW.
Cheers!</issue_description>

Comments on the Issue (you are @copilot in this section)

@arkq > BTW the output filetype says wav twice in its help message

Thanks for reporting that, I've pushed the fix into the master.</comment_new>

• Fixes support opus #22

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[arkq]

@copilot use libopus-dev (/usr/include/opus/opus.h) instead of libopusenc-dev

[Copilot]

@copilot use libopus-dev (/usr/include/opus/opus.h) instead of libopusenc-dev

Done! Rewrote the Opus writer to use libopus (/usr/include/opus/opus.h) instead of libopusenc. The implementation now manually handles OGG muxing using libogg, following RFC 7845 for Opus encapsulation in OGG containers. See commit 4bd45bf.

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)