Fix startup crash when recording audio encoder is not registered

[summeroff]

Description

Guards against a null codec in the recording audio encoder setup, which crashes the backend at startup when the AAC encoder type is not registered.

Crash

Sentry reports an EXCEPTION_ACCESS_VIOLATION_READ / 0x0 with this signature:

strlen
std::_Narrow_char_traits<char>::length        (__msvc_string_view.hpp:456)
std::operator<<(ostream&, const char*)         (__msvc_ostream.hpp:774)
OBS_service::setupRecordingAudioEncoder        (nodeobs_service.cpp:1199)
... OBS_API::OBS_API_initAPI                   (nodeobs_api.cpp:1027)

setupRecordingAudioEncoder() streams the codec from obs_get_encoder_codec(id) into an ostringstream:

const char *codec = obs_get_encoder_codec(id.c_str());   // id defaults to "ffmpeg_aac"
nameStream << "adv_audio_recording_" << codec << "_" << i;

When the encoder type is not registered, obs_get_encoder_codec() returns NULL (libobs obs-encoder.c: return info ? info->codec : NULL;), and operator<<(ostream&, const char*) calls strlen(NULL) → AV.

Root cause

The default recording audio encoder ffmpeg_aac is provided by obs-ffmpeg.dll. In the affected reports that module is not loaded (Failed to load module file '.../obs-ffmpeg.dll', file not found, and in one report all modules fail to register on re-init), so ffmpeg_aac is absent. The logs corroborate it: Failed to get properties for encoder '' (ffmpeg_aac) / Could not enumerate any AAC encoder bitrates.

Fix

Null-guard the codec in both recording audio paths and skip + log instead of dereferencing, so OBS_API_initAPI completes rather than crashing:

• setupRecordingAudioEncoder() (advanced output)
• updateAudioRecordingEncoder() (simple output) — also guards a null audioEncoder config value before std::string(codec)

This mirrors the existing null-check pattern in GetVideoEncoderName(). Surfacing the missing-plugin condition to the frontend is handled separately (on top of #1733).

How Has This Been Tested?

• Incremental build of obs-studio-server-lib (Release, VS 2022): 0 errors.
• clang-format 18.1.3 --dry-run -Werror on the changed lines: clean.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Guards against a startup crash in OBS_service when the configured recording audio encoder isn’t registered (e.g., obs-ffmpeg.dll not loaded), by null-checking the codec returned from obs_get_encoder_codec() and skipping encoder setup with an error log instead of streaming a null const char* into an ostringstream.

Changes:

• Add a null-guard for codec in advanced recording audio encoder setup (setupRecordingAudioEncoder()).
• Add a null-guard for both the configured encoder id and codec in simple recording audio encoder setup (updateAudioRecordingEncoder()), logging and returning early.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[summeroff]

Good catch — addressed in dd24e88, but at the root rather than in the guard. clearRecordingAudioEncoder() released the encoders without nulling the pointers, so the dangling state existed independently of this guard (it was only masked because setupRecordingAudioEncoder() previously always overwrote the slots). It now nulls each pointer after release, so after clear()+early-return the tracks read as absent and updateRecordingAudioTracks()/obs_output_set_audio_encoder() are safe. This also fixes the latent release-without-null for all callers, not just the early-return path.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

[summeroff]

Fixed in 1618d95 by moving the guard above the audioSimpleRecEncID = "" reset, so the early-return path mutates nothing — the cached ID and audioSimpleRecordingEncoder stay in their prior consistent state instead of ID-cleared-but-encoder-kept. (After the guard, audioEncoder is guaranteed non-null, so the reset is now unconditional.) This bails before touching anything, so it can't disrupt an existing/active encoder.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.