Compatibility Report

Name of the game with compatibility issues: Atomic Heart
Steam AppID of the game: 668580

System Information

• GPU: Gigabyte RTX 4070 Windforce
• Driver/LLVM version: NVIDIA 615.71.09
• Kernel version: 7.2.4-3-cachyos
• Distro: CachyOS (Arch-based)
• Proton versions tested: proton-cachyos-11.0-20260703-slr, Proton Experimental (Valve, stock), GE-Proton (latest) - all three show identical behavior

I confirm:

• [x] This report is not for a duplicate issue. I have checked the open and closed issues.
• [x] This report is not for a third-party program, such as ReShade, ENB, DXVK-Async, EAC, BattlEye, or anything else not part of Steam Play or Steam Linux Runtime.

Symptoms

Cartoon videos ("Nu, Pogodi!") played on the in-world TVs inside save rooms display video correctly but have no audio, on all Proton builds tested. All other game audio (SFX, music, dialogue, menu sounds) works normally.

Reported by other users as not reproducible on native Windows (Focus/VK Play build) - unconfirmed by me directly, but consistent across multiple people I've talked to.

Steps to reproduce

1. Launch Atomic Heart, reach any save room with a working TV screen.
2. Interact with / walk into view of the TV so the "Nu, Pogodi!" cartoon starts playing.
3. Video plays normally. No audio is heard, on any output device or channel configuration.

What I've already ruled out

• The media file itself is not the problem. Extracted the relevant Nu_Pogodi_*.mp4 asset (H.264 + AAC-LC, 48kHz stereo, standard MP4/mp42 container, Mainconcept encoder) and confirmed via ffprobe and direct local playback (mpv) that the audio track is valid and plays correctly outside the game.
• Re-encoding the audio track (forcing ffmpeg to rewrite a clean esds/codec_data atom) made no difference in-game, even though it eliminated an early, apparently non-fatal aacparse warning (see below).
• Not a Proton-fork-specific patch. Tested proton-cachyos, Valve's stock Proton Experimental, and GE-Proton - identical symptom on all three, which rules out downstream fork patches as the cause.
• Not the PROTON_USE_PIPEWIRE audio driver setting. Tested with PROTON_USE_PIPEWIRE=0 (falls back off winepipewire.drv) - no change.
• In-game "Streamer Mode" toggle - tried both on and off, no change.

Log analysis (WINEDEBUG=+mfplat,+quartz,+wmvcore,+strmbase,+xaudio2,+dsound PROTON_LOG=1)

• The GStreamer aacparse element logs Need codec_data for raw AAC on its first negotiation attempt for the TV's AAC stream, but subsequently renegotiates successfully with the correct codec_data and produces valid output caps.
• A wg_transform (Wine's MFT wrapper) is created for this exact stream with:

  input caps audio/mpeg, channels=2, codec_data=(buffer)1190, stream-format=raw, mpegversion=4
  output caps audio/x-raw, format=S16LE, channels=2, rate=48000
  

  i.e. decoding to valid PCM completes successfully.
• Despite this, no activity is logged on the xaudio2, dsound, or mmdevapi channels for this stream at any point (only DLL load/unload boilerplate and one unrelated mmdevapi:SAC_GetMaxDynamicObjectCount fixme). This holds regardless of which audio backend (pipewire/pulse) is active.

Conclusion so far: decoding is not the bottleneck - the decoded PCM samples from the Media Foundation source reader for this specific media playback path never reach any Windows audio API call that Wine would need to service. Whatever mechanism the game uses to route this particular MediaPlayer/MediaSoundComponent audio into its own mixer does not appear to fire under Proton, on any tested build. I cannot go further without either game-engine source access or a Wine-side debugger, which is why I'm filing this upstream.

Related existing reports

• #6554 (this repo) - describes the inverse symptom on Proton 7.0-6 (video missing, audio present) for the same category of in-world screens in this game, suggesting this asset-playback path has been fragile across multiple Proton versions since launch.
• Steam Community reports from launch week describing the same "white screen, audio-only" inverse symptom on various Proton versions.

Attachments

• relevant2.log - filtered log excerpt (grep on aacparse|codec_data|xaudio|dsound|wmardev|IMFSample|audio.*sink|audio.*device) from a repro session with the above WINEDEBUG channels enabled.

relevant2.log