mirror/AC6_recomp
1
0
Fork 0
mirror of https://github.com/sal063/AC6_recomp synced 2026-08-21 23:00:53 -04:00
Code Issues Packages Projects Releases Wiki Activity

Preserve the XMA stream timeline across undecodable frames

Browse Source 
A frame the decoder backend rejects advances the read offset but emitted nothing, silently shortening that stream by 512 samples, permanent desync for multi-stream sources (5.1 premixes as parallel stereo XMA). Emit the frame as silence instead so the timeline holds. Robustness: no in-game trigger known in AC6. audio_xma_preserve_timeline (default on).
This commit is contained in:
Dipshet
2026-07-31 04:23:20 +02:00
parent b6b94bac91
commit 8c922abd77
2 changed files with 35 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
thirdparty/rexglue-sdk/src/native/audio/audio_system.cpp
Vendored
+10
View File
@@ -19,6 +19,16 @@ REXCVAR_DEFINE_BOOL(audio_trace_render_driver_verbose, false, "Audio",
"Trace render-driver activity");
REXCVAR_DEFINE_BOOL(audio_deep_trace, false, "Audio",
"Enable verbose runtime audio tracing");
REXCVAR_DEFINE_BOOL(audio_xma_preserve_timeline, true, "Audio",
"When the XMA decoder backend rejects a damaged frame, emit that "
"frame's worth of silence instead of dropping it. The input read "
"offset advances past the frame either way, so dropping the output "
"silently shortens the stream's timeline by 512 samples per damaged "
"frame - which would permanently desynchronize multi-stream sources "
"(5.1 premixes carried as parallel stereo streams, e.g. AC6's "
"cutscene mixes). Robustness fix - no in-game trigger is known in "
"AC6 (instrumented runs decode every frame). On by default; off "
"restores the legacy drop behavior.");
namespace rex::audio {
thirdparty/rexglue-sdk/src/native/audio/xma/context.cpp
Vendored
+25 -3
View File
@@ -17,6 +17,7 @@
#include <native/stream.h>
REXCVAR_DECLARE(bool, audio_deep_trace);
REXCVAR_DECLARE(bool, audio_xma_preserve_timeline);
namespace rex::audio {
@@ -853,11 +854,32 @@ void XmaContext::Decode(XMA_CONTEXT_DATA* data) {
.sample_rate = static_cast<uint32_t>(GetSampleRate(data->sample_rate)),
.is_two_channel = bool(data->is_stereo),
};
if (decoder_backend_ &&
const bool frame_decoded =
decoder_backend_ &&
decoder_backend_->DecodePacket(
decode_request, std::span<uint8_t>(raw_frame_.data(), raw_frame_.size()))) {
decode_request, std::span<uint8_t>(raw_frame_.data(), raw_frame_.size()));
if (!frame_decoded && REXCVAR_GET(audio_xma_preserve_timeline)) {
// A frame the decoder rejects still occupies exactly kSamplesPerFrame
// samples of the stream's timeline, and the read offset advances past it
// below either way. Dropping the output entirely (the legacy behavior)
// silently shortens the stream by one frame - a latent correctness bug
// for multi-stream sources that must stay sample-locked, e.g. 5.1
// premixes carried as parallel stereo streams (AC6's cutscene mixes).
// Instrumented AC6 runs decode every cutscene frame successfully, so no
// in-game trigger is known - this is robustness against decode errors,
// not a fix for an audible symptom. Deliver the frame as silence
// instead - raw_frame_ is zero-filled above, so falling through emits
// one frame of silence in this stream (~10 ms, masked by the other
// streams) and the timeline holds.
REXAPU_DEBUG(
"XmaContext {}: undecodable frame (packet={} offset={} frame_bits={}) - "
"emitting silence to preserve the stream timeline",
id(), last_packet_index_, last_input_read_offset_before_,
packet_info.current_frame_size_);
}
if (frame_decoded || REXCVAR_GET(audio_xma_preserve_timeline)) {
current_frame_remaining_subframes_ = 4 << data->is_stereo;
last_decode_succeeded_ = true;
last_decode_succeeded_ = frame_decoded;
if (is_loop_end_frame) {
loop_frame_output_limit_ = (data->loop_subframe_end + 1) << data->is_stereo;