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kvm
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[WIP] Fix: crackling sound when seeking forwars

This commit is contained in:
Alex P 2025-09-30 12:58:49 +00:00
parent fc38830af1
commit e989cad633
1 changed files with 29 additions and 0 deletions
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29
internal/audio/c/audio.c
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@ -587,6 +587,8 @@ int jetkvm_audio_capture_init() {
*/ */
__attribute__((hot)) int jetkvm_audio_read_encode(void * __restrict__ opus_buf) { __attribute__((hot)) int jetkvm_audio_read_encode(void * __restrict__ opus_buf) {
static short SIMD_ALIGN pcm_buffer[1920]; static short SIMD_ALIGN pcm_buffer[1920];
static short prev_max_sample = 0; // Track previous frame's peak for discontinuity detection
static int silence_count = 0; // Count consecutive silent frames
unsigned char * __restrict__ out = (unsigned char*)opus_buf; unsigned char * __restrict__ out = (unsigned char*)opus_buf;
SIMD_PREFETCH(out, 1, 3); SIMD_PREFETCH(out, 1, 3);
@ -671,12 +673,39 @@ retry_read:
short max_sample = simd_find_max_abs_s16(pcm_buffer, total_samples); short max_sample = simd_find_max_abs_s16(pcm_buffer, total_samples);
if (max_sample < 50) { if (max_sample < 50) {
silence_count++;
if (silence_count > 2) {
prev_max_sample = 0; // Reset after extended silence
}
if (trace_logging_enabled) { if (trace_logging_enabled) {
printf("[AUDIO_OUTPUT] jetkvm_audio_read_encode: Silence detected (max=%d), skipping frame\n", max_sample); printf("[AUDIO_OUTPUT] jetkvm_audio_read_encode: Silence detected (max=%d), skipping frame\n", max_sample);
} }
return 0; return 0;
} }
// Detect audio discontinuity (video seek): sudden level change after silence
// If audio level jumps >4x after 2+ silent frames, likely a seek occurred
if (silence_count >= 2 && prev_max_sample > 0) {
int level_ratio = (max_sample > prev_max_sample) ?
(max_sample / (prev_max_sample + 1)) :
(prev_max_sample / (max_sample + 1));
if (level_ratio > 4) {
if (trace_logging_enabled) {
printf("[AUDIO_OUTPUT] Discontinuity detected (level jump %dx: %d→%d), resetting encoder\n",
level_ratio, prev_max_sample, max_sample);
}
// Reset Opus encoder state to prevent mixing old/new audio context
opus_encoder_ctl(encoder, OPUS_RESET_STATE);
// Drop and reprepare ALSA to flush any buffered old audio
snd_pcm_drop(pcm_capture_handle);
snd_pcm_prepare(pcm_capture_handle);
}
}
silence_count = 0;
prev_max_sample = max_sample;
// Apply moderate 2.5x gain to prevent quantization noise on transients // Apply moderate 2.5x gain to prevent quantization noise on transients
// Balances between being audible at low volumes and not overdriving at high volumes // Balances between being audible at low volumes and not overdriving at high volumes
simd_scale_volume_s16(pcm_buffer, frame_size * channels, 2.5f); simd_scale_volume_s16(pcm_buffer, frame_size * channels, 2.5f);