Fix audio timestamp loss in Video→SyncQueue→ImageConcat→VideoWriter pipeline

[Copilot]

When recording video through SyncQueue and ImageConcat, audio timestamps were lost during synchronization, resulting in no audio in final output files (MP4/AVI/MKV).

Root Cause

SyncQueue extracted only raw audio data, discarding timestamps:

# Before: timestamp lost
synced_data = valid_items[0]['data']
output_data[data_type][slot_idx] = synced_data

# After: timestamp preserved
synced_item = valid_items[0]
synced_data = synced_item['data']
synced_timestamp = synced_item['timestamp']

if data_type == 'audio' and isinstance(synced_data, dict):
    synced_data = synced_data.copy()
    synced_data['timestamp'] = synced_timestamp
elif data_type == 'audio':
    synced_data = {'data': synced_data, 'timestamp': synced_timestamp}

Changes

SyncQueue (node_sync_queue.py)

• Wraps audio data with timestamp when synchronizing
• Preserves complete dict structure (data + sample_rate + timestamp)

ImageConcat (node_image_concat.py)

• Checks for existing timestamps before queue lookup
• Handles both raw numpy arrays and dict-wrapped audio

VideoWriter (node_video_writer.py)

• Supports SyncQueue-wrapped audio format ({'data': array, 'timestamp': float})
• Sorts multi-slot audio chunks by timestamp for temporal ordering
• Adds debug output for audio collection and merge diagnostics

Tests

• test_video_audio_sync_pipeline.py: End-to-end validation of timestamp preservation through entire pipeline

Original prompt

je prends le node video, je recupére les flux images et chunk audio, avec leurs timestamp, ensuite, quand je les synchronise avec syncQueue, que je les envoies au node imageconcat puis videowriter pour la fusion du flux input image et des flux chunk audio , quand je stop pour avoir ma video en AVI, mpeg4 ou mkv, le process prends beaucoup de temps, freeze, et au final pas de son sur la video finale, pourquoi ? explique et corrige. Merci.

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