lhotseWorkspace/process_single_chunk.py

import sys
import os
import re
import gc
import lhotse

def main():
    if len(sys.argv) != 3:
        print("Usage: python process_single_chunk.py <base_output_dir> <manifest_path>")
        sys.exit(1)

    base_output_dir = sys.argv[1]
    tiny_manifest_path = sys.argv[2]

    # Extract the index from the filename (e.g., "manifest_0042.jsonl.gz" -> 42)
    match = re.search(r'manifest_(\d+)', os.path.basename(tiny_manifest_path))
    if match:
        chunk_idx = int(match.group(1))
    else:
        print(f"[Worker] Could not extract chunk index from {tiny_manifest_path}. Aborting.")
        sys.exit(1)

    # 1. Setup Backends
    from lhotse.audio.backend import (
        CompositeAudioBackend, LibsndfileBackend, TorchaudioFFMPEGBackend
    )
    from lhotse import set_caching_enabled
    set_caching_enabled(False)
    gc.set_threshold(100, 2, 2)
    
    composite = CompositeAudioBackend(backends=[
        LibsndfileBackend(), TorchaudioFFMPEGBackend()  
    ])
    lhotse.audio.set_current_audio_backend(composite)

    # 2. Setup output directory
    output_dir = os.path.join(base_output_dir, f"chunk_{chunk_idx:04d}")
    os.makedirs(output_dir, exist_ok=True)
    print(f"[Worker] Starting Chunk {chunk_idx} using {os.path.basename(tiny_manifest_path)}")

    try:
        # 3. Load the TINY manifest
        chunk_cutset = lhotse.CutSet.from_jsonl(tiny_manifest_path)

        # 4. Export the SHAR data
        chunk_cutset.to_shar(
            output_dir,
            fields={"recording": "opus"},
            shard_size=10000,
            num_jobs=1, 
            fault_tolerant=True
        )
        print(f"[Worker] Finished Chunk {chunk_idx}.")

        # 5. Delete the manifest to mark as complete
        os.remove(tiny_manifest_path)
        print(f"[Worker] Deleted manifest {os.path.basename(tiny_manifest_path)}")

    except Exception as e:
        print(f"[Worker] FAILED Chunk {chunk_idx}. Manifest kept for retry. Error: {e}")
        # Exit with an error code so Bash knows this specific job failed
        sys.exit(1)

if __name__ == '__main__':
    main()