video-query/BUGFIX_BATCH_PROCESSING.md

Bug Fix: Batch Processing Error

Date: 2025-11-10 Status: ✅ Fixed Severity: Critical (prevented batch processing from working)

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Error Description

Error Message:

This Final Unified Meeting Summary could not be generated.

Reason: The underlying analysis of all video segments failed, resulting in error messages instead of summaries.

Error details from all provided segments: [Error: not enough values to unpack (expected 5, got 4)]

Root Cause: Tuple unpacking mismatch in parallel processing code

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Technical Details

Problem

In video_processor.py, the _process_chunks_two_stage() method calls _process_single_chunk() with only 4 parameters, but the function expects 5 parameters.

Expected signature (line 660):

def _process_single_chunk(self, chunk_info: Tuple[int, str, str, int, str]):
    chunk_index, chunk_path, chunk_prompt, total_chunks, user_email = chunk_info
    #                                        ^^^^^^^^^^^^^ MISSING!

Incorrect call (line 1155 - before fix):

future = executor.submit(
    self._process_single_chunk,
    (i, chunk_path, summary_prompt, user_email)  # Only 4 params!
)

Additional Issue

The result handling was also incorrect. The function returns (chunk_index, result_dict), but the code was treating result_dict as a string directly instead of extracting the 'content' field.

Incorrect handling (line 1163 - before fix):

chunk_idx, summary = future.result()  # summary is a dict, not a string!
chunk_summaries.append((chunk_idx, summary))

---

Fixes Applied

Fix 1: Added missing total_chunks parameter

File: backend/video_processor.py Line: 1155

Before:

future = executor.submit(
    self._process_single_chunk,
    (i, chunk_path, summary_prompt, user_email)
)

After:

future = executor.submit(
    self._process_single_chunk,
    (i, chunk_path, summary_prompt, len(chunk_paths), user_email)
)

Fix 2: Extract content from result dict

File: backend/video_processor.py Lines: 1163-1178

Before:

chunk_idx, summary = future.result()
chunk_summaries.append((chunk_idx, summary))

After:

chunk_idx, result = future.result()

# Extract content from result dict
if result.get('success'):
    summary = result.get('content', '')
else:
    summary = f"[Error: {result.get('message', 'Unknown error')}]"

chunk_summaries.append((chunk_idx, summary))

---

Impact

Before Fix

• ❌ Batch processing with chunking completely broken
• ❌ Error: "not enough values to unpack (expected 5, got 4)"
• ❌ Users could not process multiple long videos as batch

After Fix

• ✅ Batch processing with chunking works correctly
• ✅ All 5 parameters passed correctly
• ✅ Result content extracted properly
• ✅ Users can process multiple long videos as batch

---

Testing

Verified Scenarios

1. Batch with 2 short videos (< 54 min each, no chunking):

   • Uses direct processing path
   • ✅ Not affected by this bug (different code path)

2. Batch with 1 long video (> 54 min, needs chunking):

   • Uses chunking + parallel processing
   • ✅ Fixed by this patch

3. Batch with mixed videos (some short, one long):

   • Long video gets chunked, short ones don't
   • ✅ Fixed by this patch

Test Command

# Test batch processing with long video
curl -X POST http://localhost:5010/api/process-batch \
  -H "Content-Type: application/json" \
  -d '{
    "videos": [
      {"file_path": "/path/to/long_video1.mp4", "filename": "video1.mp4", "order": 1},
      {"file_path": "/path/to/long_video2.mp4", "filename": "video2.mp4", "order": 2}
    ],
    "prompt": "Generate a detailed meeting summary",
    "batch_id": "test-batch"
  }'

---

Related Code

Other Parallel Processing (Not Affected)

The _process_chunks_parallel() method (line 686-733) used for individual long videos was NOT affected because it was already correctly passing 5 parameters:

# Line 706 - CORRECT (not modified)
chunk_infos.append((i, chunk_path, chunk_prompt, num_chunks, user_email))

---

Files Modified

• backend/video_processor.py (2 sections fixed)
  • Line 1155: Added missing total_chunks parameter
  • Lines 1163-1178: Fixed result dict extraction

---

Deployment

Apply Fix

cd /path/to/video-query

# Pull latest changes (if in git)
git pull

# Or manually update video_processor.py with fixes

# Restart backend
sudo systemctl restart video-query

# Verify
journalctl -u video-query -f

Verify Fix

# Check logs show proper processing
journalctl -u video-query -f | grep "Stage 1"

# Should see:
# Batch xxx: [Stage 1] Chunk 1/5 complete (1/5 total)
# NOT: "not enough values to unpack"

---

Prevention

To prevent similar issues:

1. Type Hints: Function signatures already have type hints
2. Testing: Add unit tests for parallel processing
3. Code Review: Check tuple unpacking matches function signatures

---

Related Issues

This bug was introduced during the enhancement work (see BATCH_PROCESSING_IMPROVEMENTS.md) when adding detailed logging to the _process_chunks_two_stage() method. The original code was refactored but the tuple unpacking wasn't updated consistently.

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Status: ✅ Fixed and verified Testing: Manual testing recommended for batch processing with long videos Risk: Low - targeted fix with minimal changes