Feature Request: Compact L1 Export (CSV/Raw) to reduce IO/Storage overhead

[cryptochrome]

Context

I am the maintainer of dovi_convert, a tool that automates Profile 7 to 8.1 conversion. I use dovi_tool to analyze the RPU of full-length MKV files (typically 170k+ frames) to detect luminance expansion in the FEL.

The Problem

Currently, to analyze RPU metadata, we must use dovi_tool export ... -d all=dump.json.
While comprehensive, the JSON output is extremely verbose for L1 analysis.

• Expansion Factor: ~16x (Binary RPU -> JSON)
• Real World Impact: A 35MB RPU binary for a standard movie results in a ~560MB - 1GB JSON file.
• Performance Cost:
  1. Disk I/O: Writing 1GB of text to /tmp is a significant bottleneck on slower storage/networks.
  2. Memory: Downstream tools (like Python) require massive RAM (3GB+) to parse such large JSON files using standard libraries.

Feature Request
Could you please consider adding a lightweight export mode that outputs only the frame-level L1 metadata in a compact format (CSV or similar)?

Proposed Interface:
dovi_tool export -i input.rpu --mode l1-csv > output.csv

Desired Output (Example):
A headerless or simple CSV structure containing just the essential L1 metrics per frame:

frame_index,max_pq,avg_pq,min_pq
0,3050,400,0
1,3055,402,0
...

Impact

• Size Reduction: 560MB -> ~5MB (99% reduction).
• Speed: Removes the disk I/O bottleneck and memory usage entirely.
• Integration: Trivial to parse line-by-line in scripts without memory overhead.

Thank you for the amazing tool!

[quietvoid]

It's definitely possible to add.