Recent benchmarks for this string emphasize the transition to HD and 4K technology , suggesting that the "conversion" refers to upscaling or re-encoding older fan-subbed content into modern high-definition formats.
If engsub is (common in JAV rips), conversion requires OCR: sone385engsub convert020002 min
: Use software that supports multi-stream mapping without re-encoding the entire video. Recent benchmarks for this string emphasize the transition