Depends on resolution and JPG codec. A 1080p PNG frame is typically 2 to 5 MB; a 1080p JPG at quality-85 is 200 to 500 KB; a 4K PNG is 6 to 15 MB. At the extreme, every-frame PNG extraction of a 10-minute 1080p MKV produces ~50 GB total.
Frame extraction is fast — typically 20 to 30% of source duration on the standard pipeline. A 5-minute MKV → JPG bundle finishes in about a minute regardless of frame count, because the bottleneck is the JPG encoder, not the MKV demuxer.
Yes, subject to whatever licence governs the source MKV content. The format change adds no claim — we add no watermark and assert no licence over the JPG output. Copyright tracks the source, not the converter.
