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 DivX produces ~50 GB total.
Frame extraction is fast — typically 20 to 30% of source duration on the standard pipeline. A 5-minute DivX → JPG bundle finishes in about a minute regardless of frame count, because the bottleneck is the JPG encoder, not the DivX demuxer.
