Lossy video compression standard — MPEG-2 for DVD/broadcast, MPEG-4 (H.264) for archival and streaming. Quality degrades per generation cycle; never use as master format.
You're working with material that has been compressed – and you quickly realize you no longer have all the information you need. This is MPEG: a compression standard that reduces video data through mathematical algorithms. It's not for nothing that it's called lossy – what's gone is gone. MPEG-2 was the industrial standard for DVDs and broadcast transmissions for a long time; MPEG-4, especially in its H.264 variant, has become prevalent for digital archives and streaming pipelines. Each generation of the standard promises better compression at the same quality, but in practice, it means you start with less.
On set or in post-production, you need to know where MPEG is useful and where it traps you. For the rough cut – review, initial edits, client approvals – MPEG is practical. The file size is manageable, playback is smooth even on older systems. But as soon as you move into color correction or VFX integration, you'll need to change your approach. MPEG compression creates artifacts in dark areas and on edges; these inaccuracies are multiplied during grading or rotoscoping. That's why, for master formats, you exclusively work with intermediate codecs like ProRes, DNxHR, or DCP – uncompressed or lossless.
A practical workflow: You receive MPEG-4 material from a client or from an older archive. Initial review, first editing decisions – okay, you can work with it. But for the final deliverable or for intensive post-processing, you immediately transcode it into a professional format. This costs time and storage, yes, but it's necessary. Some editing assistants make the mistake of cutting directly in MPEG; later, you realize that color corrections don't sit cleanly or that motion blur effects flicker.
Keep in mind: MPEG compression works via keyframes and difference data – only every tenth frame is fully encoded, the rest are predictions. With fast camera movements or high-frequency patterns, the system breaks down. That's why, with fast cuts or action sequences in MPEG material, you quickly see macroblocks – rectangular artifacts that the eye cannot forgive. This is known and accepted in the broadcast context; not so in cinema or for premium streaming.