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ProRes 422 vs H.264 bitrate
Obviously ProRess 422 is going to be a better editing codec, even with the Mercury Playback engine doing its thing but can someone explain why this is so. Looking at some Proress encoded 720p footage in QT I see that the clip bitrate is 78Mpbs. My 1080p footage from my 7D is 48Mbps.
On paper the 7D footage should tax the computer less?? Guess it’s because h.264 is an inter-frame codec? -
1 Reply
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[Richard Jacana] “On paper the 7D footage should tax the computer less?? Guess it’s because h.264 is an inter-frame codec?”
H.264 is a codec that’s efficient on space – i.e. maximum quality in the minimum bits possible. You’re right: it’s inter-frame, i.e. a group of frames is encoded together; to decode a single frame, the whole group must be decoded.
ProRes is an intra-frame codec that is much less efficient in terms of space, but is much less taxing on computer.
An inter-frame such as H.264 can easily be 10 times more efficient than an intra-frame one like MJPEG, ProRes or DV, e.g. a 100Mbit/s ProRes stream could be encoded into a 10Mbit’s H.264 w/o significant loss of quality.
HTH
Alex (DV411)
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