600D and Video Bitrates

Issue #1361 wontfix
Former user created an issue

I shot a test video with my 600d at CBR 1.5x. Video came out to ~36mbps. What surprised me however is that the clips lasted up to 17 minutes. What's going on here? I thought it had a 12 minute limit. Does low ISO really do better than dropping bit rate to negative numbers? Does that mean we could get the full 30 minutes at lowest iso + default bitrate?

Comments (4)

  1. Former user Account Deleted

    I've been looking out for the meter and I believe I enabled it but I still can't see it on the screen. Maybe I'm blind :(

    I need to make a chart for ISO vs CBR vs complex scenes and see what this thing can do. The guide doesn't really tell you what you can expect to get without the movie stopping. Sometimes I can do 1.4 with audio... at iso "3200" I don't think it even does 1.3. I guess needs moar testing.

  2. Alex

    Look in the Bitrate submenu.

    I don't think a chart can help, there are many factors that affect the bitrate. The QScale indicator is the only reliable measure: if it's -16, bitrate is already at maximum and won't increase further.

  3. Former user Account Deleted

    Qscale seems to me to be related scene complexity. When I move the camera or a car goes by, qscale goes up to -16. Also sometimes lower values shut off faster than higher values with CBR. 1.7x will die immediately and 1.9x keeps going. Around 75mbps seems where the camera starts to struggle with the buffer. Unfortunately you can't pick and lock in 75mbps.. it always goes higher or drops through the floor. 60's would be super stable... the high 80's and 90s is where I'm maxing out. Looks very pretty though.

    In dark scenes you can shoot at 3.0x and still get like 20mbps. Seems not many people have done testing on this or at its buried somewhere in the forums. You would think everyone would be all over this. A 70mbps cam is worth its weight in small cars... esp with interchangeable lenses and HDR video.

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