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I have 60Gb of DV footage that I need to store, but 60Gb is WAY too big. I need to transcode it to a lossy format, but I need the resulting video to be robust such that it can be easily edited with a NLV editor later on.

By robust I mean: able to chop it up easily without losing sync. I suppose this has something to do with the regularity of keyframes.

I am on Ubuntu, so tools at my disposal are ffmpeg/avconv, Handbrake, and various other NLVEs.

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For DV footage, anything below 4.7 minutes per gigabyte is going to start being sub-standard for editing. That's the standard data rate for lossy compressed DV footage. Each generation of compression and the lower quality you make the compression, the less suitable for video editing it becomes.

If you use a highly lossy format to store the video, after you edit it and try to encode your final video, you will have a sloppy mess because the source video is too low quality. It will make you have to increase the settings on your final output to preserve any kind of quality and will mean you have a larger final product than you could have otherwise gotten away with.

By modern standards, 60GB is about $4 of HDD storage or $5 of optical. Just buy the extra storage if you need it.

If you still want to compress it more (or if you aren't yet at 4.7 minutes per gigabyte) then any standard DV format would work well. It isn't quite as ideal for editing, but a high quality (high data rate) h.264 high profile VBR 2-pass could be used as well. Using 3500 KBPS (I'd probably also try all I frame and see how it goes) should give you a good high quality compression. It is worth noting that h.264 is more demanding for editing with though. That's still not going to give you any lower than the 4.7 minutes per gigabyte though, so if you have around 5 hours of footage, 60GB really is as small as you want to go.

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I appreciate the angle you're coming from, but I am not interested (for this particular footage) in quality, but I do need av sync to be maintained after I chop it up a bit later on.e.g. there are intermediate formats, e.g. ProRes, which offer editability with compression because each frame is preserved, however these do not offer enough compression for this job. –  artfulrobot Jan 22 at 14:24
    
h.264 with all I frame should preserve each frame. Adjust quality level to your liking. Motion JPEG formats can also work fairly well if you want frame by frame compression rather than cross-frame compression. Note that formats that store all frames are inherently much weaker compressions though and will result in further quality loss at a given size since they can't make use of frame to frame similarities. –  AJ Henderson Jan 22 at 14:27
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I'm using ffmpeg -i input.dv -strict experimental -c:v libx264 -vf yadif -keyint_min 1 -x264opts 'keyint=1' -refs 0 -qp 25 output.mp4 –  artfulrobot Jan 22 at 15:52
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Making h264 all I-frame is kinda knobbling it, because it gets its efficiency from all the intra-frame compression. I doubt it would perform that much better than motion JPEG. What's your hourly rate? Storage is so cheap these days you'd have to look at whether it is worth your time scratching around to squeeze a few more MB out of your footage, when you can go and buy a couple of terrabytes for less than a hundred bucks. –  stib Jan 23 at 5:11
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@stib - yeah, agreed on the assessment about all i-frame, I didn't know if ffmpeg handles mjpeg or not though. Also, thanks for concurring that it's really not worth saving the space since 60gb is really a throw away. –  AJ Henderson Jan 23 at 15:08
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