Does recoding a 7gb mkv file require a lot of hard disk space?

[dave in or]

I'm working with MediaCoder. I've been doing some test conversions with 20-30 seconds of video to find some good settings. I just recently noticed one of the statistics while recoding - "Raw Video" On a 20 sec clip this goes up to about 1 GB. So I'm wondering about when I start the full conversion (2 hrs), if a smaller hard drive will not have enough space to complete the conversion. My hard drive is 80GB. If that's not enough space, I do have 2 other 80GB drives and a 100GB - could I just hook all of them up to my motherboard if needed?

[Baldrick]

Recoding to what? Uncompressed or lossless video then yes. But if you just shrink it more then no.

[dave in or]

I'm altering some of the settings to create an MKV file that is playable on my blu ray player (streaming from the computer). It is h264 video. This file has a reference frame value of 8, but my player can only handle up to 5 ref frames. So I'm not recoding for the sake of making a smaller file. I wouldn't mind if the file increased in size. My concern at this point is if can be done with my limited amount of disk space.

Can it be done with 80 gb, if not can I use multiple drives? Or how much space would be required?

Also, I was under the impression an MKV recode couldn't be lossless. I know demux/remux would be, but to actually alter reference frame values?

My goal is to have the best video quality possible with a reference frame value of 5

[jagabo]

MKV is a container -- a "box" that holds video, audio, subs, etc. You can use whatever compression codecs you want within the container. The process of re-encoding a video involves first decompressing the frames, then compressing them with the new encoder. But only a handful of frames are decompressed at a time. So it doesn't take a lot of memory or disk space to hold the uncompressed intermediate.

I'm not real familiar with exactly how Mediacoder handles video. It may save separate intermediate compressed audio and video elementary streams first, multiplex them together into the requested container (MKV), then finally delete the intermediate elementary streams. So it will probably require about twice the size of the final output file.

Baldrick's reference to "lossless" was about converting the video to a lossless compression codec. That will be much larger than your h.264 source because the h.264 frames would first be decompressed to uncompressed YV12 or RGB (dozens of times bigger than the source) then compressed with a lossless codec which would only cut that size down by about half. So your 7GB source would probably grow to a few hundred GB. Obviously, in your case you want to re-encode with an h.264 encoder with a bitrate similar to your source.