HDV: How much can I compress?

[Marcus Marchesseault]

Since you are doing color correction already while the file is un-compressed or losslessly compressed, it seems that you no longer need the original Photo-JPEG files as they have fulfilled their goal of converting to 24p. Now, most of what is left to do is cutting and audio so you shouldn't need any uncompressed files. It's not disastrous to do color correction and the like on compressed files anyway.

I am curious as to one thing. Are you getting 5GB/hour with your h.264 compression? That is highly compressed and may be challenging to edit. If you aren't having sluggish performance then you shouldn't worry if it is going to be the same as your highest quality distribution format. If you are simply going to add cuts, fades then tweak the audio, this same H.264 format can be your HD master. Assuming that your only conversion from there will be to a lower SD format, you should see no significant further degradation. I don't know how efficient the conversion from H.264 to MPEG2-DVD will be, but you are at least maintaining a greater-to-lesser conversion path.

I should add that HDV is about 13GB/hour but it is supposedly less efficient than H.264 compression. You may now be editing at lesser than HDV quality, but you have already done the step that really needs the quality (color correction). I don't know if you would get better results going to DVD if you converted to SD from a greater format, but it is something you might want to experiment with before trashing your big files.

[Brian Boyko]

Originally Posted by Marcus Marchesseault

I am curious as to one thing. Are you getting 5GB/hour with your h.264 compression? That is highly compressed and may be challenging to edit. If you aren't having sluggish performance then you shouldn't worry if it is going to be the same as your highest quality distribution format. If you are simply going to add cuts, fades then tweak the audio, this same H.264 format can be your HD master. Assuming that your only conversion from there will be to a lower SD format, you should see no significant further degradation. I don't know how efficient the conversion from H.264 to MPEG2-DVD will be, but you are at least maintaining a greater-to-lesser conversion path.

I should add that HDV is about 13GB/hour but it is supposedly less efficient than H.264 compression. You may now be editing at lesser than HDV quality, but you have already done the step that really needs the quality (color correction). I don't know if you would get better results going to DVD if you converted to SD from a greater format, but it is something you might want to experiment with before trashing your big files.

Indeed, I'm keeping the un-color corrected files around in 24p as they came off the tape as my "backup" (plus, I also have the tapes!) Editing from the H.264 stream means a quicker turnaround time and it allows me to store a copy of my raw footage on my online account as well as transfer it over the Internet to partners around the world.

I would expect around maybe 7GB/hr for an action packed video, but most of these videos are of interviews - hour-long interviews. Background doesn't change and the talking heads don't move too much. I'm not surprised at the 5GB/Hr video rate.