h264 with ALL key frames

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h264 with ALL key frames
by David Johnson on May 10, 2010 at 6:41:03 pm

I was looking into the H264 key frame options and finally noticed the option to encode everything as a key frame. This seems contrary to how h264 works.

What uses might that be for?
Is that an intermediate format used for editing?
What is the base compression in a h264 key frame? Is it jpeg or something more advanced?
Is this better than photoJPEG?

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Re: h264 with ALL key frames
by Daniel Low on May 10, 2010 at 9:23:41 pm

Actually these are called I-Frames.

I-Frame only encoding is popular with broadcasters using the MPEG-2 format (Usually at 50Mb/s) but've not heard of anyone using it with MPEG-4 AVC.

I-Frame only allows each and every frame a full amount of data whether it needs it or not, there are no predictive frames. The base compression is similar to PhotoJPEG but more advanced. JPEG2000 is the equivalent and is used in many Digital Cinema applications.

I-Frame only is the least efficient method of video compression other than using uncompressed of course.

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Re: h264 with ALL key frames
by David Johnson on May 11, 2010 at 2:45:27 pm

Thanks. That was a key piece of information.
Panasonic does this in the high end and Apple with the "iFrames" thought it was a good idea as a capture format for low end (960x540).
Jpeg 2k may have the quality, but it is slow for encode and decode - and takes a lot more space than anything else.

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