H.264 Codec, Wow

[samsc]

This codec is amazing!

Apple will soon be releasing a groundbreaking/all definition codec for quicktime called H.264.
Christian Choi

Christian does it use interframe compression?


if it uses interframe compression it wont work so well with what we do.

[samsc]

1. Dividing each video frame into blocks of pixels so that processing of the video frame can be
conducted at the block level.
2. Exploiting the spatial redundancies that exist within the video frame by coding some of the original
blocks through transform, quantization and entropy coding (or variable-length coding).
3. Exploiting the temporal dependencies that exist between blocks in successive frames, so that only
changes between successive frames need to be encoded. This is accomplished by using motion
estimation and compensation. For any given block, a search is performed in the previously coded one
or more frames to determine the motion vectors that are then used by the encoder and the decoder to
predict the subject block.
4. Exploiting any remaining spatial redundancies that exist within the video frame by coding the
residual blocks, i.e., the difference between the original blocks and the corresponding predicted
blocks, again through transform, quantization and entropy coding.

This is the compression paradigm for h264 from the above attachment.

Note step 3.
This step - 'Exploiting the temporal dependencies that exist between blocks in successive frames, so that only
changes between successive frames need to be encoded"

this assumes that the video goes linearily and uniformly in one direction - forwards.

Not at all good for random frame access - or seemless looping between any two points in a movie.

[litemover]

Crap, I knew it was too good to be true.

The preservation of color was beautiful. Do you think that it might still be a good codec to use if all videos were being played back linearly but looped?

Christian Choi

[samsc]

Crap, I knew it was too good to be true.

The preservation of color was beautiful. Do you think that it might still be a good codec to use if all videos were being played back linearly but looped?

Christian Choi

codecs that use interframe compression will work - if used in certain ways.

i mean mpeg2 works - but just not as well. and you will not get predictable playback performance.
And they wont play backwards very well. that kind of thing

[samsc]

this thing seems to be designed to do video conferencing

[litemover]

this thing seems to be designed to do video conferencing

Can do, they were displaying it as a phone movie codec, a streaming codec, and a professional HD codec. They had one g5 running the Troy trailer full screen on a 23" cinema display 1080p and on another they had 720p, 480 and video phone resolution simultaneously decoding on the G5's internal hardrive, again very good quality.

Will be interesting to see how it does when it comes out.

Christian

[samsc]

Can do, they were displaying it as a phone movie codec, a streaming codec, and a professional HD codec. They had one g5 running the Troy trailer full screen on a 23" cinema display 1080p and on another they had 720p, 480 and video phone resolution simultaneously decoding on the G5's internal hardrive, again very good quality.

Will be interesting to see how it does when it comes out.

Christian

all going in the forwards direction.....all interframe compression codecs have to assume the uniform flow of time or movie data in the forwards direction.