about POC mode

[angelzhang]

hi,experts
there are three POC mode choice in the H.264 reference encoder, but i don't know what's the feature and difference between them.
so please give me some suggestions or hints. or give me some materials as well!

thanks a lot!

best regards
angel

[mediator]

Look at the following excerpt from:

"http://ftp3.itu.ch/av-arch/jvt-site/2002_12_Awaji/JVT-F044.doc":


There are currently three POC coding modes in the draft standard. The modes can be characterized as follows:

Mode 0 can be used for non-periodic picture output rates in error-free environments. Mode 0 predicts the value of the picture order count from the picture order count of the most recently decoded reference picture. Thus, mode 0 is not tolerant to losses of reference pictures.

Mode 1 can be used for periodic picture output rates in error-free and error-prone environments. Mode 1 predicts the value of the picture order count from the picture order count of the most recent IDR picture.

Mode 2 can be used if there are no B slices and no more than one consecutive non-reference frame in decoding order. In mode 2, no picture order count information is present.


Additionally a nice (but not too much detailed) explanation can be found at:

http://www.vcodex.com/h264.html (H.264 Picture Management)

[angelzhang]

hi mediator,

so thanks for your help, and i will go to study those materials...

[angelzhang]

hi,mediator
I set PicOrderCntType as 1, and i find the output SNR value of encoder is different from the output SNR value of decoder with corresponding 264 bitstream builded by encoder.
can you give me some interpretations about such thing. in my opinion, the output of decoder should be equal to the encoder.

[mediator]

It shouldn't matter if the encoder measures the SNR on it's output or another decoder. I guess there is something else wrong.

[angelzhang]

Yes, the cause is that i set FramSkip value as random value other than 0. when i set FrameSkip as 0, the SNR of decoder is same as that of encoder. so there are must be some things happen between these two parameters.

thanks for your guide.