codec/h264/h264dec/pps.go: comment PPS struct fields

[Saxon Milton]

The fields of the PPS struct should be commented as has been done for the NAL unit syntax structures e.g. here. These comments are slightly modified excerpts from the H.264 specifications (also attached - use this if you want handy bookmarks that help to navigate). Use section 7.4.2.2 from the specifications to find semantics for fields.

You will need to clone this repo:

git clone https://bitbucket.org/ausocean/av

create a new branch for this feature (probably name is comment-pps or similar):

git branch <name of branch>

then checkout your new branch:

git checkout <name of branch>

when you’ve made all the changes you’ve wanted to, and you wish to commit your changes to a remote version of your branch ready for a pull request, do this:

git add pps.go
git commit -m <briefly explain your changes>
git push --set-upstream origin <name of branch>

Then create a pull request here. Make sure you select your branch as the source and ausocean/av as the dest repo and master as the dest branch. DO NOT use scruzin/av as the destination.

[Saxon Milton]

Efforts towards the H.264 decoder have been put on hold