add other functions used to functions section

[dericed]

There's a few functions used but not referenced in https://github.com/FFmpeg/FFV1/blob/master/ffv1.md#bitstream-functions. It may be helpful for a reader to know what functions to expect as they do with the operators currently used.

The sentence The log2_run function is also used within [@ISO.14495-1.1999]. could be moved to the functions section.

Here are some functions used but with no definition or citation for it:

• ABS( )
• encode( )
• get_bits( )
• get_bits1( )
• log2( )
• MIN( )
• put_rac( )
• put_symbol( )
• QuantizationTablePerContext( )

[dericed]

Also Pixel () is used twice in https://github.com/FFmpeg/FFV1/blob/master/ffv1.md#line but not defined.

[michaelni]

Functions related to write/put/encode can be defined as "inverse" of the read/get functions

[michaelni]

for put_symbol/rac this could be used maybe:

diff --git a/ffv1.md b/ffv1.md
index 9b7a67d..abbe791 100644
--- a/ffv1.md
+++ b/ffv1.md
@@ -451,9 +451,9 @@ Note, this is different from JPEG-LS, which doesn’t use prediction in run mode
 |------|--------------------------------------------------------|
 | u(n) | unsigned big endian integer using n bits               |
 | sg   | Golomb Rice coded signed scalar symbol coded with the method described in [Huffman Coding Mode](#huffman-coding-mode) |
-| br   | Range coded Boolean (1-bit) symbol with the method described in [Range binary values](#range-binary-values)  |
-| ur   | Range coded unsigned scalar symbol coded with the method described in [Range non binary values](#range-non-binary-values) |
-| sr   | Range coded signed scalar symbol coded with the method described in [Range non binary values](#range-non-binary-values) |
+| br   | Range coded Boolean (1-bit) symbol with put_rac() described in [Range binary values](#range-binary-values)  |
+| ur   | Range coded unsigned scalar symbol coded with put_symbol() described in [Range non binary values](#range-non-binary-values) |
+| sr   | Range coded signed scalar symbol coded with put_symbol() described in [Range non binary values](#range-non-binary-values) |
 
 The same context which is initialized to 128 is used for all fields in the header.

[dericed]

@michaelni, the spec currently says

The log2_run function is also used within [@ISO.14495-1.1999].

But when I checked a copy of ISO 14496-12 at http://l.web.umkc.edu/lizhu/teaching/2016sp.video-communication/ref/mp4.pdf I can't find any reference to the log2_run function.

[dericed]

BTW I changed MIN and ABS to min and abs (personally preference for lowercase functions). If there's a reason to leave those functions in caps, I can change back. I was guided a bit by https://tools.ietf.org/html/rfc6716#section-1.1.

[retokromer]

+1 for functions in minuscules

[dericed]

My mistake: QuantizationTablePerContext is defined, within the same QuantizationTable section is which it is used.