[NUT-devel] Welcome...

[Oded Shimon]

On Sun, Feb 12, 2006 at 07:04:31PM +0100, Michael Niedermayer wrote:
> On Sun, Feb 12, 2006 at 07:37:55PM +0200, Oded Shimon wrote:
> > Anyway, the only thing I'm kind of worried about is how to put this in 
> > spec. Just have 2 fixed codes in the stream header, for keyframes and for 
> > non keyframes?... Also, do ALL frames get it, or can it be flagged off?
> 
> dunno, but we might even add it into the framecode table so each framecode
> could have a different "prefix"
> * no flag needed
> * fully optional on the muxer side
> * still as easy for the demuxer as if its in the stream header
> * theoretically lower overhead / more flexible

Yeah, I was thinking same thing, only reason I wanted to avoid it is that 
it's just slightly unfriendly to C - dynamic array for any possible 
prefixes in stream header.. But that's just a slight implementation issue.

Ok, here's my proposed patch...

Note that data_size does NOT include the length of prefix, because it would 
make all stream headers essential to demux nut file.

- ods15
-------------- next part --------------
Index: DOCS/tech/mpcf.txt
===================================================================
RCS file: /cvsroot/mplayer/main/DOCS/tech/mpcf.txt,v
retrieving revision 1.104
diff -u -r1.104 mpcf.txt
--- DOCS/tech/mpcf.txt	12 Feb 2006 17:40:02 -0000	1.104
+++ DOCS/tech/mpcf.txt	12 Feb 2006 18:25:31 -0000
@@ -130,6 +130,7 @@
     version                             v
     stream_count                        v
     max_distance                        v
+    tmp_prefix=1
     tmp_pts=0
     tmp_mul=1
     tmp_stream=0
@@ -138,16 +139,17 @@
         tmp_fields                      v
         if(tmp_fields>0) tmp_sflag      v
         else tmp_sflag=0
-        if(tmp_fields>1) tmp_pts        s
-        if(tmp_fields>2) tmp_mul        v
-        if(tmp_fields>3) tmp_stream     v
-        if(tmp_fields>4) tmp_size       v
+        if(tmp_fields>1) tmp_prefix     v
+        if(tmp_fields>2) tmp_pts        s
+        if(tmp_fields>3) tmp_mul        v
+        if(tmp_fields>4) tmp_stream     v
+        if(tmp_fields>5) tmp_size       v
         else tmp_size=0
-        if(tmp_fields>5) tmp_res        v
+        if(tmp_fields>6) tmp_res        v
         else tmp_res=0
-        if(tmp_fields>6) count          v
+        if(tmp_fields>7) count          v
         else count= tmp_mul - tmp_size
-        for(j=7; j<tmp_fields; j++){
+        for(j=8; j<tmp_fields; j++){
             tmp_reserved[i]             v
         }
         for(j=0; j<count && i<256; j++, i++){
@@ -158,6 +160,7 @@
             }
             flags[i]= tmp_flag;
             stream_flags[i]= tmp_sflag;
+            frame_prefix_plus1[i]= tmp_prefix;
             stream_id_plus1[i]= tmp_stream;
             data_size_mul[i]= tmp_mul;
             data_size_lsb[i]= tmp_size + j;
@@ -182,6 +185,10 @@
     fixed_fps                           u(1)
     reserved                            u(7)
     codec_specific_data                 vb
+    nprefixes                           v
+    prefix_data[0] = zero-length-data
+    for(i=0; i<nprefixes; i++)
+        prefix_data[i+1]                vb
 
 video_stream_header:
     stream_header
@@ -222,6 +229,9 @@
     if(flags[frame_code]&2){
         coded_stream_flags              v
     }
+    if(frame_prefix_plus1[i]==0){
+        frame_prefix                    v
+    }
     for(i=0; i<reserved_count[frame_code]; i++)
         reserved                        v
     if (after_syncpoint){
@@ -492,6 +502,11 @@
     must be <250
     if it is 0, then the stream_id is coded in the frame
 
+frame_prefix
+    Index to prefix_data array set up in stream header.
+    Specifies data to prefix to frame data, e.g. a codec startcode.
+    If frame_prefix is zero, no data is prefixed to frame.
+
 data_size_mul[frame_code]
     must be <16384
 
@@ -503,6 +518,7 @@
 
 data_size
     data_size= data_size_lsb + data_size_msb*data_size_mul;
+    data_size does not include length of frame_prefix.
 
 coded_pts
     if coded_pts < (1<<msb_pts_shift) then it is an lsb