[MPlayer-dev-eng] Lots of stuff for NUT
Oded Shimon
ods15 at ods15.dyndns.org
Mon Jan 9 11:24:29 CET 2006
On Sat, Jan 07, 2006 at 09:38:54PM -0500, Rich Felker wrote:
> On Sat, Jan 07, 2006 at 09:07:05PM +0100, Michael Niedermayer wrote:
> > Hi
> >
> > On Sat, Jan 07, 2006 at 01:41:52PM -0500, Rich Felker wrote:
> > > On Sat, Jan 07, 2006 at 12:24:48PM +0100, Michael Niedermayer wrote:
> > > > > You never really answered the question, does the overhead really bother you
> > > > > that much Michael? I want to make NUT done already. Rich wants keyframe
> > > > > exact seeking (and I agree), we all want demuxer and muxer simplicity, and
> > > > > the only solution for this is per stream pts and ptr in every syncpoint.
> > > >
> > > > i dont think pts per stream are needed for this, what exactly was the problem
> > > > anyway if we just have a rule like
> > > > output a syncpoint immedeatly if a back_ptr changes by more then t
> > > > doesnt that ensure that we never have to search more then t?
> > >
> > > The problem is: how do you find the correct syncpoint to start your
> > > search at? How do you properly assign timestamps to make it work?
> >
> > hmmmmmmm, what about the following
> >
> > * store syncpoints with timestamp and a single back pointer and a pointer
> > to the last index chunk
> > * regularely store index chunks using my proposed index format (syncpoint
> > timestamp+pos and keyframe flags for all streams and syncpoints since the last
> > index chunk)
>
> The proposal still has per-stream pts, even for the index. Without it
> you won't be able to find the correct position with just a single
> media seek.
Index still needs improoving. I want this committed...
- ods15
-------------- next part --------------
--- mpcf.3.txt 2006-01-04 17:24:32.000000000 +0200
+++ mpcf.4.txt 2006-01-05 19:41:53.000000000 +0200
@@ -138,20 +138,26 @@
for(i=0; i<256; ){
tmp_flag v
tmp_fields v
- if(tmp_fields>0) tmp_pts s
- if(tmp_fields>1) tmp_mul v
- if(tmp_fields>2) tmp_stream v
- if(tmp_fields>3) tmp_size v
+ if(tmp_fields>0) tmp_mul v
+ else tmp_mul=1
+ if(tmp_fields>1) tmp_sflag v
+ else tmp_sflag=0
+ if(tmp_fields>2) tmp_pts s
+ else tmp_pts=0
+ if(tmp_fields>3) tmp_stream v
+ else tmp_stream=0
+ if(tmp_fields>4) tmp_size v
else tmp_size=0
- if(tmp_fields>4) tmp_res v
+ if(tmp_fields>5) tmp_res v
else tmp_res=0
- if(tmp_fields>5) count v
+ if(tmp_fields>6) count v
else count= tmp_mul - tmp_size
- for(j=6; j<tmp_fields; j++){
+ for(j=7; j<tmp_fields; j++){
tmp_reserved[i] v
}
for(j=0; j<count && i<256; j++, i++){
flags[i]= tmp_flag;
+ stream_flags[i]= tmp_sflag;
stream_id_plus1[i]= tmp_stream;
data_size_mul[i]= tmp_mul;
data_size_lsb[i]= tmp_size + j;
@@ -212,6 +218,9 @@
if(flags[frame_code]&1){
data_size_msb v
}
+ if(flags[frame_code]&2){
+ coded_stream_flags v
+ }
for(i=0; i<reserved_count[frame_code]; i++)
reserved v
data
@@ -306,6 +315,11 @@
one keyframe for each stream lies between the syncpoint to which
real_back_ptr points, and the current syncpoint.
+ A stream where EOR is set is to be ignored for back_ptr.
+
+ Note: back_ptr can be zero if there is only a single relavent stream
+ and has a keyframe immediately following the syncpoint.
+
global_key_pts
After a syncpoint, last_pts of each stream is to be set to:
last_pts[i] = convert_ts(global_key_pts, timebase[stream], timebase[i])
@@ -421,17 +435,27 @@
different from the first byte of any startcode
flags[frame_code]
- first of the flags from MSB to LSB are called KD
- if D is 1 then data_size_msb is coded, otherwise data_size_msb is 0
- K is the keyframe_type
- 0 -> no keyframe,
- 1 -> keyframe,
- flags=4 can be used to mark illegal frame_code bytes
- frame_code=78 must have flags=4
- Note: frames MUST NOT depend(1) upon frames prior to the last
- frame_startcode
- Important: depend(1) means dependency on the container level (NUT) not
- dependency on the codec level
+ Bit Name Description
+ 1 data_size_msb if set, data_size_msb is at frame header,
+ otherwise data_size_msb is 0
+ 2 more_flags if set, stream control flags are at frame header.
+ 4 invalid if set, frame_code is invalid.
+
+ frame_code=78 ('N') MUST have flags=64
+
+stream_flags
+ stream_flags is "stream_flags[frame_code] ^ coded_stream_flags"
+
+ Bit Name Description
+ 1 is_key if set, frame is keyframe
+ 2 end_of_relevance if set, stream has no relevance on
+ presentation. (EOR)
+
+ EOR frames MUST be zero-length and must be set keyframe.
+ All streams SHOULD end with EOR, where the pts of the EOR indicates the
+ end presentation time of the final frame.
+ An EOR set stream is unset by the first content frames.
+ When an EOR is unset, dts_cache of the stream is reset to -1.
stream_id_plus1[frame_code]
must be <250
@@ -480,7 +504,8 @@
this buffer is initalized with decode_delay -1 elements
Pts of all frames in all streams MUST be bigger or equal to dts of all
- previous frames in all streams, compared in common timebase.
+ previous frames in all streams, compared in common timebase. (EOR
+ frames are NOT exempt from this rule)
width/height
MUST be set to the coded width/height
-------------- next part --------------
--- mpcf.4.txt 2006-01-05 19:41:53.000000000 +0200
+++ mpcf.final.txt 2006-01-09 12:08:21.000000000 +0200
@@ -21,13 +21,13 @@
Compact
~0.2% overhead, for normal bitrates
- index is <10kb per hour (1 keyframe every 3sec)
+ index is <100kb per hour (1 keyframe every 3sec)
a usual header for a file is about 100 bytes (audio + video headers together)
a packet header is about ~1-5 bytes
Error resistant
seeking / playback without an index
- headers & index can be repeated
+ headers can be repeated
damaged files can be played back with minimal data loss and fast
resync times
@@ -134,7 +134,6 @@
version v
stream_count v
max_distance v
- max_index_distance v
for(i=0; i<256; ){
tmp_flag v
tmp_fields v
@@ -228,12 +227,36 @@
index:
index_startcode f(64)
packet header
- stream_id v
max_pts v
- index_length v
- for(i=0; i<index_length; i++){
- index_pts v
- index_position v
+ syncpoints v
+ for(i=0; i<syncpoints; i++){
+ syncpoint_pos_div8 v
+ }
+ for(i=0; i<stream_count; i++) {
+ j = 0
+ while (j < syncpoints) {
+ repeat v
+ type = repeat & 1
+ repeat = repeat >> 1
+ b = repeat & 1
+ repeat = (repeat >> 1) + 1
+ if (type) {
+ key_pts v
+ key_pts += syncpoint[j-1].stream[i].key_pts
+ for(k=0; k<repeat; k++) {
+ syncpoint[j+k].stream[i].back_ptr = syncpoint[j-b].pos_div8
+ syncpoint[j+k].stream[i].key_pts = key_pts
+ }
+ } else {
+ for(k=0; k<repeat; k++) {
+ syncpoint[j+k].stream[i].back_ptr = syncpoint[j+k-b].pos_div8
+ key_pts v
+ key_pts += syncpoint[j+k-1].stream[i].key_pts
+ syncpoint[j+k].stream[i].key_pts = key_pts
+ }
+ }
+ j += repeat
+ }
}
reserved_bytes
checksum u(32)
@@ -268,7 +291,21 @@
coded_pts v
stream = coded_pts % stream_count
global_key_pts = coded_pts/stream_count
- back_ptr v
+ back_ptr_div8[0] v
+ back_ptr[stream] = back_ptr_div8[0]
+ key_pts[stream] = global_key_pts
+ n=1
+ for (i=0; i<stream_count; i++) {
+ if (i == stream) continue
+ coded_pts v
+ A= coded_pts % (n+1)
+ B= coded_pts / (n+1)
+ if(A == n)
+ back_ptr_div8[n++] v
+ back_ptr[i]= back_ptr_div8[A]
+ key_pts[i] = covert_ts(global_key_pts, timebase[stream], timebase[i])
+ key_pts[i] -= B
+ }
Complete definition:
@@ -294,9 +331,7 @@
}
}
if (next_code == index_startcode){
- while(!eof){
- index
- }
+ index
index_ptr u(64)
}
@@ -308,22 +343,31 @@
size of the packet data (exactly the distance from the first byte
after the forward_ptr to the first byte of the next packet)
-back_ptr
+back_ptr[stream]
real_back_ptr = back_ptr * 8 + 7
- real_back_ptr must point to a position such that a syncpoint
- startcode begins within the next 8 bytes, and such that at least
- one keyframe for each stream lies between the syncpoint to which
- real_back_ptr points, and the current syncpoint.
-
- A stream where EOR is set is to be ignored for back_ptr.
-
- Note: back_ptr can be zero if there is only a single relavent stream
- and has a keyframe immediately following the syncpoint.
+ real_back_ptr must point to a position within 8 bytes of a syncpoint
+ startcode. This syncpoint MUST be the closest syncpoint such that at
+ least one keyframe for this stream lies between it and the current
+ syncpoint, or immediately after the current syncpoint.
+
+ Note: back_ptr can be zero, when the frame immediately following is
+ a keyframe of this stream, or EOR has been set for this stream.
+ back_ptr of a stream where EOR is set MUST be zero.
global_key_pts
After a syncpoint, last_pts of each stream is to be set to:
last_pts[i] = convert_ts(global_key_pts, timebase[stream], timebase[i])
+ To be able to code key_pts for every stream, global_key_pts MUST be the
+ max key_pts across all streams.
+
+key_pts[stream]
+ The pts of the first keyframe in the back_ptr region, including the
+ frame immediately following the syncpoint.
+
+ Note: After an EOR, key_pts MUST be set to global_key_pts in correct
+ timebase. This is to be done by using coded_pts of 0.
+
file_id_string
"nut/multimedia container\0"
@@ -339,10 +383,6 @@
syncpoint_startcode
0xE4ADEECA4569ULL + (((uint64_t)('N'<<8) + 'K')<<48)
- syncpoint_startcodes SHOULD be placed immediately before a keyframe if the
- previous frame of the same stream was a non-keyframe, unless such
- non-keyframe - keyframe transitions are very frequent
-
index_startcode
0xDD672F23E64EULL + (((uint64_t)('N'<<8) + 'X')<<48)
@@ -358,17 +398,16 @@
be used by the demuxer to detect damaged frame headers if the damage
results in too long of a chain
+ Syncpoints MUST be placed immediately before a non-EOR keyframe if the
+ back_ptr of this stream in the last syncpoint is greater than
+ max_distance.
+
+ The begginning of a frame is defined by the first byte of the frame header.
+
SHOULD be set to <=32768 or at least <=65536 unless there is a very
good reason to set it higher, otherwise reasonable error recovery will
be impossible
-max_index_distance
- max distance of keyframes which are represented in the index, the
- distance between consecutive entries A and B may only be larger if
- there are no keyframes within this stream between A and B
- SHOULD be set to <=32768 or at least <=65536 unless there is a very
- good reason to set it higher
-
stream_id
Stream identifier
stream_id MUST be < stream_count
@@ -532,23 +571,22 @@
forward_ptr until last byte before the checksum).
max_pts
- The highest pts in the stream.
-
-index_pts
- value of the pts of a keyframe relative to the last keyframe
- stored in this index
-
-index_position
- position in bytes of the first byte of a keyframe, relative to the
- last keyframe stored in this index
- there MUST be no keyframe with the same stream_id as this index between
- two consecutive index entries if they are more than max_index_distance
- apart
+ s = max_pts % stream_count
+ pts = max_pts / stream_count
+ The highest pts in the entire file in the timebase of stream 's'.
+
+syncpoints
+ amount of syncpoints in the file.
+
+syncpoint_pos_div8
+ offset from begginning of file to up to 7 bytes before the syncpoint
+ referred to in this index entry. Relative to position of last
+ syncpoint.
index_ptr
- Length in bytes from the first byte of the first index startcode
- to the first byte of the index_ptr. If there is no index, index_ptr
- MUST NOT be written.
+ Length in bytes from the first byte of the index startcode to the first
+ byte of the index_ptr. If there is no index, index_ptr MUST NOT be
+ written.
id
the ID of the type/name pair, so it is more compact
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