[Matroska-devel] Invitation to discuss about USF in MKV

Christian HJ Wiesner chris at matroska.org
Fri May 20 14:53:43 CEST 2005


we decided to try to hold a brainstorming meeting to define how to store 
USF in MKV in the best possible way, the IRC meeting is taking place 
tomorrow on irc.corecodec.com #matroska-dev at saturday 21st May, 5 PM .

Requested Participants :


but everybody else is gladly invited to join and contribute. If any of 
the people listed above cant join then, please come up with an 
alternative date/time. To get an idea about what we will have to 
discuss, read here :


	ChrisHJW_ 	lo MosuAtWork

	ChrisHJW_ 	long time no see


	ChrisHJW_ 	unmei , MosuAtWork : 
<----- kaiousama knows how to make girls happy :D

	ChrisHJW_ 	Italians :)


	ChrisHJW_ 	lol

	ChrisHJW_ 	MosuAtWork : tell me when you are ready and have the time 
for a brainstorming with kaiousama and unmei about how to mux USF into 
MKV in best way, i will gladly try to organize an IRC meeting then

	ChrisHJW_ 	alexnoe said its not as easy as muxing SSA if we want to do 
it right

	ChrisHJW_ 	as USF will allow colour palette changes in a single stream

	ChrisHJW_ 	i understand that if we take the SSA route, we needed a 
codec state element, as colour palette is defined in the track header ??

	MosuAtWork <irc://,isnick> 	this weekend should be 
fine, but not sunday evening, i'll be watching the sith ;)

	alexnoe <irc://,isnick> 	:)

	ChrisHJW_ 	MosuAtWork : great :)

	robUx4 <irc://,isnick> 	is going to watch it tonight

	ChrisHJW_ 	I'll send an email to -general , cc. to kaiousama and unmei, 
to meet saturday afternnon ?

	ChrisHJW_ 	robUx4 : you wonna join ?

	MosuAtWork <irc://,isnick> 	well CodecState has 
been added for such changes mid-stream. we just have to revive it

	robUx4 <irc://,isnick> 	nop

	MosuAtWork <irc://,isnick> 	and start using it

	robUx4 <irc://,isnick> 	I'm leaving to LA on tuesday so 
I'm quite busy here

	alexnoe <irc://,isnick> 	codec state is b0rked


	ChrisHJW_ 	MosuAtWork : i agree, a spec conformant way to do this would 
be to use codec state

	ChrisHJW_ 	robUx4 : k

	robUx4 <irc://,isnick> 	codec state is meant for the 
container to know about things needed for seeking

	robUx4 <irc://,isnick> 	but from what I understood it 
may not be needed for USF

	ChrisHJW_ 	robUx4 : right, for colour palette only the container 
wouldnt need to know and we could define this in the USF stream, but 
what about allowing resolution changes also ?

	robUx4 <irc://,isnick> 	matroska does not support 
resolution change

	MosuAtWork <irc://,isnick> 	it's not resolution change

	MosuAtWork <irc://,isnick> 	it's out-of-band 
configuration change

	ChrisHJW_ 	robUx4 : in any case, if we leave colour palette in the USF 
stream, should we also add it to the track header then ( the 'initial' 
palette ), or leave it away completely ?

	robUx4 <irc://,isnick> 	kaiousama and unmei can tell 

	MosuAtWork <irc://,isnick> 	robUx4: at the moment 
the description of codecstate seems to be just fine

	MosuAtWork <irc://,isnick> 	for this purpose

	ChrisHJW_ 	MosuAtWork : can we handle codec state on DirectShow ?

	MosuAtWork <irc://,isnick> 	no clue

	robUx4 <irc://,isnick> 	ok

	ChrisHJW_ 	maybe Haali could tell

	MosuAtWork <irc://,isnick> 	Haali will have to 
comment on that

	ChrisHJW_ 	alexnoe : why is codec state b0rked ?


	MosuAtWork <irc://,isnick> 	Haali will have to 
comment on that

	ChrisHJW_ 	alexnoe : why is codec state b0rked ?

	MosuAtWork <irc://,isnick> 	but the container 
should be more or less indedependant of the OS APIs ;)

	robUx4 <irc://,isnick> 	so we need to handle the codec 
state in the cue as originally planned

	alexnoe <irc://,isnick> 	ChrisHJW_ because it makes 
remuxing b0rked

	MosuAtWork <irc://,isnick> 	robUx4: it HAS to! 
otherwise the decoder won't have the current information after seeking

	robUx4 <irc://,isnick> 	alexnoe, nop

	MosuAtWork <irc://,isnick> 	alexnoe: why should it?

	robUx4 <irc://,isnick> 	yup, that's my idea

	ChrisHJW_ 	alexnoe : USF cant be used in any other container than MKV 
yet, so why should we care ?

	alexnoe <irc://,isnick> 	it would allow to join 
incompatible streams into one segment, making it necessary to create new 

	robUx4 <irc://,isnick> 	alexnoe, it's not much 
different than block addition

	alexnoe <irc://,isnick> 	:(

	robUx4 <irc://,isnick> 	only the meaning is different

	robUx4 <irc://,isnick> 	and the occurence

	ChrisHJW_ 	Hmmm .... somehow i wonder if using codec state would mean 
we have reinitialize the stream on DShow ?

	ChrisHJW_ 	codec state is read and used by the parser, right ?

	ChrisHJW_ 	only alternative i see is to create another API sitting on 
top of DShow, with USF decoder and MKV parser communicating directly

	ChrisHJW_ 	like what Toff did with Gabest's splitter, to read out track 

	robUx4 <irc://,isnick> 	you pass the codec state each 
time with the codec data

	robUx4 <irc://,isnick> 	or only when needed, as an 
optional field in a structure (maybe EBML like)

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