[Matroska-devel] Protocol of my 2+ hrs telephone conversation with Frank Klemm

Steve Lhomme steve.lhomme at free.fr
Sun Nov 16 12:18:01 CET 2003


Christian HJ Wiesner wrote:

> He mentioned more than one time that MP3, from his point of view, is not 
> at all well specified and implemented and can even lead to drop-outs 
> during playback under certain conditions. He sees AC3 as a very good 
> standard for his needs, because of well existing hardware decoders in 
> external receivers, a proper and well done specification and 
> implementation, and because with DVD burners beoming more and more 
> popular, low bitrates for audio compression will be only interesting for 
> streaming in future, and he doesnt see the big market for streaming at 
> all. He told me he is maybe interested in making a proper AC3 encoder, 
> using his own psy model, that in principal can be transferred from one 
> encoder to another.

Mmm, low bitrates are good for exchanging or publishing music too (and 
still forcing people to buy the music). I use it a lot ! Not to mention 
that you gain some extra bandwidth when muxed with video (which is less 
used for legal stuff). Anyway, the net distribution of content with 
sound/music has a great future. And that's where compression matters a lot.

> After learning that, i honestly question the future of musepack in its 
> current form. It was maybe a better idea to make a good, free and 

Mmm, you'd better have good proof of what you say. If that's the case, 
that means we can drop the "plans" for SV8. Anyway, I personally also 
give AAC a lot of credit, even with the license restrictions. (after all 
you have encoders/players for free on Windows and OSX)

> opensource AAC encoder, or to fork from Vorbis and making a new 
> compression format, if Frank ever finds the motivation again to invest 
> serious work into making a new audio codec. The other alternative is, 
> and that is what Frank obviously had in mind for musepack also, make a 
> clear cut with subband coding for the future and make SV8 a 
> transformation codec also. Frank told me that in his opinion the AAC 
> standard has a couple of quirks in it, and we could maybe make a new 
> compression format, still call it musepack and MPC, overcoming those 
> problems, but on the other hand staying decoder compatible with AAC ??

I suggest not using MPC for the name, as it would confuse many people.

> 3. Frank has doubts if our developers, mainly Toff, have really found a 
> way to read a complete block of data from a SV7 file for muxing into 
> matroska. He says the current bitstream is weired, there are sometimes 
> bits from one block attached to the next or to the preceding block, so 
> without calling the decoder on the blocks there is no way of finding 
> out. Even then, proper seeking might be impossible because in worst case 
> the decoding of a block can depend on up to 32 blocks before this block.
> He promised to look into a repacking app, reading SV7, unpack the data 
> and repack them into SV8 bitstream, forming a kind of SV 7.5 version if 
> you want, as i convinced him there is no use of allowing subband coding 
> in SV8 at all, if he feels it doesnt have any advantages to 
> transformation encoding. With this app we could pack SV7 files into 
> matroska fine, just a new decoder is necessary that can handle the new 
> byte order as specified for SV8 ( big endian ).

Sure ! That's all we need from MPC SV7 !

> Its time for us to ask ourselves if we want musepack to evolve further, 
> or if we are happy with what it is today. Whilst it is usable for music 
> compression already, its not for use with video. If we want musepack to 
> progress, we all have to work together to improve it. Looking forward to 
> hear your comments.

Let me explain why I use compressed audio :

1) publish my mixes on the net (mp3PRO for any dumb user to be able to 
read it)
2) DJing with TraktorDJ. It only supports MP3 but I want to make an 
equivalent software that could read much more formats
3) Storing tagged music on my machines instead of having to switch of 
CD/vynil all the time
4) Storing TV captures (currently using Vorbis in Matroska)

I think MPC could go in 2/3/4 but I use mostly MP3 because I know it 
will work in all other cases. So as long as MPC (or Vorbis) doesn't work 
in 2 I will use MP3 for almost everything... That's why I want to make a 
good DJing software ASAP. Then I'll see if MPC is worth... If there is 
SV7 in Matroska, it should cover all my needs !




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