[Matroska-devel] Re: [mpc-devel] [Fwd: Antwort: Re: Erste Datei]
Christian HJ Wiesner
chris at matroska.org
Mon Nov 24 10:34:37 CET 2003
Christian HJ Wiesner wrote:
>First goal of "transpacked SV7" SV8 is to make the blocks independent from
>SV7 uses differential encoding acrossing block boundaries.
>This (the removal of this cross block differential coding) need some
>but it makes software design much more simple and makes it easier to write
Forgive me if i am talking complete rubbish, but i have more and more
problems understanding what you are trying to do here :
From my understanding the SV8 framing should not only bring a new
framing, but also introduce serious changes to the blocks itself ? If
you make an app that simply 're-packs' SV7 files into a SV8 framing,
will the old blocks be converted also, so they are SV8 compliant, or do
you plan to introduce a 'SV7 compatibility mode' in SV8, so that SV7
blocks can be put into the new framing ?
For the changes to the blocks itself, i do understand that the follwoing
new features require a new block design :
- multichannel ( 5.1 )
- more flexible sampling rate support
Now with respect to what you told me on the phone, i mean your ideas
about leaving the subband encoder design completely for next musepack,
how about considering tow steps for this :
1. SV8 : subband encoder like SV7, but adding all the new features
2. SV9 / new codec name : new encoder based on tranformation encoding,
or a new OSS AAC encoder
>First we should discuss about the size of these independent blocks.
>AC3 calls this blocks audioblocks.
>* Basic block size of SV7 is 1152 samples. I would use a multiple of this
> for "transpacked SV7" SV8. Examples:
> a) 2 blocks => 2304 samples ( 52 ms for 44.1 kHz, 48 ms for 48
> b) 4 blocks => 4608 samples (104 ms for 44.1 kHz, 96 ms for 48
> c) 8 blocks => 9216 samples (209 ms for 44.1 kHz, 192 ms for 48
> Samples should be stored in a way so it is possible to decode
> block to minimize memory consumption, even when this is not done
> reference implementation.
>* Native SV8 for 32 kHz...64 kHz sample frequency.
> a) 4096 samples ( 93 ms for 44.1 kHz, 85 for 48 kHz)
> b) 8192 samples (186 ms for 44.1 kHz, 171 for 48 kHz)
>For 8...16 kHz this is quartered, for 16...32 kHz it is halved, for
>64...128 kHz doubled
>and for 128...256 kHz four times larger. But this only as remark.
More information about the Matroska-devel