Re: [mpc-devel] Re: Adding a lossless mode to MPC SV8

Menno wrote:

>>- consider to check if its possible to allow peeling for MPC SV8, so=3D=
20
>>that users can store their MPC files with rather high=3D20
>>bitrates on DVD or=3D20
>>CD media, but can peel the files down in bitrate so they could be=3D20
>>transferred onto portable players ( of course, this is NOT a lossless=3D=
20
>>process anymore )
>>   =20
>>
>
>Current spec only allows bandwidth scalability (normal for subband =3D
>coders),
>but not scalable quality (AFAIK).
>
Hmmm ..... i hope Frank could consider to add this to the bitstream=20
specs, its an important thing to have it in the specs at least, even if=20
its done in a later stage ....

>>- add a loss less mode to SV8, and the speciality here is that mixing=3D=
20
>>lossy and lossless modes in one and the same file should be possible,=3D=
20
>>just like in the upcoming Wavpack4 from David Bryant ( who i=3D20
>>am copying=3D20
>>on this email, i dont wnat to 'steal' his idea without at=3D20
>>least telling=3D20
>>him :-)  )
>>   =20
>>
>I'm not sure if you can make a subband coder lossless. Subband =3D
>iflterbanks
>can be lossless, but you always end up with values to round in the =3D
>coder. It
>could be possible if you use some integer lifting scheme in the =3D
>filterbank,
>but I'm not sure. Of course using a completely different coding method =3D
>for
>the lossless part, or error part, is also possible.
>Menno
> =20
>
Menno, yes, i guess the easier thing to do that was to intoduce a new=20
'mode' for that, leaving subband coding completely. BTW, the same way we=20
could also add Vorbis encoding for the low bitrates ... LOL !!! I just=20
wonder if DRC could be done this way still, because normal lossless=20
compression methods dont have a DCT/iDCT stage, so that DRC could be=20
done on the Coeefficients, and no AGC-like 'pumping' could occur. AC3=20
does a pretty good job for that, and for movie soundtracks its a=20
necessity IMHO, as you can never say what speakers/amps will be used to=20
watch your movie, everything from a crappy mono TV speaker in a hotel=20
room ( at 1 AM in the morning, thats me then, on a bussiness trip to=20
some strange places and bored in the hotel  :D ), or a 5 x 500 W=20
surround system .....
=20
Comments welcome

Christian
MPC and matroska project admin

http://mpc.corecodec.org