DivX and MPEG-4

[Sohaib]

Hi there ...

Is it true that DivX is really just an encoder standard and DivX encoded streams can be played back without difficultly using an MPEG-4 ASP decoder? Does the decoder have to support GMC? WHich profile of the MPEG-4 ISO standard is needed to decode all DivX content? Will that handle DivX 3.11/4/5 ? ...

Now, if the above is NOT true, how can someone go about writing their own DivX decoder? :sly:

Is DivX 5 backwards compatible with 4 and 3.11? ...

[dimzon]

DivX 4,5,6 are MPEG4 ASP encoders
DivX 3.11 are NOT true MPEG4 ISO encoder

[shon3i]

DivX 4Don't have b-frames

[dimzon]

Don't have b-frames
Anycase it produce 100% MPEG4 Part2 ISO Compliant bitstream ;)

[Sharktooth]

Hi there ...

Is it true that DivX is really just an encoder standard and DivX encoded streams can be played back without difficultly using an MPEG-4 ASP decoder? Does the decoder have to support GMC? WHich profile of the MPEG-4 ISO standard is needed to decode all DivX content? Will that handle DivX 3.11/4/5 ? ...

Now, if the above is NOT true, how can someone go about writing their own DivX decoder? :sly:

Is DivX 5 backwards compatible with 4 and 3.11? ...
DivX IS NOT an encoder standard it is just a compatible subset of MPEG-4 ASP standard and it can be decoded by any MPEG-4 ASP spec compliant decoder (xvid, libavcodec, etc...).
The decoder does not necessarily have to support GMC unless you enabled it in the codec at encoding time, but GMC is also part of the MPEG-4 ASP specs, so any compliant decoder should have it.
The profile is MPEG-4 Part2.
It will handle DivX from 4.xx on (3.11 is not compatible).
Correctly speaking you cant write your own DivX decoder (DivX is just a brand) but your own MPEG-4 ASP decoder just following the specs.

[SeeMoreDigital]

Indeed...

DivX, XviD, NeroDigital, 3ivx etc should be considered as being nothing more than brand names and/or implementations of the MPEG-4 ISO/IEE 14496 standard.


Cheers

[nalooti]

DivX IS NOT an encoder standard it is just a compatible subset of MPEG-4 ASP standard and it can be decoded by any MPEG-4 ASP spec compliant decoder (xvid, libavcodec, etc...).
The decoder does not necessarily have to support GMC unless you enabled it in the codec at encoding time, but GMC is also part of the MPEG-4 ASP specs, so any compliant decoder should have it.
The profile is MPEG-4 Part2.
It will handle DivX from 4.xx on (3.11 is not compatible).
Correctly speaking you cant write your own DivX decoder (DivX is just a brand) but your own MPEG-4 ASP decoder just following the specs.

This is also what i think it should be. Then i don't understand why a file encoded to mpeg4 ASP with Nero Recode, can't play in my divx player while divx ones can.
The only answer i found for my question is that Nero gives the encoded file in mp4 container (.mp4). Then my philips player which is "mpeg4 compatible" isn't really one since it can only play .avi files. Am i right ?

Is there any way to tell Nero to encode in avi container instead of mp4 ?

thanks
nalooti

[Sharktooth]

no. nero just encodes into .mp4.
there is also another difference: nero uses its own profiles (buffers etc) and aac audio...
so your player must be NeroDigital certified to play files encoded with nero.
keep in mind standalones are not 100% mpeg-4 compliant... they support only subsets of the standard (certain levels, certain profiles... etc).

[LoRd_MuldeR]

This is also what i think it should be. Then i don't understand why a file encoded to mpeg4 ASP with Nero Recode, can't play in my divx player while divx ones can.
The only answer i found for my question is that Nero gives the encoded file in mp4 container (.mp4). Then my philips player which is "mpeg4 compatible" isn't really one since it can only play .avi files. Am i right ?

Is there any way to tell Nero to encode in avi container instead of mp4 ?

thanks
nalooti

If your player doesn't like MP4 files, why not extracting the MPEG-4 stream from the MP4 conatiner and mux it into an AVI file?

[SeeMoreDigital]

no. nero just encodes into .mp4.
there is also another difference....Apart from the way B-VOP's are correctly generated with Recode2...

Lets hope XviD EncRAW will carry on this fine tradition....