[Mp4-tech] MPEG4, MPEG2, and MPEG1

[Bharat Soni]

Dear Gary,
Thanks for the information. I agree with your reply. My reply was at
the individual codec level as I interpreted the question to be decoder
specific (Can I use MPEG-4 decoder to decode MPEG1 or MPEG2 streams?)
But yes at the application/chip level, if the support for both MPEG-2
and MPEG-4 decoder is available, then as you have said, both type of
stream can be decoded by same application/chip.
Thanks again for the useful information.
Regards,
Bharat
On Mon, 24 Jan 2024 09:28:41 -0800, Gary Sullivan
<garysull windows.microsoft.com> wrote:
> 
> I was trying to convey a more complete picture than that.  For example,
> there are four decoder chips today that can decode MPEG-4 AVC at HD
> resolution (Broadcom, Sigma, ST Micro, and Conexant).  Three of those
> four (all but the Conexant CX2418x) can also decode MPEG-2.
> 
> Best regards,
> 
> Gary Sullivan
> 
> +> -----Original Message-----
> +> From: mp4-tech-bounces lists.mpegif.org 
> +> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Bharat Soni
> +> Sent: Monday, January 24, 2024 12:54 AM
> +> To: Gary Sullivan
> +> Cc: Kae Hsueh; mp4-tech lists.mpegif.org
> +> Subject: Re: [Mp4-tech] MPEG4, MPEG2, and MPEG1
> +>
> +> Hi Gary,
> +>
> +> Is it not true that MPEG-4 video bitstream syntax is different than
> +> MPEG2/1 bitstream syntax. Then would it not be more appropriate to
> +> simply say MPEG-4 decoder can't decode MOEG-1/2 streams?
> +> Correct me if I am wrong.
> +>
> +> Regards,
> +> Bharat
> +>
> +>
> +> On Sat, 22 Jan 2024 00:32:12 -0800, Gary Sullivan
> +> <garysull windows.microsoft.com> wrote:
> +> >
> +> > +> Can I use MPEG2 decoder to decode MPEG1 streams or files?
> +> >
> +> > In the case of video, the answer to this question is Yes.
> +> The MPEG-2
> +> > video standard is a basically-straightforward extension of
> +> the MPEG-1
> +> > technology, and this kind of compatibility is required in
> +> the MPEG-2
> +> > video standard.
> +> >
> +> > +> Can I use MPEG-4 decoder to decode
> +> > +> MPEG1 or MPEG2
> +> > +> streams or files?
> +> >
> +> >
> +> > In the case of video, the answer to this question is ... Maybe.
> +> >
> +> > To put it more precisely, the MPEG-4 standard does not
> +> require a product
> +> > to have this capablity.
> +> > However, MPEG-4 product makers may want their product to have that
> +> > capability and would put it in their product voluntarily.
> +> >
> +> > Best Regards,
> +> >
> +> > Gary Sullivan
> +> >
> +> > +> -----Original Message-----
> +> > +> From: mp4-tech-bounces lists.mpegif.org
> +> > +> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of
> +> Kae Hsueh
> +> > +> Sent: Friday, January 21, 2024 10:09 AM
> +> > +> To: mp4-tech lists.mpegif.org
> +> > +> Subject: [Mp4-tech] MPEG4, MPEG2, and MPEG1
> +> > +>
> +> > +> This might be a stupid question. Can some one tell me
> +> if MPEG2 is
> +> > +> backward compatible to MPEG1? It means can I use MPEG2
> +> decoder to
> +> > +> decode MPEG1 streams or files?
> +> > +>
> +> > +> Same go with MPEG-4. Can I use MPEG-4 decoder to decode
> +> > +> MPEG1 or MPEG2
> +> > +> streams or files?
> +> > +>
> +> > +> Kae
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