[opendtv] Re: Interlace Artifacts
- From: "Tom McMahon" <TLM@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 12 Jan 2005 09:07:19 -0800
So those encoders and bitstreams cause decoders to blow up?
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On
Behalf Of David Workman (WINDOWS MEDIA)
Sent: Wednesday, January 12, 2005 8:57 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Interlace Artifacts
>>I read somewhere once on the MSFT site that they encode in=20
>>4:1:1 when you say you want to keep interlace. Dunno if=20 that is
>>still true.
No. The original interlace mode encoding of Windows Media 9 "Main Profile" was
4:1:1 but this has been superseded by the interlace
mode in "Advanced Profile", which is 4:2:0. The 4:1:1 mode is not supported
any longer.
David Workman
QA Manager
Core Media Processing Technology
Microsoft Corporation
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
On Behalf Of Tom Barry
Sent: Wednesday, January 12, 2005 6:23 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Interlace Artifacts
Ron Economos wrote:
>As an old MPEG-2 guy, I haven't quite wrapped my head around
>H.264 yet. Can you describe how the H.264 interlace tools have >improved
>over MPEG-2? I've also been told that the interlace
>tools in VC-1 are a complete afterthought.
I read somewhere once on the MSFT site that they encode in 4:1:1 when=20 you
say you want to keep interlace. Dunno if that is
still true.
- Tom
> Comments in-line.
>=20
> Tom McMahon wrote:
>=20
>=20
>>This discussion treads on the usual apples and oranges problem. How
do you comnpare these things when the parameters associated
>>with the acquisition devices, the encoders, the storage media, the
transmission media, the decoders and the display devices are all
>>different?
>>=20
>>
>=20
> Agree that it's very much apples and oranges. I guess the reason I
>responded was that most FOX 480p video bitstreams I've analyzed (when
>they were doing 480p) were coded at around 10 Mbps. Quite a bit higher
>than your typical 480i bitstream.
>=20
>=20
>>A key concept in this is whether or not the original image was
captured coherently as single sample point. In other words, whether
>>or not it was "sampled" as a two dimensional array of image values or
whether it was scanned out as a sequence of intensity values.
>>=20
>>
>=20
> To use a Tom Barry phrase, I couldn't parse that sentence. Can you
give
> me another clue as to what you were getting at?
>=20
>=20
>>Interlace has many dimensions. (Most of them bad.) =20
>>
>=20
> I get the feeling that folks on this list consider the interlace tools
> in MPEG-2
> (field DCT, field predictions, alternate scan) to be not adequate.
>In=20 another post you said:
>=20
> It is interesting to note that H.264/AVC has much improved interlace
>tools that help mitigate the gas-guzzling problem, but improved codec
>performance for the transmission channel does nothing for the display
>problem.
>=20
> As an old MPEG-2 guy, I haven't quite wrapped my head around
> H.264 yet. Can you describe how the H.264 interlace tools have
>improved over MPEG-2? I've also been told that the interlace tools in
>VC-1 are a complete afterthought.
>=20
> Ron
>=20
>=20
>>-----Original Message-----
>>From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of Craig Birkmaier
>>Sent: Tuesday, January 11, 2005 7:51 PM
>>To: opendtv@xxxxxxxxxxxxx
>>Subject: [opendtv] Re: Interlace Artifacts
>>
>>At 3:12 PM -0800 1/11/05, Ron Economos wrote:
>>=20
>>
>>
>>>480p@60 uses the same bitrate or less as 480i@30? That would be a
very=20
>>>magical MPEG-2 encoder.
>>>
>>>Ron
>>> =20
>>>
>>
>>I can point you to many tests done in the '90s that proved this
exactly. But there is one caveat. Most of the tests used source with
>>equal information content then measured the SNR at the output of the
decoder. Thus, comparing an SDTV source with the same source
>>deinterlaced and coded as 480P the 480P signal would have a higher
SNR than the 480i encoding.
>>
>>As a 480P signal can carry more information, it is possible that you
may need more bits to encode the source with the same SNR as
>>the information content increases. I beleive that NHK was covering
live sports in Japan with native 480P cameras with an emission
>>encoded bitrate of about 8 Mbps. This compares with about 6-8 Mbps for
480i source, but the 480P was of significantly higher
>>quality.
>>
>>Regards
>>Craig
>>=20
>>
>=20
>=20
> =20
> =20
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