[opendtv] Re: BBC Demonstrates HDTV Broadcasts over SD Channels
- From: Mark Schubin <tvmark@xxxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 23 Jun 2005 08:32:48 -0400
Correct. And both 720 and 480 are divisible by 16. So the divide-by-16
argument doesn't make sense.
TTFN,
Mark
Tom Barry wrote:
>Mark Schubin wrote:
> > Perhaps you know something about this that I do not, but your
>reasons do
> > not make sense in view of the other constraints of Table 3.
>1080, for
> > example, is not divisible by 16, and SMPTE standards call for
>different
> > production and clear apertures.
>
>I believe ATSC (A53?) specifies that 1080 will actually be encoded
>with 1088 vertical samples to get around this.
>
>- Tom
>
>
>
>>>The number of samples per line is further limited
>>>by the ATSC standard to 704 samples.
>>>
>>>
>>>
>>Agreed.
>>
>>
>>
>>
>>>The major
>>>reason for this is that the ITU-R BT601 standard
>>>which forms the basis for this profile includes
>>>the rise times for blanking within the 720
>>>samples per line. 704 is close to the active
>>>picture area, and a convenient multiple of 16 for
>>>MPEG-2 macroblock alignment.
>>>
>>>
>>>
>>>
>>Perhaps you know something about this that I do not, but your reasons do
>>not make sense in view of the other constraints of Table 3. 1080, for
>>example, is not divisible by 16, and SMPTE standards call for different
>>production and clear apertures. Table 3 should have said 720 x 480.
>>ATSC working-group rules do not permit me to say much more about the matter.
>>
>>TTFN,
>>Mark
>>
>>
>>
>>----------------------------------------------------------------------
>>You can UNSUBSCRIBE from the OpenDTV list in two ways:
>>
>>- Using the UNSUBSCRIBE command in your user configuration settings at
>>FreeLists.org
>>
>>- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
>>unsubscribe in the subject line.
>>
>>
>>
>>
>
>
>----------------------------------------------------------------------
>You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
>- Using the UNSUBSCRIBE command in your user configuration settings at
>FreeLists.org
>
>- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
>unsubscribe in the subject line.
>
>
>
>
>
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
