Agree with everything you said Gary, except for terminology. People I hang out with usually use the term "progressive encoding" to distinguish between 24P frame encoding syntax (progressive sequence) and 30i field encoding syntax (with Frame and Field pictures, repeat field flags for telecine, or reel changes, or speed changes, or special effects, titles, etc. laid down at 30i) as you described. If you go even further, interlaced source Field pictures can use frame prediction on some or all macroblocks and also be "progressive encoded", if you want to define it that way. =20 Yes, a BD player can pull down 24P to 30i on output (such things aren't defined or constrained by the disc format spec). =20 Yes, the BD format can play 30i encoded content, and it can use repeat fields, so you could tunnel 24P source as 30i with 3:2 pull down. It is likely to be treated as 30i content and not inverse telecined. If you want 24P out, encode it as 24P.=20 I suppose you might use 30i with 3:2 for inconsistent or off speed 30i masters of nominal 24P source where the encoder can't perform accurate inverse telecine. Lots of "shot on film, edited on video" TV used to be that way, and the original elements and edit decisions often aren't available (or economical) for a new transfer and edit. Warner used to have a visual comparator that would flash any frame cadence problems to an operator who would manually enter timecoded corrections in an EDL that would override the encoder on the next encoding pass until they had solid ten field 30i sequences that could be decoded to 24P. PS. How did Trip Hawkins slip in there and set progressive_sequence=3D "3DO"? Funny things happen on carriage returns on this reflector. Kilroy Hughes Sr. Media Architect Digital Media Interoperability Team Microsoft Corporation -----Original Message----- From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of Gary Hughes Sent: Wednesday, March 01, 2006 09:42 To: opendtv@xxxxxxxxxxxxx Subject: [opendtv] Re: New DVDs already sparking copy-protection confusion At 04:04 PM 2/28/2006 -0800, Kilroy Hughes wrote: >[KH] Progressive encoding is illegal on DVD-Videos. That is not quite correct >Progressive_sequence=3D3D0 is required, and only 30Hz or 25Hz frame = rates >allowed. =20 Progressive_sequence=3D0 does not prohibit progressive encoding. It only says that interlaced encoding is permitted, but not required. The picture coding extension specifies how each picture is encoded. In the 30Hz world, a correctly inverse telecined 24P source results in a sequence of progressive encoded frames, along with the repeating pattern of repeat_first_field and top_field_first flags (also in the PCE). The sequence header will indicate a frame rate of 29.97, but each second of bitstream will contain 24 progressive encoded frames. I think this meets the definition of "progressive encoding". >There has been a long battle to change production practices >and tools to support consistent and invertible telecine so 24P could be >tunneled through 30i transport streams. Accurate 24P cadence in 30i >syntax was the exception for most movies for the first few years of DVD, >but is now the rule. In my previous employment I designed the trick mode handling for a VOD server that makes use of the I frames as they exist in the original stream (to avoid the need for trick mode files). Film content that has not been through IVTC can exhibit terrible interlace flicker as you might imagine and I spent much of last year dealing with these issues. Various people maintained that non-video data, such as closed captioning, could not be accommodated in IVTC content which is of course bogus. Regrettably one of the major content providers made a decision to not use IVTC in any of their content, largely because some of their production tools did not handle the stream timestamps correctly in IVTC content (if you repeat a field, that has to be reflected in the PTS and DTS values). In the end I designed a new trick mode sequence that forces the set top decoder to deinterlace by making both fields reference the same original field when in pause etc when playing out such content. >BD format now allows 24P encoded Transport Streams. HD format doesn't, >but it identifies 24P encoded as 30i to allow accurate decoding to 24P. Which brings us back to the discussion in DVDlist :-) If I understand correctly (all numbers modulo 1000/1001 as needed) BD allows 24P content to be encoded at 24 progressive frame/sec with the sequence header frame rate set to 24 and no use of the 3:2 pulldown flags, so the decoder could drive the display at 24 frame/sec.=20 HD DVD requires 24P content to be encoded as 24 progressive frames/sec with the sequence header frame rate set to 30 and the picture coding extension containing the necessary flags to reconstruct the 3:2 pull down, and presumably drives the display at 30 frame/sec. Some questions... Can a BD player can also perform the 3:2 pull down on its output if needed? Does the BD format also allow for the 24 frames plus rff/tff IVTC approach, or was that the gist of your original comment in DVDlist? Sorry if this seems overly pedantic. MPEG does that to people (this is your brain, this is your brain on MPEG) gary Gary Hughes (ghughes@xxxxxxxxxxxxxxxxxx) Stargate Video Systems ---------------------------------------------------------------------- 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.