Digital Cable VOD/MOD specs

[disturbed1]

Anyone ever wanted to know what Time Warners' digital cable specs are?

(ripped from their "PEGASUS MOVIES ON DEMAND CONTENT SPECIFICATION")

3 ENCODING SPECIFICATIONS

3.1 Video
· MPEG-2, main level, main profile.
· NTSC in 4:3 aspect ratio.
· Possible 16:9 in future.
· 4:2:0 chroma subsampling.
· Frame rate of 29.97 for video-based source material and 23.97 for film-based source
material with 3:2 pulldown applied.
· Black level of content shall be at 0 IRE.

3.2 Bit Rate
· Content will be delivered as a single program transport stream with a base data rate of
no greater than 3.75 Mbps, including video, English audio and PSI data.
· Video data rate shall be no greater than 3.18 Mbps.
· CA and SI are not included.
· Encoding shall be CBR.
· If additional audio streams are included with the content, the delivered transport
stream will be at the rate of 3.75 Mbps plus the bit rate associated with the additional
audio tracks.
· it is expected that the VOD system will strip out additional audio tracks before
transmission to settop boxes.

3.3 Resolution
· ¾ resolution at 528x480 or ½ resolution at 352x480, at the discretion of the
compressionist to optimize signal quality.

3.4 Passes
· Inverse telecine pass, followed by encoding.
· QC cleanup if necessary using noise reduction and bandwidth limiting.

3.5 PIDs
· PMT PID 0xE1E0
· Video PID 0x1E1 (decimal 481), includes the PCR
· Audio PID one 0x1E2 (decimal 482)
· Audio PID two (optional) 0x1E3 (decimal 483)
· Audio PID three (optional) 0x1E4 (decimal 484)
· Additional audio tracks, if available, shall have audio PIDs that follow the same
numbering pattern
· All content must have accurate PAT and PMT prior to delivery to settop, and
language must be encoded with the ISO639.2 language descriptor.
· All video PMTs must be identified with stream_type=0x02 (MPEG-2)
· All audio PMTs must be identified with stream_type=0x81 (Dolby Digital)

3.6 Transport Stream Requirements
· The transport stream must carry only a single program (SPTS).
· The transport stream must consist of 188 byte packets.
· The transport stream must start on a packet boundary and contain an integral number
of transport packets.
· Encoded material shall be delivered in one continuous transport stream without
discontinuities from the beginning of the program through to the end.
· A Program Association Table (PAT) for the program must occur in the transport
stream before any Program Mapping Table (PMT) for the program.
· Both PAT and PMT must be inserted in the transport stream greater than 4 times per
second (8 times per second recommended) throughout the program to allow rapid
program acquisition.
· The Program Clock Reference (PCR) PID of the program must be the same as the
video stream PID of the program.
· PCRs must occur with a separation of less than100 mS.
· PCR accuracy at 27 MHz must be +/- 5ppm.
· A PCR time stamp must be present in any packet containing the start of a video
Packetized Elementary Stream (PES) payload.
· The first PCR packet of the stream must have the transport discontinuity_indicator
flag set to 1.
· Transport packet at the start of a GOP must have random_access_indicator set to 1.

3.7 General Elementary Stream Requirements
· Each stream within the program must start on an access unit boundary and consist of
an integral number of access units.
· Decoding Time Stamps (DTS) and Presentation Time Stamps (PTS) carried in the
program stream must be accurate as defined in the MPEG standard and clarified in
the Technical Corrigendum 2 to that standard (ISO/IEC 13818-4:1998/Cor-2:1998),
which specifies that for most circumstances the values for these must be exact.
· Each stream within the program should start without any significant leader (such as
black video frames) and end without any significant trailer to facilitate the seamless
back-to-back splicing of separate programs.

3.8 GOP - Video Stream Requirements
· Each GOP must contain an I-frame as the initial picture frame.
· Each GOP must be preceded by a sequence header and a sequence extension.
· GOPs shall nominally be 15 for 30 fps video source material and 12 for 24 fps film
material.
· GOPs shall have an M=3.
· GOPs shall be closed to start, open after that if needed.
· The video stream must be encoded to the ISO/IEC 13818-2 standard.
· The video stream must conform to the T-STD buffer model.
· The video stream must not make use of any MPEG-2 scalable extensions (Sequence
Scalable Extension, Picture Temporal Scalable Extension or Picture Spatial Scalable
Extension.
· Each picture within the video stream must be encoded with a picture_structure of
frame.
· Each picture within the video stream must be carried within a single video PES
packet.
· Each set of sequence header, sequence extension and GOP header packets within a
video stream must occur at the start of a new video PES packet that carries the
PTS/DTS of the first picture in the GOP.

3.9 Audio
· Dolby Digital at 384 kbps for Dolby 5.1, when available, and 192 kbps for two
channel stereo when Dolby Digital is not available.
· Must conform to the ATSC standard as specified in Document A/52.
· Two channel audio must be Dolby Stereo encoded for compatibility with Pro-Logic decoders.
· 48 kHz sampling.
· AC-3 registration descriptor must be included in the stream information contained
within the program PMT.

3.10 Closed Captioning / Alternate Languages / V-chip
· SCTE DVS157, with a future addition (dual carriage) of the ATSC A/53 closed
captioning format.

3.11 Subtitles
Subtitles carried in a separate PID per SCTE DVS 026. Allocation of bandwidth to be
determined.

Looong

Anyone know what Direct TV or Dish use? Or have experience with Digital Cable and Sat?

I'm very unhappy with the quality of the digital broadcast TW gives me.

[EddyH]

Excellent, just the right settings for direct stream capturing to KVCD, if you have a player that supports 3750kbps

Pity its not surround or full DVD rez tho, but that would take precious bits away from the Home Abflex Informercial Network...

[WeedVender]

Satelite transmits a CBR DVD profile. at either 8000kbps or 10000...
If they were to stream Uncompressed.. then they would only be able to support like 32 channels instead of the 500 some services provide..

[kwag]

Anyone know what Direct TV or Dish use? Or have experience with Digital Cable and Sat?

Direct TV transmits 480x480 , so it's worse that what you have

I'm very unhappy with the quality of the digital broadcast TW gives me.

Tell me about it , even on a 4DTV system, which is what I have
I wish satellite providers started to use VBR with KVCD's Q Matrix and GOP parameters Then we would all enjoy higher quality, and they wouldn't have to sacrifice channel bandwidth

-kwag

[disturbed1]

Tell me about it , even on a 4DTV system, which is what I have
I wish satellite providers started to use VBR with KVCD's Q Matrix and GOP parameters Then we would all enjoy higher quality, and they wouldn't have to sacrifice channel bandwidth

-kwag

That would be nice.

My provider just came out with a PVR unit, I'm going to check it out. No upfront costs, and only $9.95 a month. Exact same features as a TIVO with an 80gig drive, two firewire ports, and two usb ports. Promise I won't see who makes the hard drive

Just sucks that my antenna pulls in better looking TV. Fuzz can be filtered, I just can't handle the digital blocks.

Thanks for saving me the cost of trying Direct TV/Dish network.

[kwag]

Thanks for saving me the cost of trying Direct TV/Dish network.

I've been told that Dish has a very good quality
I don't know, because I haven't seen it. So maybe you should check that out

-kwag

[WeedVender]

Actually on HowStuffWorks.com they state that Satelite is transfered in DVD specifications.

Where did you get 480x480?

[kwag]

Actually on HowStuffWorks.com they state that Satelite is transfered in DVD specifications.

We wish

Where did you get 480x480?

720x480 Full D-1 is transmitted from the original sources on uplinks, which are on C-Band. This is the main band from which cable companies feed. This is also the main source for DirectTV and Dish Network. They receive C Band information, and they re-compress the information and re-transmit the newly encoded streams in KU band. And there's where the crap comes in
Everyone receiving video transmissions via small dish systems, is receiving one more generation of encoding than if you receive directly via a big dish (C Band) system. If you have a new 4DTV (Motorola) receiver, the quality will always be far better (even on strong analog chanels) than any small dish system currently available. Direct TV's signal is re-encoded at 480x480, and people watching on HDTVs can see how bad it looks, specially on action films.

-kwag

[disturbed1]

Does your Sat look this bad? BTW, these are not png image compression artifacts, it's the way it looks on TV



It's not 100% all the time like that, but at least 50%. TW says it's normal with digital compression But they do offer to remove my cable box for free

[kwag]

Hey man,

Mine is bad, but not that bad
Only on some "cheap" transponders, where apparently they pay less for the uplink (channels ~700 and higher), it looks very similar to your screenshots on action scenes. But on HBO and Showtime, the digital signal is not that bad
If I has that kind of signal, I would be a "disturbed1" too


-kwag

[Greg12]

i wouldn't pay for that crap.

[disturbed1]

I'm still thinking about just getting a two room Direct TV or Dish sat. They've always got deals, I think right now it's around $40 or so a month, which is like $5 cheaper than an equal cable package.

I just really like the Movies on Demand feature cable gives me. Nothing like switching to HBO and choosing which movie I want to see when I want to see it. When it works One good thing is the Time Warner will credit my account everytime I call and complain about the service, so my $102 cable bill has been $60 for the last 4-6 months.

But HBO does come in looking that on occ. too. Cast Away was a nightmare. Looked like they used Xing to make a VCD

[txpharoah]

DirecTV is 544x480. Dish Network is 480x480.

Bitrates differ depending on the channels. They typically vary between 2MB/s and 4MB/s VBR. Some carriers actually vary the resolution/bitrates from channel to channel. Also realize that the video is send in separate streams of Y, CR and CB, each of which is sent in a different resolution and/or bitrate and decoded for proper playback by the DSS receiver.

Typically the audio is 192k for stereo and 384k for 5.1 Dolby.

Digital carriers often consider encode information to be part of their trade secrets, so it is hard to come by, outside of known specs allowed for the DSS format and information gathered from decompiling the signals.

More for you to read:
http://www.coolstf.com/mpeg/#dss
http://www.henry-davis.com/CSD9512:MPEG.html

[Greg12]

Does anyone know what Maryland Comcast Analog cable runs at?

We get a really good picture, usually trans-vhs near dvd quality (a lil fuzz but that could be cause we have older copper transmission wires.