To DT_DC: Could you help?

Discussion in 'TiVo Coffee House - TiVo Discussion' started by TiVoPhish, Jan 9, 2006.

  1. Jan 9, 2006 #1 of 51
    TiVoPhish

    TiVoPhish New Member

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    You seems to have a great amount of knowledge on a lot of the technologies that all play with each other recarding HD, Analog, Digital, mpeg 4, multistream, bidirectional support etc... and you have a good way of describing things, so I wanted to ask you some questions that I know I'd benefit from... and maybe some others :)

    Feel free to correct me or expand on any point.

    Dish Network starts rolling out mpeg4 on February 1st. I think DirecTV has already started. The way I understand it is that mpeg4 will eventually replace mpeg2 for both SD and HD signals.

    From what I know, one of the goals of mpeg4 is to reduce bandwidth requirements... but also from what I know, some current DVRs and equipment aren't compatible. DirecTivo will not be compatible.

    If I had a Series 2 hooked up to my new mpeg4 compatible Dish Network box, would I be able to see mpeg4 content and/or record it? I know Series 2 isn't HD compatible, but what about mpeg4 SD compatible? If I had to guess, I'd say "No", but I'm really not sure. (My guess would be based on current CODECs in the Series 2).

    Originally I thought maybe the answer is "Yes" because if it's just coming in as a video signal, what prevents Series 2 from seeing it... but the TiVo is actually always slightly buffering and ready to record at the touch of the pause button... so that made me lean towards no.

    Whatever the answer, can you explain why?

    Okay, so moving on to the Series 3. I did read that it would be able to play mpeg4. Would it also be able to record it? I ask because some of the things I read weren't clear, and it could just be a matter of how the articles were worded. If I had to guess, I'd say "Yes" (the codecs will be in place) -- Considering the big move to mpeg4 I figure TiVo planned well :) -- but clarify that if you will.

    And onto CC 2.0...

    Multistream format is what allows one line coming into you box, but the ability for the box to split the signal. In other words, it allows one cablecard to support two (or more) tuners.

    Bidirectional data allows incoming and outgoing information, as required by something like PPV. HBO though, is only one way (incoming) and is unidirectional.

    The Cablecard 2.0 spec provides for decryption of the incoming signal to the box/TV, but it is up to the BOX to decode the stream (like mpeg4) through it's own codecs.


    Now this is where I think I get lost (or more lost if I've been way wrong in anything above)...

    Multistream is supported by cablecard 2.0 spec.

    Bi-Directional data flow is supported by the cablecard 2.0 spec BUT the host box must also be able to understand and interact with the incoming data -- and a standard hasn't been agreed upon yet for the format of that incoming data.


    Do I have all that right? There's a lot of conflicting information around about mpeg4 and more so about CC2.0, so I kinda hope you'd help out with some clarification. I feel as though I'm on the right track and understand the basics, but I wanted to be sure.

    Thanks!
     
  2. Jan 9, 2006 #2 of 51
    chain777

    chain777 Member

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    I'll chime in on number one, hope you don't mind. ;)

    The compression technology used by your satellite provider doesn't mean anything to your series2 Tivo. It doesn't record the raw digital stream. It records an analog signal coming from your satellite boxes S-video or composite output.

    As to the bandwidth savings, yes it saves bandwidth. Unfortunately the excess usually ends up going to cramming in more useless channels instead of improving picture quality. :rolleyes:
     
  3. Jan 9, 2006 #3 of 51
    gastrof

    gastrof Hubcaps r in fashion

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    Yeah, Phish.

    Even I know that if your TV can make use of what's coming out of your Direct box, your TiVo would be able to.

    Remember, the stand alone TiVo would be getting the video (and audio) from the A/V lines (most likely). Those lines have to work with "old style" TV equipment, and so will do it for either a TeeVEE or a TeeVoe. (I just know someone's gonna chew me out for spelling TiVo that way. :) )
     
  4. Jan 9, 2006 #4 of 51
    Stanley Rohner

    Stanley Rohner New Member

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    I hate to be a thread stealer, but since you mentioned picture quality......
    I was watching STAR TREK THE NEXT GENERATION on the G4 channel last night. I don't know if it was just me, but the quality really sucked. It was so bad that as someone walked around in a scene quickly it would pixelate a little. I ended up changing to another channel and watching something else.

    I'll answer this question in advance - It had nothing to do with the TiVo recording quality setting.
     
  5. Jan 9, 2006 #5 of 51
    Justin Thyme

    Justin Thyme Contra sceleris

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    It is like the following photo transfer process:
    • 8MegPixel photoshop file (satellite digital signal- mpeg2, mpeg4- whatever)
    • having a 5x7 printed (satelite box output via analog connectors- rca or svideo cable)
    • Photographing with a macro lens in low light. (real time conversion of analog back into Tivo's format- mpeg2).

    Just because the 5x7 came from a Tiff or a PICT, or a Photoshop file has no bearing on what the Tivo's internal format uses.

    Up until DirecTivo and later, Cablecard, all non-carrier provided DVRs recorded shows this way.

    Cablecard and carrier provided DVRs are analogously like transmiting the original 8 megapixel file to the user's box. Because of this, the box must use the same formats that the Carrier is sending.

    Obviously, this method is vastly superior to taking picture of a photo in motion. If you look at any Tivo image closely- especially washes of color, you will see all sorts of artifacts. The reason why is that you are doing the redigitizing in less than ideal conditions (taking a photo of a photo, rather than a flatbed scan of it with a full spectrum light at slow speed and highest res). These effects are not as noticable on a smaller CRT Televsion because they tend to soften the effects. But on a digital screen, the degradation is obvious to anyone with any visual acuity.

    To anyone who has dealt with photography, obviously the best way is to just get a copy of the original file- then there is no degradation.

    But's its not like the third party vendors had that option because the carriers refused access to their networks in the same way that Ma Bell refused to allow anyone to plug any non MaBell phone into the wall. The phone company had a variety of concerns that they exagerated, but it the end the government forced them to open their network.

    Third party vendors really want to skip the redigitizing so they can record the original file but carriers protested that they could not let third party machines connect to their network and make such direct copies. In 1996, Congress said the carriers had too allows such access. The FCC was allowed to tell the satellite companies didn't have to comply "for now", but the "for now" has stretched to one decade. The cable companies have taken nearly a decade to design and create a half solution which is the current cablecard support.

    If you live in Canada your cable company won't allow you to use a cablecard device.
     
  6. Jan 9, 2006 #6 of 51
    TiVoPhish

    TiVoPhish New Member

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    Makes total sense to me.

    I think part of my confusion came from a conversation I had recently with someone who insisted TiVo couldn't record Pay-Per-View shows (which I've never given any thought to). I couldn't understand how that was possible if it's just connected through composite cables sending an analog signal. I kept telling him he was wrong.

    BUT, then hooking up my S2 to cable recently, Series 2 is capable of acting as a cable box. I have it hooked up to one of my TVs as one right now... and it DOES NOT pick up/receive any of the digital channels at all. It only receive analog channels.

    Is it more correct to say a Series 2 will no longer work as a fully functional cable box (will not receive digital channel signal directly), but if you hook it up via S-video or composite through a cable or satelite box it'll be just fine?

    (ps. my fault for focusing too much on satellite and less on mpeg4 in the question -- I should have included a cable example as well.)

    It's can't receive the mpeg4 streams directly (like through an RF connection), but it just sees it as analog when hooked up that way -- that makes sense to me.

    Of course, we could vere totally off topic about the DRM TiVo could implement in future software -- but that's nothing to do with the ability to see the signal as much as the boxes willingness to cooperate ;)

    Yeah, it's was the first thing I notice after switching away from Dish... the amount of compression on some the channels is unbearable.
     
  7. dt_dc

    dt_dc Mostly Harmless

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    Yes ... you're getting the idea here (the other responses to this are also all on-target).

    When a Series 2 Tivo is hooked up to a Dish STB (or DirecTV STB or cable STB) ... it's hooked up via the analog SVideo (or composite) connections. SVideo and composite are ... SVideo and composite. It really doesn't matter if the signal gets to the STB as MPEG2 or MPEG4 (or QAM or QPSK or 8PSK or 8VSB or whatever). The box outputs an analog video signal via SVideo or composite ... and a Tivo Series 2 can record it.

    Easy as that. The key here is that these boxes provide a (standard) analog video output. Tivo can record that output.

    Allowing for recording from those analog connections (and controlling those boxes) gave Tivo a very nice "universal" solution they could use with alot of different platforms ... DirecTV, Dish, digital cable, whatever ... you could use a Tivo with any of them ...

    As far as hooking a Series 2 Tivo directly up to cable via the coax coming out from the wall ...

    Yes, when you do that the Tivo can tune, recieve, and record all the analog channels your cable company sends out. Analog cable channels and the analog over-the-air channels use (basically) the exact same RF signals (NTSC). So, by providing an RF connection (coax) that could tune and record NTSC channels ... Tivo came up a solution that could be used with analog cable OR over-the-air analog channels (without a seperate box).

    A Series 2 Tivo can not tune any digital cable channels (QAM) directly (without a box) ... or order PPV ... or order VOD ... or any of those other functions of a cable box. Without a cable STB ... it can only tune and record the analog channels.

    Although, as noted above ... if you want to record digital channels (or even PPV and other content) ... you can get a cable box and connect it via SVideo or composite and record that analog output from the cable box.
    Well ... that would be up to Tivo. :) Seriously though:
    1) I wouldn't try reading too much into the S3 stuff
    2) I'm not sure what you're asking
    I would call that reasonably close to correct (I'd quibble with a couple of the terms but the general idea is correct).
     
  8. lajohn27

    lajohn27 Fanboi.. So what?

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    Let me ask this question..

    When I hook my Motorola DCT-6408 firewire up to my PC, I can record a MPEG2 Transport Stream (.ts) file .. so that does that mean all the QAM tuned channels on my cable box are being encoded in MPEG2 for digital transmission?

    And if so.. is it likely that cableco's will switch from an MPEG2 stream, to an MPEG4 stream...

    And if THAT's likely.. it shouldn't matter, because the S3 in theory can play either?
     
  9. ZeoTiVo

    ZeoTiVo I can't explain

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    The TiVo Series 3 as reported on at CES, So this is not a final official thing, will record in mpeg2 only through the tuners. I saw no report of it being able to record Mpeg4. Now we do not know yet what hardware is inside the TiVo so we can not comment on what it may be capable of.
    The signal comes in via cable, antenna or cable card
    if the signal is Analog
    - that signal is sent to the correct tuner that can understand the signal
    - the tuner gets the correct "channel" as given to it by the guide data and record request
    - the "channel" from the tuner is passed to hardware that encodes that signal into a fornmat that is digitally written to a hard drive
    (mpeg2) that encoder hardware has the "codec" that knows how to write mpeg2, if the hardware is also capable of mpeg4 then it can write that as well but it typically takes more time/processing to do mpeg4 so is not done to allow more resources for playback of recordings or whatever else is needed with less powerful and thus less costly hardware, but we do not know what hardware is inside the series 3 yet so we have no idea about its capabilities.

    again TiVo said the series 3 will record everything as mpeg2, but that is not the final official released spec. I see no reason they would hold back mentioning such a feature as recording in mpeg4 though.

    now for a digital signal I am not sure if the TiVo is going to do any conversion of it to some TiVo standard format or just write it to the hard drive. The digital signal is a professionally highly compressed mpeg2 or mpeg4 format so it could be written directly. Again no official specs or knowledge of hardware inside the series 3 yet.


    for playback there is hardware** with the "codecs" that will decode the digital file written on the hard drive into the proper signal given the output being used by the TiVo. The unofficial specs call for mpeg2, mpeg4 and some others related to mpeg4 I forget right off but equally important for playing back downloaded content.

    so mpeg4 playback is imortant for playback of downloaded content without having to convert it and for archiving. I am very likely to get a series 3, stay on analog cable and for shows I have archived off to a harddrive store them as mpeg 4 which can be 1/2 to 1/10 the size of mpeg2 I currently have them in.

    ** the hardware for the encoder and decoder is typically the same piece of hardware
     
  10. ZeoTiVo

    ZeoTiVo I can't explain

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    now for the satellite DVRs they also need the hardware to decode mpeg2/4 but it is solely for inside the box to send the proper "signal" depending on the output.

    if it is composite or S-video it will be an SD output and anything capable of understanding that SD output will have the corresponding composite or s-video input. There is a small enough amount of data in SD that on the fly a series 2 can recieve that "channel" and send it to the encoder that will write it as mpeg2 on the TiVo hard drive.

    ignoring security of HD signals for now
    if it is a HDMI output from the Satellite box or cable box then it is HD and has 10 times the data of the SD stuff. For a TV there is little to do with that "signal" but display it on the screen and the viewer enjoys the 10 times the detail goodness.

    for a Digital Video recorder it will have to take that HD "signal" and send it to the hardware encoder so it can transform to the format used by the recorder and write it to the hard drive. the 10 times the data would overwhelm the current hardware encoder in ANY digital recorder in a consumer product.

    so getting a final full HD "signal" from anywhere is out for consumer products unless they want to spend thousands of dollars on encoder hardware that can handle the massive amount of data - also it means a lot more data on the hard drive and dramtically smaller record times.

    what consumer HD recorders do is get the professionally compressed already digital signal (either in mpeg2 or mpeg4) from the broadcaster and write that directly to the hard drive without having to do any encoding of any sort.
    for playback the recorded digital file (either in mpeg2 or mpeg4) is sent to the decoder that will decode it to SD or HD depending on the output to be used.

    this is why TiVo has had a hard time putting an HD recorder on the market. Without something that will decrypt the direct digital signal and send that digital signal to the hard drive directly there is just no way to do it.

    for cable there is now cable card (either single stream or multistream) that will do this inside the TiVo as it needs to be. It has the added benefit of being able to directly control the card to "change" to the channel needed via the tuner. No wires outside the box and the time that takes and all the remote commands to gather and troubleshoot on timing etc.. Since this is made possible by the cable card, TiVo inc. made the decision to not include SD inputs like s-video or composite and make it a nice DVR for cable and reduce the cost and complexity by whatever amount the inputs and outside wires and all that remote command data would add otherwise.

    this decision makes sense to me in part because if they added the inputs you would not record anything better than SD on a series 2 anyway which already has the codebase to work with the outside wires to change the channel on the external tuner of the satellite receiver. So for satellite you are stuck in the series 2 world unless the satellite broadcaster will make available in some agreed upon way the decrypted direct digital signal.
     
  11. Justin Thyme

    Justin Thyme Contra sceleris

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    Since the only analog to record in the S3 is Analog Cable, mpeg2 is probably just fine. Is the S3 the successor to the S2? I don't think so. An S2 would have dual encoders and be able to do HD content.

    The first set of HD video Camcorders settled on the mpeg2, so maybe that's the sweet spot between PQ (mpeg4 is harder to do in realtime), cost of hardware encoders and storage cost.

    But the $799 Sanyo HDTV Palm Camcorder records 20 minutes on 1 gigabyte, so 1 hour in just 3 gigs? Heck- that is definately an mpeg4 in there. But maybe they gave up a lot of PQ. If the Sanyo is an indication that cheap mpeg4 hidef encoders are here, but I suspect you could give up PQ. If that is the case, they could offer best quality recording in Mpeg2, and Good in mpeg4.

    My wild ass guess is that the next generation analog Tivo will use the BCM7401. If this chip has the hardware grunt to do Mpeg4 encoding of HD.
     
  12. dt_dc

    dt_dc Mostly Harmless

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    Ever hopefull eh?

    Anyway, no.

    http://www.broadcom.com/collateral/pb/7401-PB01-R.pdf

    Edit: Original 'poorly worded' ... err, or just plain wrong
    The BCM7401 can only encode SD (NTSC or PAL). No HD encoding ...

    Fix: As noted below by Dennis ... the chip in question is a decoder. No compression of any kind. It can do HD DAC (for analog HD output).
     
  13. lajohn27

    lajohn27 Fanboi.. So what?

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    Following that link it says..

    "HD analog video encoder with simultaneous SD outputs..
    - NTSC etc etc
    - 480i/480p/576i/576p/720p/1080i output formats..
    - component RGB or YPrPb Output
    - HDMI 1.1 bla bla"

    Umm.. isn't that HD encoding.. ?
     
  14. Dennis Wilkinson

    Dennis Wilkinson Active Member

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    Nope. You'll note that nowhere does it say "MPEG encoder" under the encoder heading. That part is a DAC (Digital-to-Analog Converter) that takes uncompressed HD digital input and creates simultaneous SD and HD analog outputs in a number of different formats.
     
  15. TiVoPhish

    TiVoPhish New Member

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    If cable companies stopped producing/providing STBs with analog outputs, it would be completely accurate to say that my Series 2 would no longer be "compatible" with digital content from Cable or Satellite (without maybe converter boxes)... correct?

    Agreed :)
    Now the new Series 3 provides no analog inputs (or I should say the one shown at CES didn't). So it would be completely true to say that it will only be compatible via Cablecard and not at all with Satellite (which I already knew, just not exactly why).

    I would IMAGINE that cable companies (at least) will provide boxes with analog output for at least a while.
    Any thoughts on that?

    And it's still up in the air whether Series 3 will be able to interact with PPV and VOD. If it were released today, it would not be able to. Correct?

    Yes, assuming the cable box provides the S-Video or Composite outputs (which yes, they do at this point). Is it required they continue to do so? It is likely they will (I think so, at least for a little while).

    Regarding Series 3 and mpeg4 -- I think Zeo (thanks Zeo!) went on after you to help me really put the pieces together. Tell me if you agree...

    The signal coming in is decoded and can be played back on the Series 3, whether it's mpeg2 or mpeg4, because it has the codecs in place to decode both types of content.

    But it will only record to it's own hard drive in mpeg2.

    I think that is where the information I read confused me. When I read it could "play back mpeg 4" (without any further clarification) I took that to mean it cannot record mpeg4. It can... but it is already converted to mpeg2 by the time you're viewing it through your Series 3. It cannot records IN mpeg4.


    Thanks for the confirmation -- with all the info flying around about it (and a lot of it mixing up the terms), I'm glad to know I understand the basics.
     
  16. petew

    petew Active Member

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    As would all but the latest HD TV's. The Cable Co's may stop transmitting Analog signals over the wire, making direct connection of an analog TV impossible. But it's going to be a long long time before they stop providing STB's with Analog outputs. Essentialy the new converter box that will be required in 2009 is a STB for OTA channels.




    No.

    Incoming digital contents will most likely be saved as is with no conversion. It's already in MPEG2 or 4 and can just be written to disk. It will be decoded on output. Incoming analog signals will most probably be recorded in MPEG2 in the same format as today.
     
  17. petew

    petew Active Member

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    One further thought. While a Bi-Directional cable card would be required for PPV and VOD. Digitial copy protection would most likely prevent recording of such material anyway, so having the functionality is probably a waste of space.
     
  18. ZeoTiVo

    ZeoTiVo I can't explain

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    your welcome. Sorry I was so abrupt in the rant thread.
    However I have to disagree somewhat with the following ;)
    the analog signal coming in on the cable or antenna is not in any type of mpeg format and always needs to be encoded to put on the drive. TiVo is using mpeg2 for all of this as far as reports by Megazone and others from CES have shown.

    if the cable card is being used for digital cable - that signal is the highly compressed mpeg2 or could be mpeg4. I do not know what cable companies use, I assume it is all mpeg2 right now, and so the mpeg2 is written direct to the hard drive.

    the part I nor others that have not seen inside the box can say
    is if the TiVo can put a digital mpeg4 signal from a cable company direct on the hard drive and play it back or if they can convert the mpeg4 to mpeg2 and put it on the drive. We just do not know anything about this part yet, but technically it could be in there.
    The mpeg4 is definitely there for playback anyway but I saw that as more there for internet downloads of content and perhaps the HD that Netflix wants to do with downloading movies to a box for playback.
     
  19. TiVoPhish

    TiVoPhish New Member

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    But with the CC2.0 spec, lots of equipment could have a Cablecard. Trust me, I'm not making the argument that they WILL stop providing analog outputs anytime soon... just for what will happen if/when they do.

    Hmmm... that's not how I understand it. Incoming digital content is already in mpeg2 or 4 and the host it goes to needs to have the codecs in place to play it. This is why the DirecTivo will not be compatible when DirecTV starts rolling out mpeg4.

    What it records IN is mpeg2 (or at least that is what's we know so far). So the recordings on the TiVo harddrive with NOT be mpeg4, but mpeg2.

    Not necessarily true at all. We have several on-demand channels that provide "different" types of content, of which it's possible they are not copy protected (I do not know either way). For example, we get one called Anime On-Demand. I completely hear you on PPV or HBO-On-Demand, but it's possible not everything OD would require it.

    If/As more and more channels offer the OD option, a box like TiVo Series 3 would need to address bidirectional data implementation. Now you could make the argument that if it's on-demand, why do you need to record it? Well what if you want to archive it for your own use, or transfer to a laptop or portable device to watch on-the-go?


    Yes, I know analog isn't in any type of mpeg format and that it is encoded TO mpeg2 when recorded on TiVo...

    Follow you... understand that already and agree... but let me add that mpeg4 is coming (and I think already being used) by both cable and satelite. I could be wrong about the "already being used" part, because I'm shakey on that info... but I am sure it's coming.

    And that's where we veer off a bit from agreeing. The way I understand it is that mpeg2 can be played and recorded, and so can mpeg4... but the mpeg4 will be decoded (as received/at playback) and encoded (at recording) as mpeg2 and that is how it will be recorded. So the files on your TiVo will be mpeg2.

    Totally possible (and that's the unknown) that it will have the capability to directly record the mpeg4 that's already been decoded... but all the speculation has only included the ability to record IN mpeg2.

    Mpeg4 is being used/going to be used by Cable and Satellite to open up bandwidth to allow more channels.
     
  20. petew

    petew Active Member

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    Digital contents is a very loing stream of bits. Tivo can save those bits to disk whatever format they are in. However in order to display those bits as meaningful Video and Audio it needs a matching Codec.

    No one know for certain how the Series 3 works, but it make no sense to me for Tivo to peform conversion on the MPEG4 unless it has to. It's unecessary overhead and could introduce a loss of quality. While playback of the original data is guaranteed to reproduce exactly what was transmitted.
     

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