What are we actually seeing?

[Exigeus]

When we record something with TIVO, the playback is digital, naturally, even though the station recorded may have been analog. And when we're watching live TV, and we decide to back up and watch someething again, we're watching content that is recorded, so it must be digital. So when we're just watching live TV, seen through the TIVO machine, are we watching digital, or the original analog signal?

When we hit the reverse button, there's no noticable change in the picture, so I wonder if the "live" TV we see through TIVO is actually recorded and immediately played back. It seems like it must be.

[MsRoboto]

You answered your own question. You are watching the Tivo buffer which is recorded.

[Exigeus]

So we're not getting the benefit of the superior analog signal?

[Exigeus]

I guess the real question is how good the TIVO digital recording is. I know that digital cable channels are lousy with compression error. Maybe that's not true for "live" TIVO.

[stevel]

TiVo has four "quality" levels when recording analog video. "Live TV" uses "Best" which should be indistinguishable from a quality analog feed.

[Exigeus]

That's good to hear. Digital cable channels are almost unwatchable sometimes. Of course, I am watching them through my TIVO, so I had to wonder how much of the picture degradation was original and how much was added. Does Best Quality involve any compression?

[Bierboy]

TiVo has four "quality" levels when recording analog video. "Live TV" uses "Best" which should be indistinguishable from a quality analog feed.Ah, but it IS distinguishable. On my now retired S2, the "live" video was noticeably worse than watching directly through my TV. Now, on my S3, it is nearly indistinguishable.

[ZeoTiVo]

That's good to hear. Digital cable channels are almost unwatchable sometimes. Of course, I am watching them through my TIVO, so I had to wonder how much of the picture degradation was original and how much was added. Does Best Quality involve any compression?
it all involves compression.

Think how your digital set top box is hooked to the TiVo.
You are tuning the digital channel on the box - then it goes out the composite or svideo out to the TiVo as an analog signal - then the TiVo takes that analog signal and converts it to digital mpeg to write to the hard drive. even for the live buffer that digital mpeg is read - then converted to analog output to the TV.

you are definitely not seeing the digital channel with a series 2 TiVo.
if picture quality is important to you - you may wnat to consider a Series 3 TiVo or cable company DVR which does write the digital stream from the cable straight to the hard drive, or else get another set top box to watch the digital hooked straight up to the TV.

[Exigeus]

In what way does a series three TIVO avoid that problem?

[stevel]

If you have digital cable and a CableCARD, the Series 3 can record the digital signal directly without further compression.

[Exigeus]

But what about the analog stations?

[yunlin12]

At least in my area Comcast uses a technique called ADS, Analog-Digital_Simulcast, they actually carry both the analog and digital copy of a channel. Cable signal usually have somewhere between 500-860 MHz bandwidth, and each channel is assigned a portion of the bandwidth. The cable cards tells Tivo which channels is carried on which frequency range, and then Tivo tunes to that freq and get teh signal. Often in ADS, cable cards would direct Tivo to the digital copy. An easy way to test this is to slowly unscrew the cable from the back of the Tivo, if the picture start to pixlate, it's a digital channel. If it starts to snow, then it's an analog channel.

[MickeS]

Ah, but it IS distinguishable. On my now retired S2, the "live" video was noticeably worse than watching directly through my TV. Now, on my S3, it is nearly indistinguishable.
On a Series 2 it is definitely a difference between the TiVo picture and analog picture. Especially when watching fast-moving images like sports.

The Series 1 had slightly better picture, IMO, but still noticeably different.

[mattack]

But what about the analog stations?

Many people say that the tuner in a series 3 is better even for analog stations.
(Possibly they tweaked the bit rates for the recording levels, but the tuner could be better too.)

I say "many people" since it looks pretty good to me, but I also have a lot of splitters and ancient coax cables and have weird signal problems sometimes. (one of my S1s gets a horrible signal on most of the broadcast stations. I now have enough other tuners that I haven't really fiddled with the cables long enough to permanently fix the problem... and when I say horrible it's really unwatchable sometimes. But a lot of the cable channels are just fine.)

So we're not getting the benefit of the superior analog signal?

That's funny, because my XS32 does what it seems like you were hoping the Tivos would do -- show the actual incoming analog signal when you are watching 'live', even when recording, but showing the recorded signal when in "chase play" (equivalent of rewinding in the buffer on a Tivo). It's actually pretty annoying, actually. Though it can look better on some stations when it goes to the direct analog signal, it can also look worse -- and simply the DIFFERENCE is annoying when switching between the two (which I do fairly frequently the times when I am watching something I'm recording live, since on that "VCR-like" recording system, you can't go into the menus while in chase play mode.. I sure wish the Tivo/DVD recorders had the ability to EDIT recordings, I would've bought a Tivo/DVD recorder if that were so.)

[greg_burns]

Often in ADS, cable cards would direct Tivo to the digital copy. An easy way to test this is to slowly unscrew the cable from the back of the Tivo, if the picture start to pixlate, it's a digital channel. If it starts to snow, then it's an analog channel.

Perhaps an easier way...

I thought with the S3 if it were a digital signal you could easily tell if when recording it doesn't given you any option for the quality level to record at.

[taronga]

TiVo has a Video Smoothing setting to diminish the fuzzy appearance of analog cable. It can make you lose some sharpness, but on my 20" TV, it does seem like a slight improvement over the raw cable feed.

[Dan203]

Ah, but it IS distinguishable. On my now retired S2, the "live" video was noticeably worse than watching directly through my TV. Now, on my S3, it is nearly indistinguishable.

A while back I compared the same program, recorded at the same quality from an analog station on noth a S2 and a S3 connected to the TV using the same connection type. (i.e. S-Video) The S3 picture quality was considerably better. It had a lot less grain and a lot smoother transitions between colors. Since we don't have TTG yet on the S3 we cant verify bitrate and resolution, but I'd bet that the S3 is using full 720x480 resolution (as opposed to 480x480) and a higher bitrate for each of the settings. I'm also guessing that the S3s superior video output circuitry is also improving the picture as well.

The S1s did have a little better picture then the S2s, but that's because they were using dedicated chips for both encoding and decoding made by Sony. Unfortunately those chips were really expensive and were the reason TiVo had to subsidize the units just to sell them at $400. The S2s use cheaper integrated chips made by Broadcom.

Dan

[yunlin12]

Perhaps an easier way...

I thought with the S3 if it were a digital signal you could easily tell if when recording it doesn't given you any option for the quality level to record at.


Nice! didn't think of that one.

[Exigeus]

This is excellent information, thanks. I see why the S2's were so cheap now.

That SX32 sounds like it has the right idea. I've had my S2 for a while, and with the few times I use the buffering features, I'd be fine with the switch from analog to digital. It would remind me when I need to catch up. The times I rewind tend to be on recorded material anyway. Maybe it could be optional whether you're watching buffered picture or the unaltered signal during live viewing.

Actually, I'd turn the whole buffering system off if I could. It's not worth it. I know, it's pretty much a trademark feature of TIVO, but you have the device constantly writing and reading the disk, 24/7, just for the maybe two times a week I actually rewind live TV.

Thanks to everyone for the knowledgable and forthright responses.

[ZeoTiVo]

Actually, I'd turn the whole buffering system off if I could. It's not worth it. I know, it's pretty much a trademark feature of TIVO, but you have the device constantly writing and reading the disk, 24/7, just for the maybe two times a week I actually rewind live TV.
TiVo DVRs do not have high end power supplies either- you have to bear in mind these are consumer appiances and very price sensitive - so actually having the hard drive spin down and then spin up again as it went through a recording/viewing day would likely cause more failures than prevent them. Also it makes the coding more complex as they have to allow for hard drive Spin up while dealing with real time video streams. The live TV buffering is more a result of good hardware design given the nature of the appliance then anything else.

PS - I just have a COAX cable going directly to my TV for when I want to watch live TV directly. You can also have a coax cable going from the TiVo DVR to the TV and put the TiVo in standby mode and for most models of TiVo that will sned the analog signal to the TV with just the splitter in the TiVo doing anything to the signal.