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Old 04-28-2014, 10:47 AM   #1
Schmye Bubbula
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"Backtrack" changed in Roamios?

I've had my Roamio Basic for a few months now, but from the first day I immediately noticed a change in the amount of "backtrack" when resuming play from a fast-forward or rewind at the 3x speed. It's still 3x for the first of the three available fast speeds, no? In any event, the first fast speed on my old Series2 would backtrack a little bit when resuming play, just as the two faster speeds. But on my new Roamio, the first fast speed doesn't seem to backtrack at all, or very little. In fact, sometimes it seems like it's actually jumping forward a bit, but I could be wrong.... I remember reading how the developers of the first generation TiVo did excruciating testing to empirically determine the best overall backtrack amount to try compensating for overshoot when resuming play, and it was different for each of the three fast speeds, both forward & backward. I think the Roamio might have changed the two other faster speeds' backtracks, too, but I've quickly gotten used to them — no problem. But the absence or at least very little first speed backtrack is thwarting my timing of resuming play coming out of commercials umpteen times every day, and I'm not able to get used to it and compensate. Anyone else notice a change in the first fast speed's backtrack?
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Old 04-28-2014, 05:58 PM   #2
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The series two recorded analog video and converted it into a digital file that Tivo had tight controls over (obviously). The timing on the different frame types in the resulting compressed digital video was able to be set up for perfect skips at every speed.

The newer Tivos take the digital stream directly from the source and save it, more like copying a file. Every channel uses different encoding settings with different frame timings, etc. A good example of this is when you record most of the shows by NBC Sports. E.G. The olympics or NHL hockey.... the 1x FF speed doesn't really do anything* because they are using some odd settings in their compression. Because of these differences, the timing of the skips and jumps may differ a bit.


*It cruises along at 1x speed with no sound and occasionally hop ahead a little bit, often when switching camera angles or to shots that look to be on a different kind of camera (e.g. the goalie cam vs the main cameras
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Old 04-28-2014, 07:34 PM   #3
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I'm having a hard time getting my head around that. Right now I'm watching CBS News, and the first fast forward speed looks like it's a little faster, not just the same speed as normal with the audio muted. But I guess you were saying that it's all random now, dependent on whatever "different encoding settings with different frame timings" happen to be broadcast at the moment. OK, then why does that affect the first fast forward speed, and not the two faster fast forward speeds? (My head is getting ready to explode.)
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Old 04-28-2014, 08:31 PM   #4
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The amount of FF blowback was changed dramatically between the release of the S2 and the S3. Some people liked it, some people hated it, and there was much arguing about it. There may well be variations due to encoding, but the majority of what you're experiencing was an intentional user interface change.
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Old 04-28-2014, 09:53 PM   #5
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Originally Posted by Schmye Bubbula View Post
I'm having a hard time getting my head around that. Right now I'm watching CBS News, and the first fast forward speed looks like it's a little faster, not just the same speed as normal with the audio muted. But I guess you were saying that it's all random now, dependent on whatever "different encoding settings with different frame timings" happen to be broadcast at the moment. OK, then why does that affect the first fast forward speed, and not the two faster fast forward speeds? (My head is getting ready to explode.)

There are a ton of old posts discussing many facets of this topic...

Here's an old post that explains Tivo's ff handling better/more technically than I did:

http://www.tivocommunity.com/tivo-vb...55#post7049355
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Old 04-29-2014, 09:10 AM   #6
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Originally Posted by Schmye Bubbula View Post
I'm having a hard time getting my head around that.
Do you really want to know the technical reasons why? Seems like you just want it to revert to how it used to be, and that cannot happen. Digital is different than analog, and there are more changes than you can perceive going on when you ffw/rwd or play a recording.
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Old 04-29-2014, 10:12 AM   #7
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Well, if I'm to believe jrtroo and lgnad, then getting it back to how it used to be absolutely cannot happen as an inherent technical contraint, but if kdmorse's explanation is largely the crux of the matter — that there may well be variations due to encoding, but the majority of what I'm experiencing was an intentional user interface change — then getting it back to how it used to be indeed can happen. In which case, this would be just another instance of programmers re-inventing the wheel, throwing the baby out with the bathwater, and eschewing all of the perfectly good original human testing to empirically determine the best overall backtrack amount to try compensating for overshoot when resuming play.
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Old 04-29-2014, 12:44 PM   #8
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Originally Posted by Schmye Bubbula View Post
In which case, this would be just another instance of programmers re-inventing the wheel, throwing the baby out with the bathwater, and eschewing all of the perfectly good original human testing to empirically determine the best overall backtrack amount to try compensating for overshoot when resuming play.
They didn't re-invent the wheel. They had to deal with digital encodings that have variations on each channel.
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Old 04-29-2014, 12:56 PM   #9
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I don't know if Tivo CAN change this, but its been this way for digital recordings getting on 8 years or more. Tivo clearly has higher priorities than to spend a bunch of resources to attempt to try and re-work of what is currently in place.

You are miscategorizing kdmorse's response, who simply indicated that it changed and there was discussion of the change when digital signals were initially implemented in Tivo.
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Old 04-29-2014, 01:09 PM   #10
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I beg to disagree. Someone mentioned that they saw a big difference with NBC Sports, which made the first FF speed no speed increase at all, but only muted the audio. So I think I get that there are different encoding settings with different frame timings on different channels that have this effect, but I've been using a combination of the first & third FF speeds to bypass commercials umpteen times a day for two months, and I don't watch sports, and I've observed absolutely consistent behavior with my first FF speed in terms of perceived speedup and of the absence of backtrack. In fact, I never would have known about these new considerations had you guys not explained what's technically going on in the background. In other words, for normal viewing of most TV shows & movies, the effect seems pretty steady. I think that the TiVo programmers probably did depart from the timings informed by their early research in accommodating the new complications.... And there was a time in early TiVo days when it was a high priority to spend a bunch of resources to attempt to try and work out a user-friendly, functional user interface. This Roamio is the best work they've ever done, but I'd say they dropped the ball on this one.
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Old 04-29-2014, 01:38 PM   #11
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What?! Just because its different, based upon how the program is delivered into your home, than the S2 you are saying it is not user friendly?!? You are welcome to your opinion, but this ship has sailed a few generations ago.

You should probably try some searching, as if you seem to really want to know the gory details, and they are here to uncover. I'm out.
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Old 04-29-2014, 01:47 PM   #12
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I'm sorry, but when there's consistently no backtrack at all with the first FF speed on the overwhelming majority of regular TV show & movie programming on most channels, it's no matter of opinion that it's user-hostile. (This feature used to be a major selling point of the superiority of TiVo over cable provider DVRs.)
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Old 04-30-2014, 10:42 AM   #13
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You're complaining to the wrong crowd. You need to be complaining to the networks who are using lazy encoding techniques.

It's possible that if TiVo were to try to fix the backtrack to mesh with a particular encode, they could screw it up royally for any of the other encoding methods.

It's best that they leave this alone. Most of us have gotten used to the change.
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Old 04-30-2014, 11:41 AM   #14
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Originally Posted by steve614 View Post
It's possible that if TiVo were to try to fix the backtrack to mesh with a particular encode, they could screw it up royally for any of the other encoding methods.

It's best that they leave this alone. Most of us have gotten used to the change.
It's worth noting that this actually happened. Our local FOX affiliate was using some weird encoding scheme that the original S3 didn't support correctly at launch, so we got no jump-back at any speed of fast forwarding (except maybe 3X; I forget the details). I had to do a bunch of logging for TiVoJerry to be able to diagnose the problem so the engineers could fix it. Which they did.
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Old 04-30-2014, 11:52 AM   #15
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You're missing the point, steve614; please re-read this thread again. I now understand that there are different encoding settings with different frame timings on different channels, which no longer permit a reproducible exactly same backtrack amount, but the point is, that doesn't account for the absence of any backtrack at all on the first FF speed.

Somebody said earlier that I had miscategorized kdmorse's response, claiming that he simply had indicated that the amount of FF backtrack changed, but there can be no misinterpretation of, "There may well be variations due to encoding, but the majority of what you're experiencing was an intentional user interface change."

I didn't say that TiVo should try to fix the backtrack to mesh with a particular encode (which is easy to see that doing so could screw it up royally for any of the other encoding methods); rather, what I'm saying is that what TiVo should do is set a backtrack for the first FF speed roughly suitable for some overall average of a range of encoding methods, just like they did for the current other two FF speeds. It may not be as consistent as it was for the old Series2, where TiVo had complete control, but it would be better than the present no backtrack at all.

As I said in the original post, "I think the Roamio might have changed the two other faster speeds' backtracks, too, but I've quickly gotten used to them — no problem. But the absence or at least very little first speed backtrack is thwarting my timing of resuming play coming out of commercials umpteen times every day, and I'm not able to get used to it and compensate." I submit that it's not humanly possible for most of us to have gotten used to the change, because when there's no backtrack at all, there's no way for your response time to compensate for the overshoot, due to the finite speeds of your nerve impulses. It's the whole reason backtrack was implemented in the first place.

Try this similar situation some time to illustrate: Have somebody hold a dollar bill in front of your outstretched hand, with your fingers surrounding the bill, poised to snatch. When he randomly chooses a time to drop it, it's physically impossible for you to catch it.

Thanks to FrodoB for confirming that the TiVo engineers have been able to fix an extreme case of this problem in the past.
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Old 04-30-2014, 01:40 PM   #16
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I prefer no backtrack on the first FF
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Old 04-30-2014, 02:36 PM   #17
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^ That's perfectly reasonable. Some people are more bothered by the jump-back than dealing with the overshoot. Perhaps TiVo even removed it from the first FF speed by popular demand.
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Old 05-01-2014, 07:41 AM   #18
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Originally Posted by Schmye Bubbula View Post
You're missing the point, steve614; please re-read this thread again. I now understand that there are different encoding settings with different frame timings on different channels, which no longer permit a reproducible exactly same backtrack amount, but the point is, that doesn't account for the absence of any backtrack at all on the first FF speed.
The first FF speed has been screwy ever since the implementation of digital OTA. FFx1 has been nothing more than real time speed with no audio, with occasional spurts of FF. In this instance, there is no backtrack unless you happen to hit the play button during one of those FF spurts.

I assume this is the inconsistency you are complaining about, no?

Quote:
what I'm saying is that what TiVo should do is set a backtrack for the first FF speed roughly suitable for some overall average of a range of encoding methods, just like they did for the current other two FF speeds. It may not be as consistent as it was for the old Series2, where TiVo had complete control, but it would be better than the present no backtrack at all.
But there is backtrack on FFx1 speed...if you happen to push play during one of the fast forwarding spurts.
TiVo can change the backtrack to any number they want, the inconsistency will still be there.
The only way to fix this is for all the broadcasts networks to agree on a specific standard encoding method, and I don't think that is going to happen anytime soon.
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Old 05-01-2014, 09:06 AM   #19
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^ Oh, this is very odd. I don't doubt your word with your description of what you experience during FFx1, but mine has consistently been a faster speed — across all channels, TV shows, and movies, and definitely not just real-time speed with no audio. (Dunno' if it's exactly the 3x normal speed as with the Series2, but it's unmistakably faster). I don't watch sports, so I can't speak for someone's aforementioned NBC Sports.

As we speak I'm watching a perfect example: ABC Good Morning America with a ticker-tape scroll across the bottom of the screen, letting me graphically see the speed-up during FFx1 and very accurate representation of what happens with jump-back when resuming play. (You can see by how many words jump out of place or not.) I'm seeing the spurts you're talking about, but they're the opposite: long stretches of smooth fast-forward on FFx1 — 30 seconds or more — and occasionally a very brief blip of slower speed. And when the ticker-tape is going across speeded-up in FFx1 during a long stretch without interruption and I hit Play, I can see the absence of jump-back because the words don't shift.

So for me, the FFx1 proper has been speeding up play overwhelmingly normally; it's just the jump-back when resuming play that's not occurring like it does with the other two FF speeds. I'm hooked-up to an outside antenna, not a cable provider, so I don't know if that makes a difference.
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Old 05-01-2014, 04:04 PM   #20
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I have actually seen this issue manifest itself a little differently. I commonly use 3x FF through commercials and intro's to shows. Some channels don't FF or Skip Back smoothly. Specifically Disney HD for me. The 3x FF will go fast and slow / fast and slow. The skip back is unpredictable on these channels as well. It's annoying, but it definitely is related to the way the content is encoded. Ugh. I bet DVR's from the providers would have similar issues, even if they manifest themselves differently.
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