# Roamio rewinds too far after fast forward



## pgoelz (May 1, 2005)

This applies to my Roamio basic (four tuners). 

Anyone else find that the Roamio sometimes rewinds much too far after a fast forward? This seems to be very inconsistent and seems to depend on background activity. Most of the time, the backskip amount is consistent and predictable (although more than my S3). 

When this happens, I also notice that fewer frames than usual are being displayed per second during the fast forward and the rate at which they change is inconsistent. As if the Roamio was busy doing something in the background. When I then press PLAY, the Roamio skips backwards sometimes as much as 10-20 seconds instead of the usual maybe 5 seconds. As if the current location had not updated correctly during fast forward. 

Last night it happened while I was recording two programs. In other words, the Roamio was not working particularly hard. 

??

Paul


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## jrtroo (Feb 4, 2008)

With the smoothness of the fast forward, you are not seeing lag, that only happens in the menus, but the results of how the show is compiled/transmitted. I normally see about the same amount of time impacted on skipback, but it certainly depends upon the speed of the fast forward.

Experts here will surely be able to explain in better detail how that works if you want to know. Others will support the 30 second skip, which I don't personally care for.


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## DeltaOne (Sep 29, 2013)

jrtroo said:


> Others will support the 30 second skip, which I don't personally care for.


I didn't care for the 30 second skip either. I've been using the 2nd fast forward speed and find it works well.

When I use the 3rd (the fastest) fast forward I find the 'jump back' to too much.


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## pgoelz (May 1, 2005)

jrtroo said:


> With the smoothness of the fast forward, you are not seeing lag, that only happens in the menus, but the results of how the show is compiled/transmitted. I normally see about the same amount of time impacted on skipback, but it certainly depends upon the speed of the fast forward.
> 
> Experts here will surely be able to explain in better detail how that works if you want to know. Others will support the 30 second skip, which I don't personally care for.


Not sure I'm following you here. I am talking about an extremely inconsistent skipback for the same fast forward speed. I don't see how that has anything to do with how the program was encoded. ??

Paul


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## pgoelz (May 1, 2005)

DeltaOne said:


> I didn't care for the 30 second skip either. I've been using the 2nd fast forward speed and find it works well.
> 
> When I use the 3rd (the fastest) fast forward I find the 'jump back' to too much.


Derailing my own thread 

I liked and used the 30 second skip on my S3. Each 30 second jump was pretty instantaneous. If I stacked up six presses (for a skip forward past a typical three minute block of commercials, for example), it was three minutes ahead and had started to play by the time I took my finger off the button.

Unfortunately, the 30 second skip feature on the Roamio seems to simply be a "30 second fast forward". If I press the skip button six times for a 3 minute forward jump, it visibly plays in fast forward and takes much longer than on the S3 to move three minutes forward and start playing.

Paul


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## CrispyCritter (Feb 28, 2001)

pgoelz said:


> Not sure I'm following you here. I am talking about an extremely inconsistent skipback for the same fast forward speed. I don't see how that has anything to do with how the program was encoded. ??


It's not only the original encoding of a particular program, but also how your cable company compresses it. Your signal is composed of key frames that have lots of info, each followed by a good number of other frames with much less info (mostly giving changes from the last key frame). When the TiVo jumps back, it has to find and jump back to a key frame before it can go forward again. Depending on the encoding and compression, that key frame may be far away from the optimal point of jumping back to (and the TiVo may not even have enough info to tell that.)


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## CrispyCritter (Feb 28, 2001)

pgoelz said:


> Derailing my own thread
> 
> I liked and used the 30 second skip on my S3. Each 30 second jump was pretty instantaneous. If I stacked up six presses (for a skip forward past a typical three minute block of commercials, for example), it was three minutes ahead and had started to play by the time I took my finger off the button.
> 
> Unfortunately, the 30 second skip feature on the Roamio seems to simply be a "30 second fast forward". If I press the skip button six times for a 3 minute forward jump, it visibly plays in fast forward and takes much longer than on the S3 to move three minutes forward and start playing.


Yes, that's a completely different issue. There is a user settable choice between 30 second scan and 30 second skip - look in the menu system under settings/remote (it's called Advance or something similar). There's also an undocumented third option that I don't use and can never remember what it does - you'll need a back-door sequence to set that one up.


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## pgoelz (May 1, 2005)

CrispyCritter said:


> It's not only the original encoding of a particular program, but also how your cable company compresses it. Your signal is composed of key frames that have lots of info, each followed by a good number of other frames with much less info (mostly giving changes from the last key frame). When the TiVo jumps back, it has to find and jump back to a key frame before it can go forward again. Depending on the encoding and compression, that key frame may be far away from the optimal point of jumping back to (and the TiVo may not even have enough info to tell that.)


OK, that makes sense. The only part I don't understand is why the S3 seemed to be totally unaffected.... its fast forward was always consistent. The Roamio is not.

Paul


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## tim1724 (Jul 3, 2007)

pgoelz said:


> Derailing my own thread
> 
> I liked and used the 30 second skip on my S3. Each 30 second jump was pretty instantaneous. If I stacked up six presses (for a skip forward past a typical three minute block of commercials, for example), it was three minutes ahead and had started to play by the time I took my finger off the button.
> 
> Unfortunately, the 30 second skip feature on the Roamio seems to simply be a "30 second fast forward". If I press the skip button six times for a 3 minute forward jump, it visibly plays in fast forward and takes much longer than on the S3 to move three minutes forward and start playing.


The 30-second scan is annoying indeed, especially if you're stacking several of them. To get the normal 30-second skip that the older TiVos had, enter the following code while watching a recording: Select Play Select 3 0 Select

If you do it during Live TV you have to put an extra Select at the start.

This is the same code you had to enter on the S3 to enable 30-second skip. The S3 by default does the useless skip-to-mark instead of 30-second skip.


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## pgoelz (May 1, 2005)

tim1724 said:


> The 30-second scan is annoying indeed, especially if you're stacking several of them. To get the normal 30-second skip that the older TiVos had, enter the following code while watching a recording: Select Play Select 3 0 Select
> 
> If you do it during Live TV you have to put an extra Select at the start.
> 
> This is the same code you had to enter on the S3 to enable 30-second skip. The S3 by default does the useless skip-to-mark instead of 30-second skip.


Wow, thanks! Worked perfectly. How in the world does one get to know all these little tidbits? Are they documented somewhere I missed? And if not, WHY NOT Tivo???????

Paul


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## lpwcomp (May 6, 2002)

pgoelz said:


> Wow, thanks! Worked perfectly. How in the world does one get to know all these little tidbits? Are they documented somewhere I missed? And if not, WHY NOT Tivo???????
> 
> Paul


The 30-second "skip" is and always has been an unofficial feature. I'm just glad that it is still there. I also glad that they made it persistent years ago. Originally, you had to re-enter it after a re-boot.

As to whether this and other backdoor codes are documented and how anyone gets "to know all these little tidbits", the answer is the TCF. I'm not sure why you expect TiVo to officially document features that are not officially supported.


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## kajukenbo (Jan 19, 2014)

I've found that hitting Play after FF or RW has yet to actually play from where I would expect in the video.
It is always too far forward or not far enough back.
What is the trick? I understand buffering but it does not behave as I am accustomed to.
Any tips? 

Thanks


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## pgoelz (May 1, 2005)

kajukenbo said:


> I've found that hitting Play after FF or RW has yet to actually play from where I am in the video.
> It is always too far forward or not far enough back.
> What is the trick?
> 
> Thanks


Tivo attempts to compensate for your reaction time so when you hit PLAY after a FF, the Tivo skips back an amount that is supposed to compensate for your average reaction time. It was pretty close on my TivoHD. It skips back a little too far on my Roamio for my reaction time so I have to intentionally delay pressing PLAY for a couple hundred mS after I see my program resume.

I started this thread because sometimes, it skips back WAY too far. Like occasionally 30 seconds too far. Perhaps you are seeing the same issue?

Paul


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## kajukenbo (Jan 19, 2014)

It could be. I have not timed it. But the "gap" seems to be abnormal.
I'll pay closer attention and reply if I get any useful statistics.
I teach self defense & martial arts so my reaction time might be above average but I would not expect a few hundred milliseconds to make such a difference.
Thanks for the feedback


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## gigaguy (Aug 30, 2013)

I can't get the 30s skip to work with the codes on my XL4. I keep trying.
also, one other trick I learned here is to hit pause after you hit FF button and before you hit play. this stops playback before the overscan can happen when you go from FF to play directly.


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## lpwcomp (May 6, 2002)

gigaguy said:


> I can't get the 30s skip to work with the codes on my XL4. I keep trying.


We're you playing a recording when you tried to enable it? I don't believe the double select trick works if you are using the HDUI.


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## gigaguy (Aug 30, 2013)

I am using the HD menus. I tried both codes.
can you revert to std menu and do the code and switch back to HD menus?. I'll try it. 

It worked, in SD mode and I went back to HD and it works. not sure if I was pushing the codes wrong before. kept trying.'thanks.


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## Dan203 (Apr 17, 2000)

kajukenbo said:


> I've found that hitting Play after FF or RW has yet to actually play from where I would expect in the video.
> It is always too far forward or not far enough back.
> What is the trick? I understand buffering but it does not behave as I am accustomed to.
> Any tips?
> ...


FF/RW are tricky with digital recordings. Digital recordings use either MPEG-2 or H.254 encoding, both of which are temporal compression formats. What that means is that some frames can only be constructed by first decoding the frames that came before them. With a temporal format there are complete frames, called I frames, inserted every so often so that video can be seeked. Back in the old S2 days when everything was analog TiVo had complete control over this because they were doing the encoding. So they made sure to add an I frame every 1/2 second which made FF/RW very easy to control and very smooth. With the S3 and later they started recording digital channels directly, which meant there FF/RW feature was at the mercy of whatever encoding was used on the source signal. In most cases channels still use a predictable pattern of I frames so FF/RW works OK, but some channels use an erratic pattern which makes it impossible to display a smooth FF/RW and impossible to jump back a consistent amount.

We have one channel here that's like that. I downloaded a show from it and analyzed it in VideoReDo. The spacing on the I frames was all over the board. Some were as close as 6 frames apart and some were as far apart as 30. Trust me when I say that creating a consistent FF/RW from a pattern like that is impossible.


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## kajukenbo (Jan 19, 2014)

The inconsistent I-frames makes sense.
That probably explains the behavior I am seeing.
Thanks


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