How many "streams" at once for 4 tuner Tablo?

#1

I understand 4 tuners, but how many streams are supported?
Here’s some example scenarios…
Two Roku’s watching the same show live tv plus three recordings on different channels. This should work as only 4 tuners in use.
One Roku on a channel (2.1) with another Roku on a sub channel (2.2) with three recordings on different channels should work as still only 4 “tuners” in use, even though there are 5 shows running simultaneously.
Watching a recording while 4 shows on 4 different channels are being watched or recorded should work because only 4 “tuners” are in use.

So…
Is it 4 “tuners” or 4 “streams”.

#2

Someone will correct me if I am wrong I’m sure…

You have four “connections” you can make because you have 4 tuners.

Record 3, watch one on live.

Watch 3, record 1 show.

I do not believe you can record 3 shows and “stream” two different channels because you don’t have enough tuners.

Each stream or recording will occupy a tuner and put it in use, therefore you can only watch or record up to 4 shows at one time.

I hope I explained this properly.

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#3

There are only 4 tuners, so you can only tune 4 channels at a time or record 4 shows at a time, or any mix. There is a MPEG2 video to h.264 video conversion process where the CPU power of the Tablo can only do 4 at a time.

#4

Tuners are used just for live tv (whether you are recording or not). Previous recordings do not use tuners (assuming you are not remote viewing via Tablo Connect).

If you have a wired Tablo, the max suggested connections is 6 (3 for wireless). You can conceivably watch 6 different recorded shows on 6 different devices while recording 4 live shows at the same time, though I don’t know if the Tablo hardware could handle it.

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#5

I just did a test with my 2-tuner. I have two recordings going on, and I have 5 devices (3 Rokus, a PC, and my phone) watching 5 different recordings. All are working at the highest quality setting.

#6

just to clarify, there are multiple scenarios here:

Watching live or recording different channels (obviously 4 tuners = 4 streams, but what about sub channels?)

Watching and recording the same channel(s) (4 tuners = 4+ streams)

Watching OR recording different sub channels on same physical transmitter (4 tuners = 4 raw streams + sub channel streams)

I would imagine that the maximum number of streams is a limitation of CPU/network bandwidth (Hardware).

Under “normal” digital television, sub channels don’t count against a tuner. It’s the same tuner/transmitter/digital stream it’s just decoding different data. Is this the same for Tablo?

#7

A subchannel acts the same as a regular channel for the Tablo, and I assume every OTA DVR acts the same way. So recording channels 2.1, 2.2, 2.3, and 2.4 at the same time would require all four tuners.

You can have up to 6 devices using your Tablo at the same time (according to Tablo documentation) assuming your home network is decent. Those 6 devices can be doing any combination of live/recorded tv as long as there are 4 or fewer channels being tuned at the same time.

#8

Thanks Snowcat

I have many years of experience with MythTV dating back to analog days but am new to Tablo.
In Myth using both Haupphaug tuner dongles and HD Home Runs, sub channels can be recorded at the same time using a single tuner. This makes sense as it’s a single data stream and sub channels are decoded after the tuner.
I’m finding that Tablo does some things very well but in some ways it’s sadly outdated and crude.
It does have good Wife Acceptance Factor but its lack of prioritizing tuners and intelligent rescheduling is a real pain.
I keep hearing “it’s off again” shouted from the kitchen when recordings start and it runs out of available tuners.
I’m trying to understand it’s operation so I can manually check and adjust recording scheduling to ensure she doesn’t get kicked off something she’s watching. Kind of stupid when there’s a perfectly good computer in the Tablo that could easily do it for me.

It’s a good device, but feels very unfinished and feature light. Hoping it continues to evolve to become what it could be!

#9

From my understanding the real reason why the quad tuner can only record 4 streams at one time is due to the processing power of the Tablo.

It can only convert 4 streams of video from MPEG2 video to h.264 video at one time. So even if you’re recording from 4 subchannels and using only 1 tuner, it can only record 4 streams at once. Recording and watching streams are very different, which snowcat has explained well.

Your computer has limitless processing power when compared to a standalone device like the Tablo.

For example, this is why when you’re using Tablo Connect at a lower remote streaming quality than Full Quality, it uses a “tuner” to convert the video and you have only 3 tuners available for live TV watching. Recordings are prioritized over remote viewing so if the 4th tuner was then needed for a recording, your remote viewing at a lower quality would be stopped.

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#10

Doesn’t anybody read a products data sheet before they buy the product.

And since tablo uses 100Mb speed for wired connections and the max recording quality amounts to approximately 10Mb per stream (6x10= 60+), I hope we won’t once again fall into all those questions about tablo internet capacity.

Tablo DVR Features
• Watch, pause and record live TV
• Skip commercials
• Schedule recordings
• Manage existing recordings
• Record up to 4 shows simultaneously
• Watch on up to 6 devices simultaneously
• iPad & Android Tablet Applications
• Watch on PC/Mac or iPhone/Android smartphone via browser
• Stream live AND recorded shows anywhere in the world
• Streaming to TV via AppleTV/Roku/Chromecast

#11

Well… Zippy…

Don’t YOU have an attitude!

YES I read the data sheet!
I wasnt complaining about the product that I purchased having done my research into whether it was suitable for purpose! I was just wondering how far it could be taken at this time. I was basing things upon what I knew as a computer engineer with 30 years experience, a licensed ham radio operator and instructor and a cable cutter from before there were cables to cut!

My question was a little bit more specific and included sub channels which are NOT covered in the almighty data sheet and, I couldn’t find an answer in the forums.

Perhaps if you would read the original question and the follow up before accusing people of not doing research before purchasing it would help YOU answer questions in a helpful and community spirited manner.

Also, this question had NOTHING to do with internet capacity or bandwidth so I’ve no idea what started you on that particular subject.

My questions were asked and answered in a helpful and intelligent fashion and didn’t need your uncalled for comments.

Don’t assume everyone is a lazy, entitled idiot an is complaining that the product they bought isn’t what they expected.

#12

I read your question. Doesn’t the tuner in tablo work like the tuner in a TV? Does the tuner in you TV consider channel 2.1 discreet from channel 2.2.

And I don’t think 30 years in the business compares to 42 years. But being an engineer maybe the answer can be found at the MaxLinear WEB site.

#13

Being an engineer you might also want to read the specs for ViXs XCODE 5190 since I think tablo uses this processor.

#14

Ok, lets start at the beginning. This is a basic, simplified explanation of what happens for sub channels.
The signal is transmitted from the station as a digitally encoded RF signal (RF is analog btw)
The “tuner” demodulates the RF back to the original digital data.
The digital data stream includes picture and sound for a primary channel and also optional sub channels.
The digital data stream is NOT separate for these multiple sub channels and the primary channel. It’s all one data stream that the digital part of the receiver then decodes to whatever is desired.
The TUNER is always demodulating all the streams for whatever the RF channel it is tuned too. It’s the computer downstream from the tuner that separates the sub streams.
So… in a TV, it doesn’t make sense to decode the sub streams unless your watching them, although it would allow picture in picture for those streams with only ONE tuner.
In a DVR it does make sense to only use ONE tuner if multiple streams from one channel are wanted for viewing or recording IF it has the smarts and the power to decode the raw combined data in this fashion. In fact, it could be slightly more efficient to use only one tuner as the decoder just has to send what it would normaly discard to a different target rather than totally decoding the same data multiple times as, it appears, is being done in the Tablo. I’m assuming that it’s being done in this less efficient manner due to other limitations in either the hardware or the code.

There are 4 obvious external choke points in the Tablo.
1 - the hardware (CPU, internal bus, memory, etc)
2 - the network (including routers, etc)
3 - the USB speed
4 - the storage medium speed
It must be run within the limitations of all of these. But, other limitations of the product may be more related to the way it’s programmed than the way the hardware is designed.

BTW, on the subject of bandwidth.
Recording should NOT require any of the 100Mbit network bandwidth so the 6 stream limit mentioned in the specs is not, necessarily, an Ethernet issue, it’s more likely a CPU or internal bus bandwidth issue.

#15

The 6 stream limit is for watching, the limiting factor here is likely the network speed of the Ethernet 100 Mbps port. I’m sure if you record at a lower quality of 720p 3 Mbps, you will be able to stream to more than 6 devices at the same time.

The 6 stream limit has nothing to do with the CPU processing power as watching aka playback does not require decoding by the Tablo. Your playback device such as the Roku will be doing the decoding of the video.

When watching an already recorded show on your local network, all the Tablo tuners are free.

#16

And don’t forget Digital TV Demodulator mn88436. Between the information available for the tuner, demodulator, and the CPU you should be able to find an answer.

But from a conceptual standpoint if the data stream between the various sub-channels is not discreet any error in stream 2-2 would affect 2-1. And that isn’t the case. When a new sub-channel is added it can take 3-4 weeks before both the picture and sound is properly modulated.

#17

As Wind In His Hair said: " you are hurting my ears" :laughing:

#18

Ridiculous…

Can you tell me how HD Home Run and even the old single tuner Hauppauge 850 dumb tuner stick work then?
These, along with MythTV were perfectly capable of recording all sub channels with a single tuner!

I have no idea where your getting your (incorrect) information but the sub channels are most certainly NOT transmitted using separate RF carriers. They are simply multiplexed in with all the rest of the data.
BTW, if you have a loss if RF signal for the incoming physical RF channel it WILL drop for all the sub channels as the digital error correction is overwhelmed.

Technicaly, the ATSC standard does NOT require separate tuners for sub channels. You need to separate the analog transmission domain from the digital domain where your so happy to spout part numbers that have little or no relevance to this discussion.

In the RF domain which is all the “tuner” cares about it’s all one signal and it’s output as a mixed data stream.

That’s how it works… period… it doesn’t matter how you think it works, the evidence is against you and if you don’t believe me read the ATSC specifications on their web site. For those that are visually oriented and don’t want to read it (it’s pretty heavy going), there’s a block diagram of the transmission system there that plainly shows the multiplexer placed very early in the transmission system.

#19

The older HDHomeRun units just tuned the channel, all the recording was in the native MPEG2 video done by your computer, there was no transcoding of the video by the HDHomeRun units.

#20

So let’s assume you have a 2-tuner tablo. If you have channels 8-1,8-2,8-3, 10-1,10-2,10-3.

If you run a test on your tablo you might find that using the Live TV menu you can only record from any two whether it’s a main channel, sub-channel, or different channel. The old resolve conflict menu.

But if you use the play button you can play 8-1,8-2,8-3 simultaneously on three different devices. But if you play 10-1 on one of the devices, 8-2 and 8-3 drop out of play mode.

If you are playing (Live TV) on 8-1 and 8-2 and then schedule to record the currently playing show on 10-1, then 8-2 drops out of play mode.

And when dealing with live play and the flashing red lights in the LIVE TV menu for what’'s active, it’s not always correct for sub-channels.

So what would or should a rational user plan for?