[Carsten]

I was just wondering. With the soon to be release MRV/TTG I was thinking that since the S3/HD only have 10/100Mbps ethernet cards. Why doesnt Tivo release a USB to Ethernet adaptor which will allow the Tivos to have Gigabit ethernet cards.

I am sure something as cheap as this should do it:

http://sewelldirect.com/gigabit-ethernet-usb-adapter.asp

Thoughts?

 

[moyekj]

What's the point? MRV/TTG are hindered by CPU or other factors besides ethernet. Know of any S2 machines that get anywere near 100Mbps?

 

[TydalForce]

Of note... USB 2.0 has a maximum "Burst" speed of 480mbs... just shy of half gigabit
That doesn't take into consideration that the 480 isn't sustained, and the CPU load required by it....

Such an adapter might be higher than 100mbps, but not by much... even if it worked, I wouldn't expect much of a benefit over the built-in ethernet

 

[Carsten]

What's the point? MRV/TTG are hindered by CPU or other factors besides ethernet. Know of any S2 machines that get anywere near 100Mbps?

I am affraid that once we get MRV/TTG for the S3 that it'll be my first time using it. Why would it hinder the CPU so much? Isnt it just copying the already encrypted files?

 

[moyekj]

I am affraid that once we get MRV/TTG for the S3 that it'll be my first time using it. Why would it hinder the CPU so much? Isnt it just copying the already encrypted files?

Don't know how it's done on the S3 but for TTG on the S2 there is a process of wrapping the video into an encrypted .tivo format which takes some horsepower and is therefore the bottleneck for transfer. MRV on the other hand I believe is just a straight transfer so not sure why it's transfer rate is limited - perhaps the transfer protocol in use is not very efficient. I have never heard of anyone getting anywhere close to even 50 Mbps transfers even for MRV however so I doubt S3 transfers will be much better either.

 

[Laserfan]

Now that TTG is here, has anyone tried a USB Gigabit adapter on their S3 to see what (if any) thruput improvements are possible?

 

[Mike Farrington]

Don't forget that the S3 writing up to two streams of video to the hard drive, and reading reading from another spot to display what is viewed on the television screen. The disk is heavily burdened and cannot pump out MRV files as fast as some would like.

 

[aaronwt]

Of note... USB 2.0 has a maximum "Burst" speed of 480mbs... just shy of half gigabit
That doesn't take into consideration that the 480 isn't sustained, and the CPU load required by it....

Such an adapter might be higher than 100mbps, but not by much... even if it worked, I wouldn't expect much of a benefit over the built-in ethernet

You can easily get over 200mbs sustained over a USB 2.0 connection on a PC.
It would be nice if the TiVo could get even half the speed of a 100mbs connection.

 

[andyw715]

Don't the S3's have SATA drives? I would think they'd be able to handle more than 3 or 4 "streams" of data at a time.

Also its a factor of ten faster than the current networking I/O 3000Mbps vs 100Mbps

right?

 

[wdwms]

Don't the S3's have SATA drives? I would think they'd be able to handle more than 3 or 4 "streams" of data at a time.

Also its a factor of ten faster than the current networking I/O 3000Mbps vs 100Mbps

right?

Sure they have SATAs, but the drive's read/write head can only be in one place at once.. lots of moving back and forth over the disk to perform these tasks...

Add in this as I/O wait, cpu time, etc...

Its amazing that the system can do what it can; my TivoHD can record two shows; download an HD show from my S3 and play it back - all at the same time! Amazing.. and yet people want/expect more..

-t

 

[demon]

When using MRV/TTG, the TiVo has to multiplex the audio and video into an MPEG system stream, and wrap the stream with the encryption layer; given the TiVo's relatively dinky CPU power (it's an embedded MIPS CPU design), there's no way you're going to see anything near 100 Mbps.

Also, I'm sure the Linux kernel running on the TiVo doesn't include any unnecessary drivers - that most likely includes any drivers that would support the aforementioned USB 2.0 gigabit NICs. Given that there'd be no real benefit to adding such a driver to the system image, I don't think anyone will be able to convince them to do so.

 

[Laserfan]

Is there a definitive list of drivers i.e. USB adapters that Tivo is known to include/support? Maybe NONE given the S3 has ethernet built-in?

...has anyone tried a USB Gigabit adapter on their S3 to see what (if any) thruput improvements are possible?

 

[megazone]

The S3 and HD do not support wired Ethernet adapters since they have built-in Ethernet ports. They only support WiFi adapters - and the TiVo HD only the TiVo-branded adapter.

Even if they supported USB Ethernet adapters, you wouldn't get better performance than the built-in Ethernet port, and very likely *worse*. The bottleneck is the CPU, not the interface. And the Ethernet port is a direct link to the SoC/CPU. So is USB, but USB adds more overhead and processing which would increase the load and take away cycles that could be pushing packets.