TV Station!

[mafiltenborg]

Nowadays, DVB-T receivers capable of handling both MPEG2 and MPEG4 are available in the shape of cheap and tiny USB-sticks.

I've attached one of these gizmos to my Linux-based PC. Using an application called Kaffeine, i'm now able to

• Watch live TV onscreen.
• Record TV - even several channels simultaneously.
• Stream TV (again; several channels simultaneously) to my local LAN, where client devices can pick up the streams and display content of their choice onscreen.

But this requires my 'DVB-T receiver PC' to be on. Not good. Especially not when my DS is already on.

So: I suggest that a new feature called TV Station be developed, making good use of the DS for reception, recording and realtime LAN-wide distribution of DVB-T based TV. The device is already a DLNA server node for static content (films, music and pictures), so including live TV channels here may even be possible?

I know for a fact that a computer running linux (in my case Debian Squeeze) can do this. I'm looking at it... So all the software components are there, they just need to be put together

Synology DS'es also run linux. And they have Gigabit LAN, USB2 and are meant to be on 24/7. Thus, they're perfect for this job.

Clients are required to run VLC or similar (DLNA, anyone?) in order to implement multichannel IPTV on my LAN.

Components used in my setup:

• Old Dell office-PC from the scrapheap.
• AGK DVB-T (MPEG2/4) USB receiver (http://www.agknordic.com/new/index.php?side_id=247) costing USD 35.
• Debian, KDE & Kaffeine installs.

To my knowledge, no such entertainment solution exists on the market today. Should Synology become the first to make one?

[Christian_IA]

Nowadays, DVB-T receivers capable of handling both MPEG2 and MPEG4 are available in the shape of cheap and tiny USB-sticks.

I've attached one of these gizmos to my Linux-based PC. Using an application called Kaffeine, i'm now able to

• Watch live TV onscreen.
• Record TV - even several channels simultaneously.
• Stream TV (again; several channels simultaneously) to my local LAN, where client computers running VLC can pick up the streams and display content of their choice onscreen.

Which protocol is used for streaming ?
Could the streams be watched by media players like Popcorn ?

But this requires my 'Receiver PC' to be on. Not good. Especially not when my DS is already on.

So: I suggest that a new feature called TV Station be developed, making good use of the DS for reception, recording and realtime LAN-wide distribution of DVB-T based TV. The device is already a DLNA server node for static content (films, music and pictures), so including live TV channels here may even be possible?

It would be a very very good idea.
As MPEG2 streams are mpg they are compatible with most DLNA equipment like TVs ?

I know for a fact that a computer running linux (in my case Debian Squeeze) can do this. I'm looking at it... So all the software components are there, they just need to be put together

Synology DS'es also run linux. And they have Gigabit LAN, USB2 and are meant to be on 24/7. Thus, they're perfect for this job.

The idea gets my full support as I also think the DS is the perfect equipment for that.

Clients are required to run VLC or similar (DLNA, anyone?) in order to implement multichannel IPTV on my LAN.

Components used in my setup:

• Old Dell office-PC from the scrapheap.
• AGK DVB-T (MPEG2/4) USB receiver (http://www.agknordic.com/new/index.php?side_id=247) costing USD 35.
• Debian, KDE & Kaffeine installs.

To my knowledge, no such entertainment solution exists on the market today. Should Synology become the first to make one?

Mayby there are a few, but none will have all the super specs that a DS allready have.
The major problem is craeting a usefull and good interface to enable the users to control recording and playing, but that shouldn't be a difficult task.

[Taxman]

Well first off Synology NAS units are not x86 based like your PC, which means developing/porting software to other CPU architectures.

Second performance concerns those tiny DVB sticks often are just a receiver chip the PC CPU is doing the decoding and encoding of the video stream, Synology NAS units may not have the power to handle one let alone multiple video streams along with normal duties.

It's a nice idea though.

[Christian_IA]

Well first off Synology NAS units are not x86 based like your PC, which means developing/porting software to other CPU architectures.

Synology runs NAS already on a non x86 CPU and so does a lot of other system.
Linux and derivates are made for many CPUs.

Second performance concerns those tiny DVB sticks often are just a receiver chip the PC CPU is doing the decoding and encoding of the video stream, Synology NAS units may not have the power to handle one let alone multiple video streams along with normal duties.

DVB are MPEG2 / MPEG4 stream when recieved, so there is no decoding / encoding, they are ready to either stream or store.

It's a nice idea though.

Very nice

[Taxman]

Synology runs NAS already on a non x86 CPU and so does a lot of other system.
Linux and derivates are made for many CPUs.

Yes but unless someone has already ported all the software required for this to the various CPU architectures Synology has used be it Mips or ARM or anything else I doubt Synology would give it serious consideration as thats a lot of work just because it was made for linux doesn't make it auto-magically work on other architectures.

DVB are MPEG2 / MPEG4 stream when received, so there is no decoding / encoding, they are ready to either stream or store.

Anything that handles DVB has to have a video decoder, every set top box to TV has a dedicated chip which handles the video stream. Those tiny usb DVB adapters do not, they rely on software CPU and application to do that work which is where the performance problem comes in. Some DVB adapters at least in the past had hardware decoder on board but those tended to be the more bulky variants or PCI slot cards.

For example during the early days of the DVB stream of BBC-HD channel only the official test DVB set top boxes could decode the stream, then CoreAVC software decoder added support for the H.264 profile BBC was using and PC users in range of the test signal could decode the the same video stream on their PC.

[Christian_IA]

Synology runs NAS already on a non x86 CPU and so does a lot of other system.
Linux and derivates are made for many CPUs.

Yes but unless someone has already ported all the software required for this to the various CPU architectures Synology has used be it Mips or ARM or anything else I doubt Synology would give it serious consideration as thats a lot of work just because it was made for linux doesn't make it auto-magically work on other architectures.

Unless it is very HW specific I guess most linux version runs on most linux platforms. These programs could be programs like VLC (which already runs on linux), ffmpeg (which allready runs on linux).

DVB are MPEG2 / MPEG4 stream when received, so there is no decoding / encoding, they are ready to either stream or store.

Anything that handles DVB has to have a video decoder, every set top box to TV has a dedicated chip which handles the video stream. Those tiny usb DVB adapters do not, they rely on software CPU and application to do that work which is where the performance problem comes in. Some DVB adapters at least in the past had hardware decoder on board but those tended to be the more bulky variants or PCI slot cards.

Most of the extensive computer force needed is not needed anymore as the streams recieved are all most ready to store as they are MPEG2 / MPEG4 now.

For example during the early days of the DVB stream of BBC-HD channel only the official test DVB set top boxes could decode the stream, then CoreAVC software decoder added support for the H.264 profile BBC was using and PC users in range of the test signal could decode the the same video stream on their PC.

The poster originally starting this thread runs a DVB reciever, records the streams and broadcast the stream out on the LAN with a CPU approx with the power of the DS209+II NAS.

[Taxman]

Unless it is very HW specific I guess most linux version runs on most linux platforms. These programs could be programs like VLC (which already runs on linux), ffmpeg (which allready runs on linux).

Uh no they dont if they do they have been complied specially for that architecture. An x86 only linux program will not work on an Arm linux OS. There are some universal API's out there like Java but I dont think any of the desired software in this scenario has been programmed with that.

Also I think your confusing VLC and ffmpeg, VLC is a media player built off the codecs from the ffmpeg project. Like ffdshow is a windows directshow implementation of ffmpeg.

Most of the extensive computer force needed is not needed anymore as the streams recieved are all most ready to store as they are MPEG2 / MPEG4 now.

I'm not sure if its a language issue but you dont seem to understand that the video stream has to be decoded at the client end with an MPEG-2 or MPEG-4 AVC complaint decoder (hardware or software), without that there would be no way to record the stream. Oh and another issue to add into the mix DVB video streams are not universally compatible and vary from country to country so Synology would have to somehow test against every desired video profile in use otherwise a person in country 1 may pick up DVB transmission normally but person in country 2 cannot or gets a corrupted video output.

The poster originally starting this thread runs a DVB reciever, records the streams and broadcast the stream out on the LAN with a CPU approx with the power of the DS209+II NAS.

An old Dell PC that could be anything, CPU architectures are difficult to compare even Arm gets compared to Atom CPU's and they are worse performance wise than even old Intel CPU's.

I dont see TV station happening way too much stacked against it unless Synology is feeling generous and willing to spend money on porting the software, writing optimized video decoders for the various CPU architectures they use, testing what models can handle it and writing drivers for DVB adapters as x86 linux drivers are again no use.

[mafiltenborg]

Taxman wrote:
<snip>Oh no they dont if they do they have been complied specially for that architecture. An x86 only linux program will not work on an Arm linux OS<snip>

Correct. And thus, most things have been ported to various architectures, ARM being one of these Successfully stuffing a fullblown Debian Etch into eg. a Linksys NSLU2 is no problem, including native access to ARM-specific repositories, providing nearly all the apps present in e.g. the X86-repos. If memory serves me right, there were in excess of 20.000 packages available...
I know. Been there, done that. For more info, see e.g. http://www.cyrius.com/debian/nslu2/
I finally gave up on my trusty NSLU2, replacing it with a DS209 simply because the NSLU2 didn't have the oomph to properly run SqueezeCenter. There are limits to what you can do with 266MHz and 32MB of ram But running e.g. a ssh-session, mysql, top, various daemons, squeezecenter, mc, sambaserver (catering several clients) and a few other odds and ends - simultaneously - is doable.
Same thing applies to another experiment, applied to an old Sun Ultra5 workstation: Fullblown Debian install, now including X, KDE and all the bells and whistles. The Ultra5 boasts a 266 MHz sparc CPU, meaning all apps are now found in a sparc-specific repo. Again, more than 20.000 packages available.

What i'm trying to say is that i don't buy your argument regarding the lack of available software. It's there.

Taxman wrote:
<snip>An old Dell PC that could be anything, CPU architectures are difficult to compare...<snip>
<snip>I'm not sure if its a language issue but you dont seem to understand that the video stream has to be decoded at the client end with an MPEG-2 or MPEG-4 AVC complaint decoder (hardware or software), without that there would be no way to record the stream.<snip>

Your argument seems to be that the DS won't be able to decode, store or even broadcast the stream.
As stated earlier, DVB-T gets delivered to you in the shape of an MPEG2/4 formatted stream. I'll argue that it does not need any decoding at all. No heavy lifting. Showing it onscreen is what requires cpu horsepower. I'll back this argument up by providing you with measurements, taken from a EeePC 701SD, running Debian Squeeze, KDE4 and all the eyecandy i've been able to throw at it - including wobbly windows, rotating desktop cubes and whathavewehere. And of course Kaffeine and DVB-T reception. The thing boasts a 7" screen and a whopping 630MHz Celeron ULV CPU.

Measurements made with top, running beside Kaffeine in a shellwindow.

• Kaffeine idle: ~0% CPU load.
• Kaffeine recording one DVB-T/MPEG2 channel: ~3% CPU load.
• Kaffeine streaming four MPEG2 channels to LAN simultaneously: ~9% CPU load.
• Kaffeine showing one MPEG2 channel onscreen (window): ~33% CPU load.
• Kaffeine showing AND recording one MPEG2 channel onscreen (window): ~36% CPU load.

So, does grabbing and handling MPEG2 streams from a cheap USB-DVB-T stick bog down my 600 MHz Celeron? Nope. Recording one channel requires a mere 3% of available ressources. If we skip the disk handling and simply dump the data to LAN as UDP/RTP-data (multicast), four channels can be broadcast simultaneously using only 9% CPU.

Just as you said, it's showing the MPEG2-stream that is expensive. Thus it's not a language-issue, but rather one of client/server task distribution understanding...
See the list above and observe that when i turn on the video, my CPU gets busy! But having no display, the DS cannot show anything! That's for your client-side htpc (stream->video converter) to do, right? And reading reviews of various EEEbox- or netbook-type pc's reveals that they all do reasonable video decoding. Latest EEEboxes even have HDMI for big-screen use
What the DS must do is provide streaming data. And as seen above, that's a piece of cake! No heavy lifting.

I know, the DS does not have a X86 processor, but an ARM-variant. Clocked at 1.2 GHz, it should have enough oomph to run most things. Actually the Synology folks allow audio-transcoding in realtime today (DS2.2 onwards). Indicates reasonable amounts of grunt in store, right?

I think the biggest problem with making a 'TV Station' will be related to the required add-on-hardware. There are many different USB-DVBT-receivers available out there, and making them all work flawlessly wuold be impossible. But since Synology already provides a compatibility list for hard drives and cameras, why not implement another list with 'approved DVBT-receivers'?
And for the country-specific adaptation of channel-setup, i'll refer you to the fact that DVB-T is an international standard, meaning there's a fixed set of possibilities to choose from. It's no jungle. And Kaffeine comes preconfigured with a huge set of country-specific channel-setups.
I know, because recently we've had the entire danish TV-network updated/upgraded to DVB-T technology. Authorities moved everything around, meaning a new channel setup configuration had to be written. I took a peek at the Kaffeine conf-files and in an hour had a working set, replacing the DK-conf-files. No rocket-science. Kaffeine-developers even provide user-driven update-service to the conf-files.

So, what's stopping us?

[mafiltenborg]

Hehe- just found this: http://www.videolan.org/projects/dvblast.html

DVblast is designed to stream from a DVB device to several RTP streams. VLC also does this, but requires a wee bit of tweaking.
DVblast sourcecode available.

And take note of this: Multichannel DVB-streaming allows for us to lose the extra settop-boxes and pay-tv-access-cards necessary if DVB-pay-tv is to be viewed on several TVs in the house. We need only one card and one receiver to allow all clients to see all programs at all times. Just like on oldtimes analog cable tv in-house-antenna-networks.

[Christian_IA]

Hehe- just found this: http://www.videolan.org/projects/dvblast.html

DVblast is designed to stream from a DVB device to several RTP streams. VLC also does this, but requires a wee bit of tweaking.
DVblast sourcecode available.

And take note of this: Multichannel DVB-streaming allows for us to lose the extra settop-boxes and pay-tv-access-cards necessary if DVB-pay-tv is to be viewed on several TVs in the house. We need only one card and one receiver to allow all clients to see all programs at all times. Just like on oldtimes analog cable tv in-house-antenna-networks.

Looks nice.
What if the programs are placed on 2 or more MUX'es ?
If one should buy a media player like Popcorn Hour C-200, which protocols are the streaming ?

[sidereal]

Brilliant idea mafiltenborg !! I really like the sound of this and it sounds emminently feasible too.
They could start with just a few drivers for popular/cheap USB DVT sticks and go from there.

Synology could really add even more value to thir NAS boxes..

[mafiltenborg]

Looks nice.
What if the programs are placed on 2 or more MUX'es ?
If one should buy a media player like Popcorn Hour C-200, which protocols are the streaming ?

I believe DVblast is designed to stream from one tuner device.
One tuner device can only tune to one frequency at a time - meaning only one MUX can be received at any given time. One MUX holds a number of channels (hence the name MUX: multiplex...)
If N MUXes are to be received, N tuners are needed. Luckily, USB devices coexist happily.
Assuming that several instances of DVblast can coexist, each grabbing data from a designated tuner device, they can independently dump their data to the nic. Observe that this kind of data is one-way, meaning no handshaking, no peering/management and no load scaling takes place. the nic just hammers out bucketloads of multicast packets for anyone to pick up and consume. That's the beauty of UDP/RTP/multicasting on lan; clients just pick up packets emanating from whatever [MUX/tuner/DVblast instance/Multicast] stream providing their tv-program of choice, decode the video+audio and put it onto local UI. It's possible. I've done it with one MUX and see no reason why several simultaneous instances should be a problem. Multitasking.
Example: In your area there may be two MUXes available. MUX1 distributes 5 channels, MUX2 distributes 10 channels. Get hold of two tuners, hook one into MUX1, the other into MUX2 and stream 10+5 channels onto LAN. Perfect for e.g. a dorm. I'm not sure about the details, but it should be doable.

About protocols: I don't know what to tell you there. Assuming this is done using VLC tools, one can go have a look at how VLC distributes data. Keywords like UDP, RTP and multicast spring to mind. Also, stream content is clearly MPEG2/4 inside some sort of mux-scheme. AFAIK it's standardized - i recall having used Windows Mediaplayer as client, and also have a vague idea about Winamp being able to do the trick. Perhaps also the C200 knows how? For fun, you could try multicasting something at home, then see if your favorite toy or the wife's laptop can pick up the data. Just pick a windowsbox, a DVD, a recent version of VLC and combine. In case you FUBAR, i'll be happy to provide a tiny tutorial right here

Info link: http://en.wikipedia.org/wiki/IP_multicast

These VLC guys have a real big bag of tricks. Most people know VLC only as a content player, but playing multimedia is only the tiniest tip of the iceberg. It works as a server, it integrates into webpages, it transcodes, it can be controlled via web, telnet and the list goes on... Try taking a tour in the feature matrix on VLCs homepage and have a pleasant surprise. It's simply mindboggling!
- and they have sourcecode, just waiting to be picked up and tinkered with

Nudge-nudge, synology folks...

[mafiltenborg]

Synology could really add even more value to thir NAS boxes..

Yup! This - not being a minor thing like adding tickbox X to feature Y - is of course harder to implement. But look at the market; TV networks going digital, DLNA becoming mainstream, NAS'es doing multimedia distribution on LAN, LANs getting faster and functionally relevant software becoming available for free - to me, this cries 'COMBINE!'

And in my humble opinion, Synology is in a perfect position to blow the market sky high with this idea. Really piss off some of the DVD/Harddisk-recorder manufacturers...

[mafiltenborg]

This morning I ssh'ed into my DS to take a look around and see what was inside the thing. Which kind of Linux was it? Was there a software management framework i could access? What tools were already onboard?

Well... Not much. No luck in trying to execute dpkg, gcc, mc or most of my other favourite tools. As expected. So i took the manual tour round the directory tree, looking for 'good stuff'. Guess what I found...

vlc, ffmpeg, mplayer and a few other odds and ends, just waiting to be run. Finding vlc makes me think i may be able to stream/multicast video content without having to install a thing! Not TV, mind you - just the ordinary DVD image or similar stuff. But this will prove the concept functional on actual hardware in a real life situation.

Perhaps i'll tinker a bit with this over the weekend...

[Christian_IA]

This morning I ssh'ed into my DS to take a look around and see what was inside the thing. Which kind of Linux was it? Was there a software management framework i could access? What tools were already onboard?

Well... Not much. No luck in trying to execute dpkg, gcc, mc or most of my other favourite tools. As expected. So i took the manual tour round the directory tree, looking for 'good stuff'. Guess what I found...

vlc, ffmpeg, mplayer and a few other odds and ends, just waiting to be run. Finding vlc makes me think i may be able to stream/multicast video content without having to install a thing! Not TV, mind you - just the ordinary DVD image or similar stuff. But this will prove the concept functional on actual hardware in a real life situation.

Perhaps i'll tinker a bit with this over the weekend...

Sound very promising, I'm waiting the answer with a lot of excitment