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Manchester - Local Freeview Multiplex - Information Thread |
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#176 |
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Join Date: Sep 2001
Location: Manchester
Posts: 348
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Quote:
It has nothing to do with technical conditions - this is competition law.
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But for the technical details - try read the Ofcom paper I linked to.
With 4-QAM CR 1/2 or CR 2/3 the signal will be rather robust. It was after all made available and sold in order to replace just one analogue channel (Channel M). Quote:
With DVB-T2 - maybe using the NI RTÉ/TG4 mux 16-QAM CR 1/2 parameters - the signal will be both very robust and have a 15 Mbps capacity, Using DVB-T2 will clearly be within the original ch57 auction/license conditions.
I would think they could 'borrow' channel 56 for maybe 12-18 months for DVB-T/DVB-T2 simulcast using the same TX antenna. Grenada has had DVB-T2 for 2 years now and by mid 2013 DVB-T2 receivers will surely be very common in Manchester. |
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#177 |
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Inactive Member
Join Date: Nov 2011
Posts: 236
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Quote:
Both old and new antenna should be mounted at 140 m AGL (half height) and angeled 5 deg downward. The pictures on MB21 does not look right to me ??
The difference is not as much in the signal strenght at the beams centerline, but the new pattern is wider ~50 deg vs ~30 deg. The 16-QAM CR=3/4 at 1 kW is not a robust signal. The same modulation/FEC was - pre DSO - transmittet at 10kW almost from the top of the mast. A CR=1/2 would have been a much better choice - IMHO. Now, the licence was granted in a auction - and even though there was only one bidder and the minimum price was paid - it will not be easy for Ofcom to add new permanent features to the license without calling for a new auction. Lars ![]() The height is very much more than adequate, even if you factor in Freznal zone clearance for the coverage needed.. The problem is the very poor antenna radiation pattern and low power . The restrictions imposed by the planners detailed on the restriction template simply do not stack up ,even at 1% of the time and factoring in troposcatter ,ducting ,and defraction, in particular with regards to the protection applied towards the Biddulph Relay. The calculations show a worse case scenario , a protection ratio of 40dB at 1% of the time assuming the Biddulph relay is working as it should, this of course is a extra margin of 17dB above 23dB ,if the full power 1kW ERP was allowed to be transmitted in the Biddulph direction. |
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#178 |
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Forum Member
Join Date: Jan 2001
Location: Manchester
Posts: 678
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It appears that all the Movies4Men channels have stopped broadcasting in the last few days, with a message up saying they will return soon. Channel M continues as normal.
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#179 |
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Forum Member
Join Date: Dec 2008
Location: East Midlands
Posts: 5,204
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from the Changelog, for further discussion in this thread: Quote:
The Men and Movies suite of channels which were carried on the Greater Manchester local mux from LCN201 to LCN205 have today been removed from the EPG.
Source: DMOL They had been deactivated ever since Sony Pictures bought the channels owner Dolphin TV a few weeks ago according to reports on this forum. |
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#180 |
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Forum Member
Join Date: Feb 2003
Posts: 1,256
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Confirmed, all the Movies4men channels have vanished as already reported. The mux is still running at QAM16 , FEC 3/4, GI 1/32 and just Channel M appears on 200 now.
If they are going to stay like this for long, I hope they drop back to QPSK for more robust coverage. |
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#181 |
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Join Date: Feb 2003
Posts: 1,256
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With the purchase of a decent proception TV amp from aerialsandtv I've now managed to get a strong Manchester mux signal to the tvcard in my office again, so here's an updated PID scan: Quote:
dvbsnoop V1.4.50 -- http://dvbsnoop.sourceforge.net/ The null data stuffing in PID 8191 is running approx 6790kbit/s at the moment - what a waste!--------------------------------------------------------- Transponder PID-Scan... --------------------------------------------------------- PID found: 0 (0x0000) [SECTION: Program Association Table (PAT)] PID found: 16 (0x0010) [SECTION: Network Information Table (NIT) - actual network] PID found: 17 (0x0011) [SECTION: Service Description Table (SDT) - other transport stream] PID found: 18 (0x0012) [SECTION: Event Information Table (EIT) - other transport stream, schedule] PID found: 20 (0x0014) [SECTION: Time Date Table (TDT)] PID found: 32 (0x0020) [PS/PES: ITU-T Rec. H.262 | ISO/IEC 13818-2 or ISO/IEC 11172-2 video stream] PID found: 33 (0x0021) [PS/PES: ISO/IEC 13818-3 or ISO/IEC 11172-3 audio stream] PID found: 257 (0x0101) [SECTION: Program Map Table (PMT)] PID found: 8190 (0x1ffe) [unknown] PID found: 8191 (0x1fff) [stuffing] Now that the tuner can get a solid lock on Channel M again, I've reactivated the cron scripts so should get alerted by email if any significant changes are detected. If so I'll report them here. |
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#182 |
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Forum Member
Join Date: Jun 2005
Location: Guildford / Crystal Palace
Posts: 13,114
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Quote:
With the purchase of a decent proception TV amp from aerialsandtv I've now managed to get a strong Manchester mux signal to the tvcard in my office again, so here's an updated PID scan:
The null data stuffing in PID 8191 is running approx 6790kbit/s at the moment - what a waste! Now that the tuner can get a solid lock on Channel M again, I've reactivated the cron scripts so should get alerted by email if any significant changes are detected. If so I'll report them here. I would hazard a guess the Channel M mux is now running on QPSK FEC5/6 (10.053Mbps). It used to be QPSK FEC1/2 (6.032Mbps) with just Channel M. If I'm right then signal strength should have improved. |
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#183 |
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Forum Member
Join Date: Feb 2003
Posts: 1,256
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Current parameters as reported by tvcard: Quote:
Frequency: 762000.000 kHz I've had a quick go through all the PIDs grabbing rough average bandwidth values - here goes:Inversion: OFF Bandwidth: 8 MHz Stream code rate (hi prio): FEC 3/4 Stream code rate (lo prio): FEC 1/2 Modulation: QAM 16 Transmission mode: 8k mode Guard interval: 1/32 Hierarchy: none Code:
PID kbit/s 0 8 16 1.5 17 4.8 18 772 20 0.1 32 10230 33 262 257 9.1 8190 39 8191 6780 total: 18106.5 (+/- at least 100) |
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#184 |
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Forum Member
Join Date: Feb 2004
Location: Andover, Hampshire, UK
Posts: 3,624
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Assuming PID 32 is Channel M video, that's probably the highest-bitrate SD channel ever on Freeview - possibly with the exception of The Hits which I believe was at one point (pre-launch) running at around the same.
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#185 |
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Join Date: Jul 2007
Location: London, UK
Posts: 4,751
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lol @ a local channel in SD having a higher bit rate than the national HD channels will have soon.
Actually, no, it's not funny. It's depressing. |
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#186 |
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Inactive Member
Join Date: Nov 2011
Posts: 236
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Quote:
With just one channel and 6.8Mbps of null packets, that implies a multiplex transport stream of ~10Mbps now. It was 18Mbps with the Men&Movies suite (16QAM FEC3/4).
I would hazard a guess the Channel M mux is now running on QPSK FEC5/6 (10.053Mbps). It used to be QPSK FEC1/2 (6.032Mbps) with just Channel M. If I'm right then signal strength should have improved. This will help overcome the very very severe restrictions imposed on Ch M,s digital broadcast , but with some relatively small corrections to the radiation pattern coverage this would improve coverage considerably and with a power increase to 4kW ERP (not a lot) which will not cause any CCI to other broadcasts, 16QAM could then be used with good coverage in particularly in central Manchester. . The problem is of course is if the planning done by the monopoly operators for local telly on behalf of Ofcom does provide for reasonable coverage and local telly can broadcast in 16QAM especially in DVB-T2 mode this provides competition to the monopoly operator. Now we can’t have competition, it just isn’t cricket old boy.. Rigging markets with energy companies ,bankers , utilities ,care homes, etc ,etc just doesn’t happen in good ole blighty after all we have a great big government department called the competition commission to, prevent all that type of stuff from happening. Hhmm wonder what they do all day other than sit on their bums doing nowt. If they woke up and stirred a tad and did a little work , yer never know .we could get lots of local telly stations to be commercial viable and stay in business and provide jobs which results in putting money into the pockets of the 99% . Trouble is the 1% rich folk investment bankers etc ,especially those with corks a dangling from their hats will get a bit miffed if their bonuses are cut back to only a million or two as they may have to give up a little share of the cake to the 99%. |
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#187 |
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Forum Member
Join Date: Jun 2005
Location: Guildford / Crystal Palace
Posts: 13,114
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Quote:
I've had a quick go through all the PIDs grabbing rough average bandwidth values - here goes:
Code:
PID kbit/s 0 8 16 1.5 17 4.8 18 772 20 0.1 32 10230 33 262 257 9.1 8190 39 8191 6780 total: 18106.5 (+/- at least 100) They should switch to QPSK asap & add their radios to the mux. |
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#188 |
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Forum Member
Join Date: Feb 2003
Posts: 1,256
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If I was running the mux and was intending to try to tender out the freshly released bandwidth, I'd leave it running at QAM16 rather than swapping to QPSK and then having to switch back to QAM16 again as soon someone won the tender. If I gave up on finding other channels to subsidise the mux I'd drop back to QPSK for the improved coverage.
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#189 |
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Inactive Member
Join Date: Nov 2011
Posts: 236
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Quote:
If I was running the mux and was intending to try to tender out the freshly released bandwidth, I'd leave it running at QAM16 rather than swapping to QPSK and then having to switch back to QAM16 again as soon someone won the tender. If I gave up on finding other channels to subsidise the mux I'd drop back to QPSK for the improved coverage.
Ch m know what they are doing and I sure they have a good reason running in 16QAM when QPSK has sufficient capacity to carry what content they are currently broadcasting. After all they are the only local telly station in the UK so far operating their own digital TV transmitter , multiplexer ,STL , and combining the EPG into the transport stream. This is despite all the hurdles placed before them, so you have to give them credit were credit is due. Their engineer deserves a big salary increase for overcoming all the many hurdels they had to overcome to get on air. |
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#190 |
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Forum Member
Join Date: Feb 2003
Posts: 1,256
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Please don't misunderstand me, I wasn't having a dig at Channel M. I wish them all the best - and a more powerful transmitter and more new content!
My point was that we could interpret that by leaving the mux in the 18Mb/s QAM16 mode they may now be trying to find some more channels to fill the spare bandwidth. If they drop back to QPSK that could then be a sign that they were no longer looking for more channels. |
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#191 |
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Inactive Member
Join Date: Nov 2011
Posts: 236
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Quote:
Please don't misunderstand me, I wasn't having a dig at Channel M. I wish them all the best - and a more powerful transmitter and more new content!
My point was that we could interpret that by leaving the mux in the 18Mb/s QAM16 mode they may now be trying to find some more channels to fill the spare bandwidth. If they drop back to QPSK that could then be a sign that they were no longer looking for more channels. I am personally really do hope Ch M are eventually a commercial success. I think most people in the industry do realise that local TV is so very important to our society, especially if local telly owns and operates their studios and transmitters and we end up with many local TV stations. If local telly does eventually spread throughout the UK it will help prevent the total domination of our media by current very large media organizations such as News Corp. Recent events have clearly shown in my opinion the low level of integrity when very large organizations sometimes become corrupt with too much power. The Guardian Media group does need a way into successful television other wise it could eventually get squashed by the Murdoch empire. As they own Ch M this is a possible way in to TV media. Those of us in the industry need to do all we can to help and promote Ch M. What does distress me though is the politicians just don’t get it and they continue to do naff all about media domination and also other rigging of markets such as energy and banking. Sorry about the political rant. I will try to refrain in future. |
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#192 |
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Forum Member
Join Date: Sep 2001
Location: Manchester
Posts: 348
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Quote:
As you say very sad: 10Mbps for Channel M & 7Mbps of null packets. It's quite unbelievable that they are still operating in 16QAM. But GMG are not known for their Skilled Management.
They should switch to QPSK asap & add their radios to the mux. It's possible that maximising coverage for Channel M isn't top of GMG priorities at the moment, if indeed it ever has been. Unless you actually have an insight into the running of the business, all you're doing is speculating. Greebo summed it up perfectly, what's the point in flip-flopping between modes if you think you might still need the capacity. |
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#193 |
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Join Date: May 2008
Posts: 3,061
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BBC News Channel (ch 80) on Freeview is looking exceedingly good quality tonight, Tuesday 14th Feb. 7pm ish.
Very sharp and clear pictures, almost looks as if it's in HD, or new HD cameras are being used. Relay transmitter off Winter Hill TX. Looks like something has been upgraded in the broadcast / transmission chain. Standard SD (Non HD) TV 576i SD |
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#194 |
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Forum Member
Join Date: Jun 2005
Location: Guildford / Crystal Palace
Posts: 13,114
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Quote:
Surely if they had the facilities to put the radio stations on, they'd have done it years ago.
It's possible that maximising coverage for Channel M isn't top of GMG priorities at the moment, if indeed it ever has been. Unless you actually have an insight into the running of the business, all you're doing is speculating. Greebo summed it up perfectly, what's the point in flip-flopping between modes if you think you might still need the capacity. |
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#195 |
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Join Date: Sep 2001
Location: Manchester
Posts: 348
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Quote:
They are operating Channel M right next to GMG radio racks IIRC.
That's a lot of money for what probably amounts to very little extra coverage. |
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#196 |
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Join Date: Jun 2005
Location: Guildford / Crystal Palace
Posts: 13,114
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Quote:
Even if they are, I doubt they just happen to contain DVB compatible audio service encoders and an MHEG carousel player. Getting hold of the audio would be the easy part. A Softel mediasphere will set you back about £15k plus the development costs of the MHEG apps and the encoders themselves. I doubt you'd see much change from £40k to put all 3 services on with some element of redundancy.
That's a lot of money for what probably amounts to very little extra coverage.
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#197 |
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Forum Member
Join Date: Sep 2001
Location: Manchester
Posts: 348
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Quote:
In the spirit of Channel M DIY; a Mheg caption is not essential & if they coded 5 Men&Movies audio channels
Every other radio service on Freeview has an MHEG caption including the national Smooth service, so yes, it is essential. To be fair, I hadn't figured the licences into my original figure, so you're probably looking at an additional £5k at least of all of that. |
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#198 |
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Join Date: Jun 2005
Location: Guildford / Crystal Palace
Posts: 13,114
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Quote:
How do you know didn't just remux the M4M services straight off satellite? I certainly wouldn't recompress something that's already only 3Mbit/s, unless you like legovision.
Every other radio service on Freeview has an MHEG caption including the national Smooth service, so yes, it is essential. To be fair, I hadn't figured the licences into my original figure, so you're probably looking at an additional £5k at least of all of that. Only video streams are statistically multiplexed together. So your comments about recompression are off beam wrt radio services. Although all radios on Freeview have a Mheg caption, as I said this is not essential and services have been seen devoid of captions from time to time. 303 is a good example. I think Arqiva tend to regard the captions as part of their service so on their hosted services it is "compulsory". But this would not worry Channel M as they can DIY. ![]() I reckon Channel M could add up to 5 radios for nothing bar the cost of licences and LCN numbers. |
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#199 |
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Forum Member
Join Date: Sep 2001
Location: Manchester
Posts: 348
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Quote:
The vision coding would not be needed for a radio service just an encoder for audio MPEG-2. Even though a Men & Movies MPEG-2 stream was most likely extracted from a 28.2°E satellite feed, it still needs to be multiplexed into the delivered local DVB-T transport stream. Audio services are added in fixed bitrates; a 128kbps joint stereo stream uses about 138kbps of capacity. With GMG radios supplying MPEG-2 streams for DAB there would be no need for Channel M to buy MPEG-2 audio encoders. Similarly the same multiplex inserters that were used for M&M audio could be used for GMG radios.
No Ray, you can't re-purpose a DAB encoder to feed a freeview service. Despite them both being MPEG Layer 2 they're pretty much incompatible at pretty much every level. To my knowledge the Radioscape DAB encoders used don't generate either an RTSP IP stream or an ASI or SMPTE310 compatible data stream. Not that any of that matters as the DAB encoders are supplied by Arqiva as a closed system. The only access the customer has is the audio that goes into them and an interface to update the DLS data. The box itself and the data stream generated are unavailable to the customer. The machines are locked out and connected to a private network connection back to Arqiva. The customer has no way of logging into the machine to change settings and I'd imagine any interception or capture of the data going over Arqiva's private network would place the customer in breach of contract. Even if you wanted to risk it, you'd still have to convert the Radioscape data stream, which could be proprietary, into a DVB compatible MPEG Programme Stream on either a copper ASI or RTSP connection. Quote:
Only video streams are statistically multiplexed together. So your comments about recompression are off beam wrt radio services.
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#200 |
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Forum Member
Join Date: Feb 2004
Location: Andover, Hampshire, UK
Posts: 3,624
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Quote:
No Ray, you can't re-purpose a DAB encoder to feed a freeview service. Despite them both being MPEG Layer 2 they're pretty much incompatible at pretty much every level. To my knowledge the Radioscape DAB encoders used don't generate either an RTSP IP stream or an ASI or SMPTE310 compatible data stream. Not that any of that matters as the DAB encoders are supplied by Arqiva as a closed system. The only access the customer has is the audio that goes into them and an interface to update the DLS data. The box itself and the data stream generated are unavailable to the customer. The machines are locked out and connected to a private network connection back to Arqiva. The customer has no way of logging into the machine to change settings and I'd imagine any interception or capture of the data going over Arqiva's private network would place the customer in breach of contract. Even if you wanted to risk it, you'd still have to convert the Radioscape data stream, which could be proprietary, into a DVB compatible MPEG Programme Stream on either a copper ASI or RTSP connection.
(Only slightly joking - whilst I can see there are problems with this, I also can't see that they wouldn't be able to be overcome them cheaply). |
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