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  1. I want to add IPTV system to my WISP network. I want to rebroadcast free-to-air channels from about 16 satellite transponders over my internet network to each of my customers, I will supply them with a set-top-box which they will plug into the router i have already supplied them, and plug their TV into a HDMI socket on the STB. I thought I had cracked it, when I found the product from TBSDTV, namely the TBS2951 + 4 x 4 DVB - S2 video input cards. I am currently asking questions on their forum, but seem to have hit a barrier. They new tell me I need to "Transcode" all the channels I will get from the video cards, so as to reduce the bandwidth used by each channel, down to a manageable level. What they have not told me is where this transcoding takes place? before or after the TBS2951?. My questions are, what software do I use for this transcoding? they have said it uses a lot of processing power, so what CPU, memory etc do people recommend? What format should the transcoded signal end up in?

    I am not looking to do VOD or rewind TV or anything fancy. Plus I am not looking for HD quality picture. I have about 100 customers who may take up the service, if I get it going, so what sort of bandwidth will be running around my network for all the channels? and how much bandwidth will the TV take up going to each customer?

    Thanking you in anticipation.
    Mark
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  2. Allow me to do some calculation for you: single transponder in DVB-S2 (depends on modulation and remain parameters) offer approx 52 - 54 Mbps, so 16 transponders will require approx 832 - 864Mbps sustained troughtput - this can be challenging even for wired Gigabit Ethernet.
    My professional experience with WLAN lead me to conclusion that this is highly unrealistic expectation unless you begin to distribute WLAN signal over coax to every customer...
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  3. Member Bernix's Avatar
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    You mentioned 100 customers. How far is farthest one ?
    I wrote lot's of row of text but deleted it. About server real time transcoding 24/7 from 264 to 264 lower quality more customers etc .
    So I am just curious about this one question.
    Video Avidemux, Mkvtoolnix, Subtitle edit, Vidcoder. Other software that I love :Animation: Opentoonz, Painting: Krita, Video capture: OBS studio, Video player: Potplayer, TV recording: VLC, NLE: KDEnlive
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  4. Originally Posted by pandy View Post
    Allow me to do some calculation for you: single transponder in DVB-S2 (depends on modulation and remain parameters) offer approx 52 - 54 Mbps, so 16 transponders will require approx 832 - 864Mbps sustained troughtput - this can be challenging even for wired Gigabit Ethernet.
    My professional experience with WLAN lead me to conclusion that this is highly unrealistic expectation unless you begin to distribute WLAN signal over coax to every customer...
    Thanks Pandy. Yes, 800Mb is more than we can deal with, along side our normal internet traffic. I could probably allocate 200Mb, so from what you are saying it sounds like we have to reduce our expextations of how many TV channels we can support. Does the transcoding thing not bring the overall bandwidth down?
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  5. Originally Posted by Bernix View Post
    You mentioned 100 customers. How far is farthest one ?
    I wrote lot's of row of text but deleted it. About server real time transcoding 24/7 from 264 to 264 lower quality more customers etc .
    So I am just curious about this one question.
    Furthest one is about 2 miles from its access point, and we can get about 50Mb download speed to them, if we had to.
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  6. Member Bernix's Avatar
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    That is very good.
    Thank you.
    Video Avidemux, Mkvtoolnix, Subtitle edit, Vidcoder. Other software that I love :Animation: Opentoonz, Painting: Krita, Video capture: OBS studio, Video player: Potplayer, TV recording: VLC, NLE: KDEnlive
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  7. Member Bernix's Avatar
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    Here is detailed mediainfo of 1 multiplex with 9 channels, I removed 1 radio station and audios for impaired people. It is SD in with different resolution. But in MPEG2 and with audio mpeg audio codec MP2. With reencoding to h264 aac you can get much smaller file without drop of quality significantly. Duration 1 min 0 sec. I remuxed TS file to MKV so file is about 140-150 MB = cca 20Mb/s
    Here is mediainfo of that file.
    You can notice that station that using variable bitrate, can have peak at 10 Mb/s which can do pretty high bitrate at the moment when peak is reached at same time on several station.
    Don't know if uploaded text file properly. There are also 2 correction in the text file because of ts to mkv conversion.
    Hope it will helpful in some way. But ratio between MPEGv2 and H264 is big, but that is the place you need very powerful conversion "machine"
    Bernix
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    Video Avidemux, Mkvtoolnix, Subtitle edit, Vidcoder. Other software that I love :Animation: Opentoonz, Painting: Krita, Video capture: OBS studio, Video player: Potplayer, TV recording: VLC, NLE: KDEnlive
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  8. Originally Posted by markscotford View Post
    Thanks Pandy. Yes, 800Mb is more than we can deal with, along side our normal internet traffic. I could probably allocate 200Mb, so from what you are saying it sounds like we have to reduce our expextations of how many TV channels we can support. Does the transcoding thing not bring the overall bandwidth down?
    I can imagine for H.264 around 8Mbps for HD and around 2.5Mbps for SD - quality should be acceptable close to good.
    I can imagine transcoding with help of existing relatively cheap HW (modern graphic cards are equipped with acceptable quality encoders, some cards like Quadro family from NVidia may support simultaneously few video streams).
    My main concern however is not transcoding but overall signal latency in relatively hostile transmission environment.
    Last regulation substantially reduced WLAN throughput to improve overall interoperability for various RF spectrum users - i doubt that you can efficiently use 5GHz WLAN for large area coverage, so i assume you will be forced to use quite crowdy 2.4GHz spectrum where WLAN is one of few technologies.
    I've spent few years involved in WLAN performance and interoperability testing - i can say that it is difficult to provide sustained bitrate close to half of theoretical (implied by MCS HT, channel width etc) bitrate (bandwidth).
    100 customers, WLAN... maybe you can offer few basic TV channels in HD quality, definitely for 802.11n 60 - 80Mbps is doable.

    You may try to use http://www.avalpa.com/the-key-values/15-free-software/33-opencaster - you should be able made some tests using some streams. Perhaps https://www.videohelp.com/software/Open-Broadcaster-Software will be easier as it should be less "DVB centric" and i assume that maybe DVB compatibility is not your goal.

    btw - with modern CPU you should be able to transcode in RT around 3 - 8 SD streams or 1 - 2 HD simultaneously. For more you should think about something more advanced (and more costly so probably going for cheap PC and hybrid CPU and GPU streams encoding will be more acceptable).
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  9. Member Bernix's Avatar
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    Hi Pandy,
    I thought about GPU encoding too, but not sure about 365/24/7.
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  10. Originally Posted by Bernix View Post
    Hi Pandy,
    I thought about GPU encoding too, but not sure about 365/24/7.
    I made some experiments and seem it is OK - tested NVEnc and Quickvideo on 4k h.265 for more than week non stop - NVEnc overall seem to be more stable in Windows and ffmpeg however Quickvideo for continuous streaming looks also quite OK - tested with looped real video streams (so also decoding was involved) and ffmpeg generated internal synthetic video.

    This one for OP - perhaps this https://tvheadend.org/ can be fine.
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  11. Originally Posted by pandy View Post
    Allow me to do some calculation for you: single transponder in DVB-S2 (depends on modulation and remain parameters) offer approx 52 - 54 Mbps, so 16 transponders will require approx 832 - 864Mbps sustained troughtput - this can be challenging even for wired Gigabit Ethernet.
    My professional experience with WLAN lead me to conclusion that this is highly unrealistic expectation unless you begin to distribute WLAN signal over coax to every customer...
    Pandy, I was at a customers house today who has our internet service (5Ghz backhaul) we throttle bandwidth at customers radio down to 6Mb download. He had (from another company) a MAG 250 STB (Infomir I guess) hooked up to his TV and our router, he gave me a live demonstration of the system. It had 40 plus TV channels with what appeared to be very acceptable picture quality, when I checked what he was pulling, it was about 2.3Mb. I would settle for a system like this, any day of the week, but from all the figures and other stuff being banded about here, I am obviousley out of my depth, so I contacted the company who supplied said STB, and I have done a deal with them to supply me. Shame, as I would have liked to do it myself. Thanks everyone anyway.
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