Wireless HD video and audio transmission using video senders, digest - spring'12
Dear friends, as planned, I continue the series of articles in 2012 (the first ) about current technologies and equipment for wireless HDMI transmission and high-quality audio-video signal.
In this part, we will focus on the so-called video senders (see the detailed definition in one of the articles ), and if you are too lazy to follow the link, here’s a general scheme for all video senders (light box - transmitter (transmitter), dark - receiver (receiver) ):
So, the fact that a video sample is a set of a receiver and a transmitter that mimic a cable for transmitting video and sound, I think everyone understands from the diagram. Since the most common hardware HD transmission interface is HDMI , in fact, we will talk about its possible wireless implementations . Naturally, strong encryption is used in all standards, so I’m not going to even mention it later.
')
The purpose of this article is to tell about the peculiarities of interaction within the sets, built according to different wireless standards, as well as to outline and convey to the reader the development prospects for each of these standards. As I promised earlier, the last article of the cycle will contain a table comparing the characteristics of all known wireless standards for HD transmission.
Yes, and also, a small disclaimer: if the kit contains a “whistle” for a computer that transmits a signal to the receiver using a special wireless standard, as well as if this “whistle” is already built into a PC (this can also be a Wi-Fi card on any something special chip, or a card of another wireless standard), then it cannot be called a video sender, since the full hardware imitation of the AV cable does not occur, and software is used for transmission, thanks to which the signal is broadcast.
Let's start with the traditionally considered first, ultra-wideband Wireless HD standard, which, relatively recently, joined forces with the WiGig alliance to create a wireless multi-gigabit standard.
The company that invented WirelessHD and manufactured chips is called SiBEAM, it was founded by people from Berkeley in 2001. In 2011, SiBEAM was absorbed by the infamous chipmaker Silicon Image. Since then, Sil has been promoting the industry standard.
Once,even before the word “Tandem” appeared in 2007, WirelessHD (based on ieee802.15.3) appeared to meet the growing need for transmitting a high-quality (HD) signal to a television set. In 2009, however, the largest manufacturers scratched their turnips and created the WirelessGigabit alliance, correctly assuming that Wi-Fi speeds will soon become scarce. In fact, under the WiGig were created ieee802.11ac / ad (see detailed article from wiNIKA ), which allow you to "shake" the old-good 802.11a / b / g / n by 2.4 and 5 GHz (802.11ac), and combine it with multi-gigabit 60GHz monster (802.11ad) in ramakh of one standard.
It is not surprising that later WirelessHDmerged in ecstasy and joined WiGig, as the latter began to cover tasks and is very similar in principle to WiHD. Thus, we simplify the formula to the banal Wi-Fi + WirelessHD = WiGig .
The WirelessHD standard is built on ultra-wideband broadcasting, which allows it to transmit zeroes and ones at speeds up to 7 Gbit / s (and drive FullHD 3D 7.1 without compression and delay), but only in direct line of sight. Such a wide band cannot be “dragged” through the wall. But she copes well with small obstacles - furniture, people, animals; which technology allows to "intelligently bend around."
Returning to our sheep: unfortunately, little has been heard about WirelessHD video senders lately. They reached a certain level - FullHD 1080p @ 60Hz, 3D and 7.1 sound, and all this without compression and delay, but it seems that the inability to transmit through the wall and the bulkiness of the transmitter (at least 6, even the built-in antennas) do not give proper demand on the development of technology in terms of video senders.
Although their website contains encouraging news about the release of the new version of the standard - WirelessHD 1.1, with support for speeds of 10-28 Gbit / s, built-in antennas for mobile equipment, 4K x 2K resolution and an independent data channel - 1 Gbit / s, but about new iron is not heard at all.
However, work in the WiGig camp is boiling, from fresh - a prototype of an SD card with a WiGig adapter .
The latest news about the next WirelessHD sender (more than a year ago) - video socket Rocketfish ;
VideoHand WirelessHD clearly .
The next client, traditionally WHDI. Created by Israeli firm Amimon, based on powerful MIPS chips with original firmware for HD transmission. It operates at a frequency of 5Ghz according to the principles similar to 802.11a / n, but much faster - a wireless channel of 3 Gbit / s. In order not to quarrel with Wi-Fi slowly hanging out at 5Ghz, MIMO + OFDM technology and time slots are used, which allow not interfering with WHDI and Wi-Fi to work with each other.
The current version of WHDI allows transmitting FullHD 1080p @ 60Hz with 3D and multichannel audio (HDMI 1.4 simulation) through walls, with a transmission delay of less than 1 millisecond (less than LCD monitors) and with forwarding of the IR port and USB-HID.
What do the last spells mean? Probroka IR port allows you to transmit signals from your remote to the signal source. Roughly speaking, you connected the receiver to the TV, and in another room you have a satellite receiver to which the transmitter is connected. You click the remote from the satellite receiver to the receiver, which, in turn, transmits it to another room to the transmitter and from the transmitter the IR-eye looks at the satellite receiver and controls it. The original IR signal is transmitted through the channel of the video sender.
USB-HID is about the same as the infrared override, by connecting the transmitter to a computer with an additional (besides HDMI) USB cable, control this PC using a keyboard and mouse (HID device) connected to the receiver. Roughly speaking, your TV has a receiver, a keyboard and a mouse are connected to it and you see / hear a signal from a computer and can control it.
WHDI does not use compression as such, but there is a special, patented technology, Video Modem , which allows you to transmit a signal even in conditions of strong interference and a significant reduction in bandwidth. Read about WHDI old, but a good article in Russian can be here .
Currently there are two WHDI designs:
Full - fledged transmitter and receiver are about the size of a router, but without an antenna, there are 5-6 of them and they are built in, the connection operates up to 30 meters with the overcoming of capital obstacles;
Compact (so-called Stick) , 2-3 built-in antennas, a transmitter a little more than a USB stick, the receiver is a little more than a computer mouse, both can be powered not only from the outlet, but also from any USB port. Transmits to 10-15 meters with overcoming non-capital obstacles.
Today, WHDI is one of the most promising standards, as confirmed by major manufacturers, a la Asus, HP, Belkin, PowerColor, KFA2, etc., which produce WHDI kits under their brands. It is also worth noting LG, which has already introduced a TV with a built-in WHDI module (as well as many other monsters in the industry), as well as Lenovo, which released a seven-inch Android tablet with an integrated WHDI module. Video with the latest WHDI and tablet demonstration at CES2012 can be viewed here .
WHDI plans are to reduce power consumption, support for simultaneous broadcasting by one transmitter to several receivers, support for 4K x 2K resolution, a wireless channel for transmitting data and combining WHDI and Wi-Fi into a single chip.
To date, there are video senders that are successfully used to transmit wireless HDMI, it would seem, not specifically for this purpose intended Wi-Fi. However, such kits have their advantages, not rarely dominating the disadvantages.
First of all, I will refer you again to the first article of digest'12. There are many and (I hope) clearly described the advantages and disadvantages of Wi-Fi, as the transport of video and sound without wires. Despite the fact that in this material, the transmitter is a Wi-Fi card built into the computer / smartphone, the principles are the same, only in cases with independent video tenders, you need more hardware.
So, thesis:
Features of the use of Wi-Fi in HD video providers:
Now to the specifics (by the way, I’ll send another useful article on the topic ): almost all of today's Wi-Fi video senders have LAN / PLC origin: originally HD stream was pressed by a codec to drive it over the wires from the TCP / IP layer. When Wi-Fi 802.11n appeared, which, in fact, began to cover the 100-megabit barrier, the same technologies “crawled” onto new rails.
The most interesting thing is that after compression, the HD stream requires a band no more than 50 Mbps, well-known ip-technologies are also successfully used here: rtp / rtsp , and Quality of Service (notorious, always disabled in the QoS protocol list), and UDP and so on
Due to the full "standard" and many years of knowledge of Wi-Fi from all sides, these senders successfully compete in overcoming distances and obstacles with specialized standards created exclusively for wireless transmission of HDMI. The distance can be covered up to 40 meters, and the obstacles are stitched, even being capital and in the amount of several pieces.
But you can still unscrew the screws, climb inside the transmitter, there with the miniPCIe Wi-Fi card, remove the wiring on a standard antenna and screw the reinforced ...
There are 2 original manufacturers of reference iron: Itrio, the Koreans, still sell their famous videosender worldwide, even 2008-2009 of release, under different brands - Eminent, IOGear, Peerless and others. What’s great in the bundle is that it contains both HDMI and VGA / component and even composite and stereo-jack connectors. A kind of "Swiss Knife":
Since the model is already relatively young, hence HDMI support is only 1.3, which does not detract from all the advantages of FullHD, but saddens with the lack of 3D. Also, a single-core chip inside wakes up / depresses more slowly than we would like - a transfer delay of 40-50ms (which, in general, is quite acceptable even for games, although not desirable).
The second manufacturer, Cavium, presented its latest variation of the video provider relatively recently - at the end of 2010. They called this technology (HD transmission over Wi-Fi) the word WiVu, and chips, dual-core Arm'y with hardware support for H.264 - PureVu. (Although in 2009 this technology was called NetHD and was focused on HD transmission, as already mentioned earlier, via LAN and PLC). By the way, Linux is used as a platform for working with iron, and almost the entire opensource base / kitchen for compiling firmware can be downloaded from the manufacturers resources.
This devil-machine, due to all the power enclosed under its hood, easily transmits HDMI version 1.4a, with all 3D modes and with a reduced delay of 20ms compared to Itrio (my first LCD monitor had a delay, it seems 16ms For Windows ME, this was perfectly acceptable;)). Also, there is a trace of the IR signal, USB keyboards, mice, joysticks, support for FullHD encrypted transmission and a 3D signal from the transmitter at the same time for 4 receivers.
The reference design looks like this - a brochure .
The WiVu-based kit, already released and quite popular among such devices, is actiontec mywirelesstv ( flash presentation , firmware sources ). By the way, mywirelesstv received at CES'12 an award for design and a successful engineering solution.
On prospects - as I wrote earlier, recently Cavium announced a strategic partnership with Qualcomm and Intel. With Qualcomm, work will be aimed at creating a WiVu-based Wi-Fi Display standard, while with Intel, cooperation will be in the production of WiDi receivers. So we expect the next stage of the integration of these technologies into modern devices. (The temp sets HTC with its latest, ready-made implementation of MediaLink )
PS: As an experienced geek, I have some religious prejudices regarding the use of Wi-Fi video senders:
Well, I can’t accept the fact that, already having my own Wi-Fi adapter, my PS3 itself is as powerful as its eight-core core, or a three-core PowerPC 360th Xbox with a powerful video card, or, moreover, A PC with a multi-core processor (in which intel WiDi is already built-in ), they use two (!) (Receiver and transmitter) boxes with Linux for transmitting video and sound to TV, comparable in power to a dual-core Andriod-smartphone. This is akin to if some technologists would have released a super-duper flat screwdriver with adjustable spline width in all dimensions and hydraulic boosters on horse-drawn thrust, and positioned it as a unique device for loosening the cross bolts and screws. This feeling does not leave me ...
Today everything has turned out a lot again, and who has come to here, and even find the strength to leave a practical comment - I admire! And in order to support your spirit of young wrestlers with wires, I will say that I wrote the article for almost a week, in several approaches, and the material for it accumulated in general for years, so you only got the most precious squeeze, without tinsel.
As always, we indicate in the comments whether it is necessary to further develop the topic.
In this part, we will focus on the so-called video senders (see the detailed definition in one of the articles ), and if you are too lazy to follow the link, here’s a general scheme for all video senders (light box - transmitter (transmitter), dark - receiver (receiver) ):
So, the fact that a video sample is a set of a receiver and a transmitter that mimic a cable for transmitting video and sound, I think everyone understands from the diagram. Since the most common hardware HD transmission interface is HDMI , in fact, we will talk about its possible wireless implementations . Naturally, strong encryption is used in all standards, so I’m not going to even mention it later.
')
The purpose of this article is to tell about the peculiarities of interaction within the sets, built according to different wireless standards, as well as to outline and convey to the reader the development prospects for each of these standards. As I promised earlier, the last article of the cycle will contain a table comparing the characteristics of all known wireless standards for HD transmission.
Yes, and also, a small disclaimer: if the kit contains a “whistle” for a computer that transmits a signal to the receiver using a special wireless standard, as well as if this “whistle” is already built into a PC (this can also be a Wi-Fi card on any something special chip, or a card of another wireless standard), then it cannot be called a video sender, since the full hardware imitation of the AV cable does not occur, and software is used for transmission, thanks to which the signal is broadcast.
Let's start with the traditionally considered first, ultra-wideband Wireless HD standard, which, relatively recently, joined forces with the WiGig alliance to create a wireless multi-gigabit standard.
WirelessHD / WiGig
The company that invented WirelessHD and manufactured chips is called SiBEAM, it was founded by people from Berkeley in 2001. In 2011, SiBEAM was absorbed by the infamous chipmaker Silicon Image. Since then, Sil has been promoting the industry standard.
About the WirelessHD and WiGig relationship
Once,
It is not surprising that later WirelessHD
The WirelessHD standard is built on ultra-wideband broadcasting, which allows it to transmit zeroes and ones at speeds up to 7 Gbit / s (and drive FullHD 3D 7.1 without compression and delay), but only in direct line of sight. Such a wide band cannot be “dragged” through the wall. But she copes well with small obstacles - furniture, people, animals; which technology allows to "intelligently bend around."
Returning to our sheep: unfortunately, little has been heard about WirelessHD video senders lately. They reached a certain level - FullHD 1080p @ 60Hz, 3D and 7.1 sound, and all this without compression and delay, but it seems that the inability to transmit through the wall and the bulkiness of the transmitter (at least 6, even the built-in antennas) do not give proper demand on the development of technology in terms of video senders.
Although their website contains encouraging news about the release of the new version of the standard - WirelessHD 1.1, with support for speeds of 10-28 Gbit / s, built-in antennas for mobile equipment, 4K x 2K resolution and an independent data channel - 1 Gbit / s, but about new iron is not heard at all.
However, work in the WiGig camp is boiling, from fresh - a prototype of an SD card with a WiGig adapter .
The latest news about the next WirelessHD sender (more than a year ago) - video socket Rocketfish ;
VideoHand WirelessHD clearly .
Virtues
- The fastest wireless channel;
- No compression is used.
disadvantages
- Works only in the line of sight;
- Bulky blocks due to antenna array.
WHDI
The next client, traditionally WHDI. Created by Israeli firm Amimon, based on powerful MIPS chips with original firmware for HD transmission. It operates at a frequency of 5Ghz according to the principles similar to 802.11a / n, but much faster - a wireless channel of 3 Gbit / s. In order not to quarrel with Wi-Fi slowly hanging out at 5Ghz, MIMO + OFDM technology and time slots are used, which allow not interfering with WHDI and Wi-Fi to work with each other.
The current version of WHDI allows transmitting FullHD 1080p @ 60Hz with 3D and multichannel audio (HDMI 1.4 simulation) through walls, with a transmission delay of less than 1 millisecond (less than LCD monitors) and with forwarding of the IR port and USB-HID.
What do the last spells mean? Probroka IR port allows you to transmit signals from your remote to the signal source. Roughly speaking, you connected the receiver to the TV, and in another room you have a satellite receiver to which the transmitter is connected. You click the remote from the satellite receiver to the receiver, which, in turn, transmits it to another room to the transmitter and from the transmitter the IR-eye looks at the satellite receiver and controls it. The original IR signal is transmitted through the channel of the video sender.
USB-HID is about the same as the infrared override, by connecting the transmitter to a computer with an additional (besides HDMI) USB cable, control this PC using a keyboard and mouse (HID device) connected to the receiver. Roughly speaking, your TV has a receiver, a keyboard and a mouse are connected to it and you see / hear a signal from a computer and can control it.
WHDI does not use compression as such, but there is a special, patented technology, Video Modem , which allows you to transmit a signal even in conditions of strong interference and a significant reduction in bandwidth. Read about WHDI old, but a good article in Russian can be here .
Currently there are two WHDI designs:
Full - fledged transmitter and receiver are about the size of a router, but without an antenna, there are 5-6 of them and they are built in, the connection operates up to 30 meters with the overcoming of capital obstacles;
Compact (so-called Stick) , 2-3 built-in antennas, a transmitter a little more than a USB stick, the receiver is a little more than a computer mouse, both can be powered not only from the outlet, but also from any USB port. Transmits to 10-15 meters with overcoming non-capital obstacles.
Today, WHDI is one of the most promising standards, as confirmed by major manufacturers, a la Asus, HP, Belkin, PowerColor, KFA2, etc., which produce WHDI kits under their brands. It is also worth noting LG, which has already introduced a TV with a built-in WHDI module (as well as many other monsters in the industry), as well as Lenovo, which released a seven-inch Android tablet with an integrated WHDI module. Video with the latest WHDI and tablet demonstration at CES2012 can be viewed here .
WHDI plans are to reduce power consumption, support for simultaneous broadcasting by one transmitter to several receivers, support for 4K x 2K resolution, a wireless channel for transmitting data and combining WHDI and Wi-Fi into a single chip.
Virtues
- A fairly fast wireless channel, respectively, does not use compression, no delay (1ms can be neglected);
- It supports the highest possible HD quality (with the exception of 4K x 2K, which was just born) and the functions of the IR and USB forwarding;
- Overcoming walls and the ability to use a compact design;
- The ability to use multiple transmitters with one receiver (alternately).
disadvantages
- Powered by a frequency of 5Ghz, which could potentially interfere with transmission in the extreme spectrum overflow;
- Embedded solutions and mobile devices require a separate WHDI module, in addition to Wi-Fi, until a combo is released.
Wi-Fi
To date, there are video senders that are successfully used to transmit wireless HDMI, it would seem, not specifically for this purpose intended Wi-Fi. However, such kits have their advantages, not rarely dominating the disadvantages.
First of all, I will refer you again to the first article of digest'12. There are many and (I hope) clearly described the advantages and disadvantages of Wi-Fi, as the transport of video and sound without wires. Despite the fact that in this material, the transmitter is a Wi-Fi card built into the computer / smartphone, the principles are the same, only in cases with independent video tenders, you need more hardware.
So, thesis:
Features of the use of Wi-Fi in HD video providers:
- Wi-Fi has a bandwidth limit of 300-400 megabits (802.11n, of course);
- To fit in such a band, the HD signal needs to be compressed (H.264 is mainly used);
- As for compressing content during transmission, and for releasing during reception, power and time are needed;
- The result is powerful, sometimes dual-core (!) Processors at the heart of Wi-Fi kits;
- Another result is a delay; time required for compression - from 20 to 50 ms;
- The ubiquity of Wi-Fi and H.264 makes production quite economical.
Now to the specifics (by the way, I’ll send another useful article on the topic ): almost all of today's Wi-Fi video senders have LAN / PLC origin: originally HD stream was pressed by a codec to drive it over the wires from the TCP / IP layer. When Wi-Fi 802.11n appeared, which, in fact, began to cover the 100-megabit barrier, the same technologies “crawled” onto new rails.
The most interesting thing is that after compression, the HD stream requires a band no more than 50 Mbps, well-known ip-technologies are also successfully used here: rtp / rtsp , and Quality of Service (notorious, always disabled in the QoS protocol list), and UDP and so on
Due to the full "standard" and many years of knowledge of Wi-Fi from all sides, these senders successfully compete in overcoming distances and obstacles with specialized standards created exclusively for wireless transmission of HDMI. The distance can be covered up to 40 meters, and the obstacles are stitched, even being capital and in the amount of several pieces.
But you can still unscrew the screws, climb inside the transmitter, there with the miniPCIe Wi-Fi card, remove the wiring on a standard antenna and screw the reinforced ...
There are 2 original manufacturers of reference iron: Itrio, the Koreans, still sell their famous videosender worldwide, even 2008-2009 of release, under different brands - Eminent, IOGear, Peerless and others. What’s great in the bundle is that it contains both HDMI and VGA / component and even composite and stereo-jack connectors. A kind of "Swiss Knife":
Since the model is already relatively young, hence HDMI support is only 1.3, which does not detract from all the advantages of FullHD, but saddens with the lack of 3D. Also, a single-core chip inside wakes up / depresses more slowly than we would like - a transfer delay of 40-50ms (which, in general, is quite acceptable even for games, although not desirable).
The second manufacturer, Cavium, presented its latest variation of the video provider relatively recently - at the end of 2010. They called this technology (HD transmission over Wi-Fi) the word WiVu, and chips, dual-core Arm'y with hardware support for H.264 - PureVu. (Although in 2009 this technology was called NetHD and was focused on HD transmission, as already mentioned earlier, via LAN and PLC). By the way, Linux is used as a platform for working with iron, and almost the entire opensource base / kitchen for compiling firmware can be downloaded from the manufacturers resources.
This devil-machine, due to all the power enclosed under its hood, easily transmits HDMI version 1.4a, with all 3D modes and with a reduced delay of 20ms compared to Itrio (my first LCD monitor had a delay, it seems 16ms For Windows ME, this was perfectly acceptable;)). Also, there is a trace of the IR signal, USB keyboards, mice, joysticks, support for FullHD encrypted transmission and a 3D signal from the transmitter at the same time for 4 receivers.
The reference design looks like this - a brochure .
The WiVu-based kit, already released and quite popular among such devices, is actiontec mywirelesstv ( flash presentation , firmware sources ). By the way, mywirelesstv received at CES'12 an award for design and a successful engineering solution.
On prospects - as I wrote earlier, recently Cavium announced a strategic partnership with Qualcomm and Intel. With Qualcomm, work will be aimed at creating a WiVu-based Wi-Fi Display standard, while with Intel, cooperation will be in the production of WiDi receivers. So we expect the next stage of the integration of these technologies into modern devices. (The temp sets HTC with its latest, ready-made implementation of MediaLink )
Advantages (with an asterisk in the beginning - applies only to Cavium-based)
- Very far and armor-piercing;
- * Support for the latest version of HDMI with 3D FullHD, probroska USB;
- The function of the transmission of the IR signal and support for 4 receivers simultaneously;
- * Ability to use multiple transmitters with one receiver (alternately);
- Because of the standard components, you can interfere with the iron / software and pick something up there;)
disadvantages
- Potentially, the quality of the transmission may be reduced due to the littered Wi-Fi spectrum;
- Compression is used, which requires powerful and non-compact equipment;
- Due to compression, there is a transmission delay of 20ms or more.
PS: As an experienced geek, I have some religious prejudices regarding the use of Wi-Fi video senders:
Well, I can’t accept the fact that, already having my own Wi-Fi adapter, my PS3 itself is as powerful as its eight-core core, or a three-core PowerPC 360th Xbox with a powerful video card, or, moreover, A PC with a multi-core processor (in which intel WiDi is already built-in ), they use two (!) (Receiver and transmitter) boxes with Linux for transmitting video and sound to TV, comparable in power to a dual-core Andriod-smartphone. This is akin to if some technologists would have released a super-duper flat screwdriver with adjustable spline width in all dimensions and hydraulic boosters on horse-drawn thrust, and positioned it as a unique device for loosening the cross bolts and screws. This feeling does not leave me ...
Today everything has turned out a lot again, and who has come to here, and even find the strength to leave a practical comment - I admire! And in order to support your spirit of young wrestlers with wires, I will say that I wrote the article for almost a week, in several approaches, and the material for it accumulated in general for years, so you only got the most precious squeeze, without tinsel.
As always, we indicate in the comments whether it is necessary to further develop the topic.
Source: https://habr.com/ru/post/139220/
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