I would like to know if is, there any STM32 MCU capable of receiving a video signal via I2C and sending it to an SDI video chip to convert to SDI format?

[mdhebling]

I ask because I'm starting the project of a converter that receives the video signal via optical fiber and converts it to an SDI output.

[Tesla DeLorean]

I2C ? That seems contrived..

[mdhebling]

Tesla DeLorean, It isn't contrived!

The fiber optical transceiver that is delivered for us has I2C communication protocol output.

My doubt doesn't about I2C protocol but how I can use the SMPTE protocol with STM32 MCU or MPU.

I wrote two posts with the same doubt only why I'm respect the diferences betwen famylies ST and too I'm a new member in this comunity...

[Peter BENSCH]

The doubts of @Community member​ were certainly due to the fact that insufficient information was initially provided. When talking about fiber optic, one typically has data rates of several Gbit in mind. However, there are indeed fibre optic transceivers for I2C coupling.

Nevertheless, "video signal" and I2C don't really match, because I2C normally works with 400kHz, in Fast Mode also with 1MHz, the fibre optic transceivers I saw so far only with 350kHz. With such small frequencies you can't transmit video signals in a meaningful way, because that would be like squeezing 100 trucks side by side and parallel on a normal motorway.

What is the specification of your video signal?

Regards

/Peter

[Tesla DeLorean]

"Serial digital interface (SDI) is a standard for digital video and audio transmission over coaxial or fiber optic cabling. Speeds currently range from 270 megabits per second (Mbps) up to 12 gigabits per second (Gbps) for the latest standard released in 2015."

So you see my problem here is about 3 orders of magnitude, the only use of I2C would be tangential, ie you monitor or direct the flow of the fire-hose, you're definitely not going to be able to drink from it, let alone act on it, or forward it.

I don't see any of the STM32 range being able to Input then Output at these rates, in fact I'd imagine most solutions would keep this in hardware domain with some kind of continuous flow thru model or pipeline.

[PatrickF]

Hi @mdhebling​ ,

I could assume your optical transceiver may have a ethernet interface such as RGMII + an I2C for link control. This is probably supported with Linux with STM32MP15x device.

Then, as I understand the video source come from fiber optic, it is unclear what is the destination of your video stream, but depending on video overall pixel/rate, it is probably possible to display it on LTDC/DSI or to store it on Linux Filesystem (in a compressed format).

But anyway, the STM32MP15x has no HW accelerators for video, so most processing should fit in SW which mean do not expect HD video quality..

Maybe look at following wiki pages

https://wiki.st.com/stm32mpu/wiki/DRM_KMS_overview

https://wiki.st.com/stm32mpu/wiki/GStreamer_overview

https://wiki.st.com/stm32mpu/wiki/How_to_stream_camera_over_network

Regards.

[mdhebling]

@Peter BENSCH​ thank you for answer my question.

Answer your question, the specification of my video signal is based on SMPTE 297 protocol.

Basically my converter will receive the video signal by optical fiber and convert to SDI video standard. The video signal that will be received is provenience at video camera professional with optical fiber output, but other equipment used in the studio works with the SDI video input/output.

I need to know if ST has any chip that I can use with the optical fiber transceiver preprogrammed with the SMPTE 297 protocol to do the video conversion.

I'm talking with the some suppliers of optical fiber transceiver to understand how to work the communication betwen optical transceiver and microcontroller.

[mdhebling]

@Community member​ I believe that I not supplied, initially, sufficient information to you help me, please forgive me.

If you have any suggestion, please inform me.

Thanks

[Peter BENSCH]

As far as I know, SMPTE 297 is not a protocol, but only defines fibre optics as a transport medium. Other SMPTE standards then define the data rate at which transmission takes place, e.g. SMPTE 424M with 2.97Gbps. In any case, this is about a factor of 300...3000 above what I2C can do. I also assume that you have confused something.

STMicroelectronics does not have a ready-made chip for converting such amounts of data in its portfolio.

Regards

/Peter

[Tesla DeLorean]

I'm not sure of the direct suitability of the STM32 parts MCU or MPU

I'd expect you'd need some hardware that had at least one of the data formats supported natively, and optimally both. Several of them support DSI video output, sort of thing mapping to DVI or HDMI, or directly into LCD panels. Here the bandwidth is relatively constrained too, basically a 2-Lane DSI (1Gbps, or perhaps 1.5 Gbps on an MPU, as I recall). About 1000x800 type ceiling, and below HD for sure.

There typically isn't bandwidth, or hardware assistance, to do much of anything, so no good support for filtering or scaling. I don't think any of these support STB (set top box / player) applications. ST has historically had some business in that space, but it tends to be a very closed and secretive domain, and certainly a patent and licencing minefield.

There's perhaps several of the MCU which could take a care-taker role where it's not directly touching the video stream/path, but I'd also expect SoC integration would tend to bring that into those devices directly.

I'd perhaps look at offerings from TI, Broadcom, Marvell, Qualcomm, Intel, etc. And what their reference designs tend to bolt together, and control things with.