HDMI to LVDS: Searching for Solution

Hi Joshua,

TI has a solution to only convert video-only HDMI into LVDS, supporting HDCP and 24-bit color.  That consists of a DVI receiver device and LVDS transmitter device.

This sounds a little unusual: you start with HDMI and want to connect it to a Blu-ray player; isn't that a direct-connect?  Also, what will the Blu-ray player do with this AV content; perhaps it will send it back out on HDMI output ports?  If that's the case, I'm not sure why it'd be desirable to convert HDMI->LVDS+audio->Blu-ray->HDMI.  Also, does your Blu-ray player really have the capability to receive audio over LVDS?

Thanks,
RE

Hi Ross,

Indeed it is an unusual request.  The problem stems from the fact that it is an automotive request where cable routing is extremely difficult.  Thus, they want to be able to route smaller, twisted pair cables that produce minimal noise.  LVDS fits this requirement. 

We are not concerned about the target, only the input, decryption, and output.  The request seems vague, but I also received it second hand.   We already have a method of handling audio, but the request did not specify if the audio would be transmitted via our implemented method or through the HDMI cable, so I am looking for a solution that supports both just in case.  With the two chip solution, is the audio simply ignored? Is there a possibility of routing the audio to a different chip and processing it there or is it likely that the audio would de-synchronize in that case?

Thanks very much,

Josh.

So the main reason for converting to LVDS is cable routing.

Have you looked into sending HDMI over FFC (flat flexible cable)?  I googled that, and the first result looks promising, and then if you click V-By-One on the sidebar they even have an automotive picture shown!

FFC can be shielded.  And there's a similar type that has individual loose wires like this.

But back to TI solutions, the presence of audio data isn't supported using our 2-chip solution.  You ask a great question about audio synchronization; propagation delay time on these SerDes devices is typically in tens of nanoseconds, which is many orders of magnitude away from 1 frame (16ms).  I definitely think it'd be reasonable to route audio separately from the LVDS path.

Best regards,
RE

Hi Ross,

I've looked into it some more and it seems like the serializer/deserializer solution could possibly work.  However, I am interested in parts DS90UH925Q-Q1 and DS90UH926Q-Q1.  They seem to support audio as well via I2S, but are in the preliminary stages.  Is it possible to receive more information on when these parts are expected to roll out?

Thanks,

Josh.

Greetings -

The DS90UH925/6 converts LVCMOS (RGB signals) to a single channel of LVDS based signal with embedded clock and control.  The link also supports HD CP protection and transports Video and Audio signals along with I2C and some GPIO.  The chipset is targeted at Automotive applicatioins.  Datasheets are available on the website.  Due to the HD CP feature, samples are limited to HD CP Adopters only, Company name is required to be listed on that website to obtain samples.

John Goldie

Hi,

We have since clarified requirements on this request and have found that FPD-Link III is the preferred method of transmission.  This means our module will only need the serializer DS90UH925.  If this design pans out we will indeed seek HDCP licensing and contact TI/National further for samples/pricing etc.  However, we need a graphics processor on the front end to deal with the HDMI input.  Does TI have a processor spec'd for this?  Do you have any suggestions on where to look if not?  Like I said in my first post, I am new to video and audio processing.

Thanks again,

Josh.

Joshua, TI doesn't have a discrete HDMI receiver device.  We do have DVI receivers (no HDMI audio), and DaVinci platforms may be able to receive HDMI, but that might have more complexities than you want.

Thanks,
RE

Hi there,  

I am very interested in this too - I noticed this is quite an old discussion, have there been any updates since? We are looking at using the TFP401A DVI receiver with a SN75LVDS83B to output LVDS, but we need to capture the digital audio from HDMI.... is there no way to split this with some IC prior to reaching the DVI receiver? Or is there an IC that could handle audio now?  

Many thanks, 

Pambo