Hardware inside the HD-PVR

[stuckless]

Just wondering if anyone has opened up their HD-PVR and taken a look at what is inside. Curious as to what chips they are using in their product. Or if they are running an embedded system (linux?) or something else?

[Polypro]

BTV forum had some dissected shots. A PCB with the Ambarella (sp?) chip and ports/LEDs is what I saw.

P

[stuckless]

Yeah I saw that. The ambrella chip is a mpeg2 to mpeg4 transcoder.... I was curious what chip was feeding the ambrella chip.

[SHS]

Hauppauge HD-PVR
Chipset List
Ambarella A2 platform
Analog Device ADV7401
Analog Device ADAV803
Elpida E5116AJBG-6E-E 512MB DDR2

[mikejaner]

Originally Posted by stuckless

Yeah I saw that. The ambrella chip is a mpeg2 to mpeg4 transcoder.... I was curious what chip was feeding the ambrella chip.

Ummmmm..... MPEG2 to MPEG4? That wouldn't work. The signal coming in is analog, so I imagine the chip is Analog to Mpeg4.

[stuckless]

Ummmmm..... MPEG2 to MPEG4? That wouldn't work. The signal coming in is analog, so I imagine the chip is Analog to Mpeg4.

You are right.... and wrong The signal comming in is analog, but the Ambarella chip is a mpeg2 to mpeg4 converter.... which is why I asked what chip is feeding the Ambarella chip The Unit as whole is an Analog to MPEG4 unit, but there would have to be multiple chips in the pipeline to achieve this. The Ambarella chip facilitates only part of the pipeline. There has to an analog to digital converter as well.

Hauppauge HD-PVR
Chipset List
Ambarella A2 platform
Analog Device ADV7401
Analog Device ADAV803
Elpida E5116AJBG-6E-E 512MB DDR2

Thanks SHS for the chips, I wondered if they were using ADV74XX series chip. That makes sense.

[sleonard]

Originally Posted by mikejaner

Ummmmm..... MPEG2 to MPEG4? That wouldn't work. The signal coming in is analog, so I imagine the chip is Analog to Mpeg4.

Originally Posted by stuckless

You are right.... and wrong The signal comming in is analog, but the Ambarella chip is a mpeg2 to mpeg4 converter.... which is why I asked what chip is feeding the Ambarella chip The Unit as whole is an Analog to MPEG4 unit, but there would have to be multiple chips in the pipeline to achieve this. The Ambarella chip facilitates only part of the pipeline. There has to an analog to digital converter as well.


Thanks SHS for the chips, I wondered if they were using ADV74XX series chip. That makes sense.

You're both right and both wrong.

The ADV7401 chip converts Analog video to uncompressed digital video and feeds the Ambarella.

The ADAV803 converts analog audio to digital audio and also feeds the Ambarella.

The Ambarella chip converts uncompressed digital video to H.264.

I haven't figured out where the digital audio is compressed to AAC and muxed with the H.264 video but I suspect that both are also handled by the Ambarella chip.


What's pretty clear is that nowhere is the digitized video converted to MPEG2.

S

Edit: Interestingly, the chips also work in the opposite directions, i.e. - decompression and digital to analog so, technically, Hauppauge could have made these output devices as well if they had chosen to.

[stuckless]

I stand corrected

While I knew the Ambarella chip takes YCbCr and creates mpeg4.... I got bogged down in the Ambarella literature that kept making references to mpeg2 and mpeg4. ( I was reading earlier the Ambarella document on MPEG2 to MPEG4 transcoding from thier site)

Thanks for the correction.

[mikejaner]

Originally Posted by sleonard

You're both right and both wrong.

The ADV7401 chip converts Analog video to uncompressed digital video and feeds the Ambarella.

The ADAV803 converts analog audio to digital audio and also feeds the Ambarella.

The Ambarella chip converts uncompressed digital video to H.264.

I haven't figured out where the digital audio is compressed to AAC and muxed with the H.264 video but I suspect that both are also handled by the Ambarella chip.


What's pretty clear is that nowhere is the digitized video converted to MPEG2.

S

Edit: Interestingly, the chips also work in the opposite directions, i.e. - decompression and digital to analog so, technically, Hauppauge could have made these output devices as well if they had chosen to.

Yes, that makes much more sense. I would think that putting a chip that does MPEG2, then sending it to a chip that does MPEG4 would degrade the image pretty bad, and what's coming out of these boxes looks pretty good.

Yeah, it would have been nice of them to make these chips do the opposite also, but then I look back on my PVR 350 and remember all of the headachs with that device. I am good having a dedicated decoder like the HD extender.

Thanks for the info!

[stuckless]

I would think that putting a chip that does MPEG2, then sending it to a chip that does MPEG4 would degrade the image pretty bad,

You should read the ambarella doc, titled "MPEG-2 to H.264 Transcoding:
Full Re-Encoding vs. Stream Manipulations". It talks about two approaches to transcoding mpeg2 to mpeg4 at a very high level. I don't think either approach (in their document) degrades the image much at all. It's interesting only if you are interested in transcoding tech geek speek I got the impression that Ambarella provides the technology to do this simply as a means to help the broadcast industry to go from their mpeg2 infrastructure to a mpeg4 one. But I agreee, there probably will be some degradation, just how much, I don't know.

The Ambarella chips are interesting, that's for sure. Does anyone know of any other chip maker that provides a YCbCr to mpeg4 chip?