Here's my Research Results on the Impracticality of Converting HDMI to Firewire:
How can I inexpensively and easily output a digital data stream of unprotected content from my TV's HDMI to my PC and capture it in a digital HD file format like I did with 1394 Firewire? I have VideoLAN's VLC installed on my WinXP PC.
If this is possible what hardware, drivers and software do I need?
Avio
Quote:
Originally Posted by High Def Forum Archive /forum/post/0
RSawdey 01-14-2006, 12:52 PM
Converting HDMI to Firewire wouldn't be a security violation because both are copy protected. Only converting a copy protected signal to an unprotected signal is illegal. It would, however, be very difficult (& probably expensive) because the HDMI input (at 180 MB/sec) would need to be compressed to [email protected] level in real time... Firewire carries the still compressed MPEG2 stream.
Firewire uses DTCP copy protection, while HDMI/DVI uses HDCP. A firewire signal may be marked 'copy freely', 'copy once', or 'copy never'. Current PCs can only record 'copy freely' signals, they refuse to copy any other type. This will change when the secure OS, Windows Vista, is available in about a year.
The debate over Firewire vs. DVI interfaces is a bit complicated. In order for all TVs to support Firewire, they must have a built in MPEG2 decompression chip... if all TVs were designed like that, then all source devices like HD-STBs and D-VHS and BluRay wouldn't need to have one & could be built cheaper... but it also means that TVs would be more expensive, even if they omitted the digital tuner. Manufacturers decided they wanted to reduce the price of the displays more than they wanted the advantages of cheaper source devices... a short sighted decision in my mind. Now that virtually all TVs include a digital tuner, they also now have MPEG2 chips... but because they can't be counted on to ALL have such chips (and Firewire) source devices have to have MPEG2 chips as well.
Because real time [email protected] level compression chips are still expensive, I doubt this STB will convert HDMI to Firewire... it would add too much cost. HDMI is probably only for pass-thru, which doesn't solve your problem. Firewire output will probably be limited to those signals from it's internal tuner - which can be stored while STILL compressed, rather than needing compressed on the fly. Compression chips are much more expensive than decompression chips, because MPEG is an asymetric compression system - designed for cheap DEcompression, making the compressor do ten times the work. This can be done cheaply IF it can be done off-line, taking much longer than the playing time... but when it has to do ten times the work IN REAL TIME, it will cost ten times as much.
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Phototone 01-18-2006, 09:23 PM
I have a current model Mitsubishi CRT RPTV, it has HDMI, but it also has 2 firewire ports and 2 component ports, as well as S-video inputs.
All HD cable boxes manufactured after July of last year are required to have a firewire output. While I use the HDMI port on the TV for my cable box, I did try the firewire connection, and got just as good a picture. I currently use the firewire output from the cable box to record HD material to my D-VHS deck, though.
My JVC D-VHS deck has component outputs that (to me) look just as good as a HDMI connection playing back on the Mitsubishi. All component inputs can display full 1080i signals, as well as 720p, and 480p.
Your only limitation in not having a HDMI input may be in the new BluRay and HD-DVD players which are not here yet.
http://www.highdefforum.com/archive/...php/t-659.html
Repeating My Questions:Quote:
AVS Forum > Industry Area > HDMI Q&A - The One Connector World > HDMI to Hirewire
twelvepbrs 01-30-07, 12:12 PM
Quote:
Originally Posted by Kipp Jones /forum/post/0
As long as the 5C flags allow you to.
I thought that all content was at least "copy once" meaning i could record it via 1394 from my TV to an AVHDD, and play it back, i just couldn't archive it to another device?
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HDMI_Org 01-30-07, 04:06 PM
Quote:
Originally Posted by Kipp Jones /forum/post/0
I disagree. If the original content was transmitted in MPEG2, then uncompressed and then recompressed to MPEG2 via 1394, no bit loss, the original content would be intact and therefore equal to HDMI.
Also, if a device simply had a 1394 output skipping the HDMI output, the PQ would be the same. The difference is where the uncompressing is done.
For the record, 1394 is now at 3.2Gbps over fiber as demonstrated at CEDIA 2006.
They now have enough bandwidth to transmit HDTV including 1080p uncompressed if they wanted to. Recording HDTV on top of that is a bonus.
MPEG2 (and all the other codecs like MPEG4, H264, VC1, etc) is a lossy compression. Each time it is compressed, information is lost (like an mp3). Thus, if the original MPEG2 content is uncompressed, then re-compressed one more time (i.e. more information is now lost), the quality of the 2nd compression will certainly be lower. It's similar to taking an mp3, decompressing to wav, then re-compressing into an mp3 again. The 2nd version will be lower quality than the first.
The only equivalent "lossless" way would be to never decompress the original MPEG2 content (say from the disc or off the air), transmit it over 1394, then get decompressed at the display. But you still have the problem of not being sure whether the TV has the right decompression codec.
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Kipp Jones 01-30-07, 09:23 PM
Agreed, that plays into effect with HDMI as well because you still need to uncompress at some point whether it be at the source device or at the display. Point taken though about performing the compression twice which is unrealistic anyway but technically possible.
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ptsenter 01-30-07, 10:05 PM
Quote:
Originally Posted by HDMI_Org /forum/post/0
The only equivalent "lossless" way would be to never decompress the original MPEG2 content (say from the disc or off the air), transmit it over 1394, then get decompressed at the display. But you still have the problem of not being sure whether the TV has the right decompression codec.
Yeah, it's very problematic to have TV understanding MPEG2, but one can feed 1394 into computer which, in turn, would stream it into networked media player or decode by itself to feed display.
http://www.avsforum.com/avs-vb/archi.../t-786830.html
How can I inexpensively and easily output a digital data stream of unprotected content from my TV's HDMI to my PC and capture it in a digital HD file format like I did with 1394 Firewire? I have VideoLAN's VLC installed on my WinXP PC.
If this is possible what hardware, drivers and software do I need?
Avio
