D-VHS vs DVR for recording HD? - Page 4 - AVS Forum
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post #91 of 117 Old 08-08-2013, 03:25 PM
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Quote:
Originally Posted by esdwa View Post

- is it possible the stb is producing bitstream which is not entirely compatible with dvhs recording causing described issue?

Yes. As it turns out, there's a fairly complex time-stamping mechanism for streams being sent over IEEE1394. It's required to recover the MPEG-2 Transport Stream 27 MHz clock at the receiving end. If there are any bugs in the implementation of the time-stamp, it will show up when recording to tape because of the timing constraints involved when transferring to a medium that's operating at a fixed rate (the rate of the tape over the recording head). In other words, it's very easy to have buffer overruns or underruns because you have to lay down the stream to tape as it's passing by the recording head. If you're just decoding the stream, there can be many megabytes of buffering that will cover up the problem (that is, instead of glitches every 2 seconds, it could be every 2 hours). When you're recording to the PC, the timing doesn't matter at all (as long as you capture all the packets).
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- why dvhs deck is still passing through and recording all channels in the lineup including premium ones, while when streaming from stb to pc results in just some of them being actually available? Is it because dvhs deck is 5C compatible device and PC is not?

Yes.

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post #92 of 117 Old 08-10-2013, 06:35 PM
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Can TSReader be used to convert MPEG-2 stream to ATSC/8SVB compatible stream which could be recorded to DVHS deck through Firewire? If yes, do I need Pro version and where can I find a guide for such conversion. Thanks in advance for the feedback.
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post #93 of 117 Old 08-10-2013, 07:11 PM
 
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TSReader Pro has a DVHS connection that uses firewire to send the MPEG2 stream from a live stream (or a file). It doesn't use ATSC or 8VSB to do this. You select DVHS in the menu.
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post #94 of 117 Old 08-10-2013, 08:07 PM
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Originally Posted by alk3997 View Post

TSReader Pro has a DVHS connection that uses firewire to send the MPEG2 stream from a live stream (or a file). It doesn't use ATSC or 8VSB to do this. You select DVHS in the menu.

Sounds great. But my Lite version has also "Record Program to DVHS" option. Is that the same function you are talking about? Will this MPEG-2 stream play fine once recorded on the deck? Does it have to has specific parameters like bitrate to meet DVHS specification while keeping best possible quality?
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post #95 of 117 Old 08-11-2013, 08:38 AM
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I found TSReader not very user friendly to use for recording, you will notice there is no pause or stop buttons. I remember when using XP that there was a setting in the registry to set the firewire output bit rate so that anything you output through firewire would be the correct D-VHS rate. Also I believe that CapDvhs and DVHSTool can do this when recording, D-VHSTool could also control the functions on the D-VHS deck. I never used anything other than XP when I was running D-VHS tapes.

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post #96 of 117 Old 08-11-2013, 09:19 AM
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Quote:
Originally Posted by mtallent View Post

I remember when using XP that there was a setting in the registry to set the firewire output bit rate so that anything you output through firewire would be the correct D-VHS rate. Also I believe that CapDvhs and DVHSTool can do this when recording, D-VHSTool could also control the functions on the D-VHS deck. I never used anything other than XP when I was running D-VHS tapes.

Mike T
Thanks Mike. I use XP as well for experiments I am trying to perform with my dvhs deck. I think CapDVHS captures from dvhs only while what I am trying to do is the other way around. Last night I transferred recordings from my dvhs deck to PC using CapDVHS and then sent it backto dvhs deck jsing DVHSTool. Everything went well. Now I wanted to transfer some mpeg2 stream which does not meet dvhs spec (high bitrate) from pc to dvhs. And I just want to make sure whether it is only re-encoding that needs to be done before I attempt to archive it on the deck.
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post #97 of 117 Old 08-11-2013, 10:08 AM
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Quote:
Originally Posted by esdwa View Post

[quote name="mtallent" url="/t/1265688/d-vhs-vs-dvr-for-recording-hd/90#post_23617891"I remember when using XP that there was a setting in the registry to set the firewire output bit rate so that anything you output through firewire would be the correct D-VHS rate. Also I believe that CapDvhs and DVHSTool can do this when recording, D-VHSTool could also control the functions on the D-VHS deck. I never used anything other than XP when I was running D-VHS tapes.

Mike T
Thanks Mike. I use XP as well for experiments I am trying to perform with my dvhs deck. I think CapDVHS captures from dvhs only while what I am trying to do is the other way around. Last night I transferred recordings from my dvhs deck to PC using CapDVHS and then sent it backto dvhs deck jsing DVHSTool. Everything went well. Now I wanted to transfer some mpeg2 stream which does not meet dvhs spec (high bitrate) from pc to dvhs. And I just want to make sure whether it is only re-encoding that needs to be done before I attempt to archive it on the deck.[/quote]

TSReader will not re-encode the stream before sending out through firewire. If your high-bitrate mpeg2 content exceeds the maximum D-VHS spec (?26-32 MBps?) then all bets are off. What TSReader will do though is stuff null packets into your stream to make it look to the bit bucket recorder to be constant bit-rate, but agin this assumes your maximum peak bitrate does not exceed the specification for D-VHS.

The content will remain MPEG2. It will take a program stream and send it out as a transport stream though.

Have fun.
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post #98 of 117 Old 08-11-2013, 04:05 PM
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If the mpeg2 file is below the D-VHS bit rate then you do not re-encode you just find a program that will add "null" packets to the stream to increase to a constant bit rate at the 19.3xxxxxxx mbps that is needed for recording. TSReader can do this also I think you can use VideoRedo to create the correct bit rate file. Yes, CAPDvhs has a folder "wrtDVHS" that can be used to output a stream. I will look to find the registry settings to make the firewire output to be the correct stream rate.

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post #99 of 117 Old 08-11-2013, 07:47 PM
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Thanks Mike. So I re-encoded sample 25Mbps stream file down to 19300kbps - just below required by ATSC bitrate and then ran the output file through VideoReDo to produce ATSC compatible stream. Finally I uploaded the file to my deck through firewire using DVHSTool and voila, it plays back as it should like original video with sustained HD quality, just from the tape.
There was just one glitch caused by VideoReDo. It produced output file with desynchronized audio track. Will have to work on this next. But I am so glad I was able ro finally produce and transfer proper ts file to my dvhs deck which plays back with video without the glitch!
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post #100 of 117 Old 08-12-2013, 01:13 PM
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OK, I found the info on patching the XP registry so the firewire bit rate is set to 19.3 mbps on the fly and you will not have to do anything to the ts file as long as the bit rate is not above the 19.3 for ATSC.
http://www.avsforum.com/t/209390/official-dvhstool-2-1-support-thread/1250_50#post_4686392
Look at post 1273 and beyond for info on how to set the correct bit rate for firewire streaming using XP so you don't have to process your ts files before recording onto D-VHS.

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post #101 of 117 Old 08-12-2013, 04:07 PM
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I do seem to recall reading that XP's ability to maintain high bitrate iso streams were somewhat problematic.
Dont rule out glitches being caused by the Microsoft firewire stack's latency/non-realtime capability.

I seem to recall reading that OS-X was much better at handling higher bitrates, and I am an OS-X user, having walked away from Windows 3 years ago.

Anyhow-I do not recall at what bitrate threshold the Microsoft stack becomes unstable.

Back to coding my Disc Subunit Controller class on OS-X on top of Apples Firewire SDK.
Maybe tonight I will replace naked c++ pointers for boost libraries smart pointers inside the implementation to simplify memory management........
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post #102 of 117 Old 08-13-2013, 06:12 AM
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Quote:
Originally Posted by mtallent View Post

OK, I found the info on patching the XP registry so the firewire bit rate is set to 19.3 mbps on the fly and you will not have to do anything to the ts file as long as the bit rate is not above the 19.3 for ATSC.
http://www.avsforum.com/t/209390/official-dvhstool-2-1-support-thread/1250_50#post_4686392
Look at post 1273 and beyond for info on how to set the correct bit rate for firewire streaming using XP so you don't have to process your ts files before recording onto D-VHS.
Mike T

Thanks a bunch Mike, I will try it tonight.
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Back to coding my Disc Subunit Controller class on OS-X on top of Apples Firewire SDK.
Maybe tonight I will replace naked c++ pointers for boost libraries smart pointers inside the implementation to simplify memory management........

Was that calls a subject of past discussion for Mac users interested in recording to dvhs?
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post #103 of 117 Old 08-14-2013, 08:54 PM
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A Disc Subunit is much more than a DVHS Subunit being hard drive based it offers much more functionality.
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post #104 of 117 Old 08-17-2013, 06:06 PM
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Which OSx re-encoder/muxer app would you recommend for creating dvhs compatible streams?
Recently I tried to re-encode mpeg2 25Mbps video to 18.4Mbps and then mux it with DTS (not -MA) 1536kbps track on my PC track using recommended TSmixer and VideoReDo but output file has audio and video off sync. I also have AVS video converter for PC but this one encodes DTS to mp2 stereo only so it is not what I want to try on my dvhs deck. My goal was to create a recording with dts track like on dtheater tapes.

Since I am getting my 1st MBP in couple of days, I thought about trying it on Mac. I heard about some Mandrake software, is it ok and are there other reliable (paid are ok) apps for encoding and muxing?
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post #105 of 117 Old 08-18-2013, 07:02 AM
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I do not re-encode, just edit out what I dont need/want in videoredo and export as a new ts.
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post #106 of 117 Old 08-18-2013, 07:03 AM
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Handbrake is the program I think you meant?
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post #107 of 117 Old 08-19-2013, 12:04 PM
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Yes, I did. Thanks.
Anything else besides Handbrake is worth looking for?
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post #108 of 117 Old 08-19-2013, 03:38 PM
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Your OSX options are limited:
http://www.videohelp.com/tools/sections/macos-video-tools

I dont re-encode stuff, just record / play / store on large capacity drives....
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post #109 of 117 Old 09-13-2013, 08:04 AM
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The recording through firewire from my stb to mac using AVCcapture app works fine with exception the recording happens only for copy free and copy once marked programs with another exception where copy once m2t files are unplayable using vlc (playback just does not start when loading file to vlc).

Not sure why if during recording of Copy Once program I see packets being captured and file has non zero length same as for copy free ones. Anyone care to comment?
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post #110 of 117 Old 09-13-2013, 08:44 AM
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The firewire port has copy protection called 5C with some more letters, and the method of copy protection is the data stream is encrypted. If the connecting device is not 5C compliant like a D-VHS recorder, then you can only record streams that are copy freely these are not encrypted.

The D-VHS is 5C compliant and will not stream any of the copy once recordings out its firewire port unless the connected device is 5C compliant. The only other device I remember as being 5C compliant is the old Samsung SIR-T165 but it does not record.

I am not familiar with the Mac for firewire recording, but it seems like it recorded the encrypted stream, but cannot de-crypt the data.

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post #111 of 117 Old 09-13-2013, 01:06 PM
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Yes, as you found out you cannot "fake" a 5C connection unless you work for NSA.

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post #112 of 117 Old 09-13-2013, 04:38 PM
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Quote:
Originally Posted by esdwa View Post

Thanks Mike. I was under impression that VirtualDVHS makes the stb think it talks to 5C compliant device allowing it to capture Copy Once stream to mac. I guess I was wrong, right?

All you have to do is:
(1) implement the AVCSecurity command in your custom VirtualDVHS app. See page 53 of the link below.
(2) negotiate key exchanges with the STB
(3) decrypt the transport stream packets with the negotiated key, and rotate keys when the even/odd bit flips. this is done in your mpeg packet handling callback.
(4) enjoy your in-the clear 5C removed goodness.

http://www.dtcp.com/documents/dtcp/info-20130605-dtcp-v1-rev-1-7-ed2.pdf

Let me know when you have accomplished this smile.gif
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post #113 of 117 Old 09-14-2013, 02:26 PM
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Quote:
Originally Posted by qz3fwd View Post

All you have to do is:
(1) implement the AVCSecurity command in your custom VirtualDVHS app. See page 53 of the link below.
(2) negotiate key exchanges with the STB
(3) decrypt the transport stream packets with the negotiated key, and rotate keys when the even/odd bit flips. this is done in your mpeg packet handling callback.
(4) enjoy your in-the clear 5C removed goodness.

http://www.dtcp.com/documents/dtcp/info-20130605-dtcp-v1-rev-1-7-ed2.pdf

Let me know when you have accomplished this smile.gif

That's no fun, that's the "hard way".

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post #114 of 117 Old 09-21-2013, 03:52 PM
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As the experiment done and described here some time ago to capture Copy Free program from cable box to JVC DVHS deck directly through FireWire failed producing recording full of artifacts, I found that same program recorded onto Macbook looks perfect with no loss whatsoever.

Today the attempt was made to transfer this particular recorded program from Macbook to DVHS tape and result is the same (artifacts, pixelization) as it was recorded directly from cable box without Macbook acting as "middle" guy.

So it seems that the cable box outputs stream which is not fully compatible with DVHS deck making the direct recording impossible. On the contrary, the deck records perfectly any high definition FTA programs using HDTV antenna. It also records perfectly mpeg-2 videos prepared on computer as long as they comply with stream bitrate limits for dvhs recording.

It would be interesting to find out what exactly in captured from cable box stream makes recording to dvhs impossible. Unless someone already figured it out. Anyone?
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post #115 of 117 Old 09-21-2013, 07:49 PM
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I don't remember having any problems recording from my cable box to my JVC HD-5U, I probably made over 100 recordings and many of these were copy once from the premium movie channels. Mostly used S-VHS tape which looked just as good as the D-VHS tape. I have not made any recordings in 2 or 3 years so there may have been software updates that caused some of these problems today. I was using a Motorola DCT series box then and now I have a DCH series but have no problem streaming the firewire to my XP computer. Maybe If I find the time I will try some D-VHS recordings and see if they still work now.

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post #116 of 117 Old 09-21-2013, 07:54 PM
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I just made a 10 minute recording of HBO HD 1080i channel by firewire from DCH 3416 cable box to my JVC D-VHS onto D-VHS tape and played back with no problems. So nothing has changed here on Comcast.

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post #117 of 117 Old 09-22-2013, 05:16 AM
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Quote:
Originally Posted by mtallent View Post

I just made a 10 minute recording of HBO HD 1080i channel by firewire from DCH 3416 cable box to my JVC D-VHS onto D-VHS tape and played back with no problems. So nothing has changed here on Comcast.

Mike T

Thanks Mike. I wish someone tried the same with fios motorola qip stb.
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