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  1. I don't think there is an option in the chroma decoders for it at the moment but it should be quite simple to add. You may be able to simply grab the frames manually from the TBC file, I think it's just raw RGB48 data, will have to check the code.
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  2. Originally Posted by Titan_91 View Post
    Thanks, but I'm wondering if I can skip the chroma decoding and tbcc file in vhs-decode.
    I think you can disable chroma file writing if you change the line 324 in process.py from:
    Code:
    self.outfile_chroma = open(fname_out + '.tbcc', 'wb')
    to:
    Code:
    self.outfile_chroma = None
    But this hack may not avoid background chroma processing.
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  3. It's not a big deal if chroma decoding can't be turned off, it would just significantly speed up luma only decoding for further processing of things like TV Teddy audio, closed captions, and other monochrome VBI data.
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  4. Member dellsam34's Avatar
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    Hey Zcooger and oln are we there yet?
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  5. Are we where? This is a volunteer project worked on in everyone's spare time.
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  6. Member dellsam34's Avatar
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    Are we there where a final GUI is available for the public obviously, I know it's a volunteer basis project but I'm just looking forward to a useful outcome.
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  7. The capture app for the Domesday duplicator is a GUI, capturing from conexant cards is command-line at the moment. There isn't a gui for the decoder for the moment, it's command-line, though there's an ld-analyse app to look at individual decoded frames. A more integrated GUI for decoding and various parts is certainly doable, but it hasn't been a priority yet, focus is on improving decoding. I've been a bit busy moving lately, but I'll be back working on it more again soon.
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  8. Member dellsam34's Avatar
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    I'm not interested in the Domesday duplicator since it doesn't work on the VCR's RF without tweaking and I don't have a laser disc player or discs.
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  9. Zcooger, was this PAL clip played back on a VCR or using vhs-decode? It looks fantastic. I wish I could help with the luma noise in the current NTSC version. At this stage there's potential to meet high end VCR playback results. If the noise can be filtered out I think we'll get there.

    https://youtube.com/watch?v=gs-XbbHQMvc

    Examples of noise:


    Last edited by Titan_91; 1st Jul 2020 at 18:15.
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  10. No, this video is not related to VHS-Decode project. It's my standard capture chain: Panasonic NV-HD630 (or NV-FS200) > Panasonic DMR-ES15 > Medion/Creatix 918 > Virtualdub2. Additionaly I use QTGMC MT deinterlacer with "placebo" preset and Neat Video Demo. It's enough for my need of TV advert ripping for now. I think some VCRs use some kind of noise suppression that we don't know.
    For CXADC capture I made shortcuts for it with preview window. You must have GNU Radio installed. Just click the python scripts. They save the cxadc.r8 file in the same location where they are launched.

    If you want NTSC framing for the preview - in python script change line 73 from:
    Code:
            self.video_sdl_sink_0 = video_sdl.sink_uc(0, 2291, 625, 0, 1135, 625)
    to:
    Code:
            self.video_sdl_sink_0 = video_sdl.sink_uc(0, 2275, 525, 0, 910, 525)
    Image Attached Files
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  11. Today I made first attempt to decode video and HiFi audio tracks simultaneously - I briged video RF pin in the amplifier box of the Panasonic NH-HD630 and envelope test point which contains HiFi signal.
    https://www.youtube.com/watch?v=SPfD--x0Uqo
    https://www.youtube.com/watch?v=6dqE1aoaz_s
    https://www.youtube.com/watch?v=_3PxjMIRpXw
    https://www.youtube.com/watch?v=v6bSq3Rhe6Y
    https://www.youtube.com/watch?v=XyKRcVD4r94

    The HiFi envelope by default has too strong signal so I added small potentiometer to change the gain.
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  12. Originally Posted by Zcooger View Post
    No, this video is not related to VHS-Decode project. It's my standard capture chain: Panasonic NV-HD630 (or NV-FS200) > Panasonic DMR-ES15 > Medion/Creatix 918 > Virtualdub2. Additionaly I use QTGMC MT deinterlacer with "placebo" preset and Neat Video Demo. It's enough for my need of TV advert ripping for now. I think some VCRs use some kind of noise suppression that we don't know.
    For CXADC capture I made shortcuts for it with preview window. You must have GNU Radio installed. Just click the python scripts. They save the cxadc.r8 file in the same location where they are launched.

    If you want NTSC framing for the preview - in python script change line 73 from:
    Code:
            self.video_sdl_sink_0 = video_sdl.sink_uc(0, 2291, 625, 0, 1135, 625)
    to:
    Code:
            self.video_sdl_sink_0 = video_sdl.sink_uc(0, 2275, 525, 0, 910, 525)
    Very helpful scripts, thank you! Works fine with GNU Radio Companion.



    Originally Posted by Zcooger View Post
    Today I made first attempt to decode video and HiFi audio tracks simultaneously - I briged video RF pin in the amplifier box of the Panasonic NH-HD630 and envelope test point which contains HiFi signal.
    https://www.youtube.com/watch?v=SPfD--x0Uqo
    https://www.youtube.com/watch?v=6dqE1aoaz_s
    https://www.youtube.com/watch?v=_3PxjMIRpXw
    https://www.youtube.com/watch?v=v6bSq3Rhe6Y
    https://www.youtube.com/watch?v=XyKRcVD4r94

    The HiFi envelope by default has too strong signal so I added small potentiometer to change the gain.
    That's actually brilliant, why didn't I think of that sooner? The 1.3MHz and 1.7MHz Hi-Fi FM carriers are plenty far away from the 3.4MHz - 4.4MHz video FM carrier. Because the Hi-Fi signals are deep recorded with the video signal being shallow recorded, your Hi-Fi levels are much higher than the video level.

    Originally Posted by Wikipedia
    The modulated audio carrier pair was placed in the hitherto-unused frequency range between the luminance and the color carrier (below 1.6 MHz), and recorded first. Subsequently, the video head erases and re-records the video signal (combined luminance and color signal) over the same tape surface, but the video signal's higher center frequency results in a shallower magnetization of the tape, allowing both the video and residual AFM audio signal to coexist on tape.
    Originally Posted by SENCORE tech tips
    VHS HiFi Stereo uses two separate FM carriers to record the stereo information onto the video tape. The audio is recorded linearly as well so that non-Hi-Fi Stereo VCRs can play back the tape. The left channel audio information modulates a 1.3 MHz carrier while the right channel audio information modulates a 1.7 MHz carrier as shown in Figure 3. Since the left and right audio information is kept separate and is not matrixed together, there are few stereo separation problems with this system.

    VHS Hi-Fi is the only format that uses separate audio and video heads on the rotating drum. The audio head first records the audio information. Then the video head records the luminance and chroma information over the top of the audio.

    At first this might appear to be a problem since the video head would, theoretically, erase the audio information. This is overcome by recording the audio information with heads containing wider gaps and by increasing the record current so that the signal records deep into the tape. The video information is then recorded only on the surface, leaving some audio information still embedded deep in the tape. The process of deep recording necessitates a high quality tape with sufficient oxide coating. Some problems in VHS Hi-Fi VCRs can be traced to the consumer not using a high quality tape that has a deep enough oxide layer.
    Last edited by Titan_91; 7th Jul 2020 at 21:06.
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  13. Can you go into detail on how you spliced in the Hi-Fi test point? I need to amplify my video signal quite a bit with a 3 stage process (VGA splitter, RCA video amp, onboard amp for the Conexant chip). Clearly I would need a simple way to attenuate the Hi-Fi RF coming from the test point. Maybe through wireless coupling using an exposed bit of the Hi-Fi line air gapped near my existing video wire? This would also prevent any RF backfeed returning to the VCR (or VGA splitter depending on where I would splice).
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