LD AC-3 Capture Help

[DeafYakuza]

So, I want to leave you to the mercy of my experience how to capture/rip the 6 channel tracks (Dolby Digital 5.1 - AC-3).
I did it to capture 6 channels from RF-Demodulador of LD of Ransom (1996) directly!!!

Through Hauppauge HD PVR 2 GE Plus could you to capture the 6 channel tracks by S/PDIF Input directly. You have to choice video format .ts or .m2ts to capture the AC-3 DD5.1 track. If you choise the format .mp4 you will get aac 2 channels (Stereo) only.

Code:

General ID                                       : 0 (0x0) Complete name                            : C:\Users\Public\Videos\HDPVR2_20190228_2024.ts Format                                   : MPEG-TS File size                                : 7.75 GiB Duration                                 : 1 h 31 min Overall bit rate mode                    : Variable Overall bit rate                         : 12.2 Mb/s Video ID                                       : 4113 (0x1011) Menu ID                                  : 1 (0x1) Format                                   : AVC Format/Info                              : Advanced Video Codec Format profile                           : High@L4 Format settings                          : CABAC / 3 Ref Frames Format settings, CABAC                   : Yes Format settings, RefFrames               : 3 frames Codec ID                                 : 27 Duration                                 : 1 h 30 min Bit rate                                 : 11.2 Mb/s Width                                    : 720 pixels Height                                   : 480 pixels Display aspect ratio                     : 16:9 Frame rate                               : 29.970 (30000/1001) FPS Standard                                 : Component Color space                              : YUV Chroma subsampling                       : 4:2:0 Bit depth                                : 8 bits Scan type                                : Interlaced Bits/(Pixel*Frame)                       : 0.180 Stream size                              : 7.12 GiB (92%) Color range                              : Limited Color primaries                          : BT.709 Transfer characteristics                 : BT.709 Matrix coefficients                      : BT.709 Audio ID                                       : 4352 (0x1100) Menu ID                                  : 1 (0x1) Format                                   : AC-3 Format/Info                              : Audio Coding 3 Commercial name                          : Dolby Digital Codec ID                                 : 129 Duration                                 : 1 h 30 min Bit rate mode                            : Constant Bit rate                                 : 384 kb/s Channel(s)                               : 6 channels Channel layout                           : L R C LFE Ls Rs Sampling rate                            : 48.0 kHz Frame rate                               : 31.250 FPS (1536 SPF) Bit depth                                : 16 bits Compression mode                         : Lossy Delay relative to video                  : -540 ms Stream size                              : 250 MiB (3%) Service kind                             : Complete Main

You can download the audio-sample. How is the audio? I can't hear exactly but it should looks perfect.

https://www4.zippyshare.com/v/olYoQvX7/file.html


The next test is TV card Kona LHe Plus developed by AJA and Motu HD Express HDMI Video Interface with Express Card Adapter.

I have no idea how to get or find a adapter for "S/PDIF2HDMI" so that I could get from "S/PDIF2HDMI" to HDMI-Embbeded Input on my Shuttle Box of Blackmagic Intensity 4k USB because I haven't a scaler device like DVDO iScan. There are many adapters for "HDMI2S/PDIF" everywhere to find.

[schorman]

You're not really capturing the demodulated AC3 signal here. You're recording the decoded ac3 as a six channel Wav. This isn't necessarily bad, especially if you plan to edit the audio anyway.

If you want the actual untouched AC3 track, you'll need to plug your spdif output from the ac3 demodulator directly into your Creative or Terratec spdif. There is a small chance that the drivers for either sound card may not allow you to capture an AC3 signal, this is the case with the E-MU 1616m that I have. This may affect other Creative sound cards as well. To Correctly capture the audio, you'll need to record the signal by locking the sound cards clock to the external spdif signal, then recording as a stereo PCM file at 48kHz and 16bit. The audio you capture should not look like actual audio. It will look like a bunch of regularly spaced chunks of audio at nearly full volume, and will sound like static if played back.

After capturing the raw file, you'll need to demodulate the AC3 track from the PCM file using Besplit.exe. The resulting file should be a playable AC3 file.

[DeafYakuza]

Thank you for your sharing Information!

Is there a tutorial how to do that (stept to step)? I tried to find it but I haven't found it.

[david49120]

Laserdisc AC-3 is padded within a standard 16-bit 48kHz PCM stream. You will have to recover the AC-3 using BeSplit

Thanks for your explanation, I've always wondered what that noise is ? 

I have an ESI U24XL card, which works fine by recording the signal in 24-bit 48 kHz on Audacity, then I save the file in 16-bit 48 kHz. 

I used Reaper, but after realizing that Audacity did the job I dropped it. What I do next is put it on a USB and play it on a Blu-ray player, and the amp detects the ac3 fine.

[david49120]

Thanks for this tutorial, I hope this card is still available today. It would help me a lot, in the meantime I will look for a solution to decode the signal on a PC.

[kenkenken96]

With the TASCAM DR-100MKII’s DIGITAL IN, you can easily make bit-accurate recordings without a PC.
Just take the input from the demodulator’s coaxial output and record at 48 kHz / 16-bit.
After that, open the WAV file in Audacity, trim the silence, and then extract the AC3 stream. I use XMedia Recode for this.
Since I want to keep the original AC3 untouched, I calculate the sync offset with Audacity for the target remux, and then enter that delay value in XMedia Recode. This way, you can create a new, properly synced AC3 track without re-encoding to FLAC or anything else — it stays as the original AC3.