Blu-Ray with FFMpeg reading m2ts

Audacity Help Forum Windows
1

I’m reading a blu-ray and I know its encoded with 7.1. This is a Blu-Ray with 7.1.
When I open the large m2ts, Audacity reports 4 to 6 different encodings. I picked to read the DCA encoding. I’m assuming some of them are different languages.

[1100] is DCA I’m assuming that is the ‘DTS encoded’ track. It is marked as ‘6’ channels.
[1101] is marked AC3 with 2-channels. Is this the other 2-channels to complete the 7.1? Because they are missing in the 1st encoding?
[1102] is marked AC3 with 2-channels. No idea. This could be another 2-ch track.
[1103] is marked AC3 with 6-channels. Is this a PCM track? Could be English could be another language. I haven’t tested.
[1104] is marked AC3 with 6-channels. Could be Spanish… I dunno. Audacity did not detect language.

Regardless how is 7.1 laid out? Why is it I never see 8-channels with the FFmpeg-Audacity-Win7 setup? Or is my suspicion correct that the 1100 and 1101 tracks would be combined to create the 8-channels…?

Audacity v. 2.0.6
Windows 7

2

There is an old trick we used to use with DVDs. If we started to run out of room for the stereo PCM track, we would create a 2-track “surround” AC3 and put Left and Right on that way. That’s perfectly supported and players would default to that if they couldn’t find the uncompressed PCM track.

So that’s probably what your mystery 2-track is.

Audacity supports whatever FFMpeg supports. You can look up the FFMpeg documentation. I believe Audacity by itself has no idea what 7.1 is.

Also, you might consider upgrade to 2.1.1.

http://audacityteam.org/download/windows

You may get a better FFMpeg.

Koz

3

I believe I’m on nearly the latest FFMpeg. N-75841-g5911eeb

4

I’m sorry Audacity doesn’t use the standard FFMpeg from their site…(or maybe) It is reporting this version:
F(55.33.100), C(55.52.102),U(52.66.100)

5

Since none of those are 8-channels, the additional 2 channels for 7.1 are probably matrix encoded (like the old Pro Logic encoded into 2 channels).

I’m reading a blu-ray and I know its encoded with 7.1. This is a Blu-Ray with 7.1.

Exactly what does the packaging say?

LPCM, Dolby True HD and DTS-HD are capable of 8 discrete channels ([u]Wikipedia[/u]). Does the Blu-Ray packaging indicate those formats?

I don’t know if FFmpeg can decode TrueHD or DTS HD and I don’t know of any other software decoders for those formats. I also don’t know of any software that can decode/extract the matrix channels, except maybe WinDVD or other real-time player software. (Home theater receivers with HDMI can usually decode all of the Blu-Ray formats.)

Audacity reports 4 to 6 different encodings. I picked to read the DCA encoding. I’m assuming some of them are different languages.

The Blu-ray menu should list the 5 audio options and give you a clue about what those tracks are, although they won’t be “numbered” and you might have to guess which is which. Of course, you can listen for different languages.

It’s common to have a 2-channel stereo track for people who don’t have surround sound setups. (DVD/Blu-Ray players can down-mix the surround, but a separate “intentional” stereo mix may sound better than a down-mix.)

[1103] is marked AC3 with 6-channels. Is this a PCM track?

No. AC3 is a lossy-compressed format sometimes called “Dolby Digital”. PCM is uncompressed. PCM the same underlying format as WAV and the same underlying format as audio CDs. (On video, it’s usually called LPCM for linear PCM, but CDs and regular WAV files also use linear PCM.)

[1100] is DCA I’m assuming that is the ‘DTS encoded’ track.

I have no idea what DCA is, but again the packaging or disc menu may give you a clue.

6

“dca” (DTS Coherent Acoustics) From another Audacity post.
FFMpeg is the limiting factor here. It also will only do 16bits.

http://forum.audacityteam.org/viewtopic.php?f=46&t=79051&start=0

7

VLC to the rescue?

It seems to be able to decode DTS through libCDA:

http://www.videolan.org/developers/libdca.html
http://tjaden.strangesoft.net/libcda/
https://github.com/wangp/libcda

It’s still experimental, incomplete and probably illegal in the US. Seems to be in ffmpeg too…

8

Yes but how to use that with audacity?
[Yes I assumed grabbing some music off a commercial blu-ray might have legal ramifications, the sad part is when I own it… another discussion]

9

umm guys FFMpeg may already be using libdca — hence (DCA) as an option. It may be out of date or not yet have the ability to see 7.1. An earlier post suggested it was encoded in the channels like Pro-Logic (maybe, but I doubt it…)
Regardless, according to the posts above, none of these is the PCM track. There is some good posts in that link I referenced above. I’ll study some of those.
What I have recorded has sounded awesome, awesome, awesome, so far anyway.

10

Audacity 2.0.6 and later all use the same FFmpeg 2.2.2 for import (with those F,C,U numbers as quoted).


Gale

11

Yes but how to use that with audacity?

You’d have to extract/decode the audio to a format Audacity can open. I have no idea how to do that. That’s a VLC question…

Note that single 8-channel WAV file for the whole movie/program would exceed the 2GB/4GB WAV file size limit. So if you want WAV and the whole-continuous movie/program, you’d need to extract to 8 separate WAV tracks.

Regardless, according to the posts above, none of these is the PCM track.

From what you’ve told us, there is no PCM track.



P.S.
There are websites/forums that specialize in copying/cracking DVDs & Blu-Rays. You might get better help there… Or, maybe there’s a (illegal) utility for copying/extracting Blu-Ray audio??? I know there are such tools for DVD.

Assuming the disc is not copy protected (or has already been cracked), you might try [u]SUPER[/u]. It can convert to/from many formats and/or extract the audio stream, but I don’t know if it supports 8-channel DTS-HD. SUPER uses FFmpeg, but I believe it includes at least one additional encode/decode library, so it’s worth a try.

If you download SUPER, be careful. There are ads for other software on their website, so make sure you are downloading and installing SUPERsetup.exe. Then when you install, be careful about the options because it might want to install some crapware along with it (I don’t remember).

12

Install VLC, test export, import in Audacity?

I don’t know much about ffmpeg, but VLC is my go-to tool for audio and video in the rare cases Audacity can’t import audio. If VLC fails too, there’s still SOX…

13

Ok I have played a recorded ‘dca’ method before. But this time… I grabbed the ‘DCA’ 6-channel track from a 7.1 Blu-ray (i won’t reveal). And the rear channels do seam a bit garbled. In the past they did not seem so.
So now I’m starting to believe the above poster who said ‘that the 2 rear-tracks were matrix’ed’ like pro-logic. And/Or FFMpeg is lumping them together calling it 6 when it should be 8. Therefore it gets garbled.

14

And the rear channels do seam a bit garbled. In the past they did not seem so.

That could be normal for this particular recording… I wouldn’t expect it to be distorted, but I wouldn’t expect it to sound “good” or “right” by itself without the other channels. Does it sound garbled when played back with all 6 (or 8) channels? Maybe try playing the Blue-Ray with all of the speakers disconnected except the rears, to see what’s actually in those channels.

So now I’m starting to believe the above poster who said ‘that the 2 rear-tracks were matrix’ed’ like pro-logic. And/Or FFMpeg is lumping them together calling it 6 when it should be 8. Therefore it gets garbled.

Either way, it shouldn’t be garbled. i.e. A downmix, or an un-decoded Pro Logic track sounds usually just fine in stereo.

Mixing is done by addition (summation), so if you don’t down-mix correctly (scaling-down the levels) you can get clipping (distortion).

15

I have VLC I didn’t know you could export. I’m attempting VLC export now. We’ll see how this goes. It takes a long time, as it does also for a Audacity-ffmpeg read.

16

I’ve played this movie many times. It does not sound garbled. However then my receiver is doing the decoding in DTS-HD straight from the Blu-Ray. Also I’m used to ripping music from Blu-Ray. I’m well aware of Clipping, and I can see when that happens in my channels in Audacity. Normally the multi-channel 5.1 tracks seem a bit suppressed, and I need to amplify them a bit before I archive them. But not this one. It needed no processing.

17

There is no PCM track that the software is able to see, and it may not exist on this type of disc. This may be normal for this type of 7.1 disc. The disc is marked 7.1 DTS-HD Master…
See this thread: 7.1 Audio on 5.1 speaker system = DTS core? | AVForums I believe he explains a bit.

18

Here’s what happened when I went through VLC… Not sure if I used the perfect export settings. But I created a ‘wav’ file. It created a WAV file that I could not read with any player. It is 1GB+. But I could read with Audacity. While it was reading it read with FFMpeg. It was not by choice, it just said that it was a FFmpeg compatible file, without asking me. Then I got a 6-CH display… and I swear it looks the same as the DCA version that I got from just opening the file through Audacity directly with FFMpeg installed.
I do notice that there is some clipping in some parts of the audio… But not the particular piece that I exported earlier. I can try it again. With this setup.

19

SUPER was a bad idea! I was able to skip crapware in the install… but still it had some malware or something that throws some junk on the browser when it starts. On top of this, when it wasn’t crashing, there didn’t seem to be any options greater than 6ch for audio lossless files. Then gave-up and uninstalled. Now scanning for virus and malware.

20

VLC is a bit hard when it comes to exporting. You have to be very careful when setting audio and video settings for export.

I’m guessing the export you have now is just a copy, really and provokes the same error in Audacity.

I think you might need to experiment with VLC’s export settings, strip off the video and see what happens then. VLC should be able to export audio only, decoded, either as an audio-only mp4, m4a, or maybe even as a .wav.