How to tell if the sound on the dvd is stereo or mono?

[8GuaWong]

I am trying to rip a dvd and the ac3 that was demuxed showed as mono in audacity but on the dvd cover it says sound is dolby digital 2.0 so what should i trust?

Another question i opened up a mp3 that was encoded from stereo ac3 (opened with audacity and showed waveform on both channel are different) with audacity, waveform of both channel looks the same why?

[dat720]

use mediainfo...

Audacity probably isn't importing the AC3 file correctly, how did you dump the AC3 stream?

Your last question makes no sense... are you saying that the AC3 waveform looked different for each channel but the MP3 looked the same for each channel?

[8GuaWong]

how did you dump the AC3 stream?

dgindex

are you saying that the AC3 waveform looked different for each channel but the MP3 looked the same for each channel?

yup thats what i am saying :thanks:

[LUCHOO]

many old movie on dvd the audio is in ac3 (mono1) channel ...

[dat720]

dgindex should be fine....
Why do you need to convert the AC3 audio to MP3 tho? Leave it as AC3, MP3 is only useful when you want to compress Movies for a 700mb CD... Which IMO is a fruitless effort in these current times of DVD5/9, 1TB HDD's for less than au$150 and BD Burners and media only a short time away from being mainstream affordable!

Anyway i'd say the problem is in your MP3 encode procedure.... how did you do it?

[8GuaWong]

Anyway i'd say the problem is in your MP3 encode procedure.... how did you do it?

lame with following parameters -core( -input "%input%" -output "%output%" -logfile "%log%" ) -ota( -hybridgain -d %delay% ) -azid( -L -3db -c normal ) -lame( --alt-preset 128 ) -profile( %version% )

and i tried mediainfo that only tells you how many channels the source is but it doesn't say whether or not its mono or stereo :confused:

[Keiyakusha]

and i tried mediainfo that only tells you how many channels the source is but it doesn't say whether or not its mono or stereo :confused:

Hmm... mono = 1 channel, stereo = 2 channels...

[8GuaWong]

Hmm... mono = 1 channel, stereo = 2 channels...

yea i know but when i open up the ac3 with audacity it only shows 1 channel and says mono


Complete name : X:\temp\rip\DVD\Projects\XXXXXXXXXXXXXXXXXXXXX_VTS_01_PGC1\XXXXXXXXXXXXXXXXX Track 1 English DELAY 0ms.ac3
Format : AC-3
Format/Info : Audio Coding 3
File size : 30.7 MiB
Duration : 22mn 19s
Overall bit rate : 192 Kbps

Audio
Format : AC-3
Format/Info : Audio Coding 3
Duration : 22mn 19s
Bit rate mode : Constant
Bit rate : 192 Kbps
Channel(s) : 2 channels
Channel positions : L R
Sampling rate : 48.0 KHz
Stream size : 30.7 MiB (100%)


The attachment shows the file being opend by audacity :eek:

[Keiyakusha]

Well, it's not hard to believe that you see different info here and there. If you want us to tell who is right and who is wrong - post some sample of your AC3 stream.

[8GuaWong]

Well, it's not hard to believe that you see different info here and there. If you want us to tell who is right and who is wrong - post some sample of your AC3 stream.

heres 1 http://rapidshare.com/files/239120153/steroe_or_mono.ac3.html

[dat720]

Post your images to something like Picasa, Photobucket or Flickr i'm not going to go to the effort of downloading files from rapidshare, i hate it!

[8GuaWong]

Post your images to something like Picasa, Photobucket or Flickr i'm not going to go to the effort of downloading files from rapidshare, i hate it!

thats not a pic its a sample of the ac3 file :p

[Keiyakusha]

I don't know what is going on, probably something wrong with Audacity or with its configuration. But AC3 audio is stereo 48khz.

And waveform (http://www.petaimg.com/u323/830Untitled-1.png) of both channels don't looks the same. There is just very small difference sometimes. Also you shouldn't rely on mp3 waveform because it was changed durring encoding.

[8GuaWong]

And waveform (http://www.petaimg.com/u323/830Untitled-1.png) of both channels don't looks the same. There is just very small difference sometimes.

this waveform is for some random mp3 u have?

[Keiyakusha]

8GuaWong
No, this is from your sample. 2 channels normalized and overlayed on top of each other to see the difference between them.

[8GuaWong]

8GuaWong
No, this is from your sample. 2 channels normalized and overlayed on top of each other to see the difference between them.

o okay but it doesn't look like you opend it with audacity but some other program. so does it show as mono for you in audacity as well?

[Keiyakusha]

8GuaWong
Sure I opened it in different program which I use for work. I don't have audacity right now and don't plan to install it, so have no idea what it shows. I only say that if you want to know whatever audio is stereo, mono, 5.1 or something, you can rely more on mediainfo then audacity, because if audacity shows mono in this case - something wrong with it or you doing something wrong. On your screenshot audacity shows 16000 Hz samplerate which is not right too.

[broxburn]

Audacity V1.3.6 says it's stereo.

http://i39.tinypic.com/29ffghi.jpg

[dat720]

If you look at his original screen shot it also shows the sample rate as 16000hz (where mediainfo reports 48000), if it was a DVD source there's no way in hell it would be a mono AC3 @ 16000hz.

broxburn has pretty much confirmed that his version of Audacity is at fault.

8GuaWong: hiding the track name in the screen shot just makes it look like you are doing something wrong!

[8GuaWong]

heres 1 http://rapidshare.com/files/239120153/steroe_or_mono.ac3.html

i only said here is 1 never said this 1 is the one that i posted pic on :)

[setarip_old]

@8GuaWong

Hi!i only said here is 1 never said this 1 is the one that i posted pic onAnd just what would you accomplish by posting (and what do you think members can accomplish by viewing) a graphic image from one audiostream and listening to or viewing another (different) audiostream?

BTW - "AC3Filter" indicates the following information regarding the audio clip you uploaded:Stream format: AC3 2/0 (stereo) 48000Hz
Bitstream type: byte stream