Decoding .mpg to extract audio - is there a trick?

[ChristinaS]

I have a few .mpg videos from which I wanted to extract the audio to wav. It was my understanding that the Lame mp3 codec ought to handle that, from what is said at Codec Central. Reading it again though I'm not sure any more. :confused:

I wasn't able to use dMC to convert my .mpg files at all. When trying just Test Conversion I get the error:

The file '.........\video-1.mpg' could not be opened.

(I chopped the file path as it is irrelevant here)

These videos were captured some time ago from vhs tape captured to disk by some (very lousy) video capture software. I don't remember exactly what type of hoops I had to jump through to encode them finally to mpg, but judging from what I have to do now with the newwe software I have, it must have been quite a job. Mostly nothing encodes directly to mpg anyway, so it goes to uncompressed avi and then I use a different programs to make a compressed avi or an mpg.

The thing is I have no idea which .mpg codec must have been used at the time, and the file properties don't say. The id tag is either missing or it's blank.

So, dMC in fact does not understand these .mpg files.

WMP plays them ok. So do all video programs I have. Nero burns a VCD from them.

Stoik Videopak can convert the mpg to wmv with no problem. From that I can use dMC to convert to wma (1-pass works, 2-pass hangs and cannot even be cancelled). From the wmv, dMC can also convert to wav (44.1KHz, stereo, 16-bit) with no problems.

So it's just the mpg which is unreadable by dMC (I'm not trying to delete after conversion, the file is not read-only either).

What type of mpg can dMC understand? or can it?

I'm running dMC release 11 and Powerpack release 5.

[xoas]

Re: Decoding .mpg to extract audio - is there a trick?

I have a few .mpg videos from which I wanted to extract the audio to wav. It was my understanding that the Lame mp3 codec ought to handle that, from what is said at Codec Central

I thought that dMC r11 (and the previous r11 betas from beta 3 on) used the MAD decoder rather than Lame. MAD stands for MPEG Audio Decoder. You can find some more informatiion (and links for more +) here:

http://www.underbit.com/products/mad/

I suspect that the issue has to do with your mpeg file being a video file and not an audio only file. Perhaps the link above would help you determine whether this is the case.

I had always thought that dMC was not able to directly decode audio from video files, that this required goiong through Aux. Input to record the audio while playing the video. Since you do more work in this area than I do, are you aware of video formats that dMC can handle (audio only, of course) directly (without going through Aux. Input or changing file extensions)?

Best wishes and congratulations on cracking the 700 (posts) club.
Bill Mikkelsen

[hans-j�rgen]

Re: Decoding .mpg to extract audio - is there a trick?

It would be important to find out which audio format is used in that container, this should work when playing the file in WMP and right-clicking and/or looking up its properties through the menu. My guess would be MP2 (MPEG-1/2 Layer II), so it might also work by simply renaming the file to .mp2. The sample rate may be important, too, if dbpowerAMP cannot decode the lower sample rates of MPEG-2 Layer II.

[ChristinaS]

Re: Decoding .mpg to extract audio - is there a trick?

It would be important to find out which audio format is used in that container, this should work when playing the file in WMP and right-clicking and/or looking up its properties through the menu. My guess would be MP2 (MPEG-1/2 Layer II), so it might also work by simply renaming the file to .mp2. The sample rate may be important, too, if dbpowerAMP cannot decode the lower sample rates of MPEG-2 Layer II.

Thanks, Hans.

Well, WMP says it uses the MPEG Video Decoder and the Ligos MPEG Audio Decoder. I should do a Google search on that one soon.

Renaming to mp2 still leaves the same error in place. There appears to be no decoding codec for mp2 that I can download seperately anyway, so it would have to be the one in basic dMC if that were the case. But it isn't here.

thought that dMC r11 (and the previous r11 betas from beta 3 on) used the MAD decoder rather than Lame. MAD stands for MPEG Audio Decoder. You can find some more informatiion (and links for more +) here:

http://www.underbit.com/products/mad/

I suspect that the issue has to do with your mpeg file being a video file and not an audio only file. Perhaps the link above would help you determine whether this is the case.

I had always thought that dMC was not able to directly decode audio from video files, that this required goiong through Aux. Input to record the audio while playing the video. Since you do more work in this area than I do, are you aware of video formats that dMC can handle (audio only, of course) directly (without going through Aux. Input or changing file extensions)?

Best wishes and congratulations on cracking the 700 (posts) club

Well, I have been assuming (I know, stupid notion) that if dMC mentions mpg in the formats it decodes that means it will get audio from mpg. Obviously I was wrong! Perhaps it can do it for some other types of mpg, as they seem to not be all the same anyway (to better confuse us all :smile2: ).

Of course I could get it all from Aux Input. I also was able to convert it using a very simple free program that does video conversions (Stoik Videopak) to convert mpg to wmv and then used good old dMC to convert wmv to wma.

And to answer the question of which audio formats dMC can extract from a video, well, at least extracting audio from wmv works. Haven't tried others yet.

I'll be looking into the MAD thing later.

So, Bill, I'm catching up with you? :D

[xoas]

Re: Decoding .mpg to extract audio - is there a trick?

So, Bill, I'm catching up with you?

No, you surpassed me!

Best of wishes,
Bill Mikkelsen

[ChristinaS]

Re: Decoding .mpg to extract audio - is there a trick?

No, you surpassed me!

Best of wishes,
Bill Mikkelsen

Errr. 704 < 707 still as far as I can tell :smile2:

Hey, what's a Nattering Nabob????

[hans-j�rgen]

Re: Decoding .mpg to extract audio - is there a trick?

Well, WMP says it uses the MPEG Video Decoder and the Ligos MPEG Audio Decoder.

And if you double-click on the Ligos Decoder, it should also reveal the specific properties of the audio track (at least WMP 6.0 does this).

[ChristinaS]

Re: Decoding .mpg to extract audio - is there a trick?

And if you double-click on the Ligos Decoder, it should also reveal the specific properties of the audio track (at least WMP 6.0 does this).

Sorry, nothing clickable there in WMP 9 :cry:

[hans-j�rgen]

Re: Decoding .mpg to extract audio - is there a trick?

Then you could try to analyze the .mpg file with a tool like GSpot, this will tell you the properties of the audio track.

[Spoon]

Re: Decoding .mpg to extract audio - is there a trick?

The trouble with .mpg is it encompasses many mpeg formats, looks like MAD cannot handle what ever format is in that file.

[Unregistered]

Re: Decoding .mpg to extract audio - is there a trick?

i found this thread while looking for an answer myself, and i think i've got it.

following that MAD link i saw a program called 'Audacity' mentioned, and since i already have it i thought why not. i told it to open the .mpg, it popped up with its 'converting from mp3' window and just went to it.

the 400meg file converted in under a minute and worked perfectly. the 4gig file is taking a little longer and apparently intends to take many years. i wish i'd known that this would work earlier since before i was using Audacity to record from the 'what you hear' channel and 'real-time' is so slow. i will probably have to do this for the big file.

http://audacity.sourceforge.net/

this program has been indispensable in the audio transcription i've been doing lately.

[ChristinaS]

Re: Decoding .mpg to extract audio - is there a trick?

i found this thread while looking for an answer myself, and i think i've got it.

following that MAD link i saw a program called 'Audacity' mentioned, and since i already have it i thought why not. i told it to open the .mpg, it popped up with its 'converting from mp3' window and just went to it.

the 400meg file converted in under a minute and worked perfectly. the 4gig file is taking a little longer and apparently intends to take many years. i wish i'd known that this would work earlier since before i was using Audacity to record from the 'what you hear' channel and 'real-time' is so slow. i will probably have to do this for the big file.

http://audacity.sourceforge.net/

this program has been indispensable in the audio transcription i've been doing lately.

This sounds like great testimony for Audacity.

Is your 4 Gb still an mpg file or is it uncompressed AVI?

[Unregistered]

Re: Decoding .mpg to extract audio - is there a trick?

its an .mpeg and it never did load (1.5 hrs tv recorded into high quality mp2, the recording program split the files on its own). i just left and watched tv while the comp recorded the audio from the mpeg, the quality came out just fine, but then i'm only doing more transcription so i dont need audio that is super clean and clear.


at the time of my first post i did not notice that this forum was based around the use of a program and i hope i didnt step on any toes by coming in and raving about another app.

[xoas]

Re: Decoding .mpg to extract audio - is there a trick?

i hope i didnt step on any toes by coming in and raving about another app.

Not at all! In fact we often have mentionned other programs.
Thanks for sharing that Audacity does this type of job too.
Best wishes,
Bill mikkelsen

[ChristinaS]

Re: Decoding .mpg to extract audio - is there a trick?

its an .mpeg and it never did load (1.5 hrs tv recorded into high quality mp2, the recording program split the files on its own). i just left and watched tv while the comp recorded the audio from the mpeg, the quality came out just fine, but then i'm only doing more transcription so i dont need audio that is super clean and clear.


at the time of my first post i did not notice that this forum was based around the use of a program and i hope i didnt step on any toes by coming in and raving about another app.

Not a problem, in fact the information is quite welcome. Even if this forum is based one one particular set of applications, there is often a great need for many others in order to achieve all the different types of conversions people run into.