Comments on: Covert .mp3 to .wav and .ogg from command http://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/ A technology news blog covering software, mobile phones, gadgets, security, the Internet and other relevant areas. Sun, 12 Feb 2012 02:07:05 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: kwanbishttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-967191 kwanbis Thu, 11 Feb 2010 12:51:10 +0000 http://www.ghacks.net/?p=22829#comment-967191 Zvaral, you are the most suborn people in the world. Time after time we proved you wrong, gave you reasons, told you to try yo LISTEN to the encodes, etc. You keep telling the same BS. EVEN THE VORBIS OFFICIAL PAGE SAYS IT IS WRONG TO DO MP3 TO VORBIS (IT IS NOT CALLED OGG). But you keep insisting! Yo never replied to my previous post, where i clearly show you the degradation after doing simply 99 encodes (so it is more obvious). So, if you want to believe MP3->Vorbis is OK, do so, but do not help spread a lie. Zvaral, you are the most suborn people in the world. Time after time we proved you wrong, gave you reasons, told you to try yo LISTEN to the encodes, etc. You keep telling the same BS.

EVEN THE VORBIS OFFICIAL PAGE SAYS IT IS WRONG TO DO MP3 TO VORBIS (IT IS NOT CALLED OGG).

But you keep insisting!

Yo never replied to my previous post, where i clearly show you the degradation after doing simply 99 encodes (so it is more obvious).

So, if you want to believe MP3->Vorbis is OK, do so, but do not help spread a lie.

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-967082 zvaral Thu, 11 Feb 2010 09:50:29 +0000 http://www.ghacks.net/?p=22829#comment-967082 The problem with your sound sample, Owl, is that it is full of noise-like effects. This means that every spectral components of your sound sample is almost equally presented. (You can try it to plot with the code I showed you before.) This was not my case therefore I had not to care too much about the high frequency components. The simplest solution to get essentially the same sound quality after ten times re-encoding with ogg to choose a higher bit rate because higher frequencies require higher number of sampling points. I've tried it with 192 and the quality was OK but you can choose even higher and I am sure you won't here any difference. You have also the choice to change the spectral treatment behaviour of vorbis encoder with the --advanced-encode-option and their properly selected parameters which helps to prevent loosing any further information after existing encoded files. This is also a proof that you can avoid loosing information If you know what you do. So, loosing information after lossy file conversion is not statutory. But everybody speak about that it is always happen which is not true. Not always. And do not forget that we are talking about a lot of encodings with the same encoder. In practice you need only one or two encodings. Turning to the original subject you do not have to fear of encoding any mp3 to ogg. The reverse order is problematic (as benq also stated above) but I showed you that mp3 files uses less information and ogg won't change it after re-encoding with the same parameters. Sorry guys, but I have to deal with my official project now.:-) But do not forget mp3 to ogg is ok. See again: https://docs.google.com/fileview?id=0BzG2hFQvTug6NWY3ZGUyMTEtYTA4Yi00NDYzLTgyZDUtZTZiNTJiMGUxOWJj&hl=en And take care! The problem with your sound sample, Owl, is that it is full of noise-like effects. This means that every spectral components of your sound sample is almost equally presented. (You can try it to plot with the code I showed you before.) This was not my case therefore I had not to care too much about the high frequency components. The simplest solution to get essentially the same sound quality after ten times re-encoding with ogg to choose a higher bit rate because higher frequencies require higher number of sampling points. I’ve tried it with 192 and the quality was OK but you can choose even higher and I am sure you won’t here any difference.

You have also the choice to change the spectral treatment behaviour of vorbis encoder with the
–advanced-encode-option
and their properly selected parameters which helps to prevent loosing any further information after existing encoded files.

This is also a proof that you can avoid loosing information If you know what you do. So, loosing information after lossy file conversion is not statutory. But everybody speak about that it is always happen which is not true. Not always.

And do not forget that we are talking about a lot of encodings with the same encoder. In practice you need only one or two encodings. Turning to the original subject you do not have to fear of encoding any mp3 to ogg. The reverse order is problematic (as benq also stated above) but I showed you that mp3 files uses less information and ogg won’t change it after re-encoding with the same parameters.

Sorry guys, but I have to deal with my official project now.:-) But do not forget mp3 to ogg is ok. See again:
https://docs.google.com/fileview?id=0BzG2hFQvTug6NWY3ZGUyMTEtYTA4Yi00NDYzLTgyZDUtZTZiNTJiMGUxOWJj&hl=en

And take care!

]]> By: Owlhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-966713 Owl Wed, 10 Feb 2010 20:01:44 +0000 http://www.ghacks.net/?p=22829#comment-966713 If it's VBR it's because you used VBR, since I used the exact same switches as you when encoding... As I clearly stated :) If it’s VBR it’s because you used VBR, since I used the exact same switches as you when encoding… As I clearly stated :)

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-966651 zvaral Wed, 10 Feb 2010 17:53:10 +0000 http://www.ghacks.net/?p=22829#comment-966651 By the way Owl, you did not do the same than me because you used VBR encoding instead of CBR. Of course, it is very difficult to keep the quality using VBR after subsequent compressions. My 10 times compressed file has almost the same quality than the first compression. And the difference is only that amount you can see on the graphs I posted in the first document (because there are some): https://docs.google.com/fileview?id=0BzG2hFQvTug6NTcyMTI3ZWQtYmYzMS00MDhmLWE3NDUtMDA2NDMxM2RmOWRl&hl=en By the way Owl, you did not do the same than me because you used VBR encoding instead of CBR. Of course, it is very difficult to keep the quality using VBR after subsequent compressions. My 10 times compressed file has almost the same quality than the first compression. And the difference is only that amount you can see on the graphs I posted in the first document (because there are some):
https://docs.google.com/fileview?id=0BzG2hFQvTug6NTcyMTI3ZWQtYmYzMS00MDhmLWE3NDUtMDA2NDMxM2RmOWRl&hl=en

]]> By: kwanbishttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-966618 kwanbis Wed, 10 Feb 2010 16:48:14 +0000 http://www.ghacks.net/?p=22829#comment-966618 "but it is most likely that the resulting file will SOUND WORSE". Re-Encoding looses a little bit of information each time. How important depends on the listener ears. There are people that can tell on the first encode, and there would be people that can not tell after 5 encodes. But you ALWAYS LOOSE QUALITY at each re-encode. Even on the same format. “but it is most likely that the resulting file will SOUND WORSE”. Re-Encoding looses a little bit of information each time. How important depends on the listener ears. There are people that can tell on the first encode, and there would be people that can not tell after 5 encodes. But you ALWAYS LOOSE QUALITY at each re-encode. Even on the same format.

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-966584 zvaral Wed, 10 Feb 2010 15:41:57 +0000 http://www.ghacks.net/?p=22829#comment-966584 You are right guys, it may occur that the quality changes. But not this is what I wanted to tell you. What I wanted to tell you is that this is not statutory! What I claim is that quality loss converting from one format to an other one is not essential. Ok, it may occur, but if you know what you do this is not always happen. This is supported by benq as well who gave us some quotes from the vorbis faq: "The decoded MP3 will be missing the parts of the original audio that the MP3 encoder chose to discard. The Ogg Vorbis encoder will then discard other audio components when it compresses the data. At best, the result will be an Ogg file that sounds the same as your original MP3, but it is most likely that the resulting file will sound worse..." Thus, at best you will obtain the same quality ogg which fact is also scientifically justified by my document posted a few hours before: https://docs.google.com/fileview?id=0BzG2hFQvTug6NWY3ZGUyMTEtYTA4Yi00NDYzLTgyZDUtZTZiNTJiMGUxOWJj&hl=en Take Care! You are right guys, it may occur that the quality changes. But not this is what I wanted to tell you. What I wanted to tell you is that this is not statutory! What I claim is that quality loss converting from one format to an other one is not essential. Ok, it may occur, but if you know what you do this is not always happen.

This is supported by benq as well who gave us some quotes from the vorbis faq:

“The decoded MP3 will be missing the parts of the original audio that the MP3 encoder chose to discard. The Ogg Vorbis encoder will then discard other audio components when it compresses the data. At best, the result will be an Ogg file that sounds the same as your original MP3, but it is most likely that the resulting file will sound worse…”

Thus, at best you will obtain the same quality ogg which fact is also scientifically justified by my document posted a few hours before:
https://docs.google.com/fileview?id=0BzG2hFQvTug6NWY3ZGUyMTEtYTA4Yi00NDYzLTgyZDUtZTZiNTJiMGUxOWJj&hl=en

Take Care!

]]> By: Owlhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-2/#comment-966474 Owl Wed, 10 Feb 2010 13:23:50 +0000 http://www.ghacks.net/?p=22829#comment-966474 "But the final problem was if you reencode an ogg file many times if it degrade the quality." The answer to that is yes zvaral. That's a nice pdf and all but did you actually listen to the 10th encode you did? I think not, because if you did you wouldn't be arguing. A thought experiment and a theoretical conclusion does not suffice, it doesn't matter how nicely presented it is :) I did check the frequency grafs in Audacity and they are very similar, not an exact match, but very similar. The audio however isn't when you LISTEN to it. Do the experiment and listen to the files ok. Or listen to my test, nothing fishy in the zips, just 3 wav/ogg files. After 1, 10 and 20 ogg encodes done exactly as you wrote zvaral. It's a 30s snippet of one of my own crappy tunes, so don't worry about any copyright stuff :) The 3 wav files: http://www.sendspace.com/file/ntphd1 Or the 3 ogg files: http://www.sendspace.com/file/z2ufl9 “But the final problem was if you reencode an ogg file many times if it degrade the quality.”
The answer to that is yes zvaral. That’s a nice pdf and all but did you actually listen to the 10th encode you did? I think not, because if you did you wouldn’t be arguing. A thought experiment and a theoretical conclusion does not suffice, it doesn’t matter how nicely presented it is :)

I did check the frequency grafs in Audacity and they are very similar, not an exact match, but very similar. The audio however isn’t when you LISTEN to it. Do the experiment and listen to the files ok.

Or listen to my test, nothing fishy in the zips, just 3 wav/ogg files. After 1, 10 and 20 ogg encodes done exactly as you wrote zvaral. It’s a 30s snippet of one of my own crappy tunes, so don’t worry about any copyright stuff :)
The 3 wav files: http://www.sendspace.com/file/ntphd1
Or the 3 ogg files: http://www.sendspace.com/file/z2ufl9

]]> By: kwanbishttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-966469 kwanbis Wed, 10 Feb 2010 13:19:38 +0000 http://www.ghacks.net/?p=22829#comment-966469 zvaral. Because of the nature of the psycoacustic methods, comparing graphics is not correct to determine if an encoder is better than other. In general, Vorbis is a better format than MP3, but LAME, has improved so much, that most users won't tell the difference. I recommend you again to go to hydrogenaudio an learn a little. In HydrogenAudio, you would find the devs of foobar2000, lame, vorbis, nero aac, flac, wavpack, tak, eac, dbpoweramp, etc. People that have been working for YEARS on audio issues. zvaral. Because of the nature of the psycoacustic methods, comparing graphics is not correct to determine if an encoder is better than other. In general, Vorbis is a better format than MP3, but LAME, has improved so much, that most users won’t tell the difference. I recommend you again to go to hydrogenaudio an learn a little. In HydrogenAudio, you would find the devs of foobar2000, lame, vorbis, nero aac, flac, wavpack, tak, eac, dbpoweramp, etc. People that have been working for YEARS on audio issues.

]]> By: benqhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-966468 benq Wed, 10 Feb 2010 13:19:01 +0000 http://www.ghacks.net/?p=22829#comment-966468 Sorry, I did not make a scientific theory about that, I used what comes with Amarok's transcoding capacities, however, the end result files had about the same size (vbr) than the input ogg files, so I am confident that the transcoding did attempt to match the bitrate as closely as possible. Here is what the "makes" of vorbis say: You can convert any audio format to Ogg Vorbis. However, converting from one lossy format, like MP3, to another lossy format, like Vorbis, is generally a bad idea. Both MP3 and Vorbis encoders achieve high compression ratios by throwing away parts of the audio waveform that you probably won't hear. However, the MP3 and Vorbis codecs are very different, so they each will throw away different parts of the audio, although there certainly is some overlap. Converting a MP3 to Vorbis involves decoding the MP3 file back to an uncompressed format, like WAV, and recompressing it using the Ogg Vorbis encoder. The decoded MP3 will be missing the parts of the original audio that the MP3 encoder chose to discard. The Ogg Vorbis encoder will then discard other audio components when it compresses the data. At best, the result will be an Ogg file that sounds the same as your original MP3, but it is most likely that the resulting file will sound worse than your original MP3. In no case will you get a file that sounds better than the original MP3. see http://www.vorbis.com/faq/ I can confirm the above quote with my unscientific test. I did what average Joe would do and I can trust my ears. mp3 to ogg is a don't. Sorry, I did not make a scientific theory about that, I used what comes with Amarok’s transcoding capacities, however, the end result files had about the same size (vbr) than the input ogg files, so I am confident that the transcoding did attempt to match the bitrate as closely as possible.

Here is what the “makes” of vorbis say:
You can convert any audio format to Ogg Vorbis. However, converting from one lossy format, like MP3, to another lossy format, like Vorbis, is generally a bad idea. Both MP3 and Vorbis encoders achieve high compression ratios by throwing away parts of the audio waveform that you probably won’t hear. However, the MP3 and Vorbis codecs are very different, so they each will throw away different parts of the audio, although there certainly is some overlap. Converting a MP3 to Vorbis involves decoding the MP3 file back to an uncompressed format, like WAV, and recompressing it using the Ogg Vorbis encoder. The decoded MP3 will be missing the parts of the original audio that the MP3 encoder chose to discard. The Ogg Vorbis encoder will then discard other audio components when it compresses the data. At best, the result will be an Ogg file that sounds the same as your original MP3, but it is most likely that the resulting file will sound worse than your original MP3. In no case will you get a file that sounds better than the original MP3.

see http://www.vorbis.com/faq/

I can confirm the above quote with my unscientific test. I did what average Joe would do and I can trust my ears. mp3 to ogg is a don’t.

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-966462 zvaral Wed, 10 Feb 2010 13:09:58 +0000 http://www.ghacks.net/?p=22829#comment-966462 I made some analyses on mp3 and ogg conversions and also to convert from one format to an other one. The results are really-really exciting!!! I recommend it for anybody. You will see that ogg has a superior performance over mp3! The document is here: https://docs.google.com/fileview?id=0BzG2hFQvTug6NWY3ZGUyMTEtYTA4Yi00NDYzLTgyZDUtZTZiNTJiMGUxOWJj&hl=en I made some analyses on mp3 and ogg conversions and also to convert from one format to an other one. The results are really-really exciting!!! I recommend it for anybody. You will see that ogg has a superior performance over mp3!

The document is here:
https://docs.google.com/fileview?id=0BzG2hFQvTug6NWY3ZGUyMTEtYTA4Yi00NDYzLTgyZDUtZTZiNTJiMGUxOWJj&hl=en

]]> By: kwanbishttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965843 kwanbis Tue, 09 Feb 2010 16:51:27 +0000 http://www.ghacks.net/?p=22829#comment-965843 zvaral, First of all, this post was about mp3 -> ogg. Then you stated that your theory was only applicable between OGG -> OGG. Anyway. Since it seems it is difficult for you to grasp the concepts, let me try to give you an analogy. If you go to a models party (wav file), it would be easy to discard the ugglier ones (first encode), since they would stand out easily from the models. Now, if you make a party, each time with the remaining ladies, it would be each time more difficult to discard uggly ones, cause you already did on the previous parties. Now, so you can really see what i mean, i have encoded a WAV once, and then 99 more times. And since you like numbers so much, i have this graphics for you. Do you still think they look the same? Try it, encode a wav 1 and another 99 times, and then LISTEN to the songs. Do you think they sound the same? (If you do, you should go to a doctor). http://imgur.com/j2xvw.png http://imgur.com/E7jkP.png http://imgur.com/kZqFi.png http://imgur.com/IvfPE.png zvaral, First of all, this post was about mp3 -> ogg. Then you stated that your theory was only applicable between OGG -> OGG. Anyway.

Since it seems it is difficult for you to grasp the concepts, let me try to give you an analogy. If you go to a models party (wav file), it would be easy to discard the ugglier ones (first encode), since they would stand out easily from the models. Now, if you make a party, each time with the remaining ladies, it would be each time more difficult to discard uggly ones, cause you already did on the previous parties.

Now, so you can really see what i mean, i have encoded a WAV once, and then 99 more times.

And since you like numbers so much, i have this graphics for you.

Do you still think they look the same?

Try it, encode a wav 1 and another 99 times, and then LISTEN to the songs. Do you think they sound the same? (If you do, you should go to a doctor).

http://imgur.com/j2xvw.png
http://imgur.com/E7jkP.png
http://imgur.com/kZqFi.png
http://imgur.com/IvfPE.png

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965717 zvaral Tue, 09 Feb 2010 13:21:24 +0000 http://www.ghacks.net/?p=22829#comment-965717 Dear Folk, I know mp3 and ogg is different. But the final problem was if you reencode an ogg file many times if it degrade the quality. This although a little relate to encoding from mp3 to ogg. Please, see my analysis here below and decide your self. https://docs.google.com/fileview?id=0BzG2hFQvTug6NTcyMTI3ZWQtYmYzMS00MDhmLWE3NDUtMDA2NDMxM2RmOWRl&hl=en Yours Dear Folk,

I know mp3 and ogg is different. But the final problem was if you reencode an ogg file many times if it degrade the quality. This although a little relate to encoding from mp3 to ogg.

Please, see my analysis here below and decide your self.

https://docs.google.com/fileview?id=0BzG2hFQvTug6NTcyMTI3ZWQtYmYzMS00MDhmLWE3NDUtMDA2NDMxM2RmOWRl&hl=en

Yours

]]> By: Owlhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965649 Owl Tue, 09 Feb 2010 10:53:31 +0000 http://www.ghacks.net/?p=22829#comment-965649 I'm gonna skip any screens of wavefoms, MD5 checksums and what have you and just get to it.. First off you sort of assume that the ogg and mp3 formats are one and the same, that the codecs used to encode do exacly the same things.. this is not true. Vorbis and Lame (for instance) does things differently, discard different things in different ways.. They are not the same and do not remove the same things. And if you don't believe me... take it from the Vorbis guys themselves. http://www.vorbis.com/faq/#transcode Alright on to the test... I tried several different ways of encoding, using "-b 128" for the mp3s and the same settings on the ogg conversion as you zvarai. 1. wav --> mp3 --> wav --> mp3... repeat until you've done it 10 times. 2. wav --> ogg --> wav --> ogg... repeat. 3. wav --> mp3 --> wav --> ogg... repeat. 4. wav --> mp3 --> ogg --> mp3... repeat. 5. wav --> mp3 --> mp3 ---> mp3... repeat. you can see where this is going right..? 6. wav --> ogg --> ogg --> ogg... repeat. Results then... The difference between the first and the second encode is nominal in all tests, hard to tell a difference, but they do sound a little different. The difference between the first and the last encode, in all tests, is like night and day.. encode ten sounds really really bad. I don't know how you can't hear a difference man, it's an apparant change in sound. It sounds like some old streaming realmedia file (if you remember those). You can listen to them in sequence and you'll hear the sound gradually degrade as you go. Anyways.. I didn't really do this for an online argument, but to settle my own curiosity after reading your results. I’m gonna skip any screens of wavefoms, MD5 checksums and what have you and just get to it..

First off you sort of assume that the ogg and mp3 formats are one and the same, that the codecs used to encode do exacly the same things.. this is not true. Vorbis and Lame (for instance) does things differently, discard different things in different ways.. They are not the same and do not remove the same things.

And if you don’t believe me… take it from the Vorbis guys themselves.
http://www.vorbis.com/faq/#transcode

Alright on to the test…
I tried several different ways of encoding, using “-b 128″ for the mp3s and the same settings on the ogg conversion as you zvarai.

1. wav –> mp3 –> wav –> mp3… repeat until you’ve done it 10 times.
2. wav –> ogg –> wav –> ogg… repeat.
3. wav –> mp3 –> wav –> ogg… repeat.
4. wav –> mp3 –> ogg –> mp3… repeat.
5. wav –> mp3 –> mp3 —> mp3… repeat.

you can see where this is going right..?

6. wav –> ogg –> ogg –> ogg… repeat.

Results then…
The difference between the first and the second encode is nominal in all tests, hard to tell a difference, but they do sound a little different. The difference between the first and the last encode, in all tests, is like night and day.. encode ten sounds really really bad. I don’t know how you can’t hear a difference man, it’s an apparant change in sound. It sounds like some old streaming realmedia file (if you remember those). You can listen to them in sequence and you’ll hear the sound gradually degrade as you go.

Anyways.. I didn’t really do this for an online argument, but to settle my own curiosity after reading your results.

]]> By: thomas.tmchttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965621 thomas.tmc Tue, 09 Feb 2010 09:08:55 +0000 http://www.ghacks.net/?p=22829#comment-965621 zvaral, you are wrong... Just based on the psychoacoustic model of the encoder alone, both OGG and MP3 would have to use very close to the same model, which they don't. All the various MP3 encoders implement widely varying psychoacoustic models, while OGG's approach is unique. Also, it's not true to say that since the original audio has already been encoded at 128 kbps once it will not be effected by re-encoding it again at 128 kbps. I'll give you that not always does the common sense result turn out to be the actual result... but in this case it is. Lossy compression put through more lossy compression actually results in extremely LOSSY compression. Go figure... zvaral, you are wrong…

Just based on the psychoacoustic model of the encoder alone, both OGG and MP3 would have to use very close to the same model, which they don’t. All the various MP3 encoders implement widely varying psychoacoustic models, while OGG’s approach is unique.

Also, it’s not true to say that since the original audio has already been encoded at 128 kbps once it will not be effected by re-encoding it again at 128 kbps.

I’ll give you that not always does the common sense result turn out to be the actual result… but in this case it is. Lossy compression put through more lossy compression actually results in extremely LOSSY compression. Go figure…

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965608 zvaral Tue, 09 Feb 2010 08:04:28 +0000 http://www.ghacks.net/?p=22829#comment-965608 You are wrong again! Of course if you have a single bit difference between two files the md5sum will give a totally different result. This is not a proof! And I do not say that two files after recompression will be 100% same but 99.988%. On the other hand you do not know what you are doing. Of course, you do not have to compare the original wav file and the ten times compressed one. But a compressed file and a later compressed one. Your graphs clearly shows that you used the original wav file first because the high frequency components are presented but second you use a compressed and decoded file where the high frequency components are missing. This is what sound compression do. Finally, I invite you to study a bit more Fourier analysis and do not cheat! You are wrong again! Of course if you have a single bit difference between two files the md5sum will give a totally different result. This is not a proof! And I do not say that two files after recompression will be 100% same but 99.988%. On the other hand you do not know what you are doing. Of course, you do not have to compare the original wav file and the ten times compressed one. But a compressed file and a later compressed one. Your graphs clearly shows that you used the original wav file first because the high frequency components are presented but second you use a compressed and decoded file where the high frequency components are missing. This is what sound compression do. Finally, I invite you to study a bit more Fourier analysis and do not cheat!

]]> By: kwanbishttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965440 kwanbis Mon, 08 Feb 2010 22:16:39 +0000 http://www.ghacks.net/?p=22829#comment-965440 You just show you don't understand the encoding process. Ok, i did the CBR 128, 20 times, as you wanted. Each time, the MD5 was different: e442a998a8bd93725e3a5de99f727ba8 a.wav b4d41cb8e2685f6982352880fb3b438f a.wav aab47387fbc5bf1239182b38cf10c75c a.wav af6f28b957609aa1b4b97e6bd40478e6 a.wav 5294d9e3bdd27f5db0eee5bb0ac33d0a a.wav b24fe2e6e18338c16bf75b1ffec0f074 a.wav 85e27e05fe04c034eee517e4a920bbff a.wav e837928aa7c0083e9ec1b05a5a9b06ad a.wav f1a8255cbb69f88d12500cf6214a4901 a.wav 115f5882000ccf7eb76fdf12853a8a73 a.wav 731820e658a07fc40ddff071f1f37101 a.wav 1bc92d747e87761886aaff94286385a4 a.wav 175dd2aeea415df432cb7d900063faa2 a.wav d2c73a805afc960e84070e81e683f4f5 a.wav 566cd0055107191379f0ad7fdecd267c a.wav 67b789479c0d6e3b3e65ae9c1667aceb a.wav d1784ee02d1d71a799669342703f39e3 a.wav 3d8d0a96f54344cfdebd87d1f4fd65a1 a.wav b2b2f48d7c79a6e9f56b044dd298eef2 a.wav 7db46b04cc37795f2e403fe8bb2309d3 a.wav Then, i did 2 graphs of the original and final wav, with audacity. http://imgur.com/89MrG.png http://imgur.com/X1Yuu.png Again, this probes, if it ever was the need, you are wrong. I invite you again to go to hydrogenaudio to lear a little bit. You would find very knowledgeable people. You just show you don’t understand the encoding process.

Ok, i did the CBR 128, 20 times, as you wanted. Each time, the MD5 was different:

e442a998a8bd93725e3a5de99f727ba8 a.wav
b4d41cb8e2685f6982352880fb3b438f a.wav
aab47387fbc5bf1239182b38cf10c75c a.wav
af6f28b957609aa1b4b97e6bd40478e6 a.wav
5294d9e3bdd27f5db0eee5bb0ac33d0a a.wav
b24fe2e6e18338c16bf75b1ffec0f074 a.wav
85e27e05fe04c034eee517e4a920bbff a.wav
e837928aa7c0083e9ec1b05a5a9b06ad a.wav
f1a8255cbb69f88d12500cf6214a4901 a.wav
115f5882000ccf7eb76fdf12853a8a73 a.wav
731820e658a07fc40ddff071f1f37101 a.wav
1bc92d747e87761886aaff94286385a4 a.wav
175dd2aeea415df432cb7d900063faa2 a.wav
d2c73a805afc960e84070e81e683f4f5 a.wav
566cd0055107191379f0ad7fdecd267c a.wav
67b789479c0d6e3b3e65ae9c1667aceb a.wav
d1784ee02d1d71a799669342703f39e3 a.wav
3d8d0a96f54344cfdebd87d1f4fd65a1 a.wav
b2b2f48d7c79a6e9f56b044dd298eef2 a.wav
7db46b04cc37795f2e403fe8bb2309d3 a.wav

Then, i did 2 graphs of the original and final wav, with audacity.

http://imgur.com/89MrG.png

http://imgur.com/X1Yuu.png

Again, this probes, if it ever was the need, you are wrong.

I invite you again to go to hydrogenaudio to lear a little bit.

You would find very knowledgeable people.

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965428 zvaral Mon, 08 Feb 2010 21:43:21 +0000 http://www.ghacks.net/?p=22829#comment-965428 I am very sorry but your test is wrong. If you had checked what I had written in my test you would have seen this immediately. You had had to use the --manage option because oggenc would use the VBR encoding algorithm by default. You need a CBR encoding if you want to get something similar to the previous encoding. I hope I do not have to explain why. Once more (and last) the difference in a few bits (0.012%) between two large music files does not make sense and won't be distinguished with any human sense. By the way this negligible, very small difference is also a property of the fast Fourier transformation due to the high sensitivity of small numerical values at the edge of the filtering function. I am very sorry but your test is wrong. If you had checked what I had written in my test you would have seen this immediately. You had had to use the –manage option because oggenc would use the VBR encoding algorithm by default. You need a CBR encoding if you want to get something similar to the previous encoding. I hope I do not have to explain why.

Once more (and last) the difference in a few bits (0.012%) between two large music files does not make sense and won’t be distinguished with any human sense. By the way this negligible, very small difference is also a property of the fast Fourier transformation due to the high sensitivity of small numerical values at the edge of the filtering function.

]]> By: kwanbishttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965389 kwanbis Mon, 08 Feb 2010 20:19:17 +0000 http://www.ghacks.net/?p=22829#comment-965389 zvaral, if you where right, recompressing a file would give the EXACT same file. Not only did you mention it was not the same (you said almost the same), but doing a very simpe test, you can find out: I did this test, starting with a WAV song: oggenc -q 5 0.wav -o 1.ogg && oggdec 1.ogg && md5sum 1.wav 1387e468ebbf492f3ed1f35035c64a0b 1.wav oggenc -q 5 1.wav -o 2.ogg && oggdec 2.ogg && md5sum 2.wav dfb05b074b151b167142914677a15f5a 2.wav oggenc -q 5 2.wav -o 3.ogg && oggdec 3.ogg && md5sum 3.wav 67e8db83ae3937efb6914fd5ca1b9eec 3.wav oggenc -q 5 3.wav -o 4.ogg && oggdec 4.ogg && md5sum 4.wav 752d7db0afccc41eb118dca11075a654 4.wav oggenc -q 5 4.wav -o 5.ogg && oggdec 5.ogg && md5sum 5.wav 40c67f4b4ebe19e0bd5c9a49eaf300f4 5.wav oggenc -q 5 5.wav -o 6.ogg && oggdec 6.ogg && md5sum 6.wav 07ecb05413b464ebaaa4bb3d76ebd576 6.wav As you can see, each time, the md5 checksum is different. That means there have been changes on the file. Not only that, i did an analysis of the original file, and the final file, here is the screen, after 20 iterations. As you can see, the information is not the same: http://imgur.com/YDTXI.png http://imgur.com/vUcgY.png zvaral, if you where right, recompressing a file would give the EXACT same file.

Not only did you mention it was not the same (you said almost the same), but doing a very simpe test, you can find out:

I did this test, starting with a WAV song:

oggenc -q 5 0.wav -o 1.ogg && oggdec 1.ogg && md5sum 1.wav
1387e468ebbf492f3ed1f35035c64a0b 1.wav

oggenc -q 5 1.wav -o 2.ogg && oggdec 2.ogg && md5sum 2.wav
dfb05b074b151b167142914677a15f5a 2.wav

oggenc -q 5 2.wav -o 3.ogg && oggdec 3.ogg && md5sum 3.wav
67e8db83ae3937efb6914fd5ca1b9eec 3.wav

oggenc -q 5 3.wav -o 4.ogg && oggdec 4.ogg && md5sum 4.wav
752d7db0afccc41eb118dca11075a654 4.wav

oggenc -q 5 4.wav -o 5.ogg && oggdec 5.ogg && md5sum 5.wav
40c67f4b4ebe19e0bd5c9a49eaf300f4 5.wav

oggenc -q 5 5.wav -o 6.ogg && oggdec 6.ogg && md5sum 6.wav
07ecb05413b464ebaaa4bb3d76ebd576 6.wav

As you can see, each time, the md5 checksum is different.

That means there have been changes on the file.

Not only that, i did an analysis of the original file, and the final file, here is the screen, after 20 iterations. As you can see, the information is not the same:

http://imgur.com/YDTXI.png

http://imgur.com/vUcgY.png

]]> By: zvaralhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965381 zvaral Mon, 08 Feb 2010 20:08:49 +0000 http://www.ghacks.net/?p=22829#comment-965381 Dear benq, you state something which is not supported by facts. How did you do the conversion which yielded a worse quality mp3? As you could see I gave an exact explanation and documented my claims. And everyone can follow and test what I did. And I gave also an ear test after all which seemed perfect. Therefore the white noise theory is wrong. Dear kwanbis, you stated if I compress an ogg file twenty times all compression will give a different file. I proved this is not true. At least among rational frames. I do not understand how somebody can be so simple that he/she does not understand all the mathematics behind these algorithms and say bs to a well established claim. Sad story. Dear benq, you state something which is not supported by facts. How did you do the conversion which yielded a worse quality mp3? As you could see I gave an exact explanation and documented my claims. And everyone can follow and test what I did. And I gave also an ear test after all which seemed perfect. Therefore the white noise theory is wrong.

Dear kwanbis, you stated if I compress an ogg file twenty times all compression will give a different file. I proved this is not true. At least among rational frames. I do not understand how somebody can be so simple that he/she does not understand all the mathematics behind these algorithms and say bs to a well established claim. Sad story.

]]> By: harriseldonhttp://www.ghacks.net/2010/02/05/covert-mp3-to-wav-and-ogg-from-command/comment-page-1/#comment-965325 harriseldon Mon, 08 Feb 2010 17:30:49 +0000 http://www.ghacks.net/?p=22829#comment-965325 pacpl is a good tool as well (Perl Audio Converter) pacpl.sourceforge.net It has built-in mass processing options as well pacpl is a good tool as well (Perl Audio Converter)
pacpl.sourceforge.net
It has built-in mass processing options as well

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