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Topic: TidyMP3 modified to fix digital silence problem. (Read 5122 times) previous topic - next topic
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TidyMP3 modified to fix digital silence problem.

Attached is my modified version of TidyMP3.
It attempts to fix the digitally-silent frames produced by LAME CBR which cause a burst of white noise on my hardware MP3 players.

[Edit] See this thread:
http://www.hydrogenaudio.org/forums/index....showtopic=37086

Yatsura.

TidyMP3 modified to fix digital silence problem.

Reply #1 –
Quote
Attached is my modified version of TidyMP3.
It attempts to fix the digitally-silent frames produced by LAME CBR which cause a burst of white noise on my hardware MP3 players.

Yatsura.
[a href="index.php?act=findpost&pid=326996"][{POST_SNAPBACK}][/a]



I strongly recommend that you look at a file before and after using TidyMP3.  I had to rerip my entire collection due to it modifying the audio of songs.  I tried to get a response from the author with my concerns, but she never did...

TidyMP3 modified to fix digital silence problem.

Reply #2 –
Quote
I strongly recommend that you look at a file before and after using TidyMP3. I had to rerip my entire collection due to it modifying the audio of songs. I tried to get a response from the author with my concerns, but she never did...


I did a lot of looking at files (with a hex editor) during my investigation -
I have compared the results of using 'tag.exe --remove' against those of using tidymp3.
I have yet to see any corruption of the audio caused by tidymp3.

The only modification it makes to audio frames is to repair/remove frames that are already corrupted.

Can you provide any examples ?

My reason for using it instead of 'tag' is that it also removes embedded images and any other non-audio rubbish found in an mp3 file.

Yatsura.

TidyMP3 modified to fix digital silence problem.

Reply #3 –
I have seen TidyMP3 break the audio of files before. In every case, the file was an MPEG II Layer 3 file and not an MPEG I Layer 3 file. So watch those bitrates.

TidyMP3 modified to fix digital silence problem.

Reply #4 –
Quote
I did a lot of looking at files (with a hex editor) during my investigation -
I have compared the results of using 'tag.exe --remove' against those of using tidymp3.
I have yet to see any corruption of the audio caused by tidymp3.

The only modification it makes to audio frames is to repair/remove frames that are already corrupted.

Can you provide any examples ?

My reason for using it instead of 'tag' is that it also removes embedded images and any other non-audio rubbish found in an mp3 file.

Yatsura.
[{POST_SNAPBACK}][/a]


Yatsura,

I understand completely why you want to remove all non-audio information (such as lyrics tags, embedded art, etc).  That was why I was using it as well.    I saw what Otto brings up in MPEG II files I had lying around as well.

I didn't compare using a hex-editor, I visually compared the wave-form of a song before/after using Audacity.  The fact that it was changing the audio of a song at all really bothered me.

I've uploaded a quick test - [a href="http://beaker.virtualplastic.net/download/Wasp_before.mp3]before[/url] and after.  Using TidyMP3 1.4 on a 20 second Bauhaus song (encoded with CDex fullparanioa lame aps).  If you look between 10-13 seconds there appears to be some subtle changes to the song.  Please, correct me if I'm wrong - I'm only doing this visually.  I may be being picky, but if we go to all this trouble to rip music accurately, why then use an application that can subtly distort our music?

TidyMP3 modified to fix digital silence problem.

Reply #5 –
Pweifan, Otto,

  Thanks for your feedback.

  I think I'll hold off using TidyMP3 until I've done some further investigation
  (or fixed the problem).

Quote
if we go to all this trouble to rip music accurately, why then use an application that can subtly distort our music?


  I won't argue with that :-)

  Yatsura.

TidyMP3 modified to fix digital silence problem.

Reply #6 –
Pweifan,

  OK, so now I am *really* confused.

  Comparing your before and after samples with an hex editor yields the following:

  The 'before' clip has 1461 bytes of ID3 header at the start.
  The two files are then binary identical for the next 391651 bytes.
  The 'before' clip then has a single extra frame (104 bytes) of digital silence
  at the end.

  Why should these files produce different wave forms, given that the audio data is identical ?

Edit:
Ignore this - discovered that it's just a matter of sample/bitrates.
[
  Otto - I don't have any MPEG2 samples to investigate. Can you provide some,
  or point me to a free encoder ?
]

I have tested a couple of MPEG2 files now tho', and still haven't seen any corruption.
(Not that I'm saying you're wrong and that it doesn't happen - I just haven't been able
to reproduce it)
Oh well...

  Thanks,
  Yatsura.
 

TidyMP3 modified to fix digital silence problem.

Reply #7 –
Quote
  Otto - I don't have any MPEG2 samples to investigate. Can you provide some,
  or point me to a free encoder ?
[a href="index.php?act=findpost&pid=327201"][{POST_SNAPBACK}][/a]

Use LAME to encode a 44.1khz WAV at a lower bitrate, like 56 kbps. That'll produce an MPEG 2 layer 3 file, I believe. When running it through TidyMP3, some of the audio gets cut out leaving you with a weird stuttering thing. TidyMP3 doesn't understand the slightly different frame structure, I think.