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Topic: Utils > Fix MP3 Header (Read 12731 times) previous topic - next topic
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Utils > Fix MP3 Header

Hello All,

A quick search didn't yield anything, so I'm hoping that perhaps there's someone out there with some knowledge to share about using this feature.

The Problem

I have a live recording that was split into several mp3s, however they were not encoded w/ LAME.  I would like to play back (and possibly burrrn) these files gapless, and if I understand correctly, the Fix MP3 Header util would allow me to correct the reported length / manually remove gaps (as stated in the dialog's Info box).  Will this achieve my intended purpose?

Usage

I'm very confused by the three options available in the dialog...

Encoder delay.  Default 576 samples for LAME.  As stated, my files ain't LAME, however I do want them to have LAME-like accurate length info to play back gapless.  My intuition tells me to leave this at the default setting of 576, is this correct?

Padding / Desired length of track.  No idea what to do here.  I *think* padding is generally a good for tagging, so "0 to disable padding" doesn't seem so great.  At the same time entering the desired length of track is pointless if I don't know what length to correctly enter, so leaving this setting at 0 seems to be the lesser of 2 evils.  Hypothetically, if I did want to try to enter the desired length, would it be:

( a ) the # of samples of the existing file (as reported in the file info / properties box)
( b ) the # of rounded samples of the existing file (as reported in the file info / properties box)
( c ) neither of the above

Rebuild entire stream.  Thinking I only want this if I'm using the util to repair a damaged/corrupt MP3 file.  Correct?

Lastly, as I believe this operation will irreversibly alter the MP3 file, would it make sense to create backup copies of my original files in case anything gets screwed up?

Any light that could be shed on the above would be greatly appreciated.  Thanks in advance for your assistance.

Utils > Fix MP3 Header

Reply #1 –
It's not a "definitive answer" but this is what I do:

I copy the number of samples (Properties/Technical info tab) and I enter that number into second box of 'Fix MP3 Header' dialog. This fixes the reported length problem, don't know about gap-less playback....

For the first box (Encoder delay...) I have no idea what should go there if the mp3 ain't LAME encoded...

Utils > Fix MP3 Header

Reply #2 –
Thanks for the reply roentgen, fortunately I'm not having reported length problems, just wondering how to properly use it to correct non-LAME MP3s for gapless playback (if this is indeed possible).

Anyone else out there use this util??? 

Utils > Fix MP3 Header

Reply #3 –
Is there no one out there who knows how to use Foobar's Fix MP3 header?

Utils > Fix MP3 Header

Reply #4 –
Sorry but I dont understand how "fixing" an mp3 header is supposed to give you gapless playback unless the song length is being incorrectly reported resulting in an unexpected gap at the end of the song. Wether the song was encoded with lame or something else, this will not give you "gapless" playback unless your encoder detects when the sound stops and chops the silence at the end of the track.

I think what you are looking for is some sort of component or dsp that wil auto-detect and remove silence from the ends of your tracks so that when they play back they sound gapless.  You might also want to consider crossfadng to give you a gapless sounding playback.

Utils > Fix MP3 Header

Reply #5 –
Just out of curiosity: how do you detect if an mp3 is LAME encoded within foobar?

Utils > Fix MP3 Header

Reply #6 –
See also this thread were several other users are discussing gapless playback. Apparently there is a way to hack up your files by screwing with the header, that thread would be a better place to discuss it.

Utils > Fix MP3 Header

Reply #7 –
Quote from: Yotsuya on
Sorry but I dont understand how "fixing" an mp3 header is supposed to give you gapless playback unless the song length is being incorrectly reported resulting in an unexpected gap at the end of the song. Wether the song was encoded with lame or something else, this will not give you "gapless" playback unless your encoder detects when the sound stops and chops the silence at the end of the track.

I think what you are looking for is some sort of component or dsp that wil auto-detect and remove silence from the ends of your tracks so that when they play back they sound gapless.  You might also want to consider crossfadng to give you a gapless sounding playback.

My apologies, allow me to back up for a minute.

Firstly, what attributes / technical metadata do LAME-encoded MP3s possess (and many other encoders lack) that allow them to be played gaplessly in Foobar, burned gaplessly in Burrrn, etc.?

From my novice observations I've observed that LAME MP3s have enc_delay, enc_padding,
and mp3_accurate_length technical info, whereas many non-LAME MP3s do not (and also don't play gaplessly). (@ roentgen: these are flags that the file is *likely* LAME-encoded, you can be more certain by using EncSpot or Mr. QuestionMan to scan the file's directory.)

My initial thought was that if you could give the non-LAME MP3 the above information (enc_delay, enc_padding, mp3_accurate_length) - which Fix MP3 Header does BTW - the resulting files would play back gaplessly.  I do of course see the flaw in this reasoning - simply putting wings on my car doesn't mean it will fly!


EDIT: Thanks for the link Yotsuya.

Utils > Fix MP3 Header

Reply #8 –
why isnt there a way to do this process on multiple files, using just the default options?

Utils > Fix MP3 Header

Reply #9 –
Hallo all here,
I read you use the function Fix MP3 header. Please could somebody tell me, where is this function hidden now? I used to use this function in version 083, but unfortunately I cannot find it in 092. Sometimes I use it to get correct info about bitrate and length of mp3 files and this is now the only one thing why I must keep old version fb2k installed.
Thanks
Michal

Utils > Fix MP3 Header

Reply #10 –
Quote from: myjed on
I read you use the function Fix MP3 header. Please could somebody tell me, where is this function hidden now? I used to use this function in version 083, but unfortunately I cannot find it in 092. Sometimes I use it to get correct info about bitrate and length of mp3 files and this is now the only one thing why I must keep old version fb2k installed.
Haven't you ever added a command? Preferences/display/context menu/utils, right click, insert command "utils/fix mp3 header"

Quote from: NogginJ on
why isnt there a way to do this process on multiple files, using just the default options?

As far as I understood it foobar has to calculate individual values per file. But I agree, a batch mode would be helpful.

Utils > Fix MP3 Header

Reply #11 –
Quote from: Squeller on
Quote from: NogginJ on
why isnt there a way to do this process on multiple files, using just the default options?

As far as I understood it foobar has to calculate individual values per file. But I agree, a batch mode would be helpful.

I agree, that would be awesome.  However it's kinda moot if one doesn't know how to properly use the settings (see O.P.)

I tried the default settings on a "mix" album of non-LAME MP3s (FhG according to EncSpot), and it seemed to work, i.e. playback in Foobar was (by my perception) gapless afterwards.  However I tried the same process on a completely different "mix" album (also FhG) and it didn't work, i.e., there were still noticeable gaps between tracks.

EDIT: typo

Utils > Fix MP3 Header

Reply #12 –
i dont have any idea really (well i have SOME idea) what the different parameters do but im not about to sit down and do all my files and like calculate exactly what value i need. thats what i use computers for. as such, i would really like it if the fix header command could run a batch file and just hit 'ok' for the default values on random mp3s id like to fix. the fact that foobar will not burn a cd properly anymore without fixing these mp3s is pretty annoying, yea i guess its good in the long run, but its a pain in the ass to remember to fix each individual file every time.

crap see im just now remembering i burned a cd for somebody and i bet its going to be all wacky because of this.

sounds like an easy plugin to code, but ive never tried so i cant talk.

Utils > Fix MP3 Header

Reply #13 –
Quote from: Squeller on
Quote from: myjed on
I read you use the function Fix MP3 header. Please could somebody tell me, where is this function hidden now? I used to use this function in version 083, but unfortunately I cannot find it in 092. Sometimes I use it to get correct info about bitrate and length of mp3 files and this is now the only one thing why I must keep old version fb2k installed.
Haven't you ever added a command? Preferences/display/context menu/utils, right click, insert command "utils/fix mp3 header"

Quote from: NogginJ on
why isnt there a way to do this process on multiple files, using just the default options?

As far as I understood it foobar has to calculate individual values per file. But I agree, a batch mode would be helpful.


Many thanks Squeller. You're right. I've never been there yet, I had no idea what is context menu for. Now everything's O.K. :-))
 

Utils > Fix MP3 Header

Reply #14 –
I've edited some live-and-gapless stuff where mp3's were not recorded with LAME. Here are the values I've found:

FHG: 671 samples
iTunes: 527 or 528
God kills a kitten every time you encode with CBR 320