[X] technical info. is different a little bit


#1

At first, sorry for my poor english.

There are different technical info. in some files between mp3tag and foobar2K (or winamp).
What's wrong?

<mp3tag 2.37f>
length 6:26 / codec MPEG 2.5 layer I / Frequency 8000 Hz

<foobar2K 0.9.4.2 & Winamp 5.3.3>
length 3:15 / codec MPEG 1 layer III / Frequency 44100 Hz

Sample file is attatched..
or Link is here.

Moderation: Link to complete file removed due to copyright restrictions. Please post samples next time or send the files to Florian's support address.

Thanks for good tool~


#2

It seems that there is some junk between the tag and the first valid MP3 frame. foobar2000 and Winamp probably display the correct information because they decode more than one frame.

Florian, how exactly are you looking for frame headers? Are you evaluating the first frame that starts with 0xFF 0xF_? A good approach would be doing something like this:

  1. Search for a sync word starting with 0xFF 0xF_ and assume it's a good frame.
  2. Calculate the frame size and store result in x and move the file pointer x bytes forward.
    3a. If you found a valid frame there, it means that the first frame was indeed valid.
    3b. If you didn't find a valid frame there, the first frame found was a false positive and you should search for another frame.
  3. Repeat steps until you get to 3a.

#3

Thanks for your kind reply. :slight_smile:

I tried a tentative test with 'rebuild MP3 stream' function in foobar2K.
foobar2K says this function is:

This will fully rewrite your MP3 files, stripping any non-MP3 data from them, then rewrite tags according to current settings.

After this work, mp3tag show me the same technical info. of winamp's tag info.
But I don't know exact reason yet. :huh:

I'm aftaid this work affect sound quality of MP3 file. :frowning:


#4

My post states why. :slight_smile: There is junk between the ID3 tag and the first valid frame of the MP3 bitstream. That junk looks a bit like a MPEG frame since it has the same sync word like a MPEG frame header.

The quality of the file is not affected since foobar2000 will only remove tags and any non-MP3 data. It alters the MP3 audio frames in no way.