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POJava/JAudiotagger: Mp3 wrong ID3 tag size
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copied!<p>I'm building an mp3 tagging application using the <a href="http://www.jthink.net/jaudiotagger/index.jsp" rel="nofollow noreferrer">JAudiotagger</a> library. My application reads the mp3 metadata fine, and can write the metadata fine too, <em>except for the artworks</em>. So my problem is as follows:</p> <p>When I add a number of artworks in the mp3 file, and save it, the file is getting bigger, which makes sense. But when I remove one or all the artworks, <em>the file size doesn't get smaller</em>. <p>The actual problem lies in the ID3v2 tag of my mp3 file. When I remove an artwork, it is actually removed from the tag, but the tag size itself doesn't shrink at all.</p> <p><p>The method I'm using when deleting an artwork is this:</p> <pre><code> // Get the artworkList from the parentFrame. List<Artwork> list = parentFrame.getArtworkList(); // Get the tag from the parentFrame's mp3File. AbstractID3v2Tag tag = parentFrame.getTag(); // Get the index of the artwork the user is currently looking at (and // wants to delete too). int visibleArtworkIndex = parentFrame.getVisibleArtworkIndex(); // Remove it from the list. list.remove(visibleArtworkIndex); // Update the parentFrame's copy of the artworkList. parentFrame.setArtworkList(list); // Update the tag (delete its whole artwork field). tag.deleteArtworkField(); // If the list has more artworks left, add them to the tag. if (!list.isEmpty()) { Iterator<Artwork> iterator = list.iterator(); while (iterator.hasNext()) { try { tag.addField(iterator.next()); } catch (FieldDataInvalidException e1) { e1.printStackTrace(); } } } </code></pre> <p>, which actually removes an artwork from the list, and then updates the tag itself by deleting all of its artworks and copying them all over again from the updated list.</p> <p><p>My attempts for a solution were:</p> <ul> <li><p>To create a new tag from the updated old tag (after calling <code>tag.deleteArtworkField()</code>), then adding the artworks to the new tag, but the new tag had the same size as the old one.</p></li> <li><p>To trim the mp3 file just before saving it by using <code>tag.adjustPadding(File fileToBeTrimmed, int sizeToStoreTagBeforeAudioInBytes, long audioStartByte)</code>, which adjusts the length of the padding at the beginning of the MP3 file. <br>The problem here is that I know the wrong tag size only and not the correct, so I can't trim the mp3 correctly and I end up losing audio data.</p></li> </ul> <p><p>To illustrate the problem better I have included some images:</p> <p><p>The mp3 file before:</p> <p><p><a href="http://imageshack.us/a/img694/3766/mp3filebefore.jpg" rel="nofollow noreferrer">before http://imageshack.us/a/img694/3766/mp3filebefore.jpg</a></p> <p><p>The mp3 file after the removal of one artwork. Notice the tag kept its previous size although it has less artworks:</p> <p><p><a href="http://imageshack.us/a/img513/2476/mp3fileafterwrong.jpg" rel="nofollow noreferrer">after wrong http://imageshack.us/a/img513/2476/mp3fileafterwrong.jpg</a></p> <p><p> And how the file should be:</p> <p><p><a href="http://imageshack.us/a/img818/1506/mp3fileaftercorrect.jpg" rel="nofollow noreferrer">after correct http://imageshack.us/a/img818/1506/mp3fileaftercorrect.jpg</a></p> <p><p>I hope anyone has any ideas. Thanks in advance.</p>

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