Adding v2.3 Tags changes MP3 properties

[Unregistered]

I have a bunch of MP3s with v1.1 tags in them. They were encoded using EAC & LAME --alt-preset standard, so they are VBR files. I have dMC configured to write both v1 & v2 tags. When I "Edit Tag" to add a Comment or non-standard Genre, the Popup & dAP information changes for that MP3. Both the Length (m:ss) and Average Bitrate are effected.

I created some test v2.3 tags and prepended them to an existing MP3 file and found that there is a specific tag size that breaks the Popup & dAP information parsing...

For example the original MP3 has a reported Length of 3:31 & an Average Bitrate of 205. If I add a v2.3 tag that is less than 1849 bytes (this includes the 10 byte v2.3 header), then the file has a reported Length of 3:30 & ABR of 206. This small difference I could live with. If I add a v2.3 tag that is 1849 bytes or more, then the file has a reported Length of 2:45 & an ABR of 262.

I tried prepending the same tags to a different MP3 and found an error at the same size threshold (1849). The Lengths & ABRs reported were 1:52 & 225 for the original file, 1:52 & 226 for the "small" tags & 2:46 & 152 for the "large" tags.

I can send you the tags files I created for the tests if you like...

[LoF]

Re: Adding v2.3 Tags changes MP3 properties

I have a bunch of MP3s with v1.1 tags in them. They were encoded using EAC & LAME --alt-preset standard, so they are VBR files. I have dMC configured to write both v1 & v2 tags. When I "Edit Tag" to add a Comment or non-standard Genre, the Popup & dAP information changes for that MP3. Both the Length (m:ss) and Average Bitrate are effected.

I created some test v2.3 tags and prepended them to an existing MP3 file and found that there is a specific tag size that breaks the Popup & dAP information parsing...

For example the original MP3 has a reported Length of 3:31 & an Average Bitrate of 205. If I add a v2.3 tag that is less than 1849 bytes (this includes the 10 byte v2.3 header), then the file has a reported Length of 3:30 & ABR of 206. This small difference I could live with. If I add a v2.3 tag that is 1849 bytes or more, then the file has a reported Length of 2:45 & an ABR of 262.

I tried prepending the same tags to a different MP3 and found an error at the same size threshold (1849). The Lengths & ABRs reported were 1:52 & 225 for the original file, 1:52 & 226 for the "small" tags & 2:46 & 152 for the "large" tags.

I can send you the tags files I created for the tests if you like...

Ok, I'm registered now. I did leave out some important information... I am using dMC Release 10, Power Pack Release 3 & dAP Release 3 beta 4 on Win2k.

Thanks...

[Spoon]

Re: Adding v2.3 Tags changes MP3 properties

Just one of the problems of ID3v2, normally a XING vbr header is written with the exact length, otherwise the length has to be calculated from the file length and the bitrate of the first 200 or so frames.

[Unregistered]

Re: Adding v2.3 Tags changes MP3 properties

Just one of the problems of ID3v2, normally a XING vbr header is written with the exact length, otherwise the length has to be calculated from the file length and the bitrate of the first 200 or so frames.

All of the MP3s mentioned have valid Xing & Lame headers. EncSpot parses all of the files just fine. I don't understand why adding a valid v2.3 tag to an MP3 should change the way dMC or dAP parse the Length and ABR.

LoF

[Spoon]

Re: Adding v2.3 Tags changes MP3 properties

I will mark it down as a bug to look at, to make sure that the XIng header is being read with an ID3v2 tag.

[LoF]

Re: Adding v2.3 Tags changes MP3 properties

Thanks Spoon, can't ask for any more than that! As a fellow programmer, I am interested in hearing what you find...

LoF