APETag parsing in MPEGfile.cpp

[Sander Jansen]

On Thu, Aug 22, 2013 at 7:48 AM, harish jenny <harishjennykn at yahoo.com>wrote:

> Hi,
>
> I have a file which has APEtag as well as Id3V1 tag.
>
> However , MPEG::File::findAPE() function is not able to detect APE
> footerLocation.
>
> When I add the code something like -
>
>     seek(d->hasID3v1 ? -160 : -32, End);
>
>     long p = tell();
>
>     if(readBlock(8) == APE::Tag::fileIdentifier()) {
>       d->APEFooterLocation = p;
>       seek(d->APEFooterLocation);
>       APE::Footer footer(readBlock(APE::Footer::size()));
>       d->APELocation = d->APEFooterLocation - footer.completeTagSize()
>     + APE::Footer::size();
>       return;
>     }
>   ++  else
>   ++  {
>   ++      seek(!d->hasID3v1 ? -160 : -32, End);
>
> ++       long p = tell();
>
> ++        if(readBlock(8) == APE::Tag::fileIdentifier()) {
> ++          d->APEFooterLocation = p;
> ++          seek(d->APEFooterLocation);
> ++          APE::Footer footer(readBlock(APE::Footer::size()));
> ++          d->APELocation = d->APEFooterLocation -
> footer.completeTagSize()
> ++        + APE::Footer::size();
> ++          return;
> ++        }
> ++    }
>
> it is able to parse APEtag.
>
> Does the standard say , if ID3V1 tag is present , then check for APETAGEX
> in -160 location from end ?
>


According to this:
http://wiki.hydrogenaudio.org/index.php?title=APEv2_specification

The id3v1 tag should come last. I don't think you'll find many players that
can support a id3v1 tag not located at the end.


Is it fine to parse again from -32 location since I was able to find proper
> metadata?
>

No, as a matter of fact, if you can read a id3v1 tag at -128 and read a
apetag at -32, it means the file is most likely broken (ie. overlapping
tags, id3v1 is truncated by the apetag).

Cheers,

Sander
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