Some files with ReplayGain added to MP3 data by Foobar2000 won't play

[mypod]

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[Llorean]

If you have replaygain data in the tags and the MP3 data, you do realize that means a player capable of using the tags will then be playing the files incorrectly because the gain is adjusted twice (once by the player, and once in the MP3 data) right?

As for what's happening, if it's only some modified files that don't work and not all of them, odds are good you'd need to provide a sample of a non-working file for someone to look at and see what's going on. You'd do this by filing a proper bug report. Files with gain added to the mp3 data should be valid MP3s, but you may want to see if a more verbose MP3 decoder of some sort (I couldn't recommend one) identifies them as having problems. It may be that some players are more tolerant of problems where Rockbox just skips problematical files, or it may be that the files are fine but Rockbox doesn't think so because of a bug in it. More info is basically needed.

[saratoga]

I can duplicate the problem.  Looking at libmad, it reports that the header is broken.  ffmpeg decodes the file, but with some weird debug output.  Most likely theres something wrong with the file originally, and foobar's attempt to hack up the bitstream with replaygain cannot deal with this properly.  But you'd have to find an mp3 expert to be sure. 

[BigPapi]

I've always just done the "Scan per-file Track Gain" option in Foobar2000 and click "Update File Tags" and it has worked fine.....so I don't understand why you would even want to apply that ReplayGain info to the MP3 data itself.

[mypod]

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[Lear]

Looks like a bug in foobar2000. One checker I found complained about CRC errors and not enough frames found. libmad rejects files with CRC errors (unless told otherwise, which we don't do in Rockbox). That checker thought the original file was fine.

No problem with another random file I tested, which I'd guess doesn't use CRC...

[Edit] Problem in foobar2000 reported.

[Llorean]

You'd want to update the MP3 data in order to get the proper volume out of a media player that can't read the tags.

But as I said, if you have that and the tags, you'll get improper volume out of the ones that do read the tags. You really should only ever use one or the other, not both. As noted above though, it's a bug in Foobar2000, not Rockbox, that is causing the files to actually be skipped - they're bad.

[mypod]

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[Llorean]

For anyone else who encounters this problem, you can fix it for now by turning off the CRC protection bit in the afflicted MP3 file or by removing its CRC data completely. WinMP3Packer (download link at the bottom) removes the CRC field automatically, regardless of any options you select. (In other words, there's no need to select one of the "Strip non-MP3 data" options unless you want to.)

Couldn't this conceivably prove problematic if files have real errors? Why not just use a non-broken scanner instead, or not use the broken feature?

You really should only ever use one or the other, not both.

You have contributed literally nothing to this conversation at any point. From the perspective of volume it is fine to use both. When Foobar2000 applies global gain directly to the MP3 data it simultaneously adjusts the ReplayGain tag in accordance with the new overall loudness of the file.

Please don't misuse the word "literally." I may have literally contributed nothing you found helpful, but there is no question as to whether I posted. It's right there. Something was contributed. I asked initially for information people would've needed had they not been able to reproduce the bug, something that is often a necessity. In this case it wasn't, but that doesn't mean it wasn't a contribution.

As to Foobar2000 adjusting the gain tags, how does that work exactly? If the MP3 file is already adjusted to the proper gain, shouldn't the tags always contain +0db? There's nothing to put in them if it no longer needs further adjustment... in which case there's no point in having them in the first place. It's simple addition.

[saratoga]

As to Foobar2000 adjusting the gain tags, how does that work exactly? If the MP3 file is already adjusted to the proper gain, shouldn't the tags always contain +0db? There's nothing to put in them if it no longer needs further adjustment... in which case there's no point in having them in the first place. It's simple addition.

Altering the gain of the mp3 file can only be done in course steps, so the resulting file doesn't get set to exactly the right volume.  Foobar updates the replaygain tag to have the new adjustment needed to get the desired volume (typically on the order of 1dB or so). 

mypod:  If you don't want people to give you advice, then you should solve your own problems rather then ask for help . . .