Problems with Conversions (Flac>MP3)

[a.wright]

Re: Problems with Conversions (Flac>MP3)

It looks like I can salvage my MP3 files by using the following procedure:

• Copy ID3V2 tags to ID3V1 tags
• Remove all ID3V2 tags
• Copy ID3V1 tags to ID3V2 tags
• Add back Album Art
• Add back Rating, Disc Number etc

Luckily I can do all but the album art & rating etc as one big batch so it should not take more than about an hour or so to sort out. I don't really use many other tags anyway. As my MP3Gain tags are stored in APE format, they don't get touched so everything is fine in terms of normalisation too.

Also some more tests this evening showed that if I only add basic tags to FLAC files at the ripping stage (i.e. just the ones shown at the top of the CD Ripper screen + album art) then conversion to MP3 seems ok and the files play. I had been including all the accuraterip, encoder, source etc tags when ripping so I am guessing it must have been one of these that caused the issues when converting as it was written into the MP3 files.

Unfortunately I don't have enough technical knowledge to draw any scientific conclusion as to the reason (especially as the rogue files played off a USB pen but didn't stream) and I certainly don't have enough time to test every permutation of possible tag combination to see which caused the problem!

My only concern now is that I have masses of FLAC files which potentially might not convert to various formats due to similar tagging issues and whilst I can delete alot of the tags that I can see, I won't know if there are any hidden ones that I can't access.

Need sleep....

[a.wright]

Re: Problems with Conversions (Flac>MP3)

Just another suggestion: from own experience I know, that tag&rename sometimes does weird things...
Mayne, you also want to try the following: take any recording device (windows recorder or similar) and record just 2 seconds @ 44.1kHz/16bit silence as wav.
Process that file as you used to - convert it to flac, then to mp3, tag it, whatever you do. From each step, save a copy.
These short files, you can open in notepad - at least, you can see in the first lines (before the unreadable "audio"), what kind of headers or tags there are written. That way, I discoverd, what changes tag&rename makes to certain tags....
Maybe, that helps you a bit further...

I can't see it is doing anything odd apart from creating a tag called <BAND> when it should be "Album Artist". It also seems to add a "Music Match Preference" tag which seems to be read by foobar as the "Comment" tag.

However I know it's not this that is causing a problem because I did a test by removing all tags (using foobar) and then re-tagging with T&R and I have been using T&R for the past couple of years without any issue.

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

Please send an effected mp3 file:

http://www.dbpoweramp.com/email.htm

(with the tag <ENCODER> before it is removed)

Done

[dvdr]

Re: Problems with Conversions (Flac&gt;MP3)

Just another suggestion: from own experience I know, that tag&rename sometimes does weird things...
Mayne, you also want to try the following: take any recording device (windows recorder or similar) and record just 2 seconds @ 44.1kHz/16bit silence as wav.
Process that file as you used to - convert it to flac, then to mp3, tag it, whatever you do. From each step, save a copy.
These short files, you can open in notepad - at least, you can see in the first lines (before the unreadable "audio"), what kind of headers or tags there are written. That way, I discoverd, what changes tag&rename makes to certain tags....
Maybe, that helps you a bit further...

[Spoon]

Re: Problems with Conversions (Flac&gt;MP3)

Please send an effected mp3 file:

http://www.dbpoweramp.com/email.htm

(with the tag <ENCODER> before it is removed)

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

Ok this is definitely a tagging issue. If I use foobar to remove any one of the bracketed e.g. <ENCODER> tags that are listed, it takes with it all ID3V2 tags. The file then plays without a problem. If I remove all tags and then re-tag the stuff I would normally, the file plays without a problem. The only things I ever tag are the simple stuff (basically equivalent to the ID3V1 tags plus album art).

So I know that somewhere there is an issue with an ID3V2 tag. The other thing I know for sure through a long process of elimination is that whatever tag has been written has been written during the dMC process but that it is not written when ripping directly to MP3 using CD ripper.

The problem is I can't find what offending tag has been written because removing the ones I have access to in Tag&Rename individually has no effect. It's only when I remove all ID3V2 tags that the file plays.

Comparing the tags in the FLAC original rip to the dMC MP3 files shows the following differences in mappings:

<ALBUMARTIST> maps to <BAND>
<RATING> maps to Comment ("3" in RATING tag to "Good" in Comment tag)

Everything else appears to be the same but there must be another tag somewhere which is causing the problem. The question is which individual tag can do so much damage so as to stop a file streaming?

I need some sleep now :(

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

Andrew

If you are ripping from CDs why aren't you ripping to FLAC and MP3 simultaneously (ie taking a conversion from FLAC to MP3 right out of the equation) using the multi encoder codec?

Joe

Overall it seems to be quicker to rip the CDs straight to FLAC, get them all organised on my external HD and then just leave the converter to churn through huge batches at the same time. I can convert hundreds of files in literally a matter of minutes.

Ripping to FLAC & MP3 using the multi-encoder seems to take more than twice as long than just ripping to FLAC. Oddly enough when just ripping to FLAC (or MP3) it starts ripping the next track while the last one is encoding but using the multi-encoder doesn't seem to do this.

I probably will use the multi-encoder from now on as the MP3 files work (per my explanation earlier in the thread) but the whole point of keeping a FLAC archive is so that I can convert to the format of my choice, when I want. I have called a halt to proceedings though until I can work out what the problem is.

[joethebus]

Re: Problems with Conversions (Flac&gt;MP3)

Andrew

If you are ripping from CDs why aren't you ripping to FLAC and MP3 simultaneously (ie taking a conversion from FLAC to MP3 right out of the equation) using the multi encoder codec?

Joe

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

Nope, still no joy. I also downloaded the little utility that is supposed to perform a binary comparison between two or more tracks and report differences. No differences reported. I downloaded the little utility that checks specified media files for decoding errors, and there were none.

So, can we conlcude it is definitely a tagging issue and that there must be something with the way the tags have transferred from the original FLAC encode to the MP3 converted files that is written differently to how CD ripper does it? Problem is I can't see any difference!

[dvdr]

Re: Problems with Conversions (Flac&gt;MP3)

Try one thing with the nonworking mp3's: download Foobar 2000, load one of the files, right click on its entry in the foobar-window - there are options/tools to correct faulty mp3's. Try both options and see, if the files play. Maybe, that helps to sort out, what is happening (just my 2Cents, I could correct some files, that did not play for whatever reason...)

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

In that case I am at a total loss to know what to do. :thumbdown

[Spoon]

Re: Problems with Conversions (Flac&gt;MP3)

No.

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

There might be differences but they will only be in the ID tags.

Again, that's what I thought but I removed just about all of them and no luck. How can I see every ID tag that has been written and how it has been written? I use Tag & Rename but that just uses a standard interface which, for example, writes to an Ensemble tag when you fill in the Album Artist field when tagging FLAC files.

I also tried doing a multi-encode when ripping a CD with minimal tags and as far as I could see (by right clicking on the files and looking at the properties) everything was the same on the FLAC & MP3 versions. If that's the case I don't understand why converting from FLAC to MP3 might cause issues with tags.

Is there any way of carrying out an analysis of 2 different MP3 files to see if something has happened with the encoding?

[Spoon]

Re: Problems with Conversions (Flac&gt;MP3)

There might be differences but they will only be in the ID tags.

[a.wright]

Re: Problems with Conversions (Flac&gt;MP3)

The mp3 file if on USB or streamed is 100% the same, so is an issue with the streamer.

But in that case the same CDs that I ripped directly to MP3 via CD ripper (without using dMC to convert from FLAC) should exhibit the same issue, but they don't.

The settings for LAME have not been touched and I use minimal tags but the direct ripped files work, the dMC ones converted from FLAC (themselves ripped with CD ripper) don't.

I admit I am no tech wizard but the evidence would suggest there is something different about the converted files...