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[dlmax63]

Having recently picked up an IPod Classic 160G, I'd like to use a lossless format and set the tags for replay gain on M4A files to take advantage of the 'sound check' in the IPod. Unfortunately, it looks like MC does not currently (and probably not in the future) support tagging (or converting) M4A. Since the IPod doesn't support FLAC or APE, M4A is needed. As a work around, I've tested by converting to FLAC, analyzing and tagging in MC and then reconverting to M4A (using dbPoweramp). When I look at the M4A tags using dbPoweramp, the replay gain, along with the other tags, have values. However, when I view the tags in MC, there are no values for any of the extra tags.

Since MC doesn't support tagging in M4A, is MC just not showing the existing tag info but it's still there anyway?

Does anyone have a suggestion of an application which would make this process simpler? (BTW, I don't want to have redundant files)

[Alex B]

iPods do not read file tags directly. All file metadata is obtained from the iPod database. The program that is used for syncing must provide the info.

MC can read only a few basic m4a tags. Unfortunately the Replay Gain tag is not supported.

You could try if the DirectShow playback mode works on your PC. If it works you can analyze your ALAC files with MC. After that MC should be able to convert the Replay Gain info to Apple's Sound Check info and include it in the iPod database.

For decoding ALAC files through DirectShow you need the DC-Bass Source Filter from here: http://www.dsp-worx.de/index.php?n=15

More info about DirecShow support in MC is here:
http://wiki.jrmediacenter.com/index.php/DirectShow_Playback_Guide
and here:
http://wiki.jrmediacenter.com/index.php/MP4_and_M4A_File_Support

[dlmax63]

Thanks Alex, I'll look at those links and see what I can do.

[dlmax63]

Alex, I installed the DC-Bass directshow filter using the 'install' option and then enabling M4A & M4P in MC's video directshow playback settings. I was not able to analyze an M4A file. Instead, I got an error which read "Only audio files on a local drive that can be played in the native playback engine can be analyzed". Out of curiosity, I analyzed a FLAC version of the same song and MC showed it's replay gain. I then used dBpoweramp to convert the song to M4A. The dBpoweramp ID tag editor showed that the replay gain was in the M4A tag. I then imported that file into MC. MC did not display the value.

You indicated that the iPods don't read the tag information directly but instead get the information from the syncing program via a separate database. Does this mean that I'm 'SOL' since JRiver has chosen not to support the required fields in the M4A tags? How 'bout MC13?

In another post in the forum, I read that there's some question as to the legality of writing to M4A files and that these licensing fees were beyond a company of JRiver's size. What about relaying the information that is already enclosed in the M4A file. JRiver already supports other fields in the file anyway. In this case, MC would not be touching the M4A file but instead would merely be relaying the existing information it contains. I'm no lawyer, but this doesn't appear to be a case of infringement. Perhaps the lawyers should take another look. I'm sure there are many thousands of MC users out there who could/would benefit from this support.

[ADDiCT]

I've fiddled a lot with replay gain in all its appearances (meta data, rg on various devices, etc.), and i've found what i think is the perfect solution for my needs.

The problem: there is no real standard for rg. Some players (software and hardware) support it, some don't. There is no rg implementation that will work on all devices, and with every software.

Solution: apply "hard" volume correction, as opposed to using meta data. I use foobar2000 to apply rg info to my source files, and then convert the files to the "final" format (mp3, m4a, etc.), with volume correction applied. foobar2000 is able to change the volume of mp3 files directly without re-encoding, too. The volume correction is done on a per-album-basis, in order to keep intentional volume differences.

[dlmax63]

Thanks ADDiCT, I'll look into it

[Alex B]

Alex, I installed the DC-Bass directshow filter using the 'install' option and then enabling M4A & M4P in MC's video directshow playback settings. I was not able to analyze an M4A file. Instead, I got an error which read "Only audio files on a local drive that can be played in the native playback engine can be analyzed". Out of curiosity, I analyzed a FLAC version of the same song and MC showed it's replay gain. I then used dBpoweramp to convert the song to M4A. The dBpoweramp ID tag editor showed that the replay gain was in the M4A tag. I then imported that file into MC. MC did not display the value. ...

I was puzzled by the fact that sometimes ALAC decoding through DS works fine and sometimes not.

After running some tests with various ALAC files I found out that an old version of dBpoweramp's ALAC codec creates different tags than the latest version or iTunes. The old version writes tags to the end of the files and the latest version of the dBpa codec and the current iTunes build write them in the beginning of the files. Possibly there are other differences too.

Apparently the DC-Bass Source filter cannot decode files that are created with the old version of the dBpoweramp codec. On the other hand, all files that were created with the latest version of the dBpa codec or iTunes decoded without problems with various DS players. I verified this with MC, WMP, Zoom Player and Media Player Classic.

Possible solutions (these all work for me, but I don't know if you are experiencing the same problem):

- Use the latest version of dBpa's m4a codec or iTunes for encoding the files.
- Fix the old files by using dBpa's "m4a Optimize" tool (it's included in the m4a Utilities codec)
- Fix the old files by using Mp3tag's "Optimize m4a" feature (select the files > right-click > Optimize m4a). Mp3tag is available here: http://www.mp3tag.de/en/

[dlmax63]

Thanks Alex,

I updated my dBpoweramp codec for M4A & MC now allows the files to be analyzed. The replay gain values now appear within MC. I also used the 'optimize' option on some existing files in my MC library, and that allowed MC to analyze also.

Once these values are visible in MC, will MC include these values in the database which is sent to the iPod for use with 'sound check'. If so, I'll find all files in my existing library and run dBpoweramp's optimize option.

[Alex B]

Once these values are visible in MC, will MC include these values in the database which is sent to the iPod for use with 'sound check'. If so, I'll find all files in my existing library and run dBpoweramp's optimize option.

I guess it should work if it works with AAC m4a files, but I have not personally tested it.

You could pick a loud track and a quiet track, create duplicate copies of the files and analyze only one of the file pairs. You should be able to notice the difference on the iPod if it works correctly.

[dlmax63]

 

I made some test tracks and synced to my iPod. The replay gain information must have been provided to the iPod because the tracks which had replay gain values in MC did indeed play as expected on my iPod.

Thank you Alex for all of your help in getting this to work as desired.