04-08-2009 04:42 PM - edited 04-08-2009 05:13 PM
Replay Gain implementation for Sansa Fuze
What is it?
Replay Gain is a method for keeping the perceived volume level constant during playback of diverse content. Typically, Albums are mixed and targeted to differing average volume levels. During playback in shuffle mode there can be wide differences in the track output volume, causing the user to make frequent corrections to the volume level.
Sansa Fuze’s Replay Gain is a method whereby average volume playback level is kept consistent automatically.
The difference in the volume level vs. a reference (typically 89dB) is stored in the track metadata fields and is used by the Sansa Fuze to adjust the volume control to produce a uniform level. It should be noted that our implementation does not modify the actual music samples. It extracts the level adjustment in decibels (dB) from track metadata and applies an adjustment to the output volume control.
Software on the user’s computer analyzes the tracks to produce the Replay Gain values for embedding in the metadata. The Sansa Fuze implementation follows the 2001 proposed Replay Gain standard which is detailed at:
More information on ReplayGain can be found on Wikipedia at:
The Sansa Fuze’s implementation was tested to work for all of its supported non-DRM formats (MP3, WMA, OGG, FLAC) using MediaMonkey. MediaMonkey is a free media manager application which can be downloaded at:
Replay Gain for DRM Protected tracks (ie Rhapsody / Napster/ Netlibrary/ Audible) as well as SanDisk SlotRadio content is not supported.
The subscription sites may apply their own track leveling.
SanDisk SlotRadio content has been volume leveled in advance at a reference of 89 dB.
How do I use Replay Gain?
On your Computer:
Configure the MediaMonkey “Volume Leveling” options under Tools>Options>Volume Leveling. You can specify to also analyze the Album volume (otherwise known as “Audiophile Volume” ) when doing the Track Analysis. “Album volume” computes an average correction for all the tracks that comprise an album. Album Gain is supported by the Fuze as well as the Track Gain method.
Select your music files and then select “Tools> Analyze Volume”. This will perform the volume level analysis based on the options you have set up. It will write the Replay Gain values to the ID3 tag for MP3, Vorbis Comments for OGG or FLAC, or WMA header for WMA content. This action can take a long time depending on the size of your collection. It’s best to run the program overnight to do a large collection. You do not need to “Level Track Volume” which will apply the correction to MP3 files’ data.
Note: Fuze does not support APEv2 tags used by MP3Gain.
On the Player:
There is a “Pre-Gain” setting which allows you to adjust the overall Playback Volume level upward to compensate for the “average” level of your library’s track adjustment. For example, if your collection is mainly classical or soft songs, you should use a Pre-Gain of 0 dB, since the average level is likely to be close to 89 dB. For Hard Rock / Hip Hop collections, the Replay Gain values will be more negative, (meaning the song is above the 89dB target) like -8 dB. In this case, higher Pre-Gain level such as 4.5 dB can be used. You can compensate the overall gain level upward in 1.5 db steps up to a maximum of +12 db. Pre-Gain is NOT applied to tracks that have no Replay Gain values available. Pre Gain is helpful for matching Replay Gain adjusted content with Rhapsody or Napster Protected Content that may be both present on the player.
Line Out mode:
Viewing the Replay Gain values on the Fuze:
Message Edited by slotmonsta on 04-08-2009 05:13 PM
04-08-2009 08:49 PM
I don't believe the Fuze actually ever did support APEv2 tags, it just ignored them so that if they were there they didn't bother anything.
A while back I did a lot of looking around on the net to find out more about MP3Gain (before using it). From what I read, even though it says it does not alter the actual music in the MP3 file it does alter the information for each block header to tell the player what level to play the block at (if the player actually pays attention to the block header info for level). It also adds other MP3 tags, as well as the APEv2 tags (for players that can make use of those instead).
As long as the proper stuff MP3Gain changed/added is in an MP3 file it can also reverse the process by reseting the block headers and removing the additional extra tags.
Anyway, that's how it all sounded like it worked from what I had read. So, as long at the Fuze read the block header data to control each blocks volume the APEv2 tags should not have been needed and were just ignored.
Now, if the above is true, I really do not understand the need for the ReplayGain feature in the latest Fuze firmware as far as MP3 playback goes. However, it may be usefull for the other file types (that MP3Gain does not work with).
I don't remember where I read about MP3Gain changing the block data now anymore. May have been on Wikipedia. Anyway, do some Googling and see if you (eventually) come up with what I mentioned above and let the rest know more here. I'm going to bed now, otherwise I'd hunt around for the info myself.
04-08-2009 09:15 PM
Once you analyze your library of music and add the replay gain information to the MP3 files ID3 tags you never need to add the extra step of applying MP3 gain to the files on the player. Some folks did not want to touch their original files for whatever reason.
Agreed that of course MP3Gain works for MP3 files before the update.
There was no clear way to do volume leveling for FLAC files for example. Lossless audio is bit for bit accurate. Now you can have consistent volume for FLAC files played back on Fuze.
04-09-2009 09:43 AM
Just one problem with that: when you switch to MSC mode, the files that you transferred in MTP mode do not appear.
No matter, I figured out a way to solve the problem. I used winamp to copy all of my songs back to my harddrive. I'm applying replay gain now, and I'll just add them back to my player again.
I think I'm going to switch to MSC mode after this, though. Seems to be much easier to work with.
04-09-2009 03:16 PM - edited 04-09-2009 07:00 PM
....Note: Fuze does not support APEv2 tags used by MP3Gain.....
This is true and false..
It's true that the Fuze won't support the APEv2 tags used by MP3Gain, but the APEv2 tags are what MP3Gain uses to note the analysis and undo information only. MP3Gain actually modifies the "global gain" on each frame of the MP3 file. As a result, players that don't support normal Replay Gain, will see obvious Gain improvements with MP3Gain. I have used MP3Gain on all my MP3's and have noted SIGNIFICANT differences in gain from files that were not modified by MP3Gain and files that were. Every Sansa I have owned noted Gain changes on files modified with MP3Gain.
Replay Gain does NOT modify the "global gain" of each frame, and as a result, a player supporting Replay Gain is required for you to notice gain changes made by Replay Gain.
Since the Sansa Fuze does not support the APEv2 tags used by MP3Gain, turning on or off Replay Gain on the Fuze will have absolutely no affect on playback in the Fuze. However if you use MP3Gain to modify an MP3 file then the gain increase or decrease you applied via MP3Gain will definitely be noticable when played back on the Fuze, even with Replay Gain off.
Many people prefer Replay Gain because all the Gain adjustments are made in the tag. Thus the actual file is not changed. The danger of using MP3Gain is that if for some reason, the APEv2 data is lost of the file, then you lose the ability to undo your gain changes, and now your MP3 is "stuck" at the gain it was at prior to losing the tags. CORRECTION: If the APEv2 tags somehow do lose their "data" you simply need to run MP3Gain again, and it will re-analyze the track and rewrite the data as the current Db level. You can then lower the gain down to a lower value. However, if you don't know what the original DB level of the track was, then you are simply lowering it back to a new value, not necessarily it's original value.
With Replay Gain, there is no modification of the global Gain values in the MP3 frames. As a result, if you lose the metadata, you lose nothing. It's safer. Another advantage is that you can easily switch between album and track gain on the player, thus if you are in shuffle, you can choose track gain, but if you are playing an album, you can choose album gain, just change how you want Replay Gain to use a different gain. This is why some people prefer Replay Gain over MP3Gain, the frames are never touched and you can choose choose gain type on the fly. With Mp3Gain, you are stuck on the type of gain you used when you modified the file using Mp3Gain. Replay Gain is more versatile, and does not modify your files. The downside is your player MUST support Replay Gain to get any benefit at all.
I prefer MP3Gain, as I don't have to worry whether or not my player will support it or not. I can play my MP3 through any application and my Gain changes will be read. Since I backup all my music regularly, then I don't feel too worried about losing the metadata, since I can always delete the corrupt file and restore from the backup.
Hope this clarifies things.
Message Edited by p_opus on 04-09-2009 06:51 PM
Message Edited by p_opus on 04-09-2009 07:00 PM