I have FLAC files that have ReplayGain tags. When I encode those to Ogg, I keep the existing tags. The question is, will the ReplayGain calculations that were used in the FLAC file, also be the correct calculation for use with the Ogg file.

I would think that it would, unless there is some gain applied during the encode process.

Maybe a stupid question, but oh well...

Not a stupid question, I understand your worries.

Peak information definetly will need to be recalculated, but total RMS power shouldn't differ much more than +/- 0.02 dB

I stripped the tags from one Ogg file and used Foobar to re-calculate. There was a slight difference from the original FLAC file. I don't have the exact numbers right now (I'm at work).

Yeah, this has been discussed before, its not a stupid question though. Because of the lossy change in audio information when encoding to Vorbis (which I am sure you meant and not Ogg), there is a chance that the dynamics will change, the peaks might change, the overall audio stream may become more compressed, etc...all this depends on how accurately the dynamics are encoded by Vorbis, and as such the amount of difference here can quite possibly be taken as being proportional to the quality setting one uses. The lower quality setting one uses, the better chance the ReplayGain setting will be way off the original. It really depends on where Vorbis has its priorities. I personally do not know how low you can go and still have a fairly equal loudness when compared to the original when using Vorbis.

Let me note that they should be VERY similar. In my experience, it is not noticeable to use the FLAC ReplayGain values for Vorbis encodes. Actually, there is a fairly new idea that came up on the boards recently about doing just this. The idea is to find the ReplayGain values before encoding (of the lossless audio stream) and apply the gain as a scale factor when lossy encoding to effectively save bits. The feelings that came out of that thread were basically that in theory, it should work fine, but it would just have to be tested over time to confirm its validity. Until someone can come up with or theorize a problem sample that might break this process within reasonable bitrate or quality settings, I would say that it is perfectly fine. Again, it all comes down to what quality setting you are using in Vorbis.

Also, to confrm that it is good theory, I don't think John33 will mind letting me note here that the next version of OggDropXPd will have an option with exactly this theory behind it, that when converting from FLAC to Vorbis, there will be an option to use the FLAC ReplayGain values that are in the tags to apply an indvidual scale factor to each of the encoded Ogg Vorbis files to save bits and also effectively allow ones Vorbis files to be equally gained on new hardware Vorbis players that do not support ReplayGain tags.

Yes, I did mean Vorbis. If I recall, Ogg is just the container. I doubt that I would notice any clipping, even if it occured.

I like being able to have the FLAC files tagged, Replaygained, and stored on DVD-R.

I can just drag & drop to get the Vorbis files, with everything tagged, and not have to re-rip anything, or re-tag anything, and hopefully, not have to re-calculate the gain.

Makes life much easier.

Edit: I'm using GT3B1 at Q5.

That makes two of us. I keep my FLACs on my hard drive, but once I get a DVD burner, they wll be backed up to DVD. Once I get my new Rio Karma player, and the new version of oggdropXPd comes out, I'll be able to drag them to the program and let it go over night, and when I come back, I have an entire separate, organized, gained, tagged set, in Vorbis, ready to go. Awesome stuff, isn't it?

Hmmm...

What new features can we look forward to in OggDrop?

Edit: Sorry, I need to read more carefully...

>next version of OggDropXPd will have an option with exactly this theory behind it