Quote from: greynol on 2010-04-07 18:56:17

Quote from: lvqcl on 2010-04-07 18:35:39

It is possible to encode +6 dB to MP3 without clipping.

Can this be done with Lame?

Yes, with "LAME 3.98.4 modified to add float wav input" from Rarewares.

If Reaper is using the old Blade replacement API functions (beEncodeChunk), then it will likely feed LAME with 16 bit short values. Though, it could use some newer functions to pass floating point values into LAME (beEncodeChunkFloatS16NI).

Reaper uses the Blade API only on Win32.

... note that Reaper does clamp the floating point output to +0dB when encoding to mp3.

Probably because of ambiguity in LAME documentation.  beEncodeChunkFloatS16NI doesn't seem to be documented at all, and lame_encode_buffer_float is documented with

* !! NOTE: !! data must still be scaled to be in the same range as short int, +/- 32768

That does say "scaled" rather than "scaled and clamped" ... before changing Reaper to allow passing unclamped floating point values to LAME for encoding), we should verify that it won't break either by looking in the LAME source code directly, or getting a statement with high confidence from someone who is familiar with the code.

LAME already has 32 bit float input support (which Reaper uses), the only issue is whether there is any maximum (normalized) absolute value for the floating point inputs.  In fact that last comment suggests that they will be clamping internally (though it isn't totally clear).

The concern would be that there may be some encoder settings where supplying >0dB inputs would break things.  Or that inputs up to +6dB will work but over +6dB would break, or other details that we don't know about.

LAME won't break if you feed float values above "full-scale".

But keep in mind, that playback might become seriously distorted, depending on your decoder and its abilities to prevent clipping.

I would have said, "will always have zero benefit" except I'm never 100% certain of anything, especially in relation to science