hi. Im experimenting at work on a Harmonic Flexa RT transcoder where i need to transcode any audiosource to a specific AAC format.
My sources are typically AC3 @ 448, 384 kbps or Mpeg1-l2 at 256 or 384kbps.
The transcoder has the option of : LC-AAC, HE-AACv1, HE-AACv2 as output
Im trying to achieve as close to audio transparency as possible, and ive landed on 96kbps on HE-AACv1.. Is this a sane rationale?
In the situation i have both a 2channel AC3(448kbps) and a 2channel mp2 track (256kbps), which one would u use as source?
PS! Im fully aware that lossy to lossy will have impact on the quality, but in this context, passthrough aint an option..
/TE
He-aac is for very low bitrates, which will never be transparent. At 96kpbs lc-aac should be nearer to transparancy.
Any idea which aac encoder is used? This can make a huge difference.
Not sure about the ac3 vs mp2. They are both not very efficent.
I'd say listen very carefully (downmixed to stereo) and choose the better one.
In the situation i have both a 2channel AC3(448kbps) and a 2channel mp2 track (256kbps), which one would u use as source?
AC3 at such an extreme bit rate will be transparent. You should use that.