How to get AacMachine to use vbrhi?

[sprit]

How do I make AacMachine v0.52 include '-vbrhi' in the aacenc arguments?

[hans-jürgen]

I haven't used AACmachine, but judging from the screen shots in its guide I would guess that there are no other possibilities than either chosing a VBR preset or defining a CBR with "quality".

If you want to stick to VBR, but fine-tune the average bitrate, you shouldn't use -vbrhi anyhow, because it would need another -br X setting to define the "base bitrate", too, which only works very roughly. For this purpose it's better to use the -qvbr switch that accepts values from 0-100 and maybe do this in another GUI like "Ivan & Menno" or foobar2000/CLI encoder.

But remember that PsyTEL AACEnc (the codec that AACmachine uses) has a multichannel bug in the M/S matrix which maps all input channels to Left and Right. So you shouldn't use it for multichannel encodings anyhow, but for stereo-only input it still sounds fine of course.

[sprit]

I am just playing with XviD, aacenc and mp4creator so the multichannel issue does not matter. In my lastest experiments (DVD ripping) the intermediate WAVs have been in excess of 2 gig, which is why I've tried AacMachine.

I have been using -vbrhi together with -streaming/-tape (no other switches used, apart from the occasional -pns) when encoding AACs before and then aacenc, when starting up, claimed to use 'VBR High Quality' instead of 'VBR Medium Quality'; I assumed the switch enabled some sort of higher quality VBR mode :-) (it does give a slighly higher bitrate). Is -vbrhi and the settings from -streaming a bad match (as normal and up uses vbrhi)?

I'm not interested in controlling the bitrate - the audio gets its share first, so I just go with what the preset gives...

[hans-jürgen]

Originally posted by sprit
I have been using -vbrhi together with -streaming/-tape (no other switches used, apart from the occasional -pns) when encoding AACs before and then aacenc, when starting up, claimed to use 'VBR High Quality' instead of 'VBR Medium Quality'; I assumed the switch enabled some sort of higher quality VBR mode :) Wow, the first interesting PsyTEL thread in months... thank you for sharing this information! :) I didn't notice that the lower presets would accept -vbrhi yet (and have never read this before), so you're right, this is of course a good idea. Maybe this is the same as the "Quality" option in Nero AAC...

(it does give a slighly higher bitrate). Is -vbrhi and the settings from -streaming a bad match (as normal and up uses vbrhi)? If it only allocates more bits than the -vr (= Medium Quality) switch, then I guess it's OK to use it. I just encoded my usual test file with that setting and got 116 kbps instead of 111 kbps without -vbrhi, and the encoding speed was the same. Now I have to do my 128 kbps listening tests and ranking again, d'oh! ;) But that doesn't really matter, because I haven't redone it since FAAC v1.18 anyhow. Did you compare the sound of these two settings yet?

By the way, another "forgotten" switch is -qual that also allocates more bits when used together with -streaming, e.g. -qual 1 gives 122 kbps with the file mentioned above. But it doesn't behave in a predictable manner, because -qual 5 and -qual 9 resulted in the same bitrate for example.