AGK audio: LPCM to MP3

[BigDid]

Here is a summary of previous posts on the topic LPCM to MP3 from the main AGK thread, as it does not seem possible to move the considered posts. :(

2005/01/10-06 :16
Fm BigDid
quote:Originally posted by len0x
... (either leave AC3/DTS/MP3 or convers to MP3 from PCM/DTS/AC3).

Exchanging about PCM, I don't know if it is AGK standard behaviour but got a 128 abr mp3 (80mb) out of a pcm to wav audio (975Mo) when keeping +ac3/dts+ switch for a 1.1Gb final size. Its the Joe Cocker across midnight concert DVD stereo 1 audio track.
As a newby I remember not knowing what pcm quality was (high) and trusting AGK when using the ac3/dts for that occasion and for keeping quality ...
I manually (with Belight) tried the alt-preset-extreme mp3 settings to get about 230kbps vbr encode, 320 and 384 ac3 encodes. I finally decided to keep the 384 ac3 for 240 Mb.
Question: is 128 abr-mp3 not a little too low in quality? as it seems a feature of AGK, could you consider a 320 cbr mp3 instead of 128 abr mp3,so if users think its too much, they can downgrade to whatever abr mp3 smaller size (same reasoning apply when ac3 tracks are too big) ?
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2005/01/10-06 :26
Fm Lenox
quote:Originally posted by BigDid
@Lenox
Exchanging about PCM, I don't know if it is AGK standard behaviour but got a 128 abr mp3 (80mb) out of a pcm to wav audio

FAQ Q 2.3
128 is enough for non-music DVDs. If you require more you can always do it via advanced settings.
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2005/01/10-08 :18
Fm BigDid
quote:Originally posted by len0x
FAQ Q 2.3
128 is enough for non-music DVDs. If you require more you can always do it via advanced settings.

I believe I missed my point which is about quality
I'll try to come back later on it.
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2005/01/10-08 :28
Fm Lenox
quote:Originally posted by BigDid
I believe I missed my point which is about quality

you missed or I missed?
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2005/01/10-08 :48
Fm BigDid
quote:Originally posted by len0x
you missed or I missed?

I confirm, your honour (french joke/saying; the original being: I plead culprit your honour);
I missed
It's about causes & consequences (and foreign langage btw):
I missed to elaborate my arguments (cause)
You made a reply based on your understanding of my point (consequence)
Your answer makes me think I missed my point about quality so I would like, once my arguments are clearer, to have a second chance elaborating on the subject

Did

[BigDid]

The last post Fm Lenox being :
« While you're at thinking - movies usually have quite a bit of silence in them (or full of highly compressible material like human speech that doesn't have the whole frequency range), so spending 320kpbs on it seems to be a waste. »

Exactly, spending 320kpbs on it seems to be a waste.
I agree totally when the auto (audio) checkbox is used for 1cd but what I said in my first post was using the ac3/dts switch for a 1.1Gb final size. In this case ac3 (which is also CBR) can give an audio filesize up to 600Mb (LOTR3 ac36ch french) or more if it’s DTS.

Actually what does AGK for Auto (fine for me)
File size 1cd :
Input AC3 output abr mp3 128
Input DTS output abr mp3 128
Input LPCM output abr mp3 128

File size more than 1 cd (have not tested all the options, fine for me except for LPCM)
Input AC3 output AC3 -> up to 600Mb
Input DTS output DTS -> more than 600Mb maybe up to 1Gb
Input LPCM output abr mp3 128 -> 80 to 100Mb
… LPCM may deserves more quality for more than 1cd file size.

I know AGK has not access, atm, to ac3 transcoding and from what I have read and exchanged (hard subject ) you need high bitrates (320 to 448 kbp/s) to have quality with besweet/ac3enc.
So the only option is mp3, what bitrate ?
I made a proposition of CBR 320 mp3 because:
- it’s the maximum quality available for mp3
- CBR is (should be) playable on all SAP
In the exemple I gave the 320kbp/s mp3 audiosize was only +-195 Mb compared to the 80Mb of the abr128

Concerning the AC3/DTS (and I thought LPCM) I used it to keep the best audio quality and had no information given by AGK about LPCM so I thought it was the same deduction which is not.
If it is not possible to have quality for LPCM input, maybe you can
- gray out the ac3/dts checkbox
- specify that LPCM cannot be keeped (either in the GUI or in the FAQ)

As for the auto- audio I am ok with 128abr mp3 for 1cd, what about raising the bitrate ( to your convenience) for more than 1cd ? ...
:)

Did

[len0x]

So, the proposition is to have higher bitrate for mp3 if source is LPCM and target size is more then 1 CD? I understand that, but also:

- VBR MP3 is better
- 320kbps is overkill anyway

If we're encoding into mp3 then difference in quality say 192/224 vs 320kbps will not be really audible unless the source is musical (and auto option is mot relevant in this case).

One thing that you forget when comparing LPCM to AC3/DTS is that AC3 is 6 channels and DTS is 7 while LPCM is just 2, so your size considerations are not quite right.

Any other takers?

[BigDid]

Originally posted by BigDid
...Concerning the AC3/DTS (and I thought LPCM) I used it to keep the best audio quality and had no information given by AGK about LPCM so I thought it was the same deduction which is not.
If it is not possible to have quality for LPCM input, maybe you can
- gray out the ac3/dts checkbox
- specify that LPCM cannot be keeped (either in the GUI or in the FAQ)

As for the auto- audio I am ok with 128abr mp3 for 1cd, what about raising the bitrate ( to your convenience) for more than 1cd ? ...

Any remarks or reactions?

What about the newcomers lost in the audio jungles :)

Did

/Edited: cross-posts with Lenox
Deeper in the audio jungle: http://forum.doom9.org/showthread.php?s=&threadid=70603
Specially posts fm planet1/

[len0x]

FAQ can be made more clear on the subject indeed. I don't think greying out AC3/DTS option can really help though...

[BigDid]

Originally posted by len0x
So, the proposition is to have higher bitrate for mp3 if source is LPCM and target size is more then 1 CD? I understand that, but also:

- VBR MP3 is better
- 320kbps is overkill anyway

If we're encoding into mp3 then difference in quality say 192/224 vs 320kbps will not be really audible unless the source is musical (and auto option is mot relevant in this case).

One thing that you forget when comparing LPCM to AC3/DTS is that AC3 is 6 channels and DTS is 7 while LPCM is just 2, so your size considerations are not quite right.

Any other takers?
No other takers I believe, I won't be a successfull politician ( maybe I need a more consistent program) :)

I agree to all: vbr is better, 320kbps is overkill (so what about 384 or 448 for ac3?), 192/224abr is fine.
As for comparing sizes, I am still moving in the audio jungle so you may be right, even if the last video concert I xvided (Tina in Wembley) states that the DTS track is 2 channels ?... i did'nt verified on my 5.1 audio because I have an auto upmix to surround I should disable to test.
I should go back fishing some times :)

Bye

Did