Hello Robert,
Tuesday, July 11, 2000, 4:44:49 PM, you wrote:
RH> OK, once again, there is no -b128 bug!!
The thing that confuses me is that with older versions of lame when
-b128 specified, I got
or 128k and above
or 32k (analog silence)
I never got anything inbetween. Now this all changed, I assumed a
bug.
RH> A typical stereo mp3 frame consists of two granules and 2 channels.
RH> So you have to encode:
RH> granule1 left-channel
RH> granule1 right-channel
RH> granule2 left-channel
RH> granule2 right-channel
RH> That makes 4 possibilities to detect analog silence.
So analog silence is 4x checked? It's possible to get 1 frame with 1
AS and 3 non-AS granules?
RH> These sections will be encoded with your selected quality
RH> resulting in a need of XYZ bits all together.
RH> Now it goes into packaging these already encoded granules
RH> into a sufficient frame, a frame which provides enough bits.
RH> If analog silence is detected, then all these 4 sections
RH> will be packed into a frame of a lower bitrate then say 128kbits,
RH> but only if XYZ bits will fit into it.
RH> It could also be packed into a frame of a larger bitrate, but
RH> that would make no difference in terms of quality, as these
RH> granules are already encoded and use XYZ bits.
RH> If you force (-F) LAME to use exactly a 128 kbits frame,
RH> this could result in a huge waste of bits on long silent
RH> passages.
This is why MT introduced a over-riding of -b* in case of AS, to take
only 32kb frames there. This feature seems lost now?
RH> Roel, maybe it is time for you to get a version of LAME with
RH> the frame analyzer MP3x included. You would need the GTK dlls
RH> too. Then you can see what LAME does on every frame.
RH> Robert
RH> PS:
RH> analog silence - there is some energy in every band, but
RH> it is below the ATH
RH> digital silence - there is no energy in every band
Then, if this all has to make sense, the algorithm was refined from
3.85 to 3.86 so that the difference is
* =<385 gave 32kbit/s frames on parts with AS on all 4 granules and
128 to all other with at least 1 granule non-AS?
I'm sorry for the extreme stubbornness from me on this issue, but I
still think there is a misunderstanding (on my behalf). I encoded countless albums
and songs with lame VBR by now, and I _never_ got anything else than
32k and 128k and up. Now I get 112,48,40,96 frames on just about all
albums. Only tells me something has changed, and I assumed this was a
bug, but I never considered this was willingly.
I am now living an existentiality crisis about the '-b' option.
thanks for the lengthy explanation.
--
Best regards,
Roel mailto:[EMAIL PROTECTED]
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