Could someone explain the reason(ing) for this change? VBR with a
maximum bitrate will be of lower quality than ABR at that bitrate. And
as the documentation below indicates, it's even lower quality than CBR
at the same bitrate.
>From the LAME 3.98 documentation:
Code:
--------------------
* -B n maximum VBR/ABR bitrate
For MPEG1 (sampling frequencies of 32, 44.1 and 48 kHz)
n = 32,40,48,56,64,80,96,112,128,160,192,224,256,320
For MPEG2 (sampling frequencies of 16, 22.05 and 24 kHz)
n = 8,16,24,32,40,48,56,64,80,96,112,128,144,160
Specifies the maximum allowed bitrate when using VBR/ABR
The use of -B is NOT RECOMMENDED. A 128kbps CBR bitstream, because of
the bit reservoir, can actually have frames which use as many bits as
a 320kbps frame. VBR modes minimize the use of the bit reservoir, and
thus need to allow 320kbps frames to get the same flexibility as CBR
streams.
--------------------
This is the r23010 checkin comment:
Code:
--------------------
Improve transcoding to MP3 for many case by removing unnecessary
resampling where possible and replacing ABR with VBR and an upper
limit. This was partially necessary because "--abr 0", without a
specified sample rate, results in 8kbps output.
--------------------
I don't quite follow the 'resampling' comment, but passing 0 as the ABR
bitrate should be very easy to avoid.
--
JJZolx
Jim
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