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--aps -b192 with 128/160 frames?, How did this happen?
post Oct 7 2003, 23:00
Post #1

getID3() developer

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Posts: 252
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From: Kingston, ON
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I came across a sample file that I'm having trouble figuring out how it was encoded. According to the LAME tag, it's encoded with LAME v3.92 and while v3.92 doesn't actually store the preset used, according to the rest of the info in the LAME tag it appears to be encoded using --alt-preset standard (vbr_quality = 78; vbr_method = vbr-old / vbr-rh; noise_shaping = 2; stereo_mode = joint; ath_type = 4; lowpass = 19000). The problem is that the LAME tag also says that a minimum bitrate of 192kbps was specified, and yet the actual bitrates are distributed like this (which looks like normal --aps):
128 -> 4
160 -> 963
192 -> 2658
224 -> 817
256 -> 246
320 -> 65
I haven't been able to replicate how the LAME tag has minimum bitrate of 192 but 128 and 160 frames appear in the file. I've tried:
--alt-preset standard -b 192
--alt-preset 192
--abr 192

Any ideas anyone?

getID3() = PHP audio & video metadata parser: http://getid3.sourceforge.net
Current version: v1.7.0 (released January 19, 2004)
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post Oct 8 2003, 19:29
Post #2

Group: Members
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Joined: 23-July 02
Member No.: 2751

As long as it is understood that arguments later in the command-line override earlier arguments by design then there is no bug as I see it.

However, there is a minor bug resulting from this feature. If you use, for example, the command-line "-b 192 --alt-preset standard" the Lame tag in the encoded file declares that the ABR Bitrate is 192 even though no ABR setting was used. Now if you had used "--alt-preset standard" the Lame tag declares ABR Bitrate is unknown.

This is the reason for some of the confusion here and why someone might blame EAC for the ABR difference.

When a user specifies "Lame MP3 Encoder" in the EAC dialog tab for External Compression, EAC adds "-b 192" to the command-line when "192 kBit/s" is selected in the bit rate drop down box. **This bit rate setting is added before any additional command-line options the user has specified.** If, instead, a user specifies "User Defined Encoder" then nothing is added to the command-line for the bit rate drop box regardless of what is selected. The only difference that results between these two encodings is that the ABR Bitrate is declared in the same way as above.
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