Ogg R9 nominal bitrates different in mono

[edgarde]

Dunno if this is a bug or a feature, and if a bug dunno if it's Xiph or Illustrate, but encoding in mono creates file where "Nominal bitrate" reads different from bitrates requested (via the Bit Rate slider bar).

Are the bitrates correct for mono in the following examples?

(All tag info read from Winamp)

file ripped mono@256k
-----
length: 3:22
average bitrate: 102 kbps
file size: 2,593,215 bytes
nominal bitrate: 140 kbps
channels: 1
sampling rate: 44100 Hz
serial number: 21656
version: 0
vendor: Xiph.Org libVorbis I 20020717


file ripped mono@140k
-----
length: 3:22
average bitrate: 73 kbps
file size: 1,857,829 bytes
nominal bitrate: 96 kbps
channels: 1
sampling rate: 44100 Hz
serial number: 22390
version: 0
vendor: Xiph.Org libVorbis I 20020717


file ripped stereo@256k
-----
length: 3:22
average bitrate: 171 kbps
file size: 4,340,223 bytes
nominal bitrate: 256 kbps
channels: 2
sampling rate: 44100 Hz
serial number: 21950
version: 0
vendor: Xiph.Org libVorbis I 20020717


file sizes (from DOS shell):

03:15 PM 1,857,829 Al Bowlley [mono encoded@140kbps].ogg
03:15 PM 2,593,215 Al Bowlley [mono encoded@256kbps].ogg
03:15 PM 4,340,223 Al Bowlley [stereo encoded@256kbps].ogg
3 File(s) 8,791,267 bytes
2 Dir(s) 120,147,968 bytes free


This is reproduceable with R9 Beta 2 and final release. (I uninstalled R9beta2 before installing the final.)

Es.

[Spoon]

What happens if you encode them as CBR?

[edgarde]

Ogg R9 nominal bitrates same in mono w/ CBR + Crash mono@256kCBR

file ripped mono@140k
-----
length: 3:22
average bitrate: 132 kbps
file size: 3,359,797 bytes
nominal bitrate: 140 kbps
min bitrate: 140 kbps
max bitrate: 140 kbps
channels: 1
sampling rate: 44100 Hz
serial number: 30917
version: 0
vendor: Xiph.Org libVorbis I 20020717


file ripped stereo@256k
-----
length: 3:22
average bitrate: 239 kbps
file size: 6,054,148 bytes
nominal bitrate: 256 kbps
min bitrate: 256 kbps
max bitrate: 256 kbps
channels: 2
sampling rate: 44100 Hz
serial number: 6613
version: 0
vendor: Xiph.Org libVorbis I 20020717

-----

Attempted to rip to mono@256k with CBR and crashed, repeatedly and reproduceably, including after reboot.

WinXP w/SP1, 512MB RAM, Athlon XP 1700+

Clicking "Convert" button for "Al Bowlley [mono encoded@256kbps CBR].ogg"
"MusicConverter.exe has experienced a problem and needs to close. We are sorry for the incovenience."

5th attempt after reboot:

Overwrite These Files? Click [OK], 0% Completed on dBpowerAMP Music Converter. Crash. An empty "Al Bowlley [mono encoded@256kbps CBR].ogg" is written.

Stereo w/ CBR encodes okay. Mono w/VBR encodes okay.

Es.

[edgarde]

weird average bitrate / wrong forum

Just noticed the peculiar average bitrate for stereo@256k CBR above. This is not a typo. I ran another encode to be sure.

file ripped stereo@256k w/ CBR
-----
length: 3:22
average bitrate: 239 kbps
file size: 6,054,148 bytes
nominal bitrate: 256 kbps
min bitrate: 256 kbps
max bitrate: 256 kbps

-----

:rolleyes: I'm also noticing I started this thread in the dAC forum; it really belongs in the dMC forum.

Es.

[Spoon]

Have you tried some of the other offical ogg encoders? I am curious to see what they give.

[edgarde]

differerent inconsistencies in OggdropXPd / ENCODED_USING tag

Confusingly, OggdropXPd (an official encoder) has correct (same as selected on encoder) "Nominal Bitrate" metadata for mono files.

However, it fails to encode mono@256 CBR (error message below). Additionally, CBR files have "Average Bitrate" metatdata that differ from "Nominal Bitrate", which certainly seems wrong, but I don't know for sure. Perhaps this needs to be reported to Xiph?

I was unable to guess the min & max rates for default ABR in dMC, so I chose min=0 and max=320. There is no "VBR" option in OggdropXPd.
-----

Settings: CBR, 256, [X] "Downmix Stereo to Mono", Re-sample to: 44100
"Error: d:\shared\Al Bowlley\[1993] Love is the Sweetest Thing\test\All Bowlley.wav: Can't encode with selected params/file attrs" [OK]
0 Kb Ogg is created.
-----


** Files made with OggdropXPd:

Al Bowlley [stereo@256k ABR OggdropXPc].ogg
-----
length: 3:22
average bitrate : 255 kbps
file size: 6,449,867 bytes
nominal bitrate: 256 kbps
max bitrate: 320kbps
channels: 2
sampling rate: 44100Hz
serial number: 6904
version: 0
vendor: Xiph.Org libVorbis I 20020717

Al Bowlley [stereo@256k CBR OggdropXPc].ogg
-----
length: 3:22
average bitrate : 239 kbps
file size: 6,054,084 bytes
nominal bitrate: 256 kbps
min bitrate: 256 kbps
max bitrate: 256 kbps
channels: 2
sampling rate: 44100Hz
serial number: 8537
version: 0
vendor: Xiph.Org libVorbis I 20020717

Al Bowlley [mono@140k CBR OggdropXPc] 2.ogg
-----
length: 3:22
average bitrate : 133 kbps
file size: 3,362,685 bytes
nominal bitrate: 140 kbps
min bitrate: 140 kbps
max bitrate: 140 kbps
channels: 1
sampling rate: 44100Hz
serial number: 9331
version: 0
vendor: Xiph.Org libVorbis I 20020717

Al Bowlley [mono@140k ABR OggdropXPc] 2.ogg
-----
length: 3:22
average bitrate : 137 kbps
file size: 3,471,947 bytes
nominal bitrate: 140 kbps
max bitrate: 320 kbps
channels: 1
sampling rate: 44100Hz
serial number: 9837
version: 0
vendor: Xiph.Org libVorbis I 20020717

-----
Here's an interesting Tag made by OggdropXPd:
"ENCODED_USING=oggdropXPd interface"

While unofficial, apparently it's something Xiph uses.

Es.

[Spoon]

The rates do seem slightly down on both, I think most of the effect for Ogg goes into the VBR mode (called quality in other programs).