Downloads
release
dev builds
extras
themes
Documentation
manual
wiki
device status
Support
forums
mailing lists
IRC
Development
bugs
patches
dev guide
Search
Donate
Search
| Go
Wiki
>
Main
>
MasLimitations
---+!! MAS Limitations %TOC% ---++ About An extended test showed that the MAS MPEG audio decoders seems to not correctly decode all valid MPEG version/ layer/ bitrate combinations. This page is about the details. Problems do exist with MPEG2.5 layer 3. These limitations usually don't affect music playback at all. Usually music does not use MPEG2.5, these low sample frequencies are aimed at speech compression. However, there is one area where the MPEG2.5 limitations may hit - creation of voice files. The voice file size is limited to ~1.5 MB. As there are more and more entries added to voicing, there are 2 options to achieve higher compression: 1 Lower the VBR quality setting (lame: =-V <n>= - increase n). With too low quality settings, this produces clearly noticeable compression artifacts. 2 Lower the sample frequency (lame: =--resample <n>= ). As soon as the sample frequency is lowered to 12 kHz, the MPEG2.5 playback problems may hit. When frame sizes of >64 kbit/s are used, dropouts occur. To avoid this, use the lame option =-B 64= as well to limit the frame size. Avoid a sample rate of 11.025 kHz. ---++ Detailed results ---+++ Legend 3507: MAS 3507D other: MAS 3587F / MAS 3539F S: Silent play T: loud twittering noise ---+++ MPEG2.5 layer 3 Stereo | *Bitrate* | *8 kHz* || *11.025 kHz* || *12 kHz* || | *kbit/s* | *3507* | *other* | *3507* | *other* | *3507* | *other* | | 8 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 16 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 24 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 32 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 40 | %Y% | %Y% | %RED% *S* %ENDCOLOR% | %Y% | %Y% | %Y% | | 48 | %Y% | %Y% | %RED% *S* %ENDCOLOR% | %Y% | %Y% | %Y% | | 56 | %Y% | %Y% | %RED% *S* %ENDCOLOR% | %Y% | %Y% | %Y% | | 64 | %Y% | %Y% | %RED% *S* %ENDCOLOR% | %Y% | %Y% | %Y% | | 80 | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | \ %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | | 96 | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | \ %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | | 112 | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | \ %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | | 128 | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | \ %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | | 144 | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | \ %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | | 160 | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | \ %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | %RED% *S* %ENDCOLOR% | ---+++ MPEG2 layer 3 Stereo | *Bitrate* | *16 kHz* || *22.05 kHz* || *24 kHz* || | *kbit/s* | *3507* | *other* | *3507* | *other* | *3507* | *other* | | 8..160 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | ---+++ MPEG1 layer 3 Stereo | *Bitrate* | *32 kHz* || *44.1 kHz* || *48 kHz* || | *kbit/s* | *3507* | *other* | *3507* | *other* | *3507* | *other* | | 32..320 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | ---+++ MPEG2 layer 2 Stereo | *Bitrate* | *16 kHz* || *22.05 kHz* || *24 kHz* || | *kbit/s* | *3507* | *other* | *3507* | *other* | *3507* | *other* | | 8..160 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | ---+++ MPEG1 layer 2 Stereo | *Bitrate* | *32 kHz* || *44.1 kHz* || *48 kHz* || | *kbit/s* | *3507* | *other* | *3507* | *other* | *3507* | *other* | | 32* | T | T | T | T | T | T | | 48* | T | T | T | T | T | T | | 56* | T | T | T | T | T | T | | 64 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 80* | %Y% | %Y% | %Y% | %Y% | T | T | | 96 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 112 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 128 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 160 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 192 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 224 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 256 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 320 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | | 384 | %Y% | %Y% | %Y% | %Y% | %Y% | %Y% | * These bitrates are forbidden for layer 2 stereo.
E
dit
|
A
ttach
|
P
rint version
|
H
istory
: r3
<
r2
<
r1
|
B
acklinks
|
V
iew topic
|
M
ore topic actions
r3 - 05 Oct 2005 - 06:10:00 -
JensArnold
Copyright © by the contributing authors.
