some info on the mode-quality mapping

git-svn-id: http://svn.xiph.org/trunk/speex@12902 0101bb08-14d6-0310-b084-bc0e0c8e3800

1 files changed, 193 insertions, 16 deletions

diff --git a/doc/manual.lyx b/doc/manual.lyx
index f04f027..b0c6a4a 100644
--- a/doc/manual.lyx
+++ b/doc/manual.lyx
@@ -1411,6 +1411,29 @@ In practice,
 frame_size
 \emph default
  will correspond to 20 ms when using 8, 16, or 32 kHz sampling rate.
+ There are many parameters that can be set for the Speex encoder, but the
+ most useful one is the quality parameter that controls the quality vs bit-rate
+ tradeoff.
+ This is set by:
+\end_layout
+
+\begin_layout LyX-Code
+speex_encoder_ctl(enc_state,SPEEX_SET_QUALITY,&quality);
+\end_layout
+
+\begin_layout Standard
+where 
+\emph on
+quality
+\emph default
+ is an integer value ranging from 0 to 10 (inclusively).
+ The mapping between quality and bit-rate is described in Fig.
+ 
+\begin_inset LatexCommand \ref{cap:quality_vs_bps}
+
+\end_inset
+
+ for narrowband.
 \end_layout
 
 \begin_layout Standard
@@ -6358,11 +6381,12 @@ begin{center}
 
 
 \begin_inset Tabular
-<lyxtabular version="3" rows="17" columns="4">
+<lyxtabular version="3" rows="17" columns="5">
 <features>
 <column alignment="center" valignment="top" leftline="true" width="0pt">
 <column alignment="center" valignment="top" leftline="true" width="0pt">
 <column alignment="center" valignment="top" leftline="true" width="0pt">
+<column alignment="center" valignment="top" leftline="true" width="0pt">
 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
 <row topline="true" bottomline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
@@ -6378,6 +6402,15 @@ Mode
 \begin_inset Text
 
 \begin_layout Standard
+Quality
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 Bit-rate
 \begin_inset LatexCommand \index{bit-rate}
 
@@ -6426,6 +6459,15 @@ Quality/description
 \begin_inset Text
 
 \begin_layout Standard
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 250
 \end_layout
 
@@ -6435,7 +6477,7 @@ Quality/description
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+0
 \end_layout
 
 \end_inset
@@ -6464,6 +6506,15 @@ No transmission (DTX)
 \begin_inset Text
 
 \begin_layout Standard
+0
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 2,150
 \end_layout
 
@@ -6502,6 +6553,15 @@ Vocoder (mostly for comfort noise)
 \begin_inset Text
 
 \begin_layout Standard
+2
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 5,950
 \end_layout
 
@@ -6540,6 +6600,15 @@ Very noticeable artifacts/noise, good intelligibility
 \begin_inset Text
 
 \begin_layout Standard
+3-4
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 8,000
 \end_layout
 
@@ -6578,6 +6647,15 @@ Artifacts/noise sometimes noticeable
 \begin_inset Text
 
 \begin_layout Standard
+5-6
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 11,000
 \end_layout
 
@@ -6616,6 +6694,15 @@ Artifacts usually noticeable only with headphones
 \begin_inset Text
 
 \begin_layout Standard
+7-8
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 15,000
 \end_layout
 
@@ -6654,6 +6741,15 @@ Need good headphones to tell the difference
 \begin_inset Text
 
 \begin_layout Standard
+9
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 18,200
 \end_layout
 
@@ -6692,6 +6788,15 @@ Hard to tell the difference even with good headphones
 \begin_inset Text
 
 \begin_layout Standard
+10
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 24,600
 \end_layout
 
@@ -6730,6 +6835,15 @@ Completely transparent for voice, good quality music
 \begin_inset Text
 
 \begin_layout Standard
+1
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
 3,950
 \end_layout
 
@@ -6768,7 +6882,16 @@ Very noticeable artifacts/noise, good intelligibility
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -6777,7 +6900,7 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset
@@ -6806,7 +6929,16 @@ reserved
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -6815,7 +6947,7 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset
@@ -6844,7 +6976,7 @@ reserved
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset
@@ -6853,7 +6985,16 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -6882,7 +7023,16 @@ reserved
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -6891,7 +7041,7 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset
@@ -6920,7 +7070,7 @@ reserved
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset
@@ -6929,7 +7079,16 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -6958,7 +7117,7 @@ Application-defined, interpreted by callback or skipped
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset
@@ -6967,7 +7126,16 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -6996,7 +7164,16 @@ Speex in-band signaling
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
+\end_layout
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\begin_layout Standard
+-
 \end_layout
 
 \end_inset
@@ -7005,7 +7182,7 @@ N/A
 \begin_inset Text
 
 \begin_layout Standard
-N/A
+-
 \end_layout
 
 \end_inset