diff --git a/Modules/.gitignore b/Modules/.gitignore
index 4d3cb06..2ebf16d 100644
--- a/Modules/.gitignore
+++ b/Modules/.gitignore
@@ -1,6 +1,6 @@
 
 chkpixels
-t
+twavm
 trnd
 
 *.pgm
diff --git a/Modules/Makefile b/Modules/Makefile
index 576c4cb..70af2ea 100644
--- a/Modules/Makefile
+++ b/Modules/Makefile
@@ -31,6 +31,7 @@ mathstuff2.o:	mathstuff2.f90 Makefile
 noisepictures.o:	noisepictures.f90 Makefile
 	gfortran $(GFOPT) -c $<
 
+# new: Wed Feb  7 01:27:48 UTC 2024
 wavmetrics.o:		wavmetrics.f90 Makefile
 	gfortran $(GFOPT) -c $<
 
@@ -59,3 +60,8 @@ t_centermag:	t_centermag.f90 Makefile libtth90modules.a
 
 trnd:		trnd.f90 Makefile libtth90modules.a
 	gfortran $(GFOPT) $<  libtth90modules.a -o $@
+
+# new: Wed Feb  7 01:27:48 UTC 2024
+twavm:		twavm.f90 Makefile libtth90modules.a
+	gfortran $(GFOPT) $<  libtth90modules.a -o $@
+
diff --git a/Modules/README.md b/Modules/README.md
index 2b6fb88..d25f2b3 100644
--- a/Modules/README.md
+++ b/Modules/README.md
@@ -3,6 +3,11 @@
 
 ## Modules disponibles
 
+### wavmetrics
+
+This module try to make some computations on *stereo* buffers.
+
+This is just a [WIP](./wavmetrics.f90), see [twavm](./twavm.f90) for a no-use case.
 
 ### spitpgm
 
@@ -32,4 +37,4 @@ See [Makefile](./Makefile) for an example.
 
 ## TODO
 
-- écrire la doc !
+- write the fscking doc !
diff --git a/Modules/twavm.f90 b/Modules/twavm.f90
new file mode 100644
index 0000000..40a47e2
--- /dev/null
+++ b/Modules/twavm.f90
@@ -0,0 +1,39 @@
+program essai
+
+  ! new: Wed Feb  7 01:27:48 UTC 2024
+
+  use mathstuff2
+  use wavmetrics
+  implicit none
+
+  write(0, *)   "----------------- essai -------------------"
+
+  call run_first_test(44100/30)
+ 
+contains
+!-----------------------------------------------------------------------
+
+subroutine run_first_test(nbs)
+  integer, intent(in)   :: nbs                ! nombre d'echantillons
+
+  type(intsample), allocatable     :: samples(:)
+  type(wavmetric)                  :: metrics
+  integer                          :: foo, bar
+
+  write(0, '(1X, "first test on ", I0, " samples.")') nbs
+
+! create the buffer, and fill it with garbage
+  allocate(samples(nbs))
+  do foo=1, nbs
+    samples(foo)%left   = mod(irand(), 65534) - 32700
+    samples(foo)%right  = mod(irand(), 60000) - 29999
+  enddo
+
+! compute and display the metrics (gi-go)
+  call compute_wavmetric(samples, nbs, metrics)
+  call display_wavmetrics(metrics)
+
+end subroutine
+!-----------------------------------------------------------------------
+
+end program
diff --git a/Modules/wavmetrics.f90 b/Modules/wavmetrics.f90
index 1d03b45..a81359a 100644
--- a/Modules/wavmetrics.f90
+++ b/Modules/wavmetrics.f90
@@ -1,15 +1,16 @@
 
-! new: Thu Jan  4 00:08:04 UTC 2024
-
 module wavmetrics
 
+  ! new: Thu Jan  4 00:08:04 UTC 2024
+
   use mathstuff2
   implicit none
 
   type wavmetric
-    integer             :: num
-    real                :: freql, freqr
-    integer             :: maxl,  maxr
+    integer             :: nbre             ! number of slices/samples
+    real                :: freql, freqr     ! zero-crossing estimation
+    integer             :: maxl,  maxr      ! maximum of abs values
+    real                :: meanl, meanr
   end type
 
   type intsample
@@ -17,14 +18,51 @@ module wavmetrics
   end type
 
   contains
-
 !-------------------------------------------------------------
-
-subroutine compute_wavmetric(samples, start, size, metrics)
+!-
+!        main computation routine, still full buggy
+!-
+subroutine compute_wavmetric(samples, size, metrics)
   type(intsample), intent(in)       :: samples(:)
-  integer, intent(in)               :: start, size
+  integer, intent(in)               :: size
   type(wavmetric), intent(out)      :: metrics
 
+  integer                           :: Lmax, Rmax
+  integer                           :: Lval, Rval
+  integer                           :: idx
+  integer                           :: Lfreq, Rfreq
+
+  real                              :: Lsum, Rsum
+
+  Lmax  = 0     ;   Rmax  = 0
+  Lfreq = 1     ;   Rfreq = 1
+  Lsum  = 0.0   ;   Rsum  = 0.0
+
+  do idx=1, size
+    Lval = samples(idx)%left
+    Rval = samples(idx)%right
+
+    ! print *, Rval, Lval
+    if (abs(Lval) .GT. Lmax)   Lmax = abs(Lval)
+    if (abs(Rval) .GT. Rmax)   Rmax = abs(Rval)
+
+    if (idx .GT. 1) then
+      if (diff_sign(samples(idx-1)%left,  Lval))  Lfreq = Lfreq + 1
+      if (diff_sign(samples(idx-1)%right, Lval))  Rfreq = Rfreq + 1
+    endif
+
+    Lsum = Lsum + Lval
+    Rsum = Rsum + Rval
+
+  enddo
+
+  metrics%num   = size
+  metrics%maxl  = Lmax   ;  metrics%maxr = Rmax
+  metrics%freql = 1.0 / (Lfreq / real(size))
+  metrics%freqr = 1.0 / (Rfreq / real(size))
+  metrics%meanl = Lsum / real(size)
+  metrics%meanr = Rsum / real(size)
+
 end subroutine
 
 !-------------------------------------------------------------
@@ -32,6 +70,13 @@ end subroutine
 subroutine display_wavmetrics(metrics)
   type(wavmetric), intent(in)      :: metrics
 
+  ! print '(1X, "metrics are :")'
+
+  print '(1X, "    | num          ", I0)',     metrics%num
+  print '(1X, "    | freq         ", 2F12.2)', metrics%freql, metrics%freqr
+  print '(1X, "    | mean         ", 2F12.2)', metrics%meanl, metrics%meanr
+  print '(1X, "    | maxi         ", 2I8)',    metrics%maxl, metrics%maxr
+
 end subroutine
 
 !-------------------------------------------------------------