Re: Datahandle State API changes

On Mon, 27 Nov 2006, Stefan Westerfeld wrote:

On Sat, Nov 25, 2006 at 05:48:51PM +0100, Tim Janik wrote:
On Mon, 6 Nov 2006, Stefan Westerfeld wrote:

+ * state which means that the value of one input sample affects not only
+ * output sample, but some samples before and some samples after the

s/and/or/ (since that depends on the filter type)

Writing "or" could mean that either some samples before or some samples
after the corresponding sample are affected, but not both.

nope, in natural language, "or" can mean exclusive or and non-exclusive or,
but i'm still fine with your new wording.

+ * "corresponding" output sample.
+ *
+ * Often the state is symmetric, so that the number of output samples
+ * before and after the "corresponding" output sample is the same. Then
+ * function returns this number. If the state is asymmetric, this function
+ * shall return the maximum of the two numbers.
+ *
+ * If multiple data handles are cascaded (for instance when resampling a

hm, "cascaded"? i'd rather say "nested" (or "chained") here.

Ok: I'll use cascaded.

i don't think "cascaded" is accurate here. cascaded handles could mean
using handles in parallel (e.g. you could line up 6 handles in a specifically
ordered cascade to produce a 5.1 dolby handle ;)
only "nested" and to some extend "chained" carry across the sequential
ordering of the handles.

Index: bse/
--- bse/	(revision 4068)
+++ bse/	(working copy)
@@ -136,7 +136,7 @@ protected:

 /* implemented by upsampling and downsampling datahandle */
-  virtual BseResampler2Mode mode	() = 0;
+  virtual BseResampler2Mode mode	() const = 0;
 virtual int64		    read_frame  (int64 frame) = 0;

@@ -222,18 +222,38 @@ public:

   return n_values;
+  GslDataHandle*
+  get_source() const
+  {
+    return gsl_data_handle_get_source (m_src_handle);
+  }
+  int64
+  get_state_length() const
+  {
+    int64 source_state_length = gsl_data_handle_get_state_length
+    if (source_state_length < 0)
+      return source_state_length;

huh? why should a datahandle every return a negative state?

Well, I thought of that line as a similar error propagation as I do in
read - that is, if the source handle does something strange, I pass it

What if the source handle had infinite state (like an IIR filter)?

then we return that, the best approximation would be G_MAXINT64.

But I
can also simplify it to a g_return_if_fail(), for as long as there are
no datahandles with non-finite state or othor "errors".

as i said previously, there's no "error" handling defined for this function.

Here is the new patch:

just pasting the changed portions would have been enough, it's not like the
patch needed a major overhaul here. provided the above stuff is fixed it should be ready to go in i think.

  Cu... Stefan


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