added helper functions for buffer<->framerate<->duration conversions

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3645 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/media/media-add-ons/mixer/MixerUtils.cpp

@@ -1,6 +1,7 @@
 #include <MediaDefs.h>
 #include <stdio.h>
 #include <string.h>
+#include <math.h>
 
 #include "MixerUtils.h"
 #include "debug.h"
@@ -159,3 +160,31 @@ CopySamples(float *_dst, int32 _dst_sample_offset,
 		dst += dst_sample_offset;
 	}
 }
+
+int64
+frames_for_duration(double framerate, bigtime_t duration)
+{
+	return (int64) ceil(framerate * double(duration) / 1000000.0);
+}
+
+bigtime_t
+duration_for_frames(double framerate, int64 frames)
+{
+	return (bigtime_t)((1000000.0 * frames) / framerate);
+}
+
+int
+bytes_per_frame(const media_multi_audio_format & format)
+{
+	return format.channel_count * (format.format & 0xf);
+}
+
+int
+frames_per_buffer(const media_multi_audio_format & format)
+{
+	int frames = 0;
+	if (bytes_per_frame(format) > 0) {
+		frames = format.buffer_size / bytes_per_frame(format);
+	}
+	return frames;
+}

src/add-ons/media/media-add-ons/mixer/MixerUtils.h

@@ -1,4 +1,3 @@
-#include <math.h>
 
 void string_for_channel_mask(char *str, uint32 mask);
 void fix_multiaudio_format(media_multi_audio_format *format);
@@ -13,13 +12,11 @@ void CopySamples(float *_dst, int32 _dst_sample_offset,
 				 const float *_src, int32 _src_sample_offset,
 				 int32 _sample_count);
 
+int bytes_per_frame(const media_multi_audio_format & format);
+int frames_per_buffer(const media_multi_audio_format & format);
 
 int64 frames_for_duration(double framerate, bigtime_t duration);
-
+bigtime_t duration_for_frames(double framerate, int64 frames);
-inline int64 frames_for_duration(double framerate, bigtime_t duration)
-{
-	return (int64) ceil(framerate * double(duration) / 1000000.0);
-}
 
 int ChannelMaskToChannelType(uint32 mask);
 uint32 ChannelTypeToChannelMask(int type);