On Mon, 29 Feb 2016 03:33:45 +0100, han.lu@intel.com wrote:

From: "Lu, Han" han.lu@intel.com

Truncate the sample frames to powers of 2, since the FFTW algorithm runs especially fast in this case, and other sizes may be computed by means of a slow, general-purpose algorithm. In my test environment applying the patch, a sound clip of 33072 frames is cut off to 32768 frames before analysis, and the time cost is reduced from 6.128s to 0.224s.

Signed-off-by: Lu, Han han.lu@intel.com

Applied, thanks.

Takashi

diff --git a/bat/analyze.c b/bat/analyze.c index 60e2d1c..5cfdac3 100644 --- a/bat/analyze.c +++ b/bat/analyze.c @@ -256,6 +256,20 @@ static int reorder_data(struct bat *bat) return 0; }

+/* truncate sample frames for faster FFT analysis process */ +static int truncate_frames(struct bat *bat) +{

• int shift = SHIFT_MAX;
• for (; shift > SHIFT_MIN; shift--)

• if (bat->frames & (1 << shift)) {
  

• 	bat->frames = 1 << shift;
  

• 	return 0;
  

• }
  

• return -EINVAL;

+}

int analyze_capture(struct bat *bat) { int err = 0; @@ -263,6 +277,13 @@ int analyze_capture(struct bat *bat) int c; struct analyze a;

• err = truncate_frames(bat);
• if (err < 0) {

• fprintf(bat->err, _("Invalid frame number for analysis: %d\n"),
  

• 		bat->frames);
  

• return err;
  

• }
• fprintf(bat->log, _("\nBAT analysis: signal has %d frames at %d Hz,"), bat->frames, bat->rate); fprintf(bat->log, _(" %d channels, %d bytes per sample.\n"),

diff --git a/bat/common.h b/bat/common.h index b8f6670..ff03fc1 100644 --- a/bat/common.h +++ b/bat/common.h @@ -68,6 +68,12 @@ #define FOUND_DC (1<<1) #define FOUND_WRONG_PEAK (1<<0)

+/* Truncate sample frames to (1 << N), for faster FFT analysis process. The

• • valid range of N is (SHIFT_MIN, SHIFT_MAX). When N increases, the analysis
• • will be more time-consuming, and the result will be more accurate. */

+#define SHIFT_MAX (sizeof(int) * 8 - 2) +#define SHIFT_MIN 8

struct wav_header { unsigned int magic; /* 'RIFF' */ unsigned int length; /* file len */ -- 2.5.0