* [PATCH 1/1] alsabat: truncate sample frames for faster FFT analysis
@ 2016-02-29 2:33 han.lu
2016-03-01 9:34 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: han.lu @ 2016-02-29 2:33 UTC (permalink / raw)
To: tiwai, liam.r.girdwood, bernard.gautier, alsa-devel; +Cc: Lu, Han
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>
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 1/1] alsabat: truncate sample frames for faster FFT analysis
2016-02-29 2:33 [PATCH 1/1] alsabat: truncate sample frames for faster FFT analysis han.lu
@ 2016-03-01 9:34 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2016-03-01 9:34 UTC (permalink / raw)
To: han.lu; +Cc: liam.r.girdwood, bernard.gautier, alsa-devel
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
>
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2016-03-01 9:34 ` Takashi Iwai
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