| Message ID | 20220528083921.16538-1-shbisws@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel] avfilter/asrc_sine: Generate full amplitude sine wave. | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | fail | Make fate failed |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | fail | Make fate failed |
| andriy/make_armv7_RPi4 | success | Make finished |
| andriy/make_fate_armv7_RPi4 | fail | Make fate failed |
On Sat, May 28, 2022 at 10:39 AM Santanu Biswas <shbisws@gmail.com> wrote: > Previously, generating a full amplitude sine wave require to either > use the 'volume' filter in combination with this filter or manually > generate sine wave using 'aevalsrc' (e.g "aevalsrc=sin(2*PI*t*440)"). > This method is not bit-exact; therefore it is much coherent to not > scale the amplitude by 1/8 and keep it as it is. > > I think you are breaking fate tests with this change. Also why this can not be set at start instead of being hardcoded? > Signed-off-by: Santanu Biswas <shbisws@gmail.com> > --- > doc/filters.texi | 2 +- > libavfilter/asrc_sine.c | 8 ++------ > 2 files changed, 3 insertions(+), 7 deletions(-) > > diff --git a/doc/filters.texi b/doc/filters.texi > index 0e10946cca..a42e27b9b5 100644 > --- a/doc/filters.texi > +++ b/doc/filters.texi > @@ -7452,7 +7452,7 @@ Set number of taps for low-pass filter. > > @section sine > > -Generate an audio signal made of a sine wave with amplitude 1/8. > +Generate an audio signal made of a sine wave. > > The audio signal is bit-exact. > > diff --git a/libavfilter/asrc_sine.c b/libavfilter/asrc_sine.c > index c0d8d2265b..6c2f9d40f3 100644 > --- a/libavfilter/asrc_sine.c > +++ b/libavfilter/asrc_sine.c > @@ -83,13 +83,11 @@ static const AVOption sine_options[] = { > AVFILTER_DEFINE_CLASS(sine); > > #define LOG_PERIOD 15 > -#define AMPLITUDE 4095 > -#define AMPLITUDE_SHIFT 3 > > static void make_sin_table(int16_t *sin) > { > unsigned half_pi = 1 << (LOG_PERIOD - 2); > - unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT; > + unsigned ampls = 32767; > uint64_t unit2 = (uint64_t)(ampls * ampls) << 32; > unsigned step, i, c, s, k, new_k, n2; > > @@ -116,9 +114,7 @@ static void make_sin_table(int16_t *sin) > sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16; > } > } > - /* Unshift amplitude */ > - for (i = 0; i <= half_pi; i++) > - sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> > AMPLITUDE_SHIFT; > + > /* Use symmetries to fill the other three quarters */ > for (i = 0; i < half_pi; i++) > sin[half_pi * 2 - i] = sin[i]; > -- > 2.35.1 > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". >
diff --git a/doc/filters.texi b/doc/filters.texi index 0e10946cca..a42e27b9b5 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -7452,7 +7452,7 @@ Set number of taps for low-pass filter. @section sine -Generate an audio signal made of a sine wave with amplitude 1/8. +Generate an audio signal made of a sine wave. The audio signal is bit-exact. diff --git a/libavfilter/asrc_sine.c b/libavfilter/asrc_sine.c index c0d8d2265b..6c2f9d40f3 100644 --- a/libavfilter/asrc_sine.c +++ b/libavfilter/asrc_sine.c @@ -83,13 +83,11 @@ static const AVOption sine_options[] = { AVFILTER_DEFINE_CLASS(sine); #define LOG_PERIOD 15 -#define AMPLITUDE 4095 -#define AMPLITUDE_SHIFT 3 static void make_sin_table(int16_t *sin) { unsigned half_pi = 1 << (LOG_PERIOD - 2); - unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT; + unsigned ampls = 32767; uint64_t unit2 = (uint64_t)(ampls * ampls) << 32; unsigned step, i, c, s, k, new_k, n2; @@ -116,9 +114,7 @@ static void make_sin_table(int16_t *sin) sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16; } } - /* Unshift amplitude */ - for (i = 0; i <= half_pi; i++) - sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT; + /* Use symmetries to fill the other three quarters */ for (i = 0; i < half_pi; i++) sin[half_pi * 2 - i] = sin[i];
Previously, generating a full amplitude sine wave require to either use the 'volume' filter in combination with this filter or manually generate sine wave using 'aevalsrc' (e.g "aevalsrc=sin(2*PI*t*440)"). This method is not bit-exact; therefore it is much coherent to not scale the amplitude by 1/8 and keep it as it is. Signed-off-by: Santanu Biswas <shbisws@gmail.com> --- doc/filters.texi | 2 +- libavfilter/asrc_sine.c | 8 ++------ 2 files changed, 3 insertions(+), 7 deletions(-)