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jeplerjepler
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MP3File: Add rms_level property
This lets a music player show it vu-meter style
1 parent 97bb46c commit ec22520

4 files changed

Lines changed: 33 additions & 0 deletions

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‎shared-bindings/audiomp3/MP3File.c‎

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Original file line numberDiff line numberDiff line change
@@ -224,6 +224,24 @@ const mp_obj_property_t audiomp3_mp3file_channel_count_obj = {
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(mp_obj_t)&mp_const_none_obj},
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};
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//| .. attribute:: rms_level
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//|
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//| The RMS audio level of a recently played moment of audio. (read only)
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//|
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STATIC mp_obj_t audiomp3_mp3file_obj_get_rms_level(mp_obj_t self_in) {
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audiomp3_mp3file_obj_t *self = MP_OBJ_TO_PTR(self_in);
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check_for_deinit(self);
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return mp_obj_new_float(common_hal_audiomp3_mp3file_get_rms_level(self));
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}
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MP_DEFINE_CONST_FUN_OBJ_1(audiomp3_mp3file_get_rms_level_obj, audiomp3_mp3file_obj_get_rms_level);
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const mp_obj_property_t audiomp3_mp3file_rms_level_obj = {
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.base.type = &mp_type_property,
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.proxy = {(mp_obj_t)&audiomp3_mp3file_get_rms_level_obj,
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(mp_obj_t)&mp_const_none_obj,
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(mp_obj_t)&mp_const_none_obj},
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};
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STATIC const mp_rom_map_elem_t audiomp3_mp3file_locals_dict_table[] = {
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// Methods
@@ -236,6 +254,7 @@ STATIC const mp_rom_map_elem_t audiomp3_mp3file_locals_dict_table[] = {
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{ MP_ROM_QSTR(MP_QSTR_sample_rate), MP_ROM_PTR(&audiomp3_mp3file_sample_rate_obj) },
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{ MP_ROM_QSTR(MP_QSTR_bits_per_sample), MP_ROM_PTR(&audiomp3_mp3file_bits_per_sample_obj) },
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{ MP_ROM_QSTR(MP_QSTR_channel_count), MP_ROM_PTR(&audiomp3_mp3file_channel_count_obj) },
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{ MP_ROM_QSTR(MP_QSTR_rms_level), MP_ROM_PTR(&audiomp3_mp3file_rms_level_obj) },
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};
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STATIC MP_DEFINE_CONST_DICT(audiomp3_mp3file_locals_dict, audiomp3_mp3file_locals_dict_table);
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‎shared-bindings/audiomp3/MP3File.h‎

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@@ -45,5 +45,6 @@ uint32_t common_hal_audiomp3_mp3file_get_sample_rate(audiomp3_mp3file_obj_t* sel
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void common_hal_audiomp3_mp3file_set_sample_rate(audiomp3_mp3file_obj_t* self, uint32_t sample_rate);
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uint8_t common_hal_audiomp3_mp3file_get_bits_per_sample(audiomp3_mp3file_obj_t* self);
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uint8_t common_hal_audiomp3_mp3file_get_channel_count(audiomp3_mp3file_obj_t* self);
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float common_hal_audiomp3_mp3file_get_rms_level(audiomp3_mp3file_obj_t* self);
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#endif // MICROPY_INCLUDED_SHARED_BINDINGS_AUDIOIO_MP3FILE_H

‎shared-module/audiomp3/MP3File.c‎

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@@ -29,6 +29,7 @@
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#include <stdint.h>
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#include <string.h>
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#include <math.h>
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#include "py/mperrno.h"
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#include "py/runtime.h"
@@ -339,3 +340,13 @@ void audiomp3_mp3file_get_buffer_structure(audiomp3_mp3file_obj_t* self, bool si
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*spacing = 1;
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}
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}
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float common_hal_audiomp3_mp3file_get_rms_level(audiomp3_mp3file_obj_t* self) {
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float sumsq = 0.f;
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// Assumes no DC component to the audio. Is that a safe assumption?
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int16_t *buffer = (int16_t *)(void *)self->buffers[self->buffer_index];
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for(size_t i=0; i<self->frame_buffer_size / sizeof(int16_t); i++) {
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sumsq += (float)buffer[i] * buffer[i];
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}
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return sqrtf(sumsq) / (self->frame_buffer_size / sizeof(int16_t));
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}

‎shared-module/audiomp3/MP3File.h‎

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@@ -67,4 +67,6 @@ void audiomp3_mp3file_get_buffer_structure(audiomp3_mp3file_obj_t* self, bool si
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bool* single_buffer, bool* samples_signed,
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uint32_t* max_buffer_length, uint8_t* spacing);
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float audiomp3_mp3file_get_rms_level(audiomp3_mp3file_obj_t* self);
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#endif // MICROPY_INCLUDED_SHARED_MODULE_AUDIOIO_MP3FILE_H

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