From 8700ca2d90afa8e20d996eb133ce99955ffb50f2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jure=20=C5=A0orn?= Date: Thu, 22 Aug 2019 21:12:57 +0200 Subject: [PATCH] Audio --- README.md | 34 ++++++++++++++++++++++++++++------ index.html | 32 ++++++++++++++++++++++++++------ 2 files changed, 54 insertions(+), 12 deletions(-) diff --git a/README.md b/README.md index 92b5f47..0ae7728 100644 --- a/README.md +++ b/README.md @@ -2651,15 +2651,38 @@ import wave, struct ```python = wave.open('', 'rb') +framerate = .getframerate() # Number of frames per second. +nchannels = .getnchannels() # Number of samples per frame. +sampwidth = .getsampwidth() # Sample size in bytes. +nframes = .getnframes() # Number of frames. = .readframes(nframes) ``` ```python = wave.open('', 'wb') -.writeframes() -.setnchannels() # Number of samples per frame. -.setsampwidth() # Sample size in bytes. -.setframerate() # Frames per second. +.setframerate() # 44100 for CD, 48000 for video. +.setnchannels() # 1 for mono, 2 for stereo. +.setsampwidth() # 2 for CD quality sound. +.writeframes() +``` + +* **Bytes object contains a seqence of frames, each consisting of one or more samples.** +* **Each sample consists of one or more bytes that, when converted to an integer, indicate the displacement of a speaker membrane at a given moment.** +* **If sample width is one, then the integer is interpreted as unsigned.** +* **For all other sample sizes the integer is interpreted as signed with little-endian byte order.** +* **In stereo signal first sample of a frame belongs to the left channel.** + + +### Sample Values +```text +┏━━━━━━━━━━━┯━━━━━━━━━━━━━┯━━━━━━┯━━━━━━━━━━━━━┓ +┃ sampwidth │ min │ zero │ max ┃ +┠───────────┼─────────────┼──────┼─────────────┨ +┃ 1 │ 0 │ 128 │ 255 ┃ +┃ 2 │ -32768 │ 0 │ 32767 ┃ +┃ 3 │ -8388608 │ 0 │ 8388607 ┃ +┃ 4 │ -2147483648 │ 0 │ 2147483647 ┃ +┗━━━━━━━━━━━┷━━━━━━━━━━━━━┷━━━━━━┷━━━━━━━━━━━━━┛ ``` ### Read Float Frames from WAV File @@ -2701,8 +2724,7 @@ write_to_wav_file('test.wav', frames_f) #### Adds noise to a mono WAV file: ```python from random import random -add_noise = lambda value: max(-1, min(1, value + (random()-0.5)*0.03)) -frames_f = (add_noise(a) for a in read_wav_file('test.wav')) +frames_f = (a + (random()-0.5) * 0.03 for a in read_wav_file('test.wav')) write_to_wav_file('test.wav', frames_f) ``` diff --git a/index.html b/index.html index 07b12c6..c48c8ad 100644 --- a/index.html +++ b/index.html @@ -2254,14 +2254,35 @@ imageio.mimsave('test.gif', frames, duration= 
<Wave_read>  = wave.open('<path>', 'rb')
+framerate    = <Wave_read>.getframerate()       # Number of frames per second.
+nchannels    = <Wave_read>.getnchannels()       # Number of samples per frame.
+sampwidth    = <Wave_read>.getsampwidth()       # Sample size in bytes.
+nframes      = <Wave_read>.getnframes()         # Number of frames.
 <bytes>      = <Wave_read>.readframes(nframes)
 
<Wave_write> = wave.open('<path>', 'wb')
-<Wave_write>.writeframes(<bytes>)
-<Wave_write>.setnchannels(<int>)                # Number of samples per frame.
-<Wave_write>.setsampwidth(<int>)                # Sample size in bytes.
-<Wave_write>.setframerate(<int>)                # Frames per second.
+<Wave_write>.setframerate(<int>)                # 44100 for CD, 48000 for video.
+<Wave_write>.setnchannels(<int>)                # 1 for mono, 2 for stereo.
+<Wave_write>.setsampwidth(<int>)                # 2 for CD quality sound.
+<Wave_write>.writeframes(<bytes>)
+
    +
  • Bytes object contains a seqence of frames, each consisting of one or more samples.
    • +
  • Each sample consists of one or more bytes that, when converted to an integer, indicate the displacement of a speaker membrane at a given moment.
    • +
  • If sample width is one, then the integer is interpreted as unsigned.
    • +
  • For all other sample sizes the integer is interpreted as signed with little-endian byte order.
    • +
  • In stereo signal first sample of a frame belongs to the left channel.
    • +
+

Sample Values

┏━━━━━━━━━━━┯━━━━━━━━━━━━━┯━━━━━━┯━━━━━━━━━━━━━┓
+┃ sampwidth │     min     │ zero │     max     ┃
+┠───────────┼─────────────┼──────┼─────────────┨
+┃     1     │           0 │  128 │         255 ┃
+┃     2     │      -32768 │    0 │       32767 ┃
+┃     3     │    -8388608 │    0 │     8388607 ┃
+┃     4     │ -2147483648 │    0 │  2147483647 ┃
+┗━━━━━━━━━━━┷━━━━━━━━━━━━━┷━━━━━━┷━━━━━━━━━━━━━┛
+
+

Read Float Frames from WAV File

def read_wav_file(filename):
     def get_int(a_bytes):
         an_int = int.from_bytes(a_bytes, 'little', signed=width!=1)
@@ -2293,8 +2314,7 @@ write_to_wav_file('test.wav', frames_f)
 
 
 
Adds noise to a mono WAV file:
from random import random
-add_noise = lambda value: max(-1, min(1, value + (random()-0.5)*0.03))
-frames_f  = (add_noise(a) for a in read_wav_file('test.wav'))
+frames_f = (a + (random()-0.5) * 0.03 for a in read_wav_file('test.wav'))
 write_to_wav_file('test.wav', frames_f)