Autosave: 2025-01-02 17:31:19

neuron/eae3c214-e7de-4efe-ad0c-420770267aa7/738d0481_sound_recording_as_wave_phenomena.md

@@ -0,0 +1,30 @@
+---
+tags: [sound, analogue, physics]
+created: Thursday, January 02, 2025
+---
+
+# 738d0481_sound_recording_as_wave_phenomena
+
+When the microphone captures alterations in sound pressure and converts it into
+an electric signal, we have a scenario where the same formal or mathematical
+relationships in the phenomena (amplitude, frequency, wavelength) are being
+expressed in two different modes of matter.
+
+This is quite profound especially as the resulting electrical waveform is
+_identical_ to the original sound wave. This is effectively what enables
+accurate playback. We can convert between the two mediums seamlessly providing
+we captured their initial expression accurately.
+
+It's like two different people doing the same dance:
+
+In air: p
+
+- The dancers are air molecules
+- They move back and forth in waves of compression and rarefaction
+- Their "dance pattern" is the sound wave
+
+In wire:
+
+- The dancers are electrons
+- They move back and forth creating waves of voltage
+- They perform the exact same "dance pattern"

neuron/eae3c214-e7de-4efe-ad0c-420770267aa7/Binary_encoding_of_sound.md

@@ -11,7 +11,7 @@ To record sound, we convert the change in air pressure into an electrical signal
 by means of a microphone. Effectively, the same natural waveform is converted
 from one medium (the vibration of air molecules) into another medium (electrical
 charge in a field) whilst retaining the same morphology. See
-[Recording and processing sound]().
+[Recording and playback of sound](Recording_and_playback_of_sound.md).
 
 The resulting electrical signal is analogue: it has a continuous and variable
 frequency and amplitude and thus can have any value at any given moment.
@@ -31,7 +31,7 @@ used to record the measurement is the **bit-depth**. Each measurement is rounded
 to the nearest available digital value. CDs have a depth of 16 bits. Thus each
 measurement can be one of $16^2 = 65,536$ possible values.
 
-With sampling at a given bit-depth established, the **bitrate** can be derived.
+With sampling at a given bit-depth established, the **bit-rate** can be derived.
 
 This is the sampling rate (number of measurements per second) divided by the
 number of bits per sample (bit-depth), multiplied by the number of channels.
@@ -44,7 +44,7 @@ $$
 
 Or 1.4 Mb/s
 
-> Even with a high bitrate (as with CDs) the process still necessarily involves
+> Even with a high bit-rate (as with CDs) the process still necessarily involves
 > a loss of information when converting sound from analogue to digital. However,
 > given a high enough value for the sampling rate and bit-depth, the differences
 > are imperceptible to the human ear.

neuron/eae3c214-e7de-4efe-ad0c-420770267aa7/Recording_and_playback_of_sound.md

@@ -0,0 +1,77 @@
+---
+tags: [sound, analogue, physics]
+created: Thursday, January 02, 2025
+---
+
+# Recording and playback of sound
+
+## Analogue
+
+### Recording
+
+The microphone converts sound waves into a continuous electrical signal.
+
+The signal drives the recording equipment.
+
+In the case of a vinyl recording: the signal drives a cutting head that carves a
+groove into the master disk.
+
+In the case of a tape recording: the signal drives electro-magnets that align
+magnetic particles on the tape.
+
+In both cases, **the recording medium physically mirrors the shape of the sound
+wave**.
+
+### Playback
+
+In the case of vinyl, the needle follows the groove, moving up and down to
+recreate the electrical signal.
+
+In the case of tape, the magnetic patterns induce electrical current in the
+playback head.
+
+In each case, the signal is transferred directly to amplifiers and speakers.
+
+## Digital
+
+### Recording
+
+Mostly covered in [Binary encoding of sound](Binary_encoding_of_sound.md).
+
+An important point to note is that the binary encoding that results from the
+sampling is lasered into the CD as microscopic impressions and depressions (pits
+and lands)
+
+### Playback
+
+A laser in the reader reads the pits and lands and converts them back to binary
+numbers. A DAC then converts the numbers back into a continuous electrical
+signal which is then channelled to the amplifiers and speakers.
+
+## From recording to production of storage medium
+
+With analogue production recordings would be made onto tape. Multiple takes are
+recorded, mixed and edited. This results in a master tape which is the final
+version of the recorded sound.
+
+This then goes to a mastering engineer for mastering which creates the master
+mix. This consists in optimising the sound for the given format (vinyl or tape).
+Also includes adjusting frequencies, levels and adding spacing between tracks.
+
+Then the master disk enters production. A recording is made onto lacquer disc
+which is very delicate. Often known as the "acetate". This is coated in metal to
+create the "metal master", after various processes this goes to the pressing
+plant who press vinyl copies from it.
+
+Each stage can introduce subtle variations, especially with re-pressings.
+Re-pressings require new stampers from the master which may have degraded in the
+interim. Plus there is a limit to the amount of pressings possible with a given
+stamper. The earlier pressings are therefore less degraded making them more
+valuable.
+
+## Degradation
+
+With tape and vinyl each playback wears the medium, degrading the quality of the
+captured signal. With CDs, there is no degradation and every copy is a perfect
+copy of the original signal. However this capture, necessarily contains less
+information than the analogue version because of sampling.

neuron/eae3c214-e7de-4efe-ad0c-420770267aa7/index.md

@@ -13,14 +13,16 @@ computer science.
 
 ![not-by-ai-badge](static/not-by-ai-alternative--light.svg)
  
-**Build ID:** cad1eefd-a429-432d-ab3c-0841f6b6f238
+**Build ID:** eae3c214-e7de-4efe-ad0c-420770267aa7
 
-**Published:** Wed 01 Jan 2025 16:46:38
+**Published:** Thu 02 Jan 2025 17:31:18
 
 ### Recent edits 
 
-- [[Audio_file_formats]] 
+- [[738d0481_sound_recording_as_wave_phenomena]] 
 - [[Binary_encoding_of_sound]] 
+- [[Recording_and_playback_of_sound]] 
+- [[Audio_file_formats]] 
 - [[Type_hinting]] 
 - [[Working_with_JSON_in_Python]] 
 - [[SQLite]] 
@@ -29,11 +31,9 @@ computer science.
 - [[Dynamic_and_static_websites]] 
 - [[User_agent]] 
 - [[Architecture_of_the_World_Wide_Web]] 
-- [[Network_packet_analysis_tools]] 
-- [[What_can_the_ISP_see]] 
 
 
-### All notes (511) 
+### All notes (513) 
 
 - [[0716531c_rewilding_the_internet]] 
 - [[241fe1a3_the_Web_versus_modem_BBSs]] 
@@ -42,6 +42,7 @@ computer science.
 - [[4a3dc316_key_figures_ARPANET]] 
 - [[4da22434_from_ARPANET_to_Internet]] 
 - [[653c0b1d_host_protocols_of_ARPANET]] 
+- [[738d0481_sound_recording_as_wave_phenomena]] 
 - [[82f9c228_dissolution_of_ARPANET]] 
 - [[861cc26e_ARPA_origins]] 
 - [[API_Gateway]] 
@@ -395,6 +396,7 @@ computer science.
 - [[Read_command__in_Bash]] 
 - [[Reading_files_in_Python]] 
 - [[Reciprocals]] 
+- [[Recording_and_playback_of_sound]] 
 - [[Recursion]] 
 - [[Redirect_to_dev_null]] 
 - [[Redirection_in_Bash]] 

zk/738d0481_sound_recording_as_wave_phenomena.md

@@ -0,0 +1,30 @@
+---
+tags: [sound, analogue, physics]
+created: Thursday, January 02, 2025
+---
+
+# 738d0481_sound_recording_as_wave_phenomena
+
+When the microphone captures alterations in sound pressure and converts it into
+an electric signal, we have a scenario where the same formal or mathematical
+relationships in the phenomena (amplitude, frequency, wavelength) are being
+expressed in two different modes of matter.
+
+This is quite profound especially as the resulting electrical waveform is
+_identical_ to the original sound wave. This is effectively what enables
+accurate playback. We can convert between the two mediums seamlessly providing
+we captured their initial expression accurately.
+
+It's like two different people doing the same dance:
+
+In air: p
+
+- The dancers are air molecules
+- They move back and forth in waves of compression and rarefaction
+- Their "dance pattern" is the sound wave
+
+In wire:
+
+- The dancers are electrons
+- They move back and forth creating waves of voltage
+- They perform the exact same "dance pattern"

zk/Binary_encoding_of_sound.md

@@ -11,7 +11,7 @@ To record sound, we convert the change in air pressure into an electrical signal
 by means of a microphone. Effectively, the same natural waveform is converted
 from one medium (the vibration of air molecules) into another medium (electrical
 charge in a field) whilst retaining the same morphology. See
-[Recording and processing sound]().
+[Recording and playback of sound](Recording_and_playback_of_sound.md).
 
 The resulting electrical signal is analogue: it has a continuous and variable
 frequency and amplitude and thus can have any value at any given moment.
@@ -31,7 +31,7 @@ used to record the measurement is the **bit-depth**. Each measurement is rounded
 to the nearest available digital value. CDs have a depth of 16 bits. Thus each
 measurement can be one of $16^2 = 65,536$ possible values.
 
-With sampling at a given bit-depth established, the **bitrate** can be derived.
+With sampling at a given bit-depth established, the **bit-rate** can be derived.
 
 This is the sampling rate (number of measurements per second) divided by the
 number of bits per sample (bit-depth), multiplied by the number of channels.
@@ -44,7 +44,7 @@ $$
 
 Or 1.4 Mb/s
 
-> Even with a high bitrate (as with CDs) the process still necessarily involves
+> Even with a high bit-rate (as with CDs) the process still necessarily involves
 > a loss of information when converting sound from analogue to digital. However,
 > given a high enough value for the sampling rate and bit-depth, the differences
 > are imperceptible to the human ear.

zk/Recording_and_playback_of_sound.md

@@ -0,0 +1,77 @@
+---
+tags: [sound, analogue, physics]
+created: Thursday, January 02, 2025
+---
+
+# Recording and playback of sound
+
+## Analogue
+
+### Recording
+
+The microphone converts sound waves into a continuous electrical signal.
+
+The signal drives the recording equipment.
+
+In the case of a vinyl recording: the signal drives a cutting head that carves a
+groove into the master disk.
+
+In the case of a tape recording: the signal drives electro-magnets that align
+magnetic particles on the tape.
+
+In both cases, **the recording medium physically mirrors the shape of the sound
+wave**.
+
+### Playback
+
+In the case of vinyl, the needle follows the groove, moving up and down to
+recreate the electrical signal.
+
+In the case of tape, the magnetic patterns induce electrical current in the
+playback head.
+
+In each case, the signal is transferred directly to amplifiers and speakers.
+
+## Digital
+
+### Recording
+
+Mostly covered in [Binary encoding of sound](Binary_encoding_of_sound.md).
+
+An important point to note is that the binary encoding that results from the
+sampling is lasered into the CD as microscopic impressions and depressions (pits
+and lands)
+
+### Playback
+
+A laser in the reader reads the pits and lands and converts them back to binary
+numbers. A DAC then converts the numbers back into a continuous electrical
+signal which is then channelled to the amplifiers and speakers.
+
+## From recording to production of storage medium
+
+With analogue production recordings would be made onto tape. Multiple takes are
+recorded, mixed and edited. This results in a master tape which is the final
+version of the recorded sound.
+
+This then goes to a mastering engineer for mastering which creates the master
+mix. This consists in optimising the sound for the given format (vinyl or tape).
+Also includes adjusting frequencies, levels and adding spacing between tracks.
+
+Then the master disk enters production. A recording is made onto lacquer disc
+which is very delicate. Often known as the "acetate". This is coated in metal to
+create the "metal master", after various processes this goes to the pressing
+plant who press vinyl copies from it.
+
+Each stage can introduce subtle variations, especially with re-pressings.
+Re-pressings require new stampers from the master which may have degraded in the
+interim. Plus there is a limit to the amount of pressings possible with a given
+stamper. The earlier pressings are therefore less degraded making them more
+valuable.
+
+## Degradation
+
+With tape and vinyl each playback wears the medium, degrading the quality of the
+captured signal. With CDs, there is no degradation and every copy is a perfect
+copy of the original signal. However this capture, necessarily contains less
+information than the analogue version because of sampling.