Flashcards
Computer Management (COMP) 1st Semester Final Exam
Cards in this deck (66)
- 1What kind of Instructions could we want to send via MIDI Code? (4)- Notes
- Pitch Bend
- Volume
- Sustain Pedal - 2What do Channel Voice Messages do? What 7 channels are there?Send Musical Performance Data. Channel Specific.
1. Note OFF
2. Note ON
3. Pitch Bend
4. Control Change (CC)
5. Program Change
6. Polyphonic Key Pressure (individual sensors)
7. Channel Pressure (Single Sensor) - 3What's "aftertouch"?Pressure on a key after the initial strike that causes patch dependent effects.
- 4What's the structure of a Channel Voice Message Structure? How many bits?Consists of 3 bytes (24-bits)
1 - Status Byte
(Which message and MIDI Channel)
2 - Data Bytes
(Message specific Details)
Ex. "Note ON" Message
- Status Byte - CH1 and "Note ON" message
- Data Bytes - Note = C4 and Note Velocity - 5What does message resolution depend on?The number of bits used (typically 128: 0-127)
- 6How can you tell if in the MIDI Code you're looking at a Status Byte or a Data Byte?- If the MSB is a 1 = Status Byte
- If the MSB is a 0 = Data Byte - 7What are the parameters of a Status Byte?after the MSB (1)..
The next 3 bits indicate what message is being sent
The last 4 bits indicate the MIDI Channel (4-bit = 16 possible values) - 8What are the parameters of Data Byte's 1 and 2?After the MSB (0)..
1: - Every bit except the MSB indicates the MIDI Note #
- 7-bit = 128 Possible Values (0-127)
2: - Every bit except the MSB indicates Velocity
- 11111110 = Max Velocity
- 7-bit = 128 Possible Values (0-127) - 9How does Pitch Bend utilize the Data Bytes?Pitch Bend requires a much higher resolution..so it combines both data bytes from 7-bit to 14-bit (16,384 Values)
- 10What does a Control Change Message do?Typically not note related..
- It can be a musical gesture (such as a sustain pedal)
- Devices aren't always capable of responding to CC Messages - 11What are CC Numbers for.. Modulation? Volume? Panning? Resonance? Reverb?Modulation - 1
Volume - 7
Panning - 10
Resonance - 71
Reverb - 91 - 12What do the Status and both Data bytes control in a CC Message?Status Byte: Channel and Message Control Change
Data Byte 1: Which controller (ex. Reverb)
Data Byte 2: How much? (ex. Max) - 13What are "System Messages"?Messages that relate to a device's overall "system". Not channel specific
- 14What are 'System Exclusive or SysEx' Messages?Messages that ARE system exclusive. Often specific to manufacturers.
ex. MIDI Show Control - Lighting Control
ex. MIDI Data Dumps - Transfer of data to and from a device like patch info, settings, etc. - 15What are System Common & Real Time Messages?Control sequencer/transport functions
- MIDI Start and Stop
- MIDI Clock
- MIDI Time Code (MTC) - 16What are the 2 building blocks of Processing? What do they do?Transistors: Used for Amplification and Switching. Basis of Logic circuits
Integrated Circuit: Many transistors in a single package (Ex. 24-bit ADC - Apollo, Chipset, CPU) - 17What are variations of a basic CPU and what are their basic functions?Multi Processor: 2+ CPU's on one Motherboard (MOBO)
Multi Core: Multiple Cores in an IC - 18What is Moore's Law?"Computing Power (#of Transistors) doubles every 18-24 months."
- 19What is the purpose of The Logic Board (AKA Motherboard)?It's a circuit board that connects all different computer components, whether they're onboard, internally, or externally connected.
- 20How does The Logic Board (Motherboard) make connections with each component?Via many different buses
- 21Why would a CPU connect directly with specific computer components? What components would those be?The CPU directly connects to components with the highest bandwidth
- System Memory
- Video/GPU
- Chipset - 22What is a Chipset?an IC that acts as a crossroad controller for most components. Dictates the Motherboard's capabilities.
- 23What is PCIe (PCI Express)?A standard that defines..
- A serial bus
- Expansion slots
- Expansion cards - 24What's the most recent spec of "PCIe"?PCIe v3
- 25Why would we want to use PCIe? What is the range of lanes used by PCIe?It's generally the highest bandwidth method to hook something up to a computer.
Lanes range from 1x - 16x
Thunderbolt is based on PCIe - 26What's a GPU? What purpose does it serve?"Graphics Processing Unit"
Processor designed specifically for graphics
- Frees up CPU
- Onboard or integrated into the CPU, or Expansion Card (discrete) - 27What's a DSP? What purpose does it serve?"Digital Signal Processor"
Specialized for working with "signals"
ex. Imaging, Audio, etc.
Dedicated performance, better latency
though...
Not as powerful as a CPU, requires dedicated hardware, not as widely developed. - 28How do DAW's and Interfaces communicate with each other?Via Drivers
- 29Drivers don't talk directly to DAW's.. Where can a driver typically be found in a typical computer setup? Where else could we find them?Typical Setup: Integrated with the OS
- Hardware (Processor, memory, i/o devices etc.)
- Operating System (Kernal, GUI, Drivers)
- Programs (User Application)
Can also find them somewhere between the OS and Hardware - 30What does API stand for? What are the API's for OSX and Windows?Application Programming Interface
OSX: CoreAudio
Windows: ASIO (Audio Streaming I/O) - 31ASIO is a 3rd party windows API.. Who makes it?Steinberg
- 32What does Class Compliant mean?Drivers are included in the OS
- 33What are some causes of Latency?Converters
Processing
Audio Buffers (API) - 34What does an Audio Buffer do? What's it measured in? Larger Buffer = What?It temporarily holds data in RAM to compensate for different bus speeds and lower the strain on the CPU
- Measured in Samples
- A Larger buffer = More Latency - 35When would we want a small audio Buffer vs. a Large Buffer?Smaller:
- For software monitoring
- Playing a soft synth w/a controller
BUT
- Risk of glitches
Larger:
- Session playback w/ many effects
BUT
Delay during recording - 36What is Hardware Monitoring accomplishing?The input signal is mirrored to the output for monitoring with next to no latency.
AKA. "Zero" or "Low Latency" Monitoring - 37What does a Direct Monitoring Switch do? Why does it require the host track to be muted?Mirrors Hardware input to output to enable Hardware Monitoring.
Must be muted to prevent latency issues with hearing the track playback against a near zero latency monitoring method. - 38Why would we want to reduce latency in Software Monitoring?Better Performing:
- Buses
- Drivers
- Programs
- Lower CPU Load - 39What is Linear PCM?Linear Pulse Code Modulation
- Modulated Binary output from the ADC
- Binary 1's represented by higher voltage pulses
- Often referred to whenever we have converted to digital audio - 40What is Quantization Error?The difference between analogue signal amplitude and the quantized digital value
Never more than 1/2 LSB - 41Where does Quantization occur?- Low amplitude signals as signal correlated Distortion
- In higher amplitude signals as low level Random Noise
Quantization Error isn't actually always noticed, even if it's there. - 42In terms of QE and Low Amplitude Signals.. What happens when you digitize a signal at half amplitude?Reduces the number of bits used (MSB) by 1. Each additional halving reduces by another MSB
- 43What's happening when Digital Clipping Distortion occurs?Input voltage exceeds the highest available quantization level and just records continuous "1's"
- 44What is the 1 reason Quantization Error isn't such a big deal?Dither!
Low level noise added to signal to raise the value of the lowest bits.
Basically a filler that boosts the initial signal you "actually" want to listen to - 45What's happening when "Truncation" occurs?2 Binary values are summed, and the result is ex. a 5-bit rather than 2 initial 4-bit values. That can't happen, so the LSB is cutoff, bringing the 5-bit word down to 4-bit.
This essentially is the cause behind QE in processing (rounding off error). - 46What is Floating Point?"Floating Point" is the binary equivalent to Decimal's "Scientific Notation"
- 47What does recording at 24-bit allow us? In terms of QE and whatnot..Greater flexibility in setting levels because of the vastly lower QE. Can set levels more conservatively
- 48What is "Aliasing"?Digitizing frequencies higher than the Nyquist Frequency creating unwanted "Alias Tones" in the audio signal
Ex. Recording at 44.1kHz
Nyquist = 22,050Hz
Input of 32,000 would violate the NF so the Alias would be 44.1kHz - 32kHz = 12,100Hz = Alias Freq. - 49How can Aliasing be prevented?An Anti Aliasing Filter can be used as an analog low-pass filter to prevent frequencies higher than the Nyquist Freq.
- 50What are 3 Filter Characteristics?Passband - Freq. that pass through the filter
Filter Start - Progressively higher freq. begin to diminish in amplitude
Max Attenuation - Freq. above this point are removed from the audio signal - 51What is Error Correction?Like the title suggests..
It's a procedure used to detect and potentially fix incorrectly transmitted or stored data
- Code is added to the binary data stream - 52Anti-Imagine Filter performs what task?Acts as an LPF that removes the high frequency components created by the DAC/S&H Circuit
- Resulting waveform ends up kinda looking like a staircase - 53What is Upsampling?Increasing the apparent sample frequency
ex. 48kHz - 96kHz - 54What's Inter-Sample Peaking? (AKA "True Peaks")Potential Clipping due to amplitude changes during upsampling.
- 55What are 2 ways we can transmit audio?As Files
Over Digital Cabling - 56Digital Audio Transmission Specs cover what?Cabling
Data Protocol
Send/Receive Hardware - 57What are some 2-channel Transmission formats?- AES 3 (XLR)
- S/PDIF (RCA and Toslink)
- AES 42 - 58What are some multi-channel formats?- TDIF (DB-25)
- ADAT Lightpipe (Toslink)
- MADI (BNC) - 59What are 3 methods to sync Clock Speeds?Method 1: Internal Clocking
- Each digital clock is set independentaly
Method 2: Clocking to incoming Audio Signal
- The sending device embeds it's clock info into it's audio signal and then the receiving end sets it's own clock according to it
Method 3: External Clock
- Both devices reference and External Clock signal - 60Can LPCM carry a clock signal?Nope! They require different modulation schemes
- 61What is BMC Modulation?"Biphase Mark Code"
Audio Transmission Modulation scheme that sends..
- Digital Audio Transmission
- Clocking Information - 62Where is BMC Encoding done in an ADC? DAC?ADC: Record Modulation storage
DAC: Reproduction DeModulation - 63What is a Phase Locked Loop? (PLL)Device that analyses phase and timing of incoming signal to recover the clock frequency
- 64What is Jitter and how can it be handled?Time based errors in an audio signal that can lead to noise and distortion in the reconstructed analogue signal
Can be handled by using..
- Better clocks & PLL's
- Better / Shorter Cables
- A Word Clock! - 65What's a Word Clock?A seperate reference clock signal, transmitted to digital devices for clock sync.
Uses BNC Cables - 66What is a Master Clock?A Standalone device that generates Word Clock
Other Devices are set to reference this. The Master sends all Word Clock to all devices in digital systems
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- Computer Management (COMP) Flashcards on Computer Management (COMP) 1st Semester Final Exam, created by Jeffrey Bulmer on 17/12/2017.
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