Workshop

Содержание и основные понятия

By table of contents
Alterna · Chapter 21.3
Workshop
The task manager for sound and video coding.
Progress of the Workshop
0 XP
Base formulas (chapter 9.4 - Discretion)
These formulas are the basis for all the tasks of Chapter 21.
Chapter 9.4
For a detailed review.
V = R × t × i × K / 8   (объём аудиофайла в байтах, R — частота, t — время, i — разрядность, K — каналы)
V = X × Y × i × fps × t / 8   (объём видео в байтах, X,Y — разрешение, i — глубина, fps — frame rate)
Tasks 7 and 9
OGE No. 7
- volume of audio file: measure by frequency, depth, channel and duration.
OGE No. 9
- Video coding: volume of video files, time, permission.
EGE · Tasks 7 and 9
EEG No. 7
– complex sound problems: determining frequency, discharge, bitrate time.
EEG No. 9
- video: volume, compression, codecs, channel capacity.
Audio - OGE No. 7
Task 1
Determine the amount of stereoaudiophile (in MB) for 1 minute at a discrete frequency of 44,100 Hz and 16 bit depth.
Decision:
V = 44100 x 60 x 16 x 2 / 8 = 84,672,000 byte = 10.6 MB. Channels = 2 (stereo).
Task 2
The Monoaudio recording has a duration of 3 minutes, a depth of 8 bits, a discrete frequency of 22,050 Hz. Determine the volume of the file in the KB.
Decision:
V = 22050 x 180 x 8 x 1 / 8 = 3,969,000 bytes = 3,878.9 KB ~ 3,789 KB Mono - K=1.
Task 3
The audio file is 256 kbps. The length is four minutes.
Decision:
256 kbps × 240 s = 61,440,000 bits = 7,680,000 byte = 7.3 MB. (V = bitrate × time / 8 / 1024 / 1024)
Task 4
WAV format file: frequency 48,000 Hz, 24 bits, stereo. Ten seconds long. What volume is in MB (accuracy 0.1)?
Decision:
V = 48,000 x 10 x 24 x 2 / 8 = 28 800 000 byte = 27.4 MB.
Video - OGE No. 9
Task 1
Video file: resolution 1280×720, 24 bits per pixel, 25 fps, 2 minute duration.
Decision:
V = 1280x720x24 x 25 x 120 / 8 = 6,912,000,000 byte = 6,596.4 MB ~ 6.6 GB. A huge volume — so the video is always squeezed!
Task 2
Resolution 1920×1080, 30 fps, 3 minutes, depth 24 bits, no compression?
Decision:
1920×1080×30×180×24/8 = 33,587,712,000 bytes ~ 33.6 HB. The pressure H.264 will be reduced to 1-3 GB.
Task 3
The video stream is 8 Mbit/s. The file was passed on for 10 minutes. What's the volume of the file in the GB?
Decision:
8 Mbit/s x 600 s = 4,800,000,000 bits = 600,000,000 byte = 0.9 GB (600 MB). This is a typical bitrate for 1080p YouTube.
EGE No. 7 and No. 9 - Complex tasks
EGE-7 Objective 1
WAV audio: 5 minutes, stereo, 44,100 Hz, 16 bits. This file has been squeezed in MP3 with a 128 kbps bitrate. What is the ratio of uncompressed volume to compressed (how many times)?
Decision:
Uncompressed: 44100 x 300x16x2/8 = 52,920,000 bytes ~ 50.5 MB: 128000 x 300/8 = 4,800,000 bytes x 4.6 MB.
EGE-7 Objective 2
The stream audio bit 128 kbps. The user listened to music for three hours. How much data (in MB) was transmitted?
Decision:
128 kbps x 10800 s = 1,382,400 000 bits = 172,800,000 bytes ~ 164.8 MB.
EGE-9 Task 1
The professional camera writes 4K (3840x2160), 30 fps, 10 bits, stereo audio 48 kHz/24 bits. What volume in 1 minute (no compression)?
Decision:
Video: 3840 x 2160 x 10 x 30 x 60/8 = 14,945,280,000 bytes. Audio: 48000 x 60 x 24 x 2/8 = 17,280,000 Bytes.
EGE-9 Task 2
Channel 100 Mbit/s. Can we broadcast the 1920x1080, 60 fps, 24 bits without buffering?
Decision:
You need: 1920 x 1080 x 24x60 = 298,598,400 bits/s E 299 Mbit/s. Channel 100 Mbps is not sufficient. Compression codes are needed (H.264 ~10 Mbits/s for 1080p).
EEG No. 10 - Data transmission speed
EEG No. 10
The data transmission rate on the 100 Mbit/s channel. A 1.5 GB file was passed on for 2 minutes. Is the capacity sufficient? Enter "yes" or "no".
Decision:
1.5 GB = 1.5 x 1024 = 1536 MB = 12,288 Mbit. Time = 2 min = 120 s. Canal capacity: 100 Mbit/s x 120 s = 12,000 Mbits. File = 12,288 Mbit > 12,000 Mbits is not sufficient.
EEG No. 10
A video of 60 seconds, resolution 1920×1080, 30 fps, 24 bits per pixel.
Decision:
V = 1920×1080×24×30 / 8 = 89 127,552,000 bits = 11,140,944,000 bytes ~ 10.4 GB.
EEG No. 10
The channel transmits 50 Mbits/s. The 100 MB file is transferred in how many seconds?
Decision:
100 MB = 100 x 8 = 800 Mbit. Time = 800 / 50 = 16 s.
Audio file calculator
V = R × t × i × K / 8
Discretion frequency (Hz)
Detachment (beat)
Channels
Duration
min
Sec
Video calculator
V = X × Y × i × fps × t / 8
Authorization
Color depth (beat)
Frame rate (fps)
Duration
min
Compression ratio (typically 50-500 for H.264/H.265)
Council
All the tasks are in two formulas:
V = R × t × i × K / 8
(audio) and
V = X × Y × i × fps × t / 8
(Video) Practice to set up numbers and check the dimension.
Chapter 9.4
.