Note on Uniform Quantization in Spatial Domain
One of the method of quantization is to quantize pixels in spatial domain (i.e. without transforming). For example, HEVC supports so called “transform skipping mode“, i.e. the transform can be skipped fully quantization is performed in spatial domain. If quantization is uniform with a step size b, the quantization error for a digital image may […]
Sumatra PDF Reader Takes 10x less Memory than Adobe Acrobat Reader
Internet users believe that Adobe Acrobat PDF Reader is the only program capable of reading PDF files. That’s a myth. For example, Sumatra PDF (download) reads pdf-files and takes 10x less memory than Adobe Acrobat Reader for same file (15.7MB versus 170.1MB) Slava23+ years’ programming and theoretical experience in the computer science fields […]
Why at the start of low-latency media session (e.g. Cloud Gaming session) audio tends to be ahead of video?
Let’s assume the first audio and video frames are rendered (or created) simultaneously. Then an audio encoder would take less time than an video encoder (video encoding is much more complex than audio one). Consequently, audio encoded frame is expected to be ready for transmission earlier than corresponding video frame. Moreover, audio frame size is […]
What’s the probability for two randomly selected integers to be relatively prime?
What’s the probability for two randomly selected integers to be relatively prime (coprime)? The answer is 6/π2 ≈ 0.6, a boring proof you can find here Practically speaking, if you choose randomly two integers then the probability that these integers are relatively prime is about 60%. Slava23+ years’ programming and theoretical experience in the computer […]
MP4Box Tool
Content Getting MP4Box Binaries Commands Getting General Info on mp4-file Encapsulation h264 elementary stream into mp4 format Concatenation of mp4 files into new mp4-file In-Place Removal Hint Tracks MPEG-DASH Segmentation How Add Copyright In-Place Add Language Tag Extract Elementary Stream Getting MP4Box Binaries MP4Box tool is an […]
VLC Media Player from Command Prompt (Alternative of ffmpeg)
You can run VLC from the command prompt, in some extent VLC is an alternative of a part of ffmpeg faculties. Upon installing VLC Media Player (by default vlc.exe is located in C:\Program Files\VideoLAN\VLC), i recommend adding “C:\Program Files\VideoLAN\VLC” to the path environment variable to run vlc.exe from any place. Running VLC in Quiet […]
R-D Cost Function and Coding Decisions
The R-D cost function (or RDO) where ‘b’ is the block under consideration, ‘d’ is the decision to be made, ‘C’ is the cost to minimize, ‘D’ is the distortion if the decision ‘d’ is taken, ‘R’ is the corresponding change in bitrate, while λ is an application-dependent Lagrangian weighting factor expressing how much bits […]
Best Lossless Compression Rate of English Text on Average
Number of English letters (incl. capital ones), punctuation symbols is less 128, hence you need 7-bits per English text symbol. The calculated entropy of the English language is 2.62 bits per letter on average. According to Shannon’s Source Coding Theorem the best compression ratio you can obtain without distorting the original text (i.e. by lossless […]
Exercise in Combinatorics for Team Leader
Let’s imagine you are a team leader (for me it’s really difficult, i’ve never been a manager). Your team consists of 5 different engineers (if you are a good leader, you must see that the engineers are mutually different, otherwise you ought to resign). You just have obtained 10 different tasks to accomplish in a […]
The Cocktail Party Paradox
In Theory of Graphs there is the following theorem: A graph with more than two vertexes has at least two vertexes with the same degree. Proof Let’s consider a party where each guest is a vertex. Two vertexes (or guests) are connected if they are acquaintances. The theorem asserts that in each party above […]