The website "FFmpeg by Example" provides a practical, example-driven guide to utilizing the FFmpeg command-line tool for various multimedia manipulation tasks. It eschews extensive theoretical explanations in favor of presenting concrete, real-world use cases and the corresponding FFmpeg commands to achieve them. The site is structured around a collection of specific examples, each demonstrating a particular FFmpeg operation. These examples cover a broad range of functionalities, including but not limited to:
Basic manipulations: These cover fundamental operations like converting between different multimedia formats (e.g., MP4 to WebM), changing the resolution of a video, extracting audio from a video file, and creating animated GIFs from video segments. The examples demonstrate the precise command-line syntax required for each task, often highlighting specific FFmpeg options and their effects.
Audio processing: The examples delve into audio-specific manipulations, such as normalizing audio levels, converting between audio formats (e.g., WAV to MP3), mixing multiple audio tracks, and applying audio filters like fade-in and fade-out effects. The provided commands clearly illustrate how to control audio parameters and apply various audio processing techniques using FFmpeg.
Video editing: The site explores more advanced video editing techniques using FFmpeg. This encompasses tasks such as concatenating video clips, adding watermarks or overlays to videos, creating slideshows from images, and applying complex video filters for effects like blurring or sharpening. The examples showcase the flexibility of FFmpeg for performing non-linear video editing operations directly from the command line.
Streaming and broadcasting: Examples related to streaming and broadcasting demonstrate how to utilize FFmpeg for encoding video and audio streams in real-time, suitable for platforms like YouTube Live or Twitch. These examples cover aspects like setting bitrates, choosing appropriate codecs, and configuring streaming protocols.
Subtitle manipulation: The guide includes examples demonstrating how to add, remove, or manipulate subtitles in video files. This encompasses burning subtitles directly into the video stream, as well as working with external subtitle files in various formats.
For each example, the site provides not only the FFmpeg command itself but also a clear description of the task being performed, the purpose of the various command-line options used, and the expected output. This approach allows users to learn by directly applying the examples and modifying them to suit their specific needs. The site focuses on practicality and immediate application, making it a valuable resource for both beginners seeking a quick introduction to FFmpeg and experienced users looking for specific command examples for common tasks. It emphasizes learning through practical application and avoids overwhelming the reader with unnecessary theoretical details.
The blog post "Bad Apple but it's 6,500 regexes that I search for in Vim" details a complex and computationally intensive method of recreating the "Bad Apple" animation within the Vim text editor. The author's approach eschews traditional methods of animation or video playback, instead leveraging Vim's regex search functionality as the core mechanism for displaying each frame.
The process begins with a pre-processed version of the Bad Apple video. Each frame of the original animation is converted into a simplified, monochrome representation. These frames are then translated into a series of approximately 6,500 unique regular expressions. Each regex is designed to match a specific pattern of characters within a specially prepared text buffer in Vim. This buffer acts as the canvas, filled with a grid of characters that represent the pixels of the video frame.
The core of the animation engine is a Vim script. This script iterates through the sequence of pre-generated regexes. For each frame, the script executes a search using the corresponding regex. This search highlights the matching characters within the text buffer, effectively "drawing" the frame on the screen by highlighting the appropriate "pixels." The rapid execution of these searches, combined with the carefully crafted regexes, creates the illusion of animation.
To further enhance the visual effect, the author utilizes Vim's highlighting capabilities. Matched characters, representing the black portions of the frame, are highlighted with a dark background, creating contrast against the unhighlighted characters, which represent the white portions. This allows for a clearer visual representation of each frame.
Due to the sheer number of regex searches and the computational overhead involved, the animation playback is significantly slower than real-time. The author acknowledges this performance limitation, attributing it to the inherent complexities of regex processing within Vim. Despite this limitation, the project demonstrates a unique and inventive application of Vim's functionality, showcasing the versatility and, perhaps, the limitations of the text editor. The author also provides insights into their process of converting video frames to regex patterns and optimizing the Vim script for performance.
The Hacker News post titled "Bad Apple but it's 6,500 regexes that I search for in Vim" (linking to an article describing the process of recreating the Bad Apple!! video using Vim regex searches) sparked a lively discussion with several interesting comments.
Many commenters expressed amazement and amusement at the sheer absurdity and technical ingenuity of the project. One commenter jokingly questioned the sanity of the creator, reflecting the general sentiment of bewildered admiration. Several praised the creativity and dedication required to conceive and execute such a complex and unusual undertaking. The "why?" question was raised multiple times, albeit rhetorically, highlighting the seemingly pointless yet fascinating nature of the project.
Some commenters delved into the technical aspects, discussing the efficiency (or lack thereof) of using regex for this purpose. They pointed out the computational intensity of repeatedly applying thousands of regular expressions and speculated on potential performance optimizations. One commenter suggested alternative approaches that might be less resource-intensive, such as using image manipulation libraries. Another discussed the potential for pre-calculating the matches to improve performance.
A few commenters noted the historical precedent of using unconventional tools for creative endeavors, drawing parallels to other esoteric programming projects and "demoscene" culture. This placed the project within a broader context of exploring the boundaries of technology and artistic expression.
Some users questioned the practical value of the project, while others argued that the value lies in the exploration and learning process itself, regardless of practical applications. The project was described as a fun experiment and a demonstration of technical skill and creativity.
Several commenters expressed interest in the technical details of the implementation, asking about the specific regex patterns used and the mechanics of syncing the searches with the audio. This demonstrated a genuine curiosity about the inner workings of the project.
Overall, the comments reflect a mixture of amusement, admiration, and technical curiosity. They highlight the project's unusual nature, its technical challenges, and its place within the broader context of creative coding and demoscene culture.
Summary of Comments ( 209 )
https://news.ycombinator.com/item?id=42695547
Hacker News users generally praised "FFmpeg by Example" for its clear explanations and practical approach. Several commenters pointed out its usefulness for beginners, highlighting the simple, reproducible examples and the focus on solving specific problems rather than exhaustive documentation. Some suggested additional topics, like hardware acceleration and subtitles, while others shared their own FFmpeg struggles and appreciated the resource. One commenter specifically praised the explanation of filters, a notoriously complex aspect of FFmpeg. The overall sentiment was positive, with many finding the resource valuable and readily applicable to their own projects.
The Hacker News post for "FFmpeg by Example" has several comments discussing the utility of the resource, alternative learning approaches, and specific FFmpeg commands.
Many commenters praise the resource. One user calls it a "great starting point" and highlights the practicality of learning through examples. Another appreciates the clear explanations and the well-chosen examples which address common use cases. A third commenter emphasizes the value of the site for its concise and focused approach, contrasting it favorably with the official documentation, which they find overwhelming. The sentiment is echoed by another who found the official documentation difficult to navigate and appreciates the example-driven learning offered by the site.
Several comments discuss alternative or supplementary resources. One commenter recommends the book "FFmpeg Basics" by Frantisek Korbel, suggesting it pairs well with the website. Another points to a different online resource, "Modern FFmpeg Wiki," which they find to be more comprehensive. A third user mentions their preference for learning through man pages and flags, reflecting a more command-line centric approach.
Some commenters delve into specific FFmpeg functionalities and commands. One user discusses the complexities of hardware acceleration and how it interacts with different FFmpeg builds. They suggest static builds are generally more reliable in this regard. Another commenter provides a specific command for extracting frames from a video, demonstrating the practical application of FFmpeg. A different user shares a command for losslessly cutting videos, a common task for video editing. This sparks a small discussion about the nuances of lossless cutting and alternative approaches using keyframes. Someone also recommends using
-avoid_negative_ts make_zerofor generating output suitable for concatenation, highlighting a lesser-known but useful flag combination.Finally, there's a comment advising caution against blindly copying and pasting commands from the internet, emphasizing the importance of understanding the implications of each command and flag used.