From d0cf22c1768167e38c1de60d8209f4c49d788420 Mon Sep 17 00:00:00 2001 From: medusa Date: Sun, 17 Mar 2024 06:47:31 +0000 Subject: [PATCH] Update docs/tech_docs/linux/video_capture.md --- docs/tech_docs/linux/video_capture.md | 44 +++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/docs/tech_docs/linux/video_capture.md b/docs/tech_docs/linux/video_capture.md index 0bd22ce..4dfd838 100644 --- a/docs/tech_docs/linux/video_capture.md +++ b/docs/tech_docs/linux/video_capture.md @@ -1,3 +1,47 @@ +Based on our discussion and the successful execution of the command to capture and scale a specific window on your Debian system, let's create a more general guide. This guide will be adaptable for various scenarios, allowing you to tweak settings as necessary for your specific needs. + +### General Guide for Capturing and Scaling Windows with FFmpeg on Linux + +#### Prerequisites +- Ensure `ffmpeg` and `x11-utils` are installed on your system. + +#### Steps + +1. **Identify the Window**: + - Determine which window you want to capture by using the `xwininfo` tool. Click on the desired window to get its details, including its geometry (size and position). + +2. **Plan Your Capture**: + - Decide on the resolution at which you want to capture the window. If the window's size doesn't match your desired output resolution, you'll need to scale the capture in `ffmpeg`. + - Consider the framerate you wish to capture at. Higher framerates like 60fps provide smoother video but are more resource-intensive. + +3. **Set Up Your Command**: + - Use the following `ffmpeg` command template to capture and scale your video: + ```bash + ffmpeg -f x11grab -framerate [FrameRate] -video_size [OriginalWidth]x[OriginalHeight] -i :0.0+[X],[Y] -vf "scale=[TargetWidth]:[TargetHeight]" -vcodec libx264 -preset [EncodingSpeed] -crf [Quality] -pix_fmt yuv420p [OutputFileName].mkv + ``` + - Replace placeholders (`[FrameRate]`, `[OriginalWidth]`, `[OriginalHeight]`, `[X]`, `[Y]`, `[TargetWidth]`, `[TargetHeight]`, `[EncodingSpeed]`, `[Quality]`, and `[OutputFileName]`) with your specific values. + +4. **Adjust for Quality and Performance**: + - **FrameRate**: Choose a framerate (e.g., 30 or 60 fps). Higher framerates provide smoother motion but require more processing power. + - **OriginalWidth x OriginalHeight**: Use the dimensions obtained from `xwininfo` for the window you're capturing. + - **X,Y**: The position of the upper-left corner of the capture area on your screen, also from `xwininfo`. + - **TargetWidth x TargetHeight**: Your desired output resolution. Adjust as necessary for your project needs. + - **EncodingSpeed (Preset)**: `veryfast` is a good starting point for balancing speed and quality. You can adjust this (to `faster`, `fast`, `medium`, `slow`, etc.) based on your system's capabilities and the quality/file size you're aiming for. + - **Quality (CRF)**: A lower CRF value means higher quality but larger file size. A value around 18 to 23 is generally a good range for HD content. + - **OutputFileName**: The name of your output file, including the `.mkv` extension. + +#### Tips for Tweaking + +- If capturing the entire desired area directly isn't feasible due to resolution constraints or performance issues, consider recording at a lower resolution and then upscaling during post-processing, or vice versa. +- Experiment with different `-crf` and `-preset` values to find the best balance between quality, file size, and encoding speed for your specific scenario. +- Monitor system performance during capture, especially when working with high resolutions or framerates, to ensure the process doesn't negatively impact other applications. + +#### Conclusion + +This general guide provides a flexible approach to capturing specific windows or areas of your screen using `ffmpeg`, with the ability to easily adjust settings for resolution, framerate, quality, and performance to meet the needs of your particular project. Experimentation and adjustment of the provided template command will help you optimize your workflow for capturing high-quality video content on Linux. + +--- + Given the comprehensive discussion we've had, it's clear you're looking for a streamlined workflow to record, process, and potentially transcribe or otherwise manipulate video content within a Linux environment, specifically Debian 12. Considering your familiarity with Linux and the context provided, the ideal solution should encompass recording X11 sessions efficiently, post-processing these recordings, and possibly extracting audio for transcription. Here's a synthesized approach to meet your needs: ### 1. **Recording X11 Sessions**