FFmpeg Concat: Download Videos with yt-dlp and Merge Them

Concatenating Videos Downloaded with youtube-dl and FFmpeg

Have you ever wanted to merge multiple videos downloaded from YouTube using youtube-dl and FFmpeg? This article will guide you through the process, addressing common issues such as handling subtitles and dealing with errors. By the end, you'll have a solid understanding of how to concatenate videos using these powerful tools.

Downloading Videos with youtube-dl

To download videos from YouTube, you'll first need to install youtube-dl. You can find installation instructions for various platforms here.

Once you've installed youtube-dl, you can download videos using the following command:

Here's a breakdown of the command:

• -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best': This selects the best available video and audio formats. The [ext=mp4] filter ensures that only MP4 files are downloaded.
• --write-sub: This flag tells youtube-dl to download subtitles and save them as separate SRT files.
• --sub-format srt: This specifies the subtitle format. SRT is widely supported and compatible with most video players.
• URL: Replace this with the URL of the YouTube video you want to download.

Preparing Videos for Concatenation with FFmpeg

Before concatenating the videos, you need to create a text file that lists the files in the correct order. You can do this using a simple text editor:

Replace /path/to/video1.mp4 and /path/to/video2.mp4 with the actual paths to your downloaded videos.

Concatenating Videos with FFmpeg

Now you can concatenate the videos using FFmpeg:

Here's a breakdown of the command:

• -f concat: This tells FFmpeg to use the concat demuxer.
• -safe 0: This flag allows FFmpeg to read files from the current directory.
• -i files.txt: This specifies the input file.
• -c copy: This tells FFmpeg to copy the existing video and audio streams without re-encoding.
• merged.mp4: This is the output file.

Handling Subtitles

To merge the subtitles into the concatenated video, you'll need to re-encode the video:

Here, -c:s mov_text tells FFmpeg to use the MOV text format for subtitles, which is compatible with most video players.

Dealing with Errors

If you encounter errors during concatenation, try using the following command:

This command re-encodes the video and audio streams using the libx264 and aac codecs, respectively. The -crf 23 flag sets the Constant Rate Factor to 23, which is a reasonable compromise between file size and quality. The -b:a 192k flag sets the audio bitrate to 192 kbps.

In this article, we've covered how to download videos using youtube-dl, prepare them for concatenation, and merge them using FFmpeg. We've also addressed common issues such as handling subtitles and dealing with errors. With this knowledge, you can now concatenate videos downloaded from YouTube with ease.

References

• youtube-dl Installation
• FFmpeg Documentation