Why Reddit Videos Download Without Sound — And How to Fix It with FFmpeg

说明与用途

从 Reddit 下载的视频常常缺少音频，因为音频和视频是分开的。使用 FFmpeg 或 yt-dlp 合并流即可恢复声音。

问题

Downloaded Reddit videos often lack audio because Reddit delivers video and audio as separate streams.

结果

Combining separate Reddit video and audio streams with FFmpeg (or yt-dlp) restores sound to silent downloads.

工作流

• Identify separate video and audio URLs from Reddit’s media endpoints.
• Download the video-only MP4 and audio-only M4A files.
• Use ffmpeg to merge streams: ffmpeg -i video_only.mp4 -i audio_only.m4a -map 0:v:0 -map 1:a:0 -c copy -movflags +faststart output.mp4.
• If audio codec incompatible, re‑encode audio: ffmpeg -i video_only.mp4 -i audio_only.m4a -map 0:v:0 -map 1:a:0 -c:v copy -c:a aac -b:a 128k output.mp4.
• Verify merged file with ffprobe to ensure both video and audio streams are present.
• Optionally use yt-dlp with -f "bv+ba/b" and --merge-output-format mp4 to automate download and merge.

证据

Reddit often delivers video and audio as separate streams.

来源

ffmpeg -i video_only.mp4 -i audio_only.m4a -map 0:v:0 -map 1:a:0 -c copy -movflags +faststart output.mp4

来源

yt-dlp -f "bv+ba/b" --merge-output-format mp4 "https://www.reddit.com/..."

来源