Tag: #troubleshooting

Audio and video drifted out of sync only after converting with FFmpeg? Learn why stream copy carries over bad timestamps, why a VFR source breaks sync, and fix it by re-encoding, rebuilding timestamps with +genpts, normalizing with aresample, or forcing constant frame rate.

Audio fine at the start but progressively out of sync by the end? That is drift, not a constant offset. Learn why a clock mismatch or VFR source causes it, why -itsoffset can't fix drift, and correct it with aresample async, then standardize with a fixed sample rate or CFR.

Convert a variable frame rate (VFR) video to constant frame rate (CFR) with FFmpeg. Use ffprobe to suspect VFR by comparing r_frame_rate and avg_frame_rate, then force CFR with -fps_mode cfr — the FFmpeg 8.x replacement for the deprecated -vsync cfr. Fixes the root cause of many sync issues.

Fix the FFmpeg error "Could not find codec parameters". Learn the three common causes — a truncated or corrupt stream, too little data probed, and an exotic codec — and apply runnable fixes: raise analyzeduration/probesize, inspect with ffprobe, or re-encode.

Fix the libx264 error "height not divisible by 2" (and the width version) caused by odd dimensions after scaling or cropping. Learn why yuv420p needs even width and height, and three runnable fixes: scale with trunc, scale=-2 to keep aspect ratio, and pad to the next even size.

Diagnose and fix the FFmpeg "Invalid data found when processing input" error. Common causes — truncated downloads, non-media data saved with a media extension, partial files — plus ffprobe checks, re-muxing with error tolerance, genpts repair, and re-encoding as a last resort.

Fix the FFmpeg error "Too many packets buffered for output stream". Learn why the muxing queue overflows when one stream's packets pile up, how to raise -max_muxing_queue_size, and why re-encoding instead of copying often resolves the underlying interleaving problem.

Fix the FFmpeg error "Unknown encoder 'libx264'". Learn why a build ships without libx264, how to confirm with ffmpeg -encoders and -codecs, how to install a full build per OS, and which alternative encoders to use when x264 is unavailable.

Diagnose and fix a missing audio track or no audio output after FFmpeg conversion: check with ffprobe, forgotten -map entries, a stray -an, container-incompatible codecs (MP4 + Opus), and only the first of several audio tracks surviving — with a fix command per cause.

Fix the FFmpeg 'permission denied' error by separating input-read from output-write failures, with solutions for Linux, macOS, Windows, and Docker: checking permissions with ls -l / ls -ld, chmod, writing to a writable directory, the Docker --user flag, and Windows file locks.

Fix the FFmpeg 'non monotonically increasing dts to muxer' error and invalid PTS/DTS problems: timestamp regeneration with genpts, negative-TS correction, VFR to CFR conversion, and setpts/asetpts resets — plus when re-encoding is required.

Understand and fix the 'moov atom not found' error in FFmpeg. A clear guide to MP4 file structure, faststart optimization, qt-faststart, and recovering truncated recordings.

All the reasons your FFmpeg-converted video or audio plays silent — missing audio streams, -an, incompatible codecs, sample-rate and channel-count issues — with diagnostics and fixes for each.

Fix FFmpeg errors like 'Unknown encoder', 'Encoder not found', and 'codec not currently supported'. Covers build flags, alternative codecs, and licensing issues.

Fix H.265/HEVC encoding failures in FFmpeg. Covers alternatives when libx265 is unavailable, profile and level settings, the hvc1 tag for Apple Silicon, and explicit Main profile specification.

Fix FFmpeg's 'No such file or directory' error. Covers the four common causes — path spaces, relative paths, extension mismatches, and glob expansion — with quick commands and verification steps.

Fix common FFmpeg errors fast: Unknown encoder, moov atom not found, height not divisible by 2, Invalid data found when processing input, and more. Each error entry shows the exact message, root cause, and the fix command — searchable quick reference.