Can I convert MKV to MP4 without losing quality?

Yes via remux when streams are MP4-compatible (H.264/H.265 + AAC/MP3/AC3): copy bit-for-bit in seconds. Only exotic streams (DTS, TrueHD, PGS, VP9) need partial or full re-encoding. Try '-c copy' first, every time.

How do I convert TS files to MP4?

Try remux first — broadcast and capture .ts files usually hold H.264 + AAC already. If audio drifts out of sync (common with broadcast captures), re-encode audio only while copying video. Concatenate split .ts segments before converting, not after.

Will converting lose my subtitles and audio tracks?

Only if you let it: default FFmpeg commands map one video + one audio stream and drop the rest. Preserve everything with '-map 0' (all streams) when the target container supports them — MKV keeps all, MP4 keeps most, and PGS subtitles need OCR-to-SRT for universal players.

How do I batch convert mixed video formats at once?

Sort by destination, not source: everything bound for universal playback becomes H.264 MP4; everything for archiving becomes H.265 MKV. Then one recipe per group with remux-where-possible logic and per-file status — mixed folders fail file-by-file, so the log matters more than the loop.

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Convert Any Video to Any Format (Batch Guide: MP4, MKV, MOV, AVI, WebM)

Q: How do I convert AVI to MP4?

Re-encode H.264 + AAC — legacy AVI codecs (DivX, Xvid, DV) don't remux into MP4. The upside is dramatic: files typically shrink 50–70% with better compatibility. Batch whole archives with one recipe; keep one AVI master per irreplaceable file just in case.

Q: How do I convert WebM to MP4?

Re-encode VP9 video to H.264 and Opus audio to AAC — WebM's streams don't transfer into MP4. Use CRF 20–23 for near-transparent quality. Reverse direction (MP4→WebM) uses VP9/AV1 for web publishing where Safari support is confirmed.

Whatever container you have, whatever you need — every common pair in one matrix, the remux-vs-reencode decision that saves hours, the track warnings that save files, and the batch workflow for mixed folders.

By Hadi Karaki, maker of FormatifSeptember 16, 202611 min read

Every pair, one verdict each

Conversion	Do it for	Verdict
MKV → MP4	Universal playback	Remux in seconds if H.264/AAC inside — zero loss. Re-encode only exotic streams.
MP4 → MKV	Archiving with tracks	Remux; MKV then holds extra audio/subs/chapters MP4 handles poorly.
AVI → MP4	Modernize legacy files	Usually re-encode (old DivX/Xvid codecs) — but file shrinks massively as a bonus.
MOV → MP4	Share Apple captures	Remux when H.264/AAC; re-encode ProRes masters (that's the point).
WebM → MP4	Universal sharing	VP9→H.264 needs re-encoding; Opus audio becomes AAC. Worth it for compatibility.
MP4 → WebM	Web publishing	VP9/AV1 re-encode for <video> tags; smaller streams, check Safari targets.
TS → MP4	Broadcast/OBS captures	Usually H.264 inside — remux works; fix timestamps if audio drifts.
FLV → MP4	Rescue old web video	Re-encode; quality is capped by the low-bitrate source forever.
MP4/MKV → MP3/WAV	Audio extraction	Not conversion — stream extraction. See our extraction guide linked below.

Two rules that prevent every conversion disaster

Rule 1: remux before you re-encode

If the streams are already MP4-compatible, copying them into the new container takes seconds with zero loss. Re-encoding first “to be safe” wastes hours and degrades quality for nothing. Always try -c copy first.

Rule 2: map all streams or lose them silently

Bare FFmpeg commands keep one video + one audio track and silently drop the rest — second languages, commentary, subtitles, gone. Add -map 0 when the target supports the tracks, and OCR image subtitles to SRT for universal players.

Watch mixed containers convert in one run

MKV, MOV, AVI, WebM and more batch-converted with remux-where-possible logic — the matrix above, running.

Quick Solution

Mixed folder in, sorted formats out.

Nine pairs above, one folder containing all of them — and every file needs the remux-vs-reencode judgment call plus stream mapping. Formatif Pro ($8.95 one-time) batch-converts 9 video containers offline — MP4, MOV, MKV, WebM, AVI, FLV, TS and more — remuxing where possible, re-encoding where needed, with per-file status on every failure.

Download free trial

The free path (and where it stops)

Universal remux attempt (always try first)

ffmpeg -i input.mkv -c copy output.mp4

Re-encode fallback + keep all streams

ffmpeg -i input.avi -map 0 -c:v libx264 -crf 20 -c:a aac output.mp4

Where it stops: per-file remux judgment, mixed folders needing two different recipes, and failure logs you can actually read. Container deep-dives live in our MKV vs MP4 and MOV vs MP4 guides.

Video conversion questions, answered

How do I convert AVI to MP4?

Re-encode H.264 + AAC — legacy codecs don't remux. Bonus: 50–70% smaller files. Keep one AVI master per irreplaceable file.

How do I convert WebM to MP4?

Re-encode VP9→H.264, Opus→AAC at CRF 20–23. Reverse (MP4→WebM) for web publishing where Safari is confirmed.

MKV to MP4 without losing quality?

Remux with -c copy when streams are compatible — bit-for-bit, seconds. Re-encode only exotic streams.

How do I convert TS to MP4?

Remux first (usually H.264+AAC inside). Re-encode audio only if sync drifts; concatenate split segments first.

Keep subtitles and audio tracks?

Add -map 0 or they drop silently. MKV keeps all; MP4 keeps most; PGS needs OCR-to-SRT.

Batch mixed video formats?

Sort by destination (H.264 MP4 universal / H.265 MKV archive), one recipe per group, per-file failure logs.

Keep learning

Convert MKV to MP4

5 tested methods with exact commands — remux in seconds.

MKV vs MP4 explained

Containers, Plex, subtitles — the full comparison.

Any image to any image

The image-side twin of this matrix.

Every container, every folder, offline.

Formatif Pro ($8.95 one-time) and Formatif AI ($12.95 one-time) handle video, image, and audio conversion offline — with batch workflows, no file size limits, and a 3-day free trial.

Download free trial Read: MKV to MP4 methods

FFmpeg is free and exact per file — batch tools earn their place on mixed folders with per-file judgment calls.

Written by

Hadi KarakiLinkedIn

Founder of Formatif, a local-first offline media processing suite for Windows and Linux. Hadi writes about video, image, and audio formats, compression, and privacy-first desktop workflows.