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 Formatif: media processing suiteSeptember 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.