# MP4 to MKV Converter Convert MP4 video files to MKV format > Canonical page: https://elysiatools.com/en/tools/mp4-to-mkv - **Category:** Media - **Keywords:** mp4, mkv, convert, video, format, ffmpeg, matroska, container, opensource ## Overview Convert MP4 videos to MKV (Matroska) container format. MKV is an open-source format that supports virtually all video and audio codecs, multiple subtitle tracks, and chapter markers. ## Inputs - **MP4 Video File** (file): Select MP4 video to convert - **Video Codec** (select) - **Audio Codec** (select) - **CRF Quality (18-28, lower is better)** (number): Only applies when re-encoding. 18-28 is recommended ## When to use - When you need to wrap an MP4 video into an MKV container to support advanced features like multiple audio tracks or soft subtitles. - When you want to change the video or audio codec of an MP4 file to open-source formats like VP9, Vorbis, or Opus. - When you need to compress an MP4 video by re-encoding it with H.265/HEVC and adjusting the CRF quality value. ## How it works - Upload your MP4 or M4V video file up to the 100MB limit. - Choose your preferred video and audio codecs, or select 'Copy' to change the container format without re-encoding. - Set the CRF quality value between 18 and 28 if you are re-encoding the video. - Click convert to process the file and download your new MKV video. ## Use cases - Remuxing MP4 files to MKV containers without re-encoding to preserve original stream quality. - Transcoding MP4 videos to H.265/HEVC with custom CRF quality settings to reduce file size. - Converting audio tracks within an MP4 file to open-source formats like Opus or Vorbis. ## Frequently asked questions ### Can I convert MP4 to MKV without losing quality? Yes, by setting both the video and audio codecs to 'Copy (No Re-encoding)', the streams are transferred directly into the MKV container without quality loss. ### What is the maximum file size supported? You can upload and convert MP4 or M4V files up to 100 MB in size. ### When should I adjust the CRF quality setting? The CRF quality setting only applies when you choose to re-encode the video (e.g., using H.264 or H.265), where a lower number yields higher quality. ### Does this tool support M4V files? Yes, the tool accepts both standard MP4 and M4V video formats as inputs. ### What audio codecs can I convert to? You can choose to copy the original audio or convert it to AAC, Vorbis, Opus, MP3, or lossless FLAC. ## Related tools - [MKV to MP4 Converter](https://elysiatools.com/en/tools/mkv-to-mp4): Convert MKV video files to MP4 format - [Batch Video Converter](https://elysiatools.com/en/tools/video-batch-converter): Convert multiple video files between different formats like MP4, WebM, MKV, AVI, MOV with quality settings and batch processing - [Video to GIF Optimized](https://elysiatools.com/en/tools/video-to-gif-optimized): Convert videos to optimized GIF format with advanced compression settings - [Stream Smart Remux](https://elysiatools.com/en/tools/stream-smart-remux): Rewrap media containers with stream copy. - [AVI to MP4 Converter](https://elysiatools.com/en/tools/avi-to-mp4): Convert AVI video files to MP4 format - [FLV to MP4 Converter](https://elysiatools.com/en/tools/flv-to-mp4): Convert FLV video files to MP4 format - [MOV to MP4 Converter](https://elysiatools.com/en/tools/mov-to-mp4): Convert MOV video files to MP4 format - [MP4 to AVI Converter](https://elysiatools.com/en/tools/mp4-to-avi): Convert MP4 video files to AVI format ## Samples - [Video AV1 Samples](https://elysiatools.com/en/samples/video-av1-samples): Sample video files encoded in AV1 format - [Video H.264 Samples](https://elysiatools.com/en/samples/video-h264-samples): Sample video files encoded in H.264 (AVC) format - [Video H.265 Samples](https://elysiatools.com/en/samples/video-h265-samples): Sample video files encoded in H.265 (HEVC) format - [Video Samples](https://elysiatools.com/en/samples/video-samples): Sample video files in different formats and orientations ## Related content - [Audio Encoding and Format Conversion Tools](https://elysiatools.com/en/hubs/audio-convert): Compare audio format conversion, bitrate changes, sample-rate conversion, codec swaps, and export tools in one hub for delivery and archive workflows. - [Video-to-Audio and Animation Conversion Tools](https://elysiatools.com/en/hubs/video-convert): Compare tools that turn video into audio, extract video streams, and convert between short-form video and animated image formats in one hub. - [Audio Editing and Cleanup Tools](https://elysiatools.com/en/hubs/audio-utility): Compare audio trimming, silence removal, fades, mixing, and denoise tools in one hub for podcast, voiceover, and music cleanup workflows. - [Video Preview, Extraction, and Subtitle Tools](https://elysiatools.com/en/hubs/video-utility): Compare video preview generation, stream extraction, audio extraction, subtitle translation, and quick flip tools in one hub for lightweight video prep workflows.