Convert MKV to MP4 via API

MKV (Matroska) files often contain H.264/H.265 video that can be remuxed to MP4 without re-encoding. When codecs differ, RenderIO re-encodes seamlessly in the cloud.

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Loading FFmpeg engine... (~31 MB)

Use the API

curl -X POST https://renderio.dev/v1/commands \
  -H "X-API-KEY: ffsk_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
  "ffmpeg_command": "-i {in_video} -c copy -movflags +faststart {out_video}",
  "input_files": {
    "in_video": "https://example.com/input.mkv"
  },
  "output_files": {
    "out_video": "output.mp4"
  }
}'

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Common Variations

Re-encode video and audio

-i input.mkv -c:v libx264 -crf 23 -c:a aac -movflags +faststart output.mp4

Copy video, re-encode audio only

-i input.mkv -c:v copy -c:a aac -movflags +faststart output.mp4

Select specific streams

-i input.mkv -map 0:v:0 -map 0:a:0 -c copy -movflags +faststart output.mp4

With subtitle burn-in

-i input.mkv -vf subtitles=input.mkv -c:v libx264 -crf 23 -c:a aac output.mp4

Related Operations

Convert MP4 to WebM via API | RenderIO Convert AVI to MP4 via API | RenderIO Convert MOV to MP4 via API | RenderIO Add Subtitles to Video via API | RenderIO

Need to process at scale?

Automate this with the RenderIO FFmpeg API. Process thousands of files programmatically or through no-code video automation.

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