WebM to MP4 Converter — FFmpeg Video Conversion
Pricing
from $39.00 / 1,000 video converteds
Convert WebM videos to MP4 with FFmpeg settings, codec controls, file-size checks, metadata, and downloadable converted files.
List of WebM videos to convert. Each item must have either a 'url' (HTTP/HTTPS link to a WebM file) or a 'kvStoreKey' (key in the actor's Key-Value Store). Min: 1, Max: 3.
[ { "url": "https://www.w3schools.com/html/mov_bbb.webm" }]Video codec to use for encoding. H.264 offers the best compatibility (all browsers, devices, platforms). H.265 produces smaller files but has limited browser support — best for archiving or mobile apps.
Encoding speed vs quality/size tradeoff. 'ultrafast' is fastest but produces larger files. 'veryslow' produces the smallest files but takes much longer. 'balanced' (default) is the best choice for most use cases.
Constant Rate Factor controls quality. Lower = better quality, larger file. 0 = lossless (very large), 18 = high quality, 23 = default, 28 = lower quality, 51 = worst quality.
Maximum video bitrate (e.g., '2M', '5M', '10M'). Leave empty for CRF-only quality control (recommended). Use this to cap file size for streaming scenarios.
Force output to a specific resolution (e.g., '1920x1080', '1280x720', '854x480'). Leave empty to keep the original resolution. Aspect ratio is preserved with padding if needed.
Scale video down if wider than this value (pixels). Aspect ratio is preserved. Ignored if 'resolution' is set.
Scale video down if taller than this value (pixels). Aspect ratio is preserved. Ignored if 'resolution' is set.
Output frames per second. Leave empty to keep the original frame rate. Common values: 24, 30, 60.
Audio codec: 'aac' (default, universal compatibility), 'mp3' (widely supported), 'none' (strip audio from output).
Audio bitrate. Common values: '64k' (low), '128k' (default, good quality), '192k' (high), '320k' (maximum).
Audio sample rate in Hz. Leave empty to keep the original sample rate. Common values: 44100, 48000.
Audio volume adjustment. 1.0 = original volume (default). 0.5 = half volume. 2.0 = double volume. Range: 0.0 to 5.0.
Prefix added to output filenames in the Key-Value Store. For example, 'converted_' produces 'converted_myvideo.mp4'.
Move the MP4 moov atom to the beginning of the file. Enables streaming playback — the browser can start playing before the entire file is downloaded. Highly recommended for web use.
Maximum number of videos to convert simultaneously. Video encoding is CPU-intensive — keep this at 1-2 unless you have excess memory and CPU available. Range: 1-3.
Timeout for downloading each source video in milliseconds. Default: 60000 (1 minute). Range: 10000-300000.
Timeout for FFmpeg conversion per video in milliseconds. Default: 300000 (5 minutes). Range: 30000-600000.
Maximum source video size per file. Default 50 MB, hard cap 100 MB.