Work in progress
This documentation is still a work in progress. Please bear with us as we continue to improve it.
We currently do not perform any transcoding of video files uploaded to our platform. For high quality and wide browser compatibility, we recommend encoding videos using ffmpeg with the following settings:
ffmpeg -i INPUT \
-preset veryslow \
-keyint_min 2 -g 24 -sc_threshold 0 \
-c:v libx264 -pix_fmt yuv420p -crf 17 \
-c:a aac -b:a 256k -ac 2 -ar 48000 \
-movflags +frag_keyframe+empty_moov+default_base_moof \
OUTPUT.mp4A CRF value below 18 is generally considered visually lossless. Similarly for audio, compression at 256 kbps or above is considered unnoticeable [1, 2].
[1] Pras et al. (2009). Subjective Evaluation of MP3 Compression for Different Musical Genres.
[2] Hines et al. (2014). Perceived Audio Quality for Streaming Stereo Music.