Prepare video for upload

Why preparation matters when the host transcodes anyway

It is fair to ask why any of this matters. The host will re-encode the file into its own ladder of renditions whatever you send. There are three reasons. First, size: a well-chosen export is a fraction of a master's size, and upload time is proportional to size. Second, acceptance: a file in an unusual container, with an unusual codec, at a variable frame rate or with a broken index can fail probing or transcode badly. Third, quality: transcoding cannot add detail, so a source that is already soft or blocky produces renditions that are softer and blockier still. Video transcoding explained shows what the host does with the file, which makes the reasoning behind each setting below clearer.

Recommended export settings

Sensible defaults for a file that will be transcoded by the host. Bitrates are rules of thumb and YouTube's published recommendations are a useful cross-check.

Container and codecs

MP4 with H.264 video and AAC audio is the safe combination, and for good reason. It is what browsers, phones and every transcoding pipeline handle natively. VideoBB accepts many other containers, and they will be transcoded. But each step away from the common case adds a chance of a surprise. MKV is fine as a container but can carry codecs the probe will not like. AVI is old and often wraps codecs that have not been current for years. WMV and FLV are accepted for older material, not as a recommendation. MP4 vs MKV vs AVI compares them. H.264 vs H.265 vs AV1 explains why H.264 is still the right upload codec, even though newer ones compress better. The host's output is what viewers receive, so the upload only has to be decodable and clean. The video formats hub covers every container and codec named here.

Resolution and frame rate

Export at the resolution the footage was shot or composed at. Upscaling a 1080p edit to 4K adds nothing but size. The host makes 1440p and 2160p renditions, which Premium members can watch, only when the source has those pixels. An upscaled source just gives a soft 4K rendition. Downscaling is only worth it to fit under a size limit, and even then reducing the bitrate is usually the better lever. Frame rate should be constant and should match the source. Phones and screen recorders often produce variable frame rate files. Many editors handle them, but they cause audio to drift out of sync across a long transcode. Most editors have a setting to conform to a constant rate on export. In FFmpeg the -vsync cfr or -fps_mode cfr option does it. Frame rate: 24, 30 and 60 fps covers the choice itself.

Preparing an existing file with FFmpeg

For a file you did not export yourself, or one that needs fixing. Each command is documented in the FFmpeg documentation.

1. Inspect it

   ffprobe -hide_banner input.mkv prints the container, streams, codecs, resolution, frame rate and duration. Read this before deciding what to do; often nothing needs re-encoding.

2. Re-mux if the codecs are already right

   If the video is H.264 and the audio AAC, change only the container: ffmpeg -i input.mkv -c copy -movflags +faststart output.mp4. This takes seconds and loses nothing.

3. Re-encode if they are not

   ffmpeg -i input.avi -c:v libx264 -preset slow -crf 19 -fps_mode cfr -c:a aac -b:a 192k -movflags +faststart output.mp4 produces a clean, constant-frame-rate H.264 file at a quality-based size.

4. Reduce size if over the limit

   Raise the CRF by one or two points (a higher CRF means a smaller file) and re-run. Only reduce resolution as a last resort.

5. Verify

   Run ffprobe again on the output and play it to the end. Confirm the duration matches the input and that audio stays in sync at the end.

Before you press upload

A final checklist; each item corresponds to a common rejection or complaint.

• The file is under 4 GB, checked in the file manager rather than the editor's estimate.
• The container is one of the accepted list, and the extension matches what is inside.
• The video plays locally from start to end with audio in sync.
• The resolution is the source's native resolution, not upscaled.
• The frame rate is constant.
• Dead air at the start and end is cut. The free trim video tool does this, and its fast mode copies the streams without re-encoding.
• Music you do not have the rights to is gone. If you need a silent copy, the mute video tool removes the whole audio track and leaves the picture untouched.
• Fast start is enabled, or the file has been re-muxed with faststart.
• If you upload often, your visibility, category and tags are set once as defaults. The help page on upload defaults shows where.
• You have kept the master export somewhere safe; the host stores what you upload, but the master is yours.

What to do with the master

The prepared upload is not your archive. Keep the high-quality master, whether that is a ProRes export or the editor project with its media, in your own storage. If a host changes its rendition ladder, if you move hosts, or if you need a higher-quality version for another purpose, the master is what you go back to. Video hosting for business makes the same point for teams, and the upload page is where the prepared file goes.