How to Convert AV1 Video to MP4

Before you start

AV1 and MP4 are not direct opposites. AV1 is a video compression format, while MP4 is a container that can hold AV1, H.264, H.265, AAC audio, subtitles, and other streams. Converting AV1 to MP4 usually means changing the video stream to a more compatible codec such as H.264 or H.265 and placing it in an MP4 container. If your target device already supports AV1 in MP4, you may only need to remux the file.

Check where the video came from and how it will be used. A file recorded from a camera, screen capture, or web-based capture source may already use variable frame rate or unusual color data. For broad compatibility, choose H.264 with a high enough bitrate rather than re-encoding to a lower quality setting only to reduce file size.

The process can run locally with desktop tools or command-line encoders. Online converters are also available, but they require uploading the recording. Avoid sending private camera footage, meeting recordings, or other sensitive material to an online service unless you have verified how the service handles uploads and retention.

Step-by-step instructions

Use a desktop converter

Open the converter and add the AV1 source file. Select MP4 as the output container. If the tool offers a profile or compatibility preset, choose one that matches the playback device, such as a general H.264 profile for older editors or a H.265 profile when smaller size is more important than maximum compatibility.

Keep the resolution and frame rate the same as the source unless you have a specific reason to change them. Preserve the original bitrate or choose a quality-based setting when available. If you must enter a bitrate manually, use a value close to the source file's reported video bitrate to avoid unnecessary quality loss.

Confirm audio handling before starting. If the source contains Opus audio and the destination player does not support it, convert the audio to AAC. If the tool shows a copy or passthrough option for audio, verify that the destination device accepts the original audio format. When in doubt, convert audio to AAC while leaving video quality settings conservative.

Choose a separate output folder or rename the output file so the original AV1 recording is not overwritten. Start the conversion and wait for the tool to finish. Some editors report only the video codec change, while others may also alter color metadata. Keep the original file until you have verified playback.

Convert with FFmpeg

FFmpeg can convert an AV1 file to a widely supported MP4 with H.264 video and AAC audio. Use a command similar to the following, replacing input and output names with your actual file names.

ffmpeg -i input.mkv -c:v libx264 -pix_fmt yuv420p -c:a aac -b:a 192k output.mp4

The -pix_fmt yuv420p option helps compatibility with older players and editors that do not support other pixel formats. The audio bitrate of 192k is only an example; a stereo voice recording can often use a lower value. Keep -c:v libx264 for broad compatibility, or use a hardware encoder if your build supports it and the target playback environment is known.

To prefer quality over a fixed bitrate, use a CRF value instead. A lower number preserves more detail and creates a larger file, while a higher number reduces quality and size. For example, CRF 18 is commonly considered visually close to the source for many recordings, but the ideal value depends on the original material and viewing conditions.

For a camera clip that already contains AAC audio and does not need a video codec change for your player, you can copy the audio stream while re-encoding only the video. This reduces processing time but should not be used when the original audio codec is unsupported by the destination.

Check the output

Play the resulting MP4 in the app or device where it will actually be used. Check the beginning, middle, and end of the recording for sync issues, missing audio, or visible blocking. A file that plays on a computer may still fail on an older camera, editor, or media player with limited codec support.

Inspect the output codec information if your converter or media tool can display it. Confirm that the video stream is H.264 or H.265, the audio stream is AAC or another intended format, and the frame rate matches the source where that is required. Resolution and duration should also match unless you intentionally changed them.

Compare file size only as a rough signal. Re-encoding can reduce size significantly, but a much smaller file may indicate a lower bitrate or reduced detail. If the destination supports both H.265 and H.264, test a short sample from the camera before converting a large batch.

Common problems and next steps

If the MP4 has no sound, the original audio codec was likely not compatible with the chosen output settings. Re-run the conversion with audio converted to AAC instead of copied. If the video plays but appears jerky, check whether the source uses variable frame rate and whether the tool or player is interpreting it incorrectly. Some editing workflows require converting variable frame rate footage to a constant frame rate.

If the file is rejected by a camera or app, H.264 with AAC audio in an MP4 container is usually the safest target. Avoid unusual pixel formats, high profile levels, or unsupported audio layouts. Convert a ten-second sample first and test it on the actual device before processing the full recording.

Convert MP4 to AV1 when your goal is smaller file size or an AV1-based workflow. This is a separate encoding direction and should follow the same approach: define the target player first, then select the codec, container, resolution, frame rate, and bitrate settings that the target can accept. Converting back and forth between lossy formats does not restore quality, so keep the earliest available master file.