mp4 is a container for video and audio formats. If supported by your player, choose AV1 as the encoder, the complete list is:

• H264, also known as MPEG-4 Part 10, or Advanced Video Coding (MPEG-4 AVC), is one of the most commonly used video formats, universal support,
• H265, also known as High Efficiency Coding (HEVC), MPEG-H Part 2. Typically is half of the filesize for same quality as h264,
• H266 (VVC) is the latest mpeg encoder, although playback support is limited,
• AV1 is the sucessor to vp9 and offers compression on a par with h266
• VP9 is a royalty free codec, AV1 should be chosen in its place.
• [copy no encode] can be used if the video is already in a compatible format and it is copied 1:1 over, saving re-encoding.

In addition to these software encoders, there is the choice of using the GPU (should a compatible one be installed), with selections for Nvidia, Intel QSV and AMD. Hardware encoders typically will have less options, and have less quality than a software encoder, however they encode many times faster. Combine with the DSP effect 'GPU Accelerated Decoding.

Audio

A multitude of audio formats are available to be chosen, with the option also to copy 1:1 from source if the audio is already in a correct format.

If re-encoding audio, on the advanced page is an option to normalize the volume.


Compression Options

A quality slider chooses the encoding quality, or bit rate, the drop combo below the slider offers 4 types of encoding (depending on encoder chosen):

• Constant Bit Rate a fixed bit rate is used through out the encoding,
• Average Bit Rate like Constant Bit Rate except there is some encoding flexibility, on difficult parts a higher bit rate is used, overall though the bit rate averages out to the requested value,
• Constant Quality a desired quality achieved throughout the encoding process, by varying the bit rate, this is the recommended mode for most people.
• Lossless encodes the video without loss of quality, expect the end files to be large, test on players to ensure compatibility.

The advanced options page offers Tuning for specific video types.